xref: /openbmc/linux/mm/memcontrol.c (revision 2dd6532e)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* memcontrol.c - Memory Controller
3  *
4  * Copyright IBM Corporation, 2007
5  * Author Balbir Singh <balbir@linux.vnet.ibm.com>
6  *
7  * Copyright 2007 OpenVZ SWsoft Inc
8  * Author: Pavel Emelianov <xemul@openvz.org>
9  *
10  * Memory thresholds
11  * Copyright (C) 2009 Nokia Corporation
12  * Author: Kirill A. Shutemov
13  *
14  * Kernel Memory Controller
15  * Copyright (C) 2012 Parallels Inc. and Google Inc.
16  * Authors: Glauber Costa and Suleiman Souhlal
17  *
18  * Native page reclaim
19  * Charge lifetime sanitation
20  * Lockless page tracking & accounting
21  * Unified hierarchy configuration model
22  * Copyright (C) 2015 Red Hat, Inc., Johannes Weiner
23  *
24  * Per memcg lru locking
25  * Copyright (C) 2020 Alibaba, Inc, Alex Shi
26  */
27 
28 #include <linux/page_counter.h>
29 #include <linux/memcontrol.h>
30 #include <linux/cgroup.h>
31 #include <linux/pagewalk.h>
32 #include <linux/sched/mm.h>
33 #include <linux/shmem_fs.h>
34 #include <linux/hugetlb.h>
35 #include <linux/pagemap.h>
36 #include <linux/vm_event_item.h>
37 #include <linux/smp.h>
38 #include <linux/page-flags.h>
39 #include <linux/backing-dev.h>
40 #include <linux/bit_spinlock.h>
41 #include <linux/rcupdate.h>
42 #include <linux/limits.h>
43 #include <linux/export.h>
44 #include <linux/mutex.h>
45 #include <linux/rbtree.h>
46 #include <linux/slab.h>
47 #include <linux/swap.h>
48 #include <linux/swapops.h>
49 #include <linux/spinlock.h>
50 #include <linux/eventfd.h>
51 #include <linux/poll.h>
52 #include <linux/sort.h>
53 #include <linux/fs.h>
54 #include <linux/seq_file.h>
55 #include <linux/vmpressure.h>
56 #include <linux/memremap.h>
57 #include <linux/mm_inline.h>
58 #include <linux/swap_cgroup.h>
59 #include <linux/cpu.h>
60 #include <linux/oom.h>
61 #include <linux/lockdep.h>
62 #include <linux/file.h>
63 #include <linux/resume_user_mode.h>
64 #include <linux/psi.h>
65 #include <linux/seq_buf.h>
66 #include "internal.h"
67 #include <net/sock.h>
68 #include <net/ip.h>
69 #include "slab.h"
70 #include "swap.h"
71 
72 #include <linux/uaccess.h>
73 
74 #include <trace/events/vmscan.h>
75 
76 struct cgroup_subsys memory_cgrp_subsys __read_mostly;
77 EXPORT_SYMBOL(memory_cgrp_subsys);
78 
79 struct mem_cgroup *root_mem_cgroup __read_mostly;
80 
81 /* Active memory cgroup to use from an interrupt context */
82 DEFINE_PER_CPU(struct mem_cgroup *, int_active_memcg);
83 EXPORT_PER_CPU_SYMBOL_GPL(int_active_memcg);
84 
85 /* Socket memory accounting disabled? */
86 static bool cgroup_memory_nosocket __ro_after_init;
87 
88 /* Kernel memory accounting disabled? */
89 static bool cgroup_memory_nokmem __ro_after_init;
90 
91 /* Whether the swap controller is active */
92 #ifdef CONFIG_MEMCG_SWAP
93 static bool cgroup_memory_noswap __ro_after_init;
94 #else
95 #define cgroup_memory_noswap		1
96 #endif
97 
98 #ifdef CONFIG_CGROUP_WRITEBACK
99 static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq);
100 #endif
101 
102 /* Whether legacy memory+swap accounting is active */
103 static bool do_memsw_account(void)
104 {
105 	return !cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_noswap;
106 }
107 
108 #define THRESHOLDS_EVENTS_TARGET 128
109 #define SOFTLIMIT_EVENTS_TARGET 1024
110 
111 /*
112  * Cgroups above their limits are maintained in a RB-Tree, independent of
113  * their hierarchy representation
114  */
115 
116 struct mem_cgroup_tree_per_node {
117 	struct rb_root rb_root;
118 	struct rb_node *rb_rightmost;
119 	spinlock_t lock;
120 };
121 
122 struct mem_cgroup_tree {
123 	struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
124 };
125 
126 static struct mem_cgroup_tree soft_limit_tree __read_mostly;
127 
128 /* for OOM */
129 struct mem_cgroup_eventfd_list {
130 	struct list_head list;
131 	struct eventfd_ctx *eventfd;
132 };
133 
134 /*
135  * cgroup_event represents events which userspace want to receive.
136  */
137 struct mem_cgroup_event {
138 	/*
139 	 * memcg which the event belongs to.
140 	 */
141 	struct mem_cgroup *memcg;
142 	/*
143 	 * eventfd to signal userspace about the event.
144 	 */
145 	struct eventfd_ctx *eventfd;
146 	/*
147 	 * Each of these stored in a list by the cgroup.
148 	 */
149 	struct list_head list;
150 	/*
151 	 * register_event() callback will be used to add new userspace
152 	 * waiter for changes related to this event.  Use eventfd_signal()
153 	 * on eventfd to send notification to userspace.
154 	 */
155 	int (*register_event)(struct mem_cgroup *memcg,
156 			      struct eventfd_ctx *eventfd, const char *args);
157 	/*
158 	 * unregister_event() callback will be called when userspace closes
159 	 * the eventfd or on cgroup removing.  This callback must be set,
160 	 * if you want provide notification functionality.
161 	 */
162 	void (*unregister_event)(struct mem_cgroup *memcg,
163 				 struct eventfd_ctx *eventfd);
164 	/*
165 	 * All fields below needed to unregister event when
166 	 * userspace closes eventfd.
167 	 */
168 	poll_table pt;
169 	wait_queue_head_t *wqh;
170 	wait_queue_entry_t wait;
171 	struct work_struct remove;
172 };
173 
174 static void mem_cgroup_threshold(struct mem_cgroup *memcg);
175 static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
176 
177 /* Stuffs for move charges at task migration. */
178 /*
179  * Types of charges to be moved.
180  */
181 #define MOVE_ANON	0x1U
182 #define MOVE_FILE	0x2U
183 #define MOVE_MASK	(MOVE_ANON | MOVE_FILE)
184 
185 /* "mc" and its members are protected by cgroup_mutex */
186 static struct move_charge_struct {
187 	spinlock_t	  lock; /* for from, to */
188 	struct mm_struct  *mm;
189 	struct mem_cgroup *from;
190 	struct mem_cgroup *to;
191 	unsigned long flags;
192 	unsigned long precharge;
193 	unsigned long moved_charge;
194 	unsigned long moved_swap;
195 	struct task_struct *moving_task;	/* a task moving charges */
196 	wait_queue_head_t waitq;		/* a waitq for other context */
197 } mc = {
198 	.lock = __SPIN_LOCK_UNLOCKED(mc.lock),
199 	.waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
200 };
201 
202 /*
203  * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
204  * limit reclaim to prevent infinite loops, if they ever occur.
205  */
206 #define	MEM_CGROUP_MAX_RECLAIM_LOOPS		100
207 #define	MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS	2
208 
209 /* for encoding cft->private value on file */
210 enum res_type {
211 	_MEM,
212 	_MEMSWAP,
213 	_KMEM,
214 	_TCP,
215 };
216 
217 #define MEMFILE_PRIVATE(x, val)	((x) << 16 | (val))
218 #define MEMFILE_TYPE(val)	((val) >> 16 & 0xffff)
219 #define MEMFILE_ATTR(val)	((val) & 0xffff)
220 
221 /*
222  * Iteration constructs for visiting all cgroups (under a tree).  If
223  * loops are exited prematurely (break), mem_cgroup_iter_break() must
224  * be used for reference counting.
225  */
226 #define for_each_mem_cgroup_tree(iter, root)		\
227 	for (iter = mem_cgroup_iter(root, NULL, NULL);	\
228 	     iter != NULL;				\
229 	     iter = mem_cgroup_iter(root, iter, NULL))
230 
231 #define for_each_mem_cgroup(iter)			\
232 	for (iter = mem_cgroup_iter(NULL, NULL, NULL);	\
233 	     iter != NULL;				\
234 	     iter = mem_cgroup_iter(NULL, iter, NULL))
235 
236 static inline bool task_is_dying(void)
237 {
238 	return tsk_is_oom_victim(current) || fatal_signal_pending(current) ||
239 		(current->flags & PF_EXITING);
240 }
241 
242 /* Some nice accessors for the vmpressure. */
243 struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg)
244 {
245 	if (!memcg)
246 		memcg = root_mem_cgroup;
247 	return &memcg->vmpressure;
248 }
249 
250 struct mem_cgroup *vmpressure_to_memcg(struct vmpressure *vmpr)
251 {
252 	return container_of(vmpr, struct mem_cgroup, vmpressure);
253 }
254 
255 #ifdef CONFIG_MEMCG_KMEM
256 static DEFINE_SPINLOCK(objcg_lock);
257 
258 bool mem_cgroup_kmem_disabled(void)
259 {
260 	return cgroup_memory_nokmem;
261 }
262 
263 static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
264 				      unsigned int nr_pages);
265 
266 static void obj_cgroup_release(struct percpu_ref *ref)
267 {
268 	struct obj_cgroup *objcg = container_of(ref, struct obj_cgroup, refcnt);
269 	unsigned int nr_bytes;
270 	unsigned int nr_pages;
271 	unsigned long flags;
272 
273 	/*
274 	 * At this point all allocated objects are freed, and
275 	 * objcg->nr_charged_bytes can't have an arbitrary byte value.
276 	 * However, it can be PAGE_SIZE or (x * PAGE_SIZE).
277 	 *
278 	 * The following sequence can lead to it:
279 	 * 1) CPU0: objcg == stock->cached_objcg
280 	 * 2) CPU1: we do a small allocation (e.g. 92 bytes),
281 	 *          PAGE_SIZE bytes are charged
282 	 * 3) CPU1: a process from another memcg is allocating something,
283 	 *          the stock if flushed,
284 	 *          objcg->nr_charged_bytes = PAGE_SIZE - 92
285 	 * 5) CPU0: we do release this object,
286 	 *          92 bytes are added to stock->nr_bytes
287 	 * 6) CPU0: stock is flushed,
288 	 *          92 bytes are added to objcg->nr_charged_bytes
289 	 *
290 	 * In the result, nr_charged_bytes == PAGE_SIZE.
291 	 * This page will be uncharged in obj_cgroup_release().
292 	 */
293 	nr_bytes = atomic_read(&objcg->nr_charged_bytes);
294 	WARN_ON_ONCE(nr_bytes & (PAGE_SIZE - 1));
295 	nr_pages = nr_bytes >> PAGE_SHIFT;
296 
297 	if (nr_pages)
298 		obj_cgroup_uncharge_pages(objcg, nr_pages);
299 
300 	spin_lock_irqsave(&objcg_lock, flags);
301 	list_del(&objcg->list);
302 	spin_unlock_irqrestore(&objcg_lock, flags);
303 
304 	percpu_ref_exit(ref);
305 	kfree_rcu(objcg, rcu);
306 }
307 
308 static struct obj_cgroup *obj_cgroup_alloc(void)
309 {
310 	struct obj_cgroup *objcg;
311 	int ret;
312 
313 	objcg = kzalloc(sizeof(struct obj_cgroup), GFP_KERNEL);
314 	if (!objcg)
315 		return NULL;
316 
317 	ret = percpu_ref_init(&objcg->refcnt, obj_cgroup_release, 0,
318 			      GFP_KERNEL);
319 	if (ret) {
320 		kfree(objcg);
321 		return NULL;
322 	}
323 	INIT_LIST_HEAD(&objcg->list);
324 	return objcg;
325 }
326 
327 static void memcg_reparent_objcgs(struct mem_cgroup *memcg,
328 				  struct mem_cgroup *parent)
329 {
330 	struct obj_cgroup *objcg, *iter;
331 
332 	objcg = rcu_replace_pointer(memcg->objcg, NULL, true);
333 
334 	spin_lock_irq(&objcg_lock);
335 
336 	/* 1) Ready to reparent active objcg. */
337 	list_add(&objcg->list, &memcg->objcg_list);
338 	/* 2) Reparent active objcg and already reparented objcgs to parent. */
339 	list_for_each_entry(iter, &memcg->objcg_list, list)
340 		WRITE_ONCE(iter->memcg, parent);
341 	/* 3) Move already reparented objcgs to the parent's list */
342 	list_splice(&memcg->objcg_list, &parent->objcg_list);
343 
344 	spin_unlock_irq(&objcg_lock);
345 
346 	percpu_ref_kill(&objcg->refcnt);
347 }
348 
349 /*
350  * A lot of the calls to the cache allocation functions are expected to be
351  * inlined by the compiler. Since the calls to memcg_slab_pre_alloc_hook() are
352  * conditional to this static branch, we'll have to allow modules that does
353  * kmem_cache_alloc and the such to see this symbol as well
354  */
355 DEFINE_STATIC_KEY_FALSE(memcg_kmem_enabled_key);
356 EXPORT_SYMBOL(memcg_kmem_enabled_key);
357 #endif
358 
359 /**
360  * mem_cgroup_css_from_page - css of the memcg associated with a page
361  * @page: page of interest
362  *
363  * If memcg is bound to the default hierarchy, css of the memcg associated
364  * with @page is returned.  The returned css remains associated with @page
365  * until it is released.
366  *
367  * If memcg is bound to a traditional hierarchy, the css of root_mem_cgroup
368  * is returned.
369  */
370 struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page)
371 {
372 	struct mem_cgroup *memcg;
373 
374 	memcg = page_memcg(page);
375 
376 	if (!memcg || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
377 		memcg = root_mem_cgroup;
378 
379 	return &memcg->css;
380 }
381 
382 /**
383  * page_cgroup_ino - return inode number of the memcg a page is charged to
384  * @page: the page
385  *
386  * Look up the closest online ancestor of the memory cgroup @page is charged to
387  * and return its inode number or 0 if @page is not charged to any cgroup. It
388  * is safe to call this function without holding a reference to @page.
389  *
390  * Note, this function is inherently racy, because there is nothing to prevent
391  * the cgroup inode from getting torn down and potentially reallocated a moment
392  * after page_cgroup_ino() returns, so it only should be used by callers that
393  * do not care (such as procfs interfaces).
394  */
395 ino_t page_cgroup_ino(struct page *page)
396 {
397 	struct mem_cgroup *memcg;
398 	unsigned long ino = 0;
399 
400 	rcu_read_lock();
401 	memcg = page_memcg_check(page);
402 
403 	while (memcg && !(memcg->css.flags & CSS_ONLINE))
404 		memcg = parent_mem_cgroup(memcg);
405 	if (memcg)
406 		ino = cgroup_ino(memcg->css.cgroup);
407 	rcu_read_unlock();
408 	return ino;
409 }
410 
411 static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz,
412 					 struct mem_cgroup_tree_per_node *mctz,
413 					 unsigned long new_usage_in_excess)
414 {
415 	struct rb_node **p = &mctz->rb_root.rb_node;
416 	struct rb_node *parent = NULL;
417 	struct mem_cgroup_per_node *mz_node;
418 	bool rightmost = true;
419 
420 	if (mz->on_tree)
421 		return;
422 
423 	mz->usage_in_excess = new_usage_in_excess;
424 	if (!mz->usage_in_excess)
425 		return;
426 	while (*p) {
427 		parent = *p;
428 		mz_node = rb_entry(parent, struct mem_cgroup_per_node,
429 					tree_node);
430 		if (mz->usage_in_excess < mz_node->usage_in_excess) {
431 			p = &(*p)->rb_left;
432 			rightmost = false;
433 		} else {
434 			p = &(*p)->rb_right;
435 		}
436 	}
437 
438 	if (rightmost)
439 		mctz->rb_rightmost = &mz->tree_node;
440 
441 	rb_link_node(&mz->tree_node, parent, p);
442 	rb_insert_color(&mz->tree_node, &mctz->rb_root);
443 	mz->on_tree = true;
444 }
445 
446 static void __mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz,
447 					 struct mem_cgroup_tree_per_node *mctz)
448 {
449 	if (!mz->on_tree)
450 		return;
451 
452 	if (&mz->tree_node == mctz->rb_rightmost)
453 		mctz->rb_rightmost = rb_prev(&mz->tree_node);
454 
455 	rb_erase(&mz->tree_node, &mctz->rb_root);
456 	mz->on_tree = false;
457 }
458 
459 static void mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz,
460 				       struct mem_cgroup_tree_per_node *mctz)
461 {
462 	unsigned long flags;
463 
464 	spin_lock_irqsave(&mctz->lock, flags);
465 	__mem_cgroup_remove_exceeded(mz, mctz);
466 	spin_unlock_irqrestore(&mctz->lock, flags);
467 }
468 
469 static unsigned long soft_limit_excess(struct mem_cgroup *memcg)
470 {
471 	unsigned long nr_pages = page_counter_read(&memcg->memory);
472 	unsigned long soft_limit = READ_ONCE(memcg->soft_limit);
473 	unsigned long excess = 0;
474 
475 	if (nr_pages > soft_limit)
476 		excess = nr_pages - soft_limit;
477 
478 	return excess;
479 }
480 
481 static void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid)
482 {
483 	unsigned long excess;
484 	struct mem_cgroup_per_node *mz;
485 	struct mem_cgroup_tree_per_node *mctz;
486 
487 	mctz = soft_limit_tree.rb_tree_per_node[nid];
488 	if (!mctz)
489 		return;
490 	/*
491 	 * Necessary to update all ancestors when hierarchy is used.
492 	 * because their event counter is not touched.
493 	 */
494 	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
495 		mz = memcg->nodeinfo[nid];
496 		excess = soft_limit_excess(memcg);
497 		/*
498 		 * We have to update the tree if mz is on RB-tree or
499 		 * mem is over its softlimit.
500 		 */
501 		if (excess || mz->on_tree) {
502 			unsigned long flags;
503 
504 			spin_lock_irqsave(&mctz->lock, flags);
505 			/* if on-tree, remove it */
506 			if (mz->on_tree)
507 				__mem_cgroup_remove_exceeded(mz, mctz);
508 			/*
509 			 * Insert again. mz->usage_in_excess will be updated.
510 			 * If excess is 0, no tree ops.
511 			 */
512 			__mem_cgroup_insert_exceeded(mz, mctz, excess);
513 			spin_unlock_irqrestore(&mctz->lock, flags);
514 		}
515 	}
516 }
517 
518 static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
519 {
520 	struct mem_cgroup_tree_per_node *mctz;
521 	struct mem_cgroup_per_node *mz;
522 	int nid;
523 
524 	for_each_node(nid) {
525 		mz = memcg->nodeinfo[nid];
526 		mctz = soft_limit_tree.rb_tree_per_node[nid];
527 		if (mctz)
528 			mem_cgroup_remove_exceeded(mz, mctz);
529 	}
530 }
531 
532 static struct mem_cgroup_per_node *
533 __mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
534 {
535 	struct mem_cgroup_per_node *mz;
536 
537 retry:
538 	mz = NULL;
539 	if (!mctz->rb_rightmost)
540 		goto done;		/* Nothing to reclaim from */
541 
542 	mz = rb_entry(mctz->rb_rightmost,
543 		      struct mem_cgroup_per_node, tree_node);
544 	/*
545 	 * Remove the node now but someone else can add it back,
546 	 * we will to add it back at the end of reclaim to its correct
547 	 * position in the tree.
548 	 */
549 	__mem_cgroup_remove_exceeded(mz, mctz);
550 	if (!soft_limit_excess(mz->memcg) ||
551 	    !css_tryget(&mz->memcg->css))
552 		goto retry;
553 done:
554 	return mz;
555 }
556 
557 static struct mem_cgroup_per_node *
558 mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
559 {
560 	struct mem_cgroup_per_node *mz;
561 
562 	spin_lock_irq(&mctz->lock);
563 	mz = __mem_cgroup_largest_soft_limit_node(mctz);
564 	spin_unlock_irq(&mctz->lock);
565 	return mz;
566 }
567 
568 /*
569  * memcg and lruvec stats flushing
570  *
571  * Many codepaths leading to stats update or read are performance sensitive and
572  * adding stats flushing in such codepaths is not desirable. So, to optimize the
573  * flushing the kernel does:
574  *
575  * 1) Periodically and asynchronously flush the stats every 2 seconds to not let
576  *    rstat update tree grow unbounded.
577  *
578  * 2) Flush the stats synchronously on reader side only when there are more than
579  *    (MEMCG_CHARGE_BATCH * nr_cpus) update events. Though this optimization
580  *    will let stats be out of sync by atmost (MEMCG_CHARGE_BATCH * nr_cpus) but
581  *    only for 2 seconds due to (1).
582  */
583 static void flush_memcg_stats_dwork(struct work_struct *w);
584 static DECLARE_DEFERRABLE_WORK(stats_flush_dwork, flush_memcg_stats_dwork);
585 static DEFINE_SPINLOCK(stats_flush_lock);
586 static DEFINE_PER_CPU(unsigned int, stats_updates);
587 static atomic_t stats_flush_threshold = ATOMIC_INIT(0);
588 static u64 flush_next_time;
589 
590 #define FLUSH_TIME (2UL*HZ)
591 
592 /*
593  * Accessors to ensure that preemption is disabled on PREEMPT_RT because it can
594  * not rely on this as part of an acquired spinlock_t lock. These functions are
595  * never used in hardirq context on PREEMPT_RT and therefore disabling preemtion
596  * is sufficient.
597  */
598 static void memcg_stats_lock(void)
599 {
600 #ifdef CONFIG_PREEMPT_RT
601       preempt_disable();
602 #else
603       VM_BUG_ON(!irqs_disabled());
604 #endif
605 }
606 
607 static void __memcg_stats_lock(void)
608 {
609 #ifdef CONFIG_PREEMPT_RT
610       preempt_disable();
611 #endif
612 }
613 
614 static void memcg_stats_unlock(void)
615 {
616 #ifdef CONFIG_PREEMPT_RT
617       preempt_enable();
618 #endif
619 }
620 
621 static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val)
622 {
623 	unsigned int x;
624 
625 	cgroup_rstat_updated(memcg->css.cgroup, smp_processor_id());
626 
627 	x = __this_cpu_add_return(stats_updates, abs(val));
628 	if (x > MEMCG_CHARGE_BATCH) {
629 		atomic_add(x / MEMCG_CHARGE_BATCH, &stats_flush_threshold);
630 		__this_cpu_write(stats_updates, 0);
631 	}
632 }
633 
634 static void __mem_cgroup_flush_stats(void)
635 {
636 	unsigned long flag;
637 
638 	if (!spin_trylock_irqsave(&stats_flush_lock, flag))
639 		return;
640 
641 	flush_next_time = jiffies_64 + 2*FLUSH_TIME;
642 	cgroup_rstat_flush_irqsafe(root_mem_cgroup->css.cgroup);
643 	atomic_set(&stats_flush_threshold, 0);
644 	spin_unlock_irqrestore(&stats_flush_lock, flag);
645 }
646 
647 void mem_cgroup_flush_stats(void)
648 {
649 	if (atomic_read(&stats_flush_threshold) > num_online_cpus())
650 		__mem_cgroup_flush_stats();
651 }
652 
653 void mem_cgroup_flush_stats_delayed(void)
654 {
655 	if (time_after64(jiffies_64, flush_next_time))
656 		mem_cgroup_flush_stats();
657 }
658 
659 static void flush_memcg_stats_dwork(struct work_struct *w)
660 {
661 	__mem_cgroup_flush_stats();
662 	queue_delayed_work(system_unbound_wq, &stats_flush_dwork, FLUSH_TIME);
663 }
664 
665 /**
666  * __mod_memcg_state - update cgroup memory statistics
667  * @memcg: the memory cgroup
668  * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item
669  * @val: delta to add to the counter, can be negative
670  */
671 void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val)
672 {
673 	if (mem_cgroup_disabled())
674 		return;
675 
676 	__this_cpu_add(memcg->vmstats_percpu->state[idx], val);
677 	memcg_rstat_updated(memcg, val);
678 }
679 
680 /* idx can be of type enum memcg_stat_item or node_stat_item. */
681 static unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx)
682 {
683 	long x = 0;
684 	int cpu;
685 
686 	for_each_possible_cpu(cpu)
687 		x += per_cpu(memcg->vmstats_percpu->state[idx], cpu);
688 #ifdef CONFIG_SMP
689 	if (x < 0)
690 		x = 0;
691 #endif
692 	return x;
693 }
694 
695 void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
696 			      int val)
697 {
698 	struct mem_cgroup_per_node *pn;
699 	struct mem_cgroup *memcg;
700 
701 	pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
702 	memcg = pn->memcg;
703 
704 	/*
705 	 * The caller from rmap relay on disabled preemption becase they never
706 	 * update their counter from in-interrupt context. For these two
707 	 * counters we check that the update is never performed from an
708 	 * interrupt context while other caller need to have disabled interrupt.
709 	 */
710 	__memcg_stats_lock();
711 	if (IS_ENABLED(CONFIG_DEBUG_VM) && !IS_ENABLED(CONFIG_PREEMPT_RT)) {
712 		switch (idx) {
713 		case NR_ANON_MAPPED:
714 		case NR_FILE_MAPPED:
715 		case NR_ANON_THPS:
716 		case NR_SHMEM_PMDMAPPED:
717 		case NR_FILE_PMDMAPPED:
718 			WARN_ON_ONCE(!in_task());
719 			break;
720 		default:
721 			WARN_ON_ONCE(!irqs_disabled());
722 		}
723 	}
724 
725 	/* Update memcg */
726 	__this_cpu_add(memcg->vmstats_percpu->state[idx], val);
727 
728 	/* Update lruvec */
729 	__this_cpu_add(pn->lruvec_stats_percpu->state[idx], val);
730 
731 	memcg_rstat_updated(memcg, val);
732 	memcg_stats_unlock();
733 }
734 
735 /**
736  * __mod_lruvec_state - update lruvec memory statistics
737  * @lruvec: the lruvec
738  * @idx: the stat item
739  * @val: delta to add to the counter, can be negative
740  *
741  * The lruvec is the intersection of the NUMA node and a cgroup. This
742  * function updates the all three counters that are affected by a
743  * change of state at this level: per-node, per-cgroup, per-lruvec.
744  */
745 void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
746 			int val)
747 {
748 	/* Update node */
749 	__mod_node_page_state(lruvec_pgdat(lruvec), idx, val);
750 
751 	/* Update memcg and lruvec */
752 	if (!mem_cgroup_disabled())
753 		__mod_memcg_lruvec_state(lruvec, idx, val);
754 }
755 
756 void __mod_lruvec_page_state(struct page *page, enum node_stat_item idx,
757 			     int val)
758 {
759 	struct page *head = compound_head(page); /* rmap on tail pages */
760 	struct mem_cgroup *memcg;
761 	pg_data_t *pgdat = page_pgdat(page);
762 	struct lruvec *lruvec;
763 
764 	rcu_read_lock();
765 	memcg = page_memcg(head);
766 	/* Untracked pages have no memcg, no lruvec. Update only the node */
767 	if (!memcg) {
768 		rcu_read_unlock();
769 		__mod_node_page_state(pgdat, idx, val);
770 		return;
771 	}
772 
773 	lruvec = mem_cgroup_lruvec(memcg, pgdat);
774 	__mod_lruvec_state(lruvec, idx, val);
775 	rcu_read_unlock();
776 }
777 EXPORT_SYMBOL(__mod_lruvec_page_state);
778 
779 void __mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val)
780 {
781 	pg_data_t *pgdat = page_pgdat(virt_to_page(p));
782 	struct mem_cgroup *memcg;
783 	struct lruvec *lruvec;
784 
785 	rcu_read_lock();
786 	memcg = mem_cgroup_from_obj(p);
787 
788 	/*
789 	 * Untracked pages have no memcg, no lruvec. Update only the
790 	 * node. If we reparent the slab objects to the root memcg,
791 	 * when we free the slab object, we need to update the per-memcg
792 	 * vmstats to keep it correct for the root memcg.
793 	 */
794 	if (!memcg) {
795 		__mod_node_page_state(pgdat, idx, val);
796 	} else {
797 		lruvec = mem_cgroup_lruvec(memcg, pgdat);
798 		__mod_lruvec_state(lruvec, idx, val);
799 	}
800 	rcu_read_unlock();
801 }
802 
803 /**
804  * __count_memcg_events - account VM events in a cgroup
805  * @memcg: the memory cgroup
806  * @idx: the event item
807  * @count: the number of events that occurred
808  */
809 void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx,
810 			  unsigned long count)
811 {
812 	if (mem_cgroup_disabled())
813 		return;
814 
815 	memcg_stats_lock();
816 	__this_cpu_add(memcg->vmstats_percpu->events[idx], count);
817 	memcg_rstat_updated(memcg, count);
818 	memcg_stats_unlock();
819 }
820 
821 static unsigned long memcg_events(struct mem_cgroup *memcg, int event)
822 {
823 	return READ_ONCE(memcg->vmstats.events[event]);
824 }
825 
826 static unsigned long memcg_events_local(struct mem_cgroup *memcg, int event)
827 {
828 	long x = 0;
829 	int cpu;
830 
831 	for_each_possible_cpu(cpu)
832 		x += per_cpu(memcg->vmstats_percpu->events[event], cpu);
833 	return x;
834 }
835 
836 static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
837 					 int nr_pages)
838 {
839 	/* pagein of a big page is an event. So, ignore page size */
840 	if (nr_pages > 0)
841 		__count_memcg_events(memcg, PGPGIN, 1);
842 	else {
843 		__count_memcg_events(memcg, PGPGOUT, 1);
844 		nr_pages = -nr_pages; /* for event */
845 	}
846 
847 	__this_cpu_add(memcg->vmstats_percpu->nr_page_events, nr_pages);
848 }
849 
850 static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
851 				       enum mem_cgroup_events_target target)
852 {
853 	unsigned long val, next;
854 
855 	val = __this_cpu_read(memcg->vmstats_percpu->nr_page_events);
856 	next = __this_cpu_read(memcg->vmstats_percpu->targets[target]);
857 	/* from time_after() in jiffies.h */
858 	if ((long)(next - val) < 0) {
859 		switch (target) {
860 		case MEM_CGROUP_TARGET_THRESH:
861 			next = val + THRESHOLDS_EVENTS_TARGET;
862 			break;
863 		case MEM_CGROUP_TARGET_SOFTLIMIT:
864 			next = val + SOFTLIMIT_EVENTS_TARGET;
865 			break;
866 		default:
867 			break;
868 		}
869 		__this_cpu_write(memcg->vmstats_percpu->targets[target], next);
870 		return true;
871 	}
872 	return false;
873 }
874 
875 /*
876  * Check events in order.
877  *
878  */
879 static void memcg_check_events(struct mem_cgroup *memcg, int nid)
880 {
881 	if (IS_ENABLED(CONFIG_PREEMPT_RT))
882 		return;
883 
884 	/* threshold event is triggered in finer grain than soft limit */
885 	if (unlikely(mem_cgroup_event_ratelimit(memcg,
886 						MEM_CGROUP_TARGET_THRESH))) {
887 		bool do_softlimit;
888 
889 		do_softlimit = mem_cgroup_event_ratelimit(memcg,
890 						MEM_CGROUP_TARGET_SOFTLIMIT);
891 		mem_cgroup_threshold(memcg);
892 		if (unlikely(do_softlimit))
893 			mem_cgroup_update_tree(memcg, nid);
894 	}
895 }
896 
897 struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
898 {
899 	/*
900 	 * mm_update_next_owner() may clear mm->owner to NULL
901 	 * if it races with swapoff, page migration, etc.
902 	 * So this can be called with p == NULL.
903 	 */
904 	if (unlikely(!p))
905 		return NULL;
906 
907 	return mem_cgroup_from_css(task_css(p, memory_cgrp_id));
908 }
909 EXPORT_SYMBOL(mem_cgroup_from_task);
910 
911 static __always_inline struct mem_cgroup *active_memcg(void)
912 {
913 	if (!in_task())
914 		return this_cpu_read(int_active_memcg);
915 	else
916 		return current->active_memcg;
917 }
918 
919 /**
920  * get_mem_cgroup_from_mm: Obtain a reference on given mm_struct's memcg.
921  * @mm: mm from which memcg should be extracted. It can be NULL.
922  *
923  * Obtain a reference on mm->memcg and returns it if successful. If mm
924  * is NULL, then the memcg is chosen as follows:
925  * 1) The active memcg, if set.
926  * 2) current->mm->memcg, if available
927  * 3) root memcg
928  * If mem_cgroup is disabled, NULL is returned.
929  */
930 struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
931 {
932 	struct mem_cgroup *memcg;
933 
934 	if (mem_cgroup_disabled())
935 		return NULL;
936 
937 	/*
938 	 * Page cache insertions can happen without an
939 	 * actual mm context, e.g. during disk probing
940 	 * on boot, loopback IO, acct() writes etc.
941 	 *
942 	 * No need to css_get on root memcg as the reference
943 	 * counting is disabled on the root level in the
944 	 * cgroup core. See CSS_NO_REF.
945 	 */
946 	if (unlikely(!mm)) {
947 		memcg = active_memcg();
948 		if (unlikely(memcg)) {
949 			/* remote memcg must hold a ref */
950 			css_get(&memcg->css);
951 			return memcg;
952 		}
953 		mm = current->mm;
954 		if (unlikely(!mm))
955 			return root_mem_cgroup;
956 	}
957 
958 	rcu_read_lock();
959 	do {
960 		memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
961 		if (unlikely(!memcg))
962 			memcg = root_mem_cgroup;
963 	} while (!css_tryget(&memcg->css));
964 	rcu_read_unlock();
965 	return memcg;
966 }
967 EXPORT_SYMBOL(get_mem_cgroup_from_mm);
968 
969 static __always_inline bool memcg_kmem_bypass(void)
970 {
971 	/* Allow remote memcg charging from any context. */
972 	if (unlikely(active_memcg()))
973 		return false;
974 
975 	/* Memcg to charge can't be determined. */
976 	if (!in_task() || !current->mm || (current->flags & PF_KTHREAD))
977 		return true;
978 
979 	return false;
980 }
981 
982 /**
983  * mem_cgroup_iter - iterate over memory cgroup hierarchy
984  * @root: hierarchy root
985  * @prev: previously returned memcg, NULL on first invocation
986  * @reclaim: cookie for shared reclaim walks, NULL for full walks
987  *
988  * Returns references to children of the hierarchy below @root, or
989  * @root itself, or %NULL after a full round-trip.
990  *
991  * Caller must pass the return value in @prev on subsequent
992  * invocations for reference counting, or use mem_cgroup_iter_break()
993  * to cancel a hierarchy walk before the round-trip is complete.
994  *
995  * Reclaimers can specify a node in @reclaim to divide up the memcgs
996  * in the hierarchy among all concurrent reclaimers operating on the
997  * same node.
998  */
999 struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
1000 				   struct mem_cgroup *prev,
1001 				   struct mem_cgroup_reclaim_cookie *reclaim)
1002 {
1003 	struct mem_cgroup_reclaim_iter *iter;
1004 	struct cgroup_subsys_state *css = NULL;
1005 	struct mem_cgroup *memcg = NULL;
1006 	struct mem_cgroup *pos = NULL;
1007 
1008 	if (mem_cgroup_disabled())
1009 		return NULL;
1010 
1011 	if (!root)
1012 		root = root_mem_cgroup;
1013 
1014 	rcu_read_lock();
1015 
1016 	if (reclaim) {
1017 		struct mem_cgroup_per_node *mz;
1018 
1019 		mz = root->nodeinfo[reclaim->pgdat->node_id];
1020 		iter = &mz->iter;
1021 
1022 		/*
1023 		 * On start, join the current reclaim iteration cycle.
1024 		 * Exit when a concurrent walker completes it.
1025 		 */
1026 		if (!prev)
1027 			reclaim->generation = iter->generation;
1028 		else if (reclaim->generation != iter->generation)
1029 			goto out_unlock;
1030 
1031 		while (1) {
1032 			pos = READ_ONCE(iter->position);
1033 			if (!pos || css_tryget(&pos->css))
1034 				break;
1035 			/*
1036 			 * css reference reached zero, so iter->position will
1037 			 * be cleared by ->css_released. However, we should not
1038 			 * rely on this happening soon, because ->css_released
1039 			 * is called from a work queue, and by busy-waiting we
1040 			 * might block it. So we clear iter->position right
1041 			 * away.
1042 			 */
1043 			(void)cmpxchg(&iter->position, pos, NULL);
1044 		}
1045 	} else if (prev) {
1046 		pos = prev;
1047 	}
1048 
1049 	if (pos)
1050 		css = &pos->css;
1051 
1052 	for (;;) {
1053 		css = css_next_descendant_pre(css, &root->css);
1054 		if (!css) {
1055 			/*
1056 			 * Reclaimers share the hierarchy walk, and a
1057 			 * new one might jump in right at the end of
1058 			 * the hierarchy - make sure they see at least
1059 			 * one group and restart from the beginning.
1060 			 */
1061 			if (!prev)
1062 				continue;
1063 			break;
1064 		}
1065 
1066 		/*
1067 		 * Verify the css and acquire a reference.  The root
1068 		 * is provided by the caller, so we know it's alive
1069 		 * and kicking, and don't take an extra reference.
1070 		 */
1071 		if (css == &root->css || css_tryget(css)) {
1072 			memcg = mem_cgroup_from_css(css);
1073 			break;
1074 		}
1075 	}
1076 
1077 	if (reclaim) {
1078 		/*
1079 		 * The position could have already been updated by a competing
1080 		 * thread, so check that the value hasn't changed since we read
1081 		 * it to avoid reclaiming from the same cgroup twice.
1082 		 */
1083 		(void)cmpxchg(&iter->position, pos, memcg);
1084 
1085 		if (pos)
1086 			css_put(&pos->css);
1087 
1088 		if (!memcg)
1089 			iter->generation++;
1090 	}
1091 
1092 out_unlock:
1093 	rcu_read_unlock();
1094 	if (prev && prev != root)
1095 		css_put(&prev->css);
1096 
1097 	return memcg;
1098 }
1099 
1100 /**
1101  * mem_cgroup_iter_break - abort a hierarchy walk prematurely
1102  * @root: hierarchy root
1103  * @prev: last visited hierarchy member as returned by mem_cgroup_iter()
1104  */
1105 void mem_cgroup_iter_break(struct mem_cgroup *root,
1106 			   struct mem_cgroup *prev)
1107 {
1108 	if (!root)
1109 		root = root_mem_cgroup;
1110 	if (prev && prev != root)
1111 		css_put(&prev->css);
1112 }
1113 
1114 static void __invalidate_reclaim_iterators(struct mem_cgroup *from,
1115 					struct mem_cgroup *dead_memcg)
1116 {
1117 	struct mem_cgroup_reclaim_iter *iter;
1118 	struct mem_cgroup_per_node *mz;
1119 	int nid;
1120 
1121 	for_each_node(nid) {
1122 		mz = from->nodeinfo[nid];
1123 		iter = &mz->iter;
1124 		cmpxchg(&iter->position, dead_memcg, NULL);
1125 	}
1126 }
1127 
1128 static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg)
1129 {
1130 	struct mem_cgroup *memcg = dead_memcg;
1131 	struct mem_cgroup *last;
1132 
1133 	do {
1134 		__invalidate_reclaim_iterators(memcg, dead_memcg);
1135 		last = memcg;
1136 	} while ((memcg = parent_mem_cgroup(memcg)));
1137 
1138 	/*
1139 	 * When cgruop1 non-hierarchy mode is used,
1140 	 * parent_mem_cgroup() does not walk all the way up to the
1141 	 * cgroup root (root_mem_cgroup). So we have to handle
1142 	 * dead_memcg from cgroup root separately.
1143 	 */
1144 	if (last != root_mem_cgroup)
1145 		__invalidate_reclaim_iterators(root_mem_cgroup,
1146 						dead_memcg);
1147 }
1148 
1149 /**
1150  * mem_cgroup_scan_tasks - iterate over tasks of a memory cgroup hierarchy
1151  * @memcg: hierarchy root
1152  * @fn: function to call for each task
1153  * @arg: argument passed to @fn
1154  *
1155  * This function iterates over tasks attached to @memcg or to any of its
1156  * descendants and calls @fn for each task. If @fn returns a non-zero
1157  * value, the function breaks the iteration loop and returns the value.
1158  * Otherwise, it will iterate over all tasks and return 0.
1159  *
1160  * This function must not be called for the root memory cgroup.
1161  */
1162 int mem_cgroup_scan_tasks(struct mem_cgroup *memcg,
1163 			  int (*fn)(struct task_struct *, void *), void *arg)
1164 {
1165 	struct mem_cgroup *iter;
1166 	int ret = 0;
1167 
1168 	BUG_ON(memcg == root_mem_cgroup);
1169 
1170 	for_each_mem_cgroup_tree(iter, memcg) {
1171 		struct css_task_iter it;
1172 		struct task_struct *task;
1173 
1174 		css_task_iter_start(&iter->css, CSS_TASK_ITER_PROCS, &it);
1175 		while (!ret && (task = css_task_iter_next(&it)))
1176 			ret = fn(task, arg);
1177 		css_task_iter_end(&it);
1178 		if (ret) {
1179 			mem_cgroup_iter_break(memcg, iter);
1180 			break;
1181 		}
1182 	}
1183 	return ret;
1184 }
1185 
1186 #ifdef CONFIG_DEBUG_VM
1187 void lruvec_memcg_debug(struct lruvec *lruvec, struct folio *folio)
1188 {
1189 	struct mem_cgroup *memcg;
1190 
1191 	if (mem_cgroup_disabled())
1192 		return;
1193 
1194 	memcg = folio_memcg(folio);
1195 
1196 	if (!memcg)
1197 		VM_BUG_ON_FOLIO(lruvec_memcg(lruvec) != root_mem_cgroup, folio);
1198 	else
1199 		VM_BUG_ON_FOLIO(lruvec_memcg(lruvec) != memcg, folio);
1200 }
1201 #endif
1202 
1203 /**
1204  * folio_lruvec_lock - Lock the lruvec for a folio.
1205  * @folio: Pointer to the folio.
1206  *
1207  * These functions are safe to use under any of the following conditions:
1208  * - folio locked
1209  * - folio_test_lru false
1210  * - folio_memcg_lock()
1211  * - folio frozen (refcount of 0)
1212  *
1213  * Return: The lruvec this folio is on with its lock held.
1214  */
1215 struct lruvec *folio_lruvec_lock(struct folio *folio)
1216 {
1217 	struct lruvec *lruvec = folio_lruvec(folio);
1218 
1219 	spin_lock(&lruvec->lru_lock);
1220 	lruvec_memcg_debug(lruvec, folio);
1221 
1222 	return lruvec;
1223 }
1224 
1225 /**
1226  * folio_lruvec_lock_irq - Lock the lruvec for a folio.
1227  * @folio: Pointer to the folio.
1228  *
1229  * These functions are safe to use under any of the following conditions:
1230  * - folio locked
1231  * - folio_test_lru false
1232  * - folio_memcg_lock()
1233  * - folio frozen (refcount of 0)
1234  *
1235  * Return: The lruvec this folio is on with its lock held and interrupts
1236  * disabled.
1237  */
1238 struct lruvec *folio_lruvec_lock_irq(struct folio *folio)
1239 {
1240 	struct lruvec *lruvec = folio_lruvec(folio);
1241 
1242 	spin_lock_irq(&lruvec->lru_lock);
1243 	lruvec_memcg_debug(lruvec, folio);
1244 
1245 	return lruvec;
1246 }
1247 
1248 /**
1249  * folio_lruvec_lock_irqsave - Lock the lruvec for a folio.
1250  * @folio: Pointer to the folio.
1251  * @flags: Pointer to irqsave flags.
1252  *
1253  * These functions are safe to use under any of the following conditions:
1254  * - folio locked
1255  * - folio_test_lru false
1256  * - folio_memcg_lock()
1257  * - folio frozen (refcount of 0)
1258  *
1259  * Return: The lruvec this folio is on with its lock held and interrupts
1260  * disabled.
1261  */
1262 struct lruvec *folio_lruvec_lock_irqsave(struct folio *folio,
1263 		unsigned long *flags)
1264 {
1265 	struct lruvec *lruvec = folio_lruvec(folio);
1266 
1267 	spin_lock_irqsave(&lruvec->lru_lock, *flags);
1268 	lruvec_memcg_debug(lruvec, folio);
1269 
1270 	return lruvec;
1271 }
1272 
1273 /**
1274  * mem_cgroup_update_lru_size - account for adding or removing an lru page
1275  * @lruvec: mem_cgroup per zone lru vector
1276  * @lru: index of lru list the page is sitting on
1277  * @zid: zone id of the accounted pages
1278  * @nr_pages: positive when adding or negative when removing
1279  *
1280  * This function must be called under lru_lock, just before a page is added
1281  * to or just after a page is removed from an lru list.
1282  */
1283 void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
1284 				int zid, int nr_pages)
1285 {
1286 	struct mem_cgroup_per_node *mz;
1287 	unsigned long *lru_size;
1288 	long size;
1289 
1290 	if (mem_cgroup_disabled())
1291 		return;
1292 
1293 	mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
1294 	lru_size = &mz->lru_zone_size[zid][lru];
1295 
1296 	if (nr_pages < 0)
1297 		*lru_size += nr_pages;
1298 
1299 	size = *lru_size;
1300 	if (WARN_ONCE(size < 0,
1301 		"%s(%p, %d, %d): lru_size %ld\n",
1302 		__func__, lruvec, lru, nr_pages, size)) {
1303 		VM_BUG_ON(1);
1304 		*lru_size = 0;
1305 	}
1306 
1307 	if (nr_pages > 0)
1308 		*lru_size += nr_pages;
1309 }
1310 
1311 /**
1312  * mem_cgroup_margin - calculate chargeable space of a memory cgroup
1313  * @memcg: the memory cgroup
1314  *
1315  * Returns the maximum amount of memory @mem can be charged with, in
1316  * pages.
1317  */
1318 static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
1319 {
1320 	unsigned long margin = 0;
1321 	unsigned long count;
1322 	unsigned long limit;
1323 
1324 	count = page_counter_read(&memcg->memory);
1325 	limit = READ_ONCE(memcg->memory.max);
1326 	if (count < limit)
1327 		margin = limit - count;
1328 
1329 	if (do_memsw_account()) {
1330 		count = page_counter_read(&memcg->memsw);
1331 		limit = READ_ONCE(memcg->memsw.max);
1332 		if (count < limit)
1333 			margin = min(margin, limit - count);
1334 		else
1335 			margin = 0;
1336 	}
1337 
1338 	return margin;
1339 }
1340 
1341 /*
1342  * A routine for checking "mem" is under move_account() or not.
1343  *
1344  * Checking a cgroup is mc.from or mc.to or under hierarchy of
1345  * moving cgroups. This is for waiting at high-memory pressure
1346  * caused by "move".
1347  */
1348 static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
1349 {
1350 	struct mem_cgroup *from;
1351 	struct mem_cgroup *to;
1352 	bool ret = false;
1353 	/*
1354 	 * Unlike task_move routines, we access mc.to, mc.from not under
1355 	 * mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
1356 	 */
1357 	spin_lock(&mc.lock);
1358 	from = mc.from;
1359 	to = mc.to;
1360 	if (!from)
1361 		goto unlock;
1362 
1363 	ret = mem_cgroup_is_descendant(from, memcg) ||
1364 		mem_cgroup_is_descendant(to, memcg);
1365 unlock:
1366 	spin_unlock(&mc.lock);
1367 	return ret;
1368 }
1369 
1370 static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
1371 {
1372 	if (mc.moving_task && current != mc.moving_task) {
1373 		if (mem_cgroup_under_move(memcg)) {
1374 			DEFINE_WAIT(wait);
1375 			prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
1376 			/* moving charge context might have finished. */
1377 			if (mc.moving_task)
1378 				schedule();
1379 			finish_wait(&mc.waitq, &wait);
1380 			return true;
1381 		}
1382 	}
1383 	return false;
1384 }
1385 
1386 struct memory_stat {
1387 	const char *name;
1388 	unsigned int idx;
1389 };
1390 
1391 static const struct memory_stat memory_stats[] = {
1392 	{ "anon",			NR_ANON_MAPPED			},
1393 	{ "file",			NR_FILE_PAGES			},
1394 	{ "kernel",			MEMCG_KMEM			},
1395 	{ "kernel_stack",		NR_KERNEL_STACK_KB		},
1396 	{ "pagetables",			NR_PAGETABLE			},
1397 	{ "percpu",			MEMCG_PERCPU_B			},
1398 	{ "sock",			MEMCG_SOCK			},
1399 	{ "vmalloc",			MEMCG_VMALLOC			},
1400 	{ "shmem",			NR_SHMEM			},
1401 #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
1402 	{ "zswap",			MEMCG_ZSWAP_B			},
1403 	{ "zswapped",			MEMCG_ZSWAPPED			},
1404 #endif
1405 	{ "file_mapped",		NR_FILE_MAPPED			},
1406 	{ "file_dirty",			NR_FILE_DIRTY			},
1407 	{ "file_writeback",		NR_WRITEBACK			},
1408 #ifdef CONFIG_SWAP
1409 	{ "swapcached",			NR_SWAPCACHE			},
1410 #endif
1411 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1412 	{ "anon_thp",			NR_ANON_THPS			},
1413 	{ "file_thp",			NR_FILE_THPS			},
1414 	{ "shmem_thp",			NR_SHMEM_THPS			},
1415 #endif
1416 	{ "inactive_anon",		NR_INACTIVE_ANON		},
1417 	{ "active_anon",		NR_ACTIVE_ANON			},
1418 	{ "inactive_file",		NR_INACTIVE_FILE		},
1419 	{ "active_file",		NR_ACTIVE_FILE			},
1420 	{ "unevictable",		NR_UNEVICTABLE			},
1421 	{ "slab_reclaimable",		NR_SLAB_RECLAIMABLE_B		},
1422 	{ "slab_unreclaimable",		NR_SLAB_UNRECLAIMABLE_B		},
1423 
1424 	/* The memory events */
1425 	{ "workingset_refault_anon",	WORKINGSET_REFAULT_ANON		},
1426 	{ "workingset_refault_file",	WORKINGSET_REFAULT_FILE		},
1427 	{ "workingset_activate_anon",	WORKINGSET_ACTIVATE_ANON	},
1428 	{ "workingset_activate_file",	WORKINGSET_ACTIVATE_FILE	},
1429 	{ "workingset_restore_anon",	WORKINGSET_RESTORE_ANON		},
1430 	{ "workingset_restore_file",	WORKINGSET_RESTORE_FILE		},
1431 	{ "workingset_nodereclaim",	WORKINGSET_NODERECLAIM		},
1432 };
1433 
1434 /* Translate stat items to the correct unit for memory.stat output */
1435 static int memcg_page_state_unit(int item)
1436 {
1437 	switch (item) {
1438 	case MEMCG_PERCPU_B:
1439 	case MEMCG_ZSWAP_B:
1440 	case NR_SLAB_RECLAIMABLE_B:
1441 	case NR_SLAB_UNRECLAIMABLE_B:
1442 	case WORKINGSET_REFAULT_ANON:
1443 	case WORKINGSET_REFAULT_FILE:
1444 	case WORKINGSET_ACTIVATE_ANON:
1445 	case WORKINGSET_ACTIVATE_FILE:
1446 	case WORKINGSET_RESTORE_ANON:
1447 	case WORKINGSET_RESTORE_FILE:
1448 	case WORKINGSET_NODERECLAIM:
1449 		return 1;
1450 	case NR_KERNEL_STACK_KB:
1451 		return SZ_1K;
1452 	default:
1453 		return PAGE_SIZE;
1454 	}
1455 }
1456 
1457 static inline unsigned long memcg_page_state_output(struct mem_cgroup *memcg,
1458 						    int item)
1459 {
1460 	return memcg_page_state(memcg, item) * memcg_page_state_unit(item);
1461 }
1462 
1463 static char *memory_stat_format(struct mem_cgroup *memcg)
1464 {
1465 	struct seq_buf s;
1466 	int i;
1467 
1468 	seq_buf_init(&s, kmalloc(PAGE_SIZE, GFP_KERNEL), PAGE_SIZE);
1469 	if (!s.buffer)
1470 		return NULL;
1471 
1472 	/*
1473 	 * Provide statistics on the state of the memory subsystem as
1474 	 * well as cumulative event counters that show past behavior.
1475 	 *
1476 	 * This list is ordered following a combination of these gradients:
1477 	 * 1) generic big picture -> specifics and details
1478 	 * 2) reflecting userspace activity -> reflecting kernel heuristics
1479 	 *
1480 	 * Current memory state:
1481 	 */
1482 	mem_cgroup_flush_stats();
1483 
1484 	for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
1485 		u64 size;
1486 
1487 		size = memcg_page_state_output(memcg, memory_stats[i].idx);
1488 		seq_buf_printf(&s, "%s %llu\n", memory_stats[i].name, size);
1489 
1490 		if (unlikely(memory_stats[i].idx == NR_SLAB_UNRECLAIMABLE_B)) {
1491 			size += memcg_page_state_output(memcg,
1492 							NR_SLAB_RECLAIMABLE_B);
1493 			seq_buf_printf(&s, "slab %llu\n", size);
1494 		}
1495 	}
1496 
1497 	/* Accumulated memory events */
1498 
1499 	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGFAULT),
1500 		       memcg_events(memcg, PGFAULT));
1501 	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGMAJFAULT),
1502 		       memcg_events(memcg, PGMAJFAULT));
1503 	seq_buf_printf(&s, "%s %lu\n",  vm_event_name(PGREFILL),
1504 		       memcg_events(memcg, PGREFILL));
1505 	seq_buf_printf(&s, "pgscan %lu\n",
1506 		       memcg_events(memcg, PGSCAN_KSWAPD) +
1507 		       memcg_events(memcg, PGSCAN_DIRECT));
1508 	seq_buf_printf(&s, "pgsteal %lu\n",
1509 		       memcg_events(memcg, PGSTEAL_KSWAPD) +
1510 		       memcg_events(memcg, PGSTEAL_DIRECT));
1511 	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGACTIVATE),
1512 		       memcg_events(memcg, PGACTIVATE));
1513 	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGDEACTIVATE),
1514 		       memcg_events(memcg, PGDEACTIVATE));
1515 	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGLAZYFREE),
1516 		       memcg_events(memcg, PGLAZYFREE));
1517 	seq_buf_printf(&s, "%s %lu\n", vm_event_name(PGLAZYFREED),
1518 		       memcg_events(memcg, PGLAZYFREED));
1519 
1520 #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
1521 	seq_buf_printf(&s, "%s %lu\n", vm_event_name(ZSWPIN),
1522 		       memcg_events(memcg, ZSWPIN));
1523 	seq_buf_printf(&s, "%s %lu\n", vm_event_name(ZSWPOUT),
1524 		       memcg_events(memcg, ZSWPOUT));
1525 #endif
1526 
1527 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1528 	seq_buf_printf(&s, "%s %lu\n", vm_event_name(THP_FAULT_ALLOC),
1529 		       memcg_events(memcg, THP_FAULT_ALLOC));
1530 	seq_buf_printf(&s, "%s %lu\n", vm_event_name(THP_COLLAPSE_ALLOC),
1531 		       memcg_events(memcg, THP_COLLAPSE_ALLOC));
1532 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
1533 
1534 	/* The above should easily fit into one page */
1535 	WARN_ON_ONCE(seq_buf_has_overflowed(&s));
1536 
1537 	return s.buffer;
1538 }
1539 
1540 #define K(x) ((x) << (PAGE_SHIFT-10))
1541 /**
1542  * mem_cgroup_print_oom_context: Print OOM information relevant to
1543  * memory controller.
1544  * @memcg: The memory cgroup that went over limit
1545  * @p: Task that is going to be killed
1546  *
1547  * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
1548  * enabled
1549  */
1550 void mem_cgroup_print_oom_context(struct mem_cgroup *memcg, struct task_struct *p)
1551 {
1552 	rcu_read_lock();
1553 
1554 	if (memcg) {
1555 		pr_cont(",oom_memcg=");
1556 		pr_cont_cgroup_path(memcg->css.cgroup);
1557 	} else
1558 		pr_cont(",global_oom");
1559 	if (p) {
1560 		pr_cont(",task_memcg=");
1561 		pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id));
1562 	}
1563 	rcu_read_unlock();
1564 }
1565 
1566 /**
1567  * mem_cgroup_print_oom_meminfo: Print OOM memory information relevant to
1568  * memory controller.
1569  * @memcg: The memory cgroup that went over limit
1570  */
1571 void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
1572 {
1573 	char *buf;
1574 
1575 	pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n",
1576 		K((u64)page_counter_read(&memcg->memory)),
1577 		K((u64)READ_ONCE(memcg->memory.max)), memcg->memory.failcnt);
1578 	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
1579 		pr_info("swap: usage %llukB, limit %llukB, failcnt %lu\n",
1580 			K((u64)page_counter_read(&memcg->swap)),
1581 			K((u64)READ_ONCE(memcg->swap.max)), memcg->swap.failcnt);
1582 	else {
1583 		pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n",
1584 			K((u64)page_counter_read(&memcg->memsw)),
1585 			K((u64)memcg->memsw.max), memcg->memsw.failcnt);
1586 		pr_info("kmem: usage %llukB, limit %llukB, failcnt %lu\n",
1587 			K((u64)page_counter_read(&memcg->kmem)),
1588 			K((u64)memcg->kmem.max), memcg->kmem.failcnt);
1589 	}
1590 
1591 	pr_info("Memory cgroup stats for ");
1592 	pr_cont_cgroup_path(memcg->css.cgroup);
1593 	pr_cont(":");
1594 	buf = memory_stat_format(memcg);
1595 	if (!buf)
1596 		return;
1597 	pr_info("%s", buf);
1598 	kfree(buf);
1599 }
1600 
1601 /*
1602  * Return the memory (and swap, if configured) limit for a memcg.
1603  */
1604 unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg)
1605 {
1606 	unsigned long max = READ_ONCE(memcg->memory.max);
1607 
1608 	if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
1609 		if (mem_cgroup_swappiness(memcg))
1610 			max += min(READ_ONCE(memcg->swap.max),
1611 				   (unsigned long)total_swap_pages);
1612 	} else { /* v1 */
1613 		if (mem_cgroup_swappiness(memcg)) {
1614 			/* Calculate swap excess capacity from memsw limit */
1615 			unsigned long swap = READ_ONCE(memcg->memsw.max) - max;
1616 
1617 			max += min(swap, (unsigned long)total_swap_pages);
1618 		}
1619 	}
1620 	return max;
1621 }
1622 
1623 unsigned long mem_cgroup_size(struct mem_cgroup *memcg)
1624 {
1625 	return page_counter_read(&memcg->memory);
1626 }
1627 
1628 static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
1629 				     int order)
1630 {
1631 	struct oom_control oc = {
1632 		.zonelist = NULL,
1633 		.nodemask = NULL,
1634 		.memcg = memcg,
1635 		.gfp_mask = gfp_mask,
1636 		.order = order,
1637 	};
1638 	bool ret = true;
1639 
1640 	if (mutex_lock_killable(&oom_lock))
1641 		return true;
1642 
1643 	if (mem_cgroup_margin(memcg) >= (1 << order))
1644 		goto unlock;
1645 
1646 	/*
1647 	 * A few threads which were not waiting at mutex_lock_killable() can
1648 	 * fail to bail out. Therefore, check again after holding oom_lock.
1649 	 */
1650 	ret = task_is_dying() || out_of_memory(&oc);
1651 
1652 unlock:
1653 	mutex_unlock(&oom_lock);
1654 	return ret;
1655 }
1656 
1657 static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
1658 				   pg_data_t *pgdat,
1659 				   gfp_t gfp_mask,
1660 				   unsigned long *total_scanned)
1661 {
1662 	struct mem_cgroup *victim = NULL;
1663 	int total = 0;
1664 	int loop = 0;
1665 	unsigned long excess;
1666 	unsigned long nr_scanned;
1667 	struct mem_cgroup_reclaim_cookie reclaim = {
1668 		.pgdat = pgdat,
1669 	};
1670 
1671 	excess = soft_limit_excess(root_memcg);
1672 
1673 	while (1) {
1674 		victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
1675 		if (!victim) {
1676 			loop++;
1677 			if (loop >= 2) {
1678 				/*
1679 				 * If we have not been able to reclaim
1680 				 * anything, it might because there are
1681 				 * no reclaimable pages under this hierarchy
1682 				 */
1683 				if (!total)
1684 					break;
1685 				/*
1686 				 * We want to do more targeted reclaim.
1687 				 * excess >> 2 is not to excessive so as to
1688 				 * reclaim too much, nor too less that we keep
1689 				 * coming back to reclaim from this cgroup
1690 				 */
1691 				if (total >= (excess >> 2) ||
1692 					(loop > MEM_CGROUP_MAX_RECLAIM_LOOPS))
1693 					break;
1694 			}
1695 			continue;
1696 		}
1697 		total += mem_cgroup_shrink_node(victim, gfp_mask, false,
1698 					pgdat, &nr_scanned);
1699 		*total_scanned += nr_scanned;
1700 		if (!soft_limit_excess(root_memcg))
1701 			break;
1702 	}
1703 	mem_cgroup_iter_break(root_memcg, victim);
1704 	return total;
1705 }
1706 
1707 #ifdef CONFIG_LOCKDEP
1708 static struct lockdep_map memcg_oom_lock_dep_map = {
1709 	.name = "memcg_oom_lock",
1710 };
1711 #endif
1712 
1713 static DEFINE_SPINLOCK(memcg_oom_lock);
1714 
1715 /*
1716  * Check OOM-Killer is already running under our hierarchy.
1717  * If someone is running, return false.
1718  */
1719 static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg)
1720 {
1721 	struct mem_cgroup *iter, *failed = NULL;
1722 
1723 	spin_lock(&memcg_oom_lock);
1724 
1725 	for_each_mem_cgroup_tree(iter, memcg) {
1726 		if (iter->oom_lock) {
1727 			/*
1728 			 * this subtree of our hierarchy is already locked
1729 			 * so we cannot give a lock.
1730 			 */
1731 			failed = iter;
1732 			mem_cgroup_iter_break(memcg, iter);
1733 			break;
1734 		} else
1735 			iter->oom_lock = true;
1736 	}
1737 
1738 	if (failed) {
1739 		/*
1740 		 * OK, we failed to lock the whole subtree so we have
1741 		 * to clean up what we set up to the failing subtree
1742 		 */
1743 		for_each_mem_cgroup_tree(iter, memcg) {
1744 			if (iter == failed) {
1745 				mem_cgroup_iter_break(memcg, iter);
1746 				break;
1747 			}
1748 			iter->oom_lock = false;
1749 		}
1750 	} else
1751 		mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_);
1752 
1753 	spin_unlock(&memcg_oom_lock);
1754 
1755 	return !failed;
1756 }
1757 
1758 static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
1759 {
1760 	struct mem_cgroup *iter;
1761 
1762 	spin_lock(&memcg_oom_lock);
1763 	mutex_release(&memcg_oom_lock_dep_map, _RET_IP_);
1764 	for_each_mem_cgroup_tree(iter, memcg)
1765 		iter->oom_lock = false;
1766 	spin_unlock(&memcg_oom_lock);
1767 }
1768 
1769 static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
1770 {
1771 	struct mem_cgroup *iter;
1772 
1773 	spin_lock(&memcg_oom_lock);
1774 	for_each_mem_cgroup_tree(iter, memcg)
1775 		iter->under_oom++;
1776 	spin_unlock(&memcg_oom_lock);
1777 }
1778 
1779 static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
1780 {
1781 	struct mem_cgroup *iter;
1782 
1783 	/*
1784 	 * Be careful about under_oom underflows because a child memcg
1785 	 * could have been added after mem_cgroup_mark_under_oom.
1786 	 */
1787 	spin_lock(&memcg_oom_lock);
1788 	for_each_mem_cgroup_tree(iter, memcg)
1789 		if (iter->under_oom > 0)
1790 			iter->under_oom--;
1791 	spin_unlock(&memcg_oom_lock);
1792 }
1793 
1794 static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
1795 
1796 struct oom_wait_info {
1797 	struct mem_cgroup *memcg;
1798 	wait_queue_entry_t	wait;
1799 };
1800 
1801 static int memcg_oom_wake_function(wait_queue_entry_t *wait,
1802 	unsigned mode, int sync, void *arg)
1803 {
1804 	struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
1805 	struct mem_cgroup *oom_wait_memcg;
1806 	struct oom_wait_info *oom_wait_info;
1807 
1808 	oom_wait_info = container_of(wait, struct oom_wait_info, wait);
1809 	oom_wait_memcg = oom_wait_info->memcg;
1810 
1811 	if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) &&
1812 	    !mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg))
1813 		return 0;
1814 	return autoremove_wake_function(wait, mode, sync, arg);
1815 }
1816 
1817 static void memcg_oom_recover(struct mem_cgroup *memcg)
1818 {
1819 	/*
1820 	 * For the following lockless ->under_oom test, the only required
1821 	 * guarantee is that it must see the state asserted by an OOM when
1822 	 * this function is called as a result of userland actions
1823 	 * triggered by the notification of the OOM.  This is trivially
1824 	 * achieved by invoking mem_cgroup_mark_under_oom() before
1825 	 * triggering notification.
1826 	 */
1827 	if (memcg && memcg->under_oom)
1828 		__wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
1829 }
1830 
1831 /*
1832  * Returns true if successfully killed one or more processes. Though in some
1833  * corner cases it can return true even without killing any process.
1834  */
1835 static bool mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
1836 {
1837 	bool locked, ret;
1838 
1839 	if (order > PAGE_ALLOC_COSTLY_ORDER)
1840 		return false;
1841 
1842 	memcg_memory_event(memcg, MEMCG_OOM);
1843 
1844 	/*
1845 	 * We are in the middle of the charge context here, so we
1846 	 * don't want to block when potentially sitting on a callstack
1847 	 * that holds all kinds of filesystem and mm locks.
1848 	 *
1849 	 * cgroup1 allows disabling the OOM killer and waiting for outside
1850 	 * handling until the charge can succeed; remember the context and put
1851 	 * the task to sleep at the end of the page fault when all locks are
1852 	 * released.
1853 	 *
1854 	 * On the other hand, in-kernel OOM killer allows for an async victim
1855 	 * memory reclaim (oom_reaper) and that means that we are not solely
1856 	 * relying on the oom victim to make a forward progress and we can
1857 	 * invoke the oom killer here.
1858 	 *
1859 	 * Please note that mem_cgroup_out_of_memory might fail to find a
1860 	 * victim and then we have to bail out from the charge path.
1861 	 */
1862 	if (memcg->oom_kill_disable) {
1863 		if (current->in_user_fault) {
1864 			css_get(&memcg->css);
1865 			current->memcg_in_oom = memcg;
1866 			current->memcg_oom_gfp_mask = mask;
1867 			current->memcg_oom_order = order;
1868 		}
1869 		return false;
1870 	}
1871 
1872 	mem_cgroup_mark_under_oom(memcg);
1873 
1874 	locked = mem_cgroup_oom_trylock(memcg);
1875 
1876 	if (locked)
1877 		mem_cgroup_oom_notify(memcg);
1878 
1879 	mem_cgroup_unmark_under_oom(memcg);
1880 	ret = mem_cgroup_out_of_memory(memcg, mask, order);
1881 
1882 	if (locked)
1883 		mem_cgroup_oom_unlock(memcg);
1884 
1885 	return ret;
1886 }
1887 
1888 /**
1889  * mem_cgroup_oom_synchronize - complete memcg OOM handling
1890  * @handle: actually kill/wait or just clean up the OOM state
1891  *
1892  * This has to be called at the end of a page fault if the memcg OOM
1893  * handler was enabled.
1894  *
1895  * Memcg supports userspace OOM handling where failed allocations must
1896  * sleep on a waitqueue until the userspace task resolves the
1897  * situation.  Sleeping directly in the charge context with all kinds
1898  * of locks held is not a good idea, instead we remember an OOM state
1899  * in the task and mem_cgroup_oom_synchronize() has to be called at
1900  * the end of the page fault to complete the OOM handling.
1901  *
1902  * Returns %true if an ongoing memcg OOM situation was detected and
1903  * completed, %false otherwise.
1904  */
1905 bool mem_cgroup_oom_synchronize(bool handle)
1906 {
1907 	struct mem_cgroup *memcg = current->memcg_in_oom;
1908 	struct oom_wait_info owait;
1909 	bool locked;
1910 
1911 	/* OOM is global, do not handle */
1912 	if (!memcg)
1913 		return false;
1914 
1915 	if (!handle)
1916 		goto cleanup;
1917 
1918 	owait.memcg = memcg;
1919 	owait.wait.flags = 0;
1920 	owait.wait.func = memcg_oom_wake_function;
1921 	owait.wait.private = current;
1922 	INIT_LIST_HEAD(&owait.wait.entry);
1923 
1924 	prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
1925 	mem_cgroup_mark_under_oom(memcg);
1926 
1927 	locked = mem_cgroup_oom_trylock(memcg);
1928 
1929 	if (locked)
1930 		mem_cgroup_oom_notify(memcg);
1931 
1932 	if (locked && !memcg->oom_kill_disable) {
1933 		mem_cgroup_unmark_under_oom(memcg);
1934 		finish_wait(&memcg_oom_waitq, &owait.wait);
1935 		mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask,
1936 					 current->memcg_oom_order);
1937 	} else {
1938 		schedule();
1939 		mem_cgroup_unmark_under_oom(memcg);
1940 		finish_wait(&memcg_oom_waitq, &owait.wait);
1941 	}
1942 
1943 	if (locked) {
1944 		mem_cgroup_oom_unlock(memcg);
1945 		/*
1946 		 * There is no guarantee that an OOM-lock contender
1947 		 * sees the wakeups triggered by the OOM kill
1948 		 * uncharges.  Wake any sleepers explicitly.
1949 		 */
1950 		memcg_oom_recover(memcg);
1951 	}
1952 cleanup:
1953 	current->memcg_in_oom = NULL;
1954 	css_put(&memcg->css);
1955 	return true;
1956 }
1957 
1958 /**
1959  * mem_cgroup_get_oom_group - get a memory cgroup to clean up after OOM
1960  * @victim: task to be killed by the OOM killer
1961  * @oom_domain: memcg in case of memcg OOM, NULL in case of system-wide OOM
1962  *
1963  * Returns a pointer to a memory cgroup, which has to be cleaned up
1964  * by killing all belonging OOM-killable tasks.
1965  *
1966  * Caller has to call mem_cgroup_put() on the returned non-NULL memcg.
1967  */
1968 struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim,
1969 					    struct mem_cgroup *oom_domain)
1970 {
1971 	struct mem_cgroup *oom_group = NULL;
1972 	struct mem_cgroup *memcg;
1973 
1974 	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
1975 		return NULL;
1976 
1977 	if (!oom_domain)
1978 		oom_domain = root_mem_cgroup;
1979 
1980 	rcu_read_lock();
1981 
1982 	memcg = mem_cgroup_from_task(victim);
1983 	if (memcg == root_mem_cgroup)
1984 		goto out;
1985 
1986 	/*
1987 	 * If the victim task has been asynchronously moved to a different
1988 	 * memory cgroup, we might end up killing tasks outside oom_domain.
1989 	 * In this case it's better to ignore memory.group.oom.
1990 	 */
1991 	if (unlikely(!mem_cgroup_is_descendant(memcg, oom_domain)))
1992 		goto out;
1993 
1994 	/*
1995 	 * Traverse the memory cgroup hierarchy from the victim task's
1996 	 * cgroup up to the OOMing cgroup (or root) to find the
1997 	 * highest-level memory cgroup with oom.group set.
1998 	 */
1999 	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
2000 		if (memcg->oom_group)
2001 			oom_group = memcg;
2002 
2003 		if (memcg == oom_domain)
2004 			break;
2005 	}
2006 
2007 	if (oom_group)
2008 		css_get(&oom_group->css);
2009 out:
2010 	rcu_read_unlock();
2011 
2012 	return oom_group;
2013 }
2014 
2015 void mem_cgroup_print_oom_group(struct mem_cgroup *memcg)
2016 {
2017 	pr_info("Tasks in ");
2018 	pr_cont_cgroup_path(memcg->css.cgroup);
2019 	pr_cont(" are going to be killed due to memory.oom.group set\n");
2020 }
2021 
2022 /**
2023  * folio_memcg_lock - Bind a folio to its memcg.
2024  * @folio: The folio.
2025  *
2026  * This function prevents unlocked LRU folios from being moved to
2027  * another cgroup.
2028  *
2029  * It ensures lifetime of the bound memcg.  The caller is responsible
2030  * for the lifetime of the folio.
2031  */
2032 void folio_memcg_lock(struct folio *folio)
2033 {
2034 	struct mem_cgroup *memcg;
2035 	unsigned long flags;
2036 
2037 	/*
2038 	 * The RCU lock is held throughout the transaction.  The fast
2039 	 * path can get away without acquiring the memcg->move_lock
2040 	 * because page moving starts with an RCU grace period.
2041          */
2042 	rcu_read_lock();
2043 
2044 	if (mem_cgroup_disabled())
2045 		return;
2046 again:
2047 	memcg = folio_memcg(folio);
2048 	if (unlikely(!memcg))
2049 		return;
2050 
2051 #ifdef CONFIG_PROVE_LOCKING
2052 	local_irq_save(flags);
2053 	might_lock(&memcg->move_lock);
2054 	local_irq_restore(flags);
2055 #endif
2056 
2057 	if (atomic_read(&memcg->moving_account) <= 0)
2058 		return;
2059 
2060 	spin_lock_irqsave(&memcg->move_lock, flags);
2061 	if (memcg != folio_memcg(folio)) {
2062 		spin_unlock_irqrestore(&memcg->move_lock, flags);
2063 		goto again;
2064 	}
2065 
2066 	/*
2067 	 * When charge migration first begins, we can have multiple
2068 	 * critical sections holding the fast-path RCU lock and one
2069 	 * holding the slowpath move_lock. Track the task who has the
2070 	 * move_lock for unlock_page_memcg().
2071 	 */
2072 	memcg->move_lock_task = current;
2073 	memcg->move_lock_flags = flags;
2074 }
2075 
2076 void lock_page_memcg(struct page *page)
2077 {
2078 	folio_memcg_lock(page_folio(page));
2079 }
2080 
2081 static void __folio_memcg_unlock(struct mem_cgroup *memcg)
2082 {
2083 	if (memcg && memcg->move_lock_task == current) {
2084 		unsigned long flags = memcg->move_lock_flags;
2085 
2086 		memcg->move_lock_task = NULL;
2087 		memcg->move_lock_flags = 0;
2088 
2089 		spin_unlock_irqrestore(&memcg->move_lock, flags);
2090 	}
2091 
2092 	rcu_read_unlock();
2093 }
2094 
2095 /**
2096  * folio_memcg_unlock - Release the binding between a folio and its memcg.
2097  * @folio: The folio.
2098  *
2099  * This releases the binding created by folio_memcg_lock().  This does
2100  * not change the accounting of this folio to its memcg, but it does
2101  * permit others to change it.
2102  */
2103 void folio_memcg_unlock(struct folio *folio)
2104 {
2105 	__folio_memcg_unlock(folio_memcg(folio));
2106 }
2107 
2108 void unlock_page_memcg(struct page *page)
2109 {
2110 	folio_memcg_unlock(page_folio(page));
2111 }
2112 
2113 struct memcg_stock_pcp {
2114 	local_lock_t stock_lock;
2115 	struct mem_cgroup *cached; /* this never be root cgroup */
2116 	unsigned int nr_pages;
2117 
2118 #ifdef CONFIG_MEMCG_KMEM
2119 	struct obj_cgroup *cached_objcg;
2120 	struct pglist_data *cached_pgdat;
2121 	unsigned int nr_bytes;
2122 	int nr_slab_reclaimable_b;
2123 	int nr_slab_unreclaimable_b;
2124 #endif
2125 
2126 	struct work_struct work;
2127 	unsigned long flags;
2128 #define FLUSHING_CACHED_CHARGE	0
2129 };
2130 static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock) = {
2131 	.stock_lock = INIT_LOCAL_LOCK(stock_lock),
2132 };
2133 static DEFINE_MUTEX(percpu_charge_mutex);
2134 
2135 #ifdef CONFIG_MEMCG_KMEM
2136 static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock);
2137 static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
2138 				     struct mem_cgroup *root_memcg);
2139 static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages);
2140 
2141 #else
2142 static inline struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock)
2143 {
2144 	return NULL;
2145 }
2146 static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
2147 				     struct mem_cgroup *root_memcg)
2148 {
2149 	return false;
2150 }
2151 static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages)
2152 {
2153 }
2154 #endif
2155 
2156 /**
2157  * consume_stock: Try to consume stocked charge on this cpu.
2158  * @memcg: memcg to consume from.
2159  * @nr_pages: how many pages to charge.
2160  *
2161  * The charges will only happen if @memcg matches the current cpu's memcg
2162  * stock, and at least @nr_pages are available in that stock.  Failure to
2163  * service an allocation will refill the stock.
2164  *
2165  * returns true if successful, false otherwise.
2166  */
2167 static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
2168 {
2169 	struct memcg_stock_pcp *stock;
2170 	unsigned long flags;
2171 	bool ret = false;
2172 
2173 	if (nr_pages > MEMCG_CHARGE_BATCH)
2174 		return ret;
2175 
2176 	local_lock_irqsave(&memcg_stock.stock_lock, flags);
2177 
2178 	stock = this_cpu_ptr(&memcg_stock);
2179 	if (memcg == stock->cached && stock->nr_pages >= nr_pages) {
2180 		stock->nr_pages -= nr_pages;
2181 		ret = true;
2182 	}
2183 
2184 	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
2185 
2186 	return ret;
2187 }
2188 
2189 /*
2190  * Returns stocks cached in percpu and reset cached information.
2191  */
2192 static void drain_stock(struct memcg_stock_pcp *stock)
2193 {
2194 	struct mem_cgroup *old = stock->cached;
2195 
2196 	if (!old)
2197 		return;
2198 
2199 	if (stock->nr_pages) {
2200 		page_counter_uncharge(&old->memory, stock->nr_pages);
2201 		if (do_memsw_account())
2202 			page_counter_uncharge(&old->memsw, stock->nr_pages);
2203 		stock->nr_pages = 0;
2204 	}
2205 
2206 	css_put(&old->css);
2207 	stock->cached = NULL;
2208 }
2209 
2210 static void drain_local_stock(struct work_struct *dummy)
2211 {
2212 	struct memcg_stock_pcp *stock;
2213 	struct obj_cgroup *old = NULL;
2214 	unsigned long flags;
2215 
2216 	/*
2217 	 * The only protection from cpu hotplug (memcg_hotplug_cpu_dead) vs.
2218 	 * drain_stock races is that we always operate on local CPU stock
2219 	 * here with IRQ disabled
2220 	 */
2221 	local_lock_irqsave(&memcg_stock.stock_lock, flags);
2222 
2223 	stock = this_cpu_ptr(&memcg_stock);
2224 	old = drain_obj_stock(stock);
2225 	drain_stock(stock);
2226 	clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
2227 
2228 	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
2229 	if (old)
2230 		obj_cgroup_put(old);
2231 }
2232 
2233 /*
2234  * Cache charges(val) to local per_cpu area.
2235  * This will be consumed by consume_stock() function, later.
2236  */
2237 static void __refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
2238 {
2239 	struct memcg_stock_pcp *stock;
2240 
2241 	stock = this_cpu_ptr(&memcg_stock);
2242 	if (stock->cached != memcg) { /* reset if necessary */
2243 		drain_stock(stock);
2244 		css_get(&memcg->css);
2245 		stock->cached = memcg;
2246 	}
2247 	stock->nr_pages += nr_pages;
2248 
2249 	if (stock->nr_pages > MEMCG_CHARGE_BATCH)
2250 		drain_stock(stock);
2251 }
2252 
2253 static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
2254 {
2255 	unsigned long flags;
2256 
2257 	local_lock_irqsave(&memcg_stock.stock_lock, flags);
2258 	__refill_stock(memcg, nr_pages);
2259 	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
2260 }
2261 
2262 /*
2263  * Drains all per-CPU charge caches for given root_memcg resp. subtree
2264  * of the hierarchy under it.
2265  */
2266 static void drain_all_stock(struct mem_cgroup *root_memcg)
2267 {
2268 	int cpu, curcpu;
2269 
2270 	/* If someone's already draining, avoid adding running more workers. */
2271 	if (!mutex_trylock(&percpu_charge_mutex))
2272 		return;
2273 	/*
2274 	 * Notify other cpus that system-wide "drain" is running
2275 	 * We do not care about races with the cpu hotplug because cpu down
2276 	 * as well as workers from this path always operate on the local
2277 	 * per-cpu data. CPU up doesn't touch memcg_stock at all.
2278 	 */
2279 	migrate_disable();
2280 	curcpu = smp_processor_id();
2281 	for_each_online_cpu(cpu) {
2282 		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
2283 		struct mem_cgroup *memcg;
2284 		bool flush = false;
2285 
2286 		rcu_read_lock();
2287 		memcg = stock->cached;
2288 		if (memcg && stock->nr_pages &&
2289 		    mem_cgroup_is_descendant(memcg, root_memcg))
2290 			flush = true;
2291 		else if (obj_stock_flush_required(stock, root_memcg))
2292 			flush = true;
2293 		rcu_read_unlock();
2294 
2295 		if (flush &&
2296 		    !test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) {
2297 			if (cpu == curcpu)
2298 				drain_local_stock(&stock->work);
2299 			else
2300 				schedule_work_on(cpu, &stock->work);
2301 		}
2302 	}
2303 	migrate_enable();
2304 	mutex_unlock(&percpu_charge_mutex);
2305 }
2306 
2307 static int memcg_hotplug_cpu_dead(unsigned int cpu)
2308 {
2309 	struct memcg_stock_pcp *stock;
2310 
2311 	stock = &per_cpu(memcg_stock, cpu);
2312 	drain_stock(stock);
2313 
2314 	return 0;
2315 }
2316 
2317 static unsigned long reclaim_high(struct mem_cgroup *memcg,
2318 				  unsigned int nr_pages,
2319 				  gfp_t gfp_mask)
2320 {
2321 	unsigned long nr_reclaimed = 0;
2322 
2323 	do {
2324 		unsigned long pflags;
2325 
2326 		if (page_counter_read(&memcg->memory) <=
2327 		    READ_ONCE(memcg->memory.high))
2328 			continue;
2329 
2330 		memcg_memory_event(memcg, MEMCG_HIGH);
2331 
2332 		psi_memstall_enter(&pflags);
2333 		nr_reclaimed += try_to_free_mem_cgroup_pages(memcg, nr_pages,
2334 							     gfp_mask, true);
2335 		psi_memstall_leave(&pflags);
2336 	} while ((memcg = parent_mem_cgroup(memcg)) &&
2337 		 !mem_cgroup_is_root(memcg));
2338 
2339 	return nr_reclaimed;
2340 }
2341 
2342 static void high_work_func(struct work_struct *work)
2343 {
2344 	struct mem_cgroup *memcg;
2345 
2346 	memcg = container_of(work, struct mem_cgroup, high_work);
2347 	reclaim_high(memcg, MEMCG_CHARGE_BATCH, GFP_KERNEL);
2348 }
2349 
2350 /*
2351  * Clamp the maximum sleep time per allocation batch to 2 seconds. This is
2352  * enough to still cause a significant slowdown in most cases, while still
2353  * allowing diagnostics and tracing to proceed without becoming stuck.
2354  */
2355 #define MEMCG_MAX_HIGH_DELAY_JIFFIES (2UL*HZ)
2356 
2357 /*
2358  * When calculating the delay, we use these either side of the exponentiation to
2359  * maintain precision and scale to a reasonable number of jiffies (see the table
2360  * below.
2361  *
2362  * - MEMCG_DELAY_PRECISION_SHIFT: Extra precision bits while translating the
2363  *   overage ratio to a delay.
2364  * - MEMCG_DELAY_SCALING_SHIFT: The number of bits to scale down the
2365  *   proposed penalty in order to reduce to a reasonable number of jiffies, and
2366  *   to produce a reasonable delay curve.
2367  *
2368  * MEMCG_DELAY_SCALING_SHIFT just happens to be a number that produces a
2369  * reasonable delay curve compared to precision-adjusted overage, not
2370  * penalising heavily at first, but still making sure that growth beyond the
2371  * limit penalises misbehaviour cgroups by slowing them down exponentially. For
2372  * example, with a high of 100 megabytes:
2373  *
2374  *  +-------+------------------------+
2375  *  | usage | time to allocate in ms |
2376  *  +-------+------------------------+
2377  *  | 100M  |                      0 |
2378  *  | 101M  |                      6 |
2379  *  | 102M  |                     25 |
2380  *  | 103M  |                     57 |
2381  *  | 104M  |                    102 |
2382  *  | 105M  |                    159 |
2383  *  | 106M  |                    230 |
2384  *  | 107M  |                    313 |
2385  *  | 108M  |                    409 |
2386  *  | 109M  |                    518 |
2387  *  | 110M  |                    639 |
2388  *  | 111M  |                    774 |
2389  *  | 112M  |                    921 |
2390  *  | 113M  |                   1081 |
2391  *  | 114M  |                   1254 |
2392  *  | 115M  |                   1439 |
2393  *  | 116M  |                   1638 |
2394  *  | 117M  |                   1849 |
2395  *  | 118M  |                   2000 |
2396  *  | 119M  |                   2000 |
2397  *  | 120M  |                   2000 |
2398  *  +-------+------------------------+
2399  */
2400  #define MEMCG_DELAY_PRECISION_SHIFT 20
2401  #define MEMCG_DELAY_SCALING_SHIFT 14
2402 
2403 static u64 calculate_overage(unsigned long usage, unsigned long high)
2404 {
2405 	u64 overage;
2406 
2407 	if (usage <= high)
2408 		return 0;
2409 
2410 	/*
2411 	 * Prevent division by 0 in overage calculation by acting as if
2412 	 * it was a threshold of 1 page
2413 	 */
2414 	high = max(high, 1UL);
2415 
2416 	overage = usage - high;
2417 	overage <<= MEMCG_DELAY_PRECISION_SHIFT;
2418 	return div64_u64(overage, high);
2419 }
2420 
2421 static u64 mem_find_max_overage(struct mem_cgroup *memcg)
2422 {
2423 	u64 overage, max_overage = 0;
2424 
2425 	do {
2426 		overage = calculate_overage(page_counter_read(&memcg->memory),
2427 					    READ_ONCE(memcg->memory.high));
2428 		max_overage = max(overage, max_overage);
2429 	} while ((memcg = parent_mem_cgroup(memcg)) &&
2430 		 !mem_cgroup_is_root(memcg));
2431 
2432 	return max_overage;
2433 }
2434 
2435 static u64 swap_find_max_overage(struct mem_cgroup *memcg)
2436 {
2437 	u64 overage, max_overage = 0;
2438 
2439 	do {
2440 		overage = calculate_overage(page_counter_read(&memcg->swap),
2441 					    READ_ONCE(memcg->swap.high));
2442 		if (overage)
2443 			memcg_memory_event(memcg, MEMCG_SWAP_HIGH);
2444 		max_overage = max(overage, max_overage);
2445 	} while ((memcg = parent_mem_cgroup(memcg)) &&
2446 		 !mem_cgroup_is_root(memcg));
2447 
2448 	return max_overage;
2449 }
2450 
2451 /*
2452  * Get the number of jiffies that we should penalise a mischievous cgroup which
2453  * is exceeding its memory.high by checking both it and its ancestors.
2454  */
2455 static unsigned long calculate_high_delay(struct mem_cgroup *memcg,
2456 					  unsigned int nr_pages,
2457 					  u64 max_overage)
2458 {
2459 	unsigned long penalty_jiffies;
2460 
2461 	if (!max_overage)
2462 		return 0;
2463 
2464 	/*
2465 	 * We use overage compared to memory.high to calculate the number of
2466 	 * jiffies to sleep (penalty_jiffies). Ideally this value should be
2467 	 * fairly lenient on small overages, and increasingly harsh when the
2468 	 * memcg in question makes it clear that it has no intention of stopping
2469 	 * its crazy behaviour, so we exponentially increase the delay based on
2470 	 * overage amount.
2471 	 */
2472 	penalty_jiffies = max_overage * max_overage * HZ;
2473 	penalty_jiffies >>= MEMCG_DELAY_PRECISION_SHIFT;
2474 	penalty_jiffies >>= MEMCG_DELAY_SCALING_SHIFT;
2475 
2476 	/*
2477 	 * Factor in the task's own contribution to the overage, such that four
2478 	 * N-sized allocations are throttled approximately the same as one
2479 	 * 4N-sized allocation.
2480 	 *
2481 	 * MEMCG_CHARGE_BATCH pages is nominal, so work out how much smaller or
2482 	 * larger the current charge patch is than that.
2483 	 */
2484 	return penalty_jiffies * nr_pages / MEMCG_CHARGE_BATCH;
2485 }
2486 
2487 /*
2488  * Scheduled by try_charge() to be executed from the userland return path
2489  * and reclaims memory over the high limit.
2490  */
2491 void mem_cgroup_handle_over_high(void)
2492 {
2493 	unsigned long penalty_jiffies;
2494 	unsigned long pflags;
2495 	unsigned long nr_reclaimed;
2496 	unsigned int nr_pages = current->memcg_nr_pages_over_high;
2497 	int nr_retries = MAX_RECLAIM_RETRIES;
2498 	struct mem_cgroup *memcg;
2499 	bool in_retry = false;
2500 
2501 	if (likely(!nr_pages))
2502 		return;
2503 
2504 	memcg = get_mem_cgroup_from_mm(current->mm);
2505 	current->memcg_nr_pages_over_high = 0;
2506 
2507 retry_reclaim:
2508 	/*
2509 	 * The allocating task should reclaim at least the batch size, but for
2510 	 * subsequent retries we only want to do what's necessary to prevent oom
2511 	 * or breaching resource isolation.
2512 	 *
2513 	 * This is distinct from memory.max or page allocator behaviour because
2514 	 * memory.high is currently batched, whereas memory.max and the page
2515 	 * allocator run every time an allocation is made.
2516 	 */
2517 	nr_reclaimed = reclaim_high(memcg,
2518 				    in_retry ? SWAP_CLUSTER_MAX : nr_pages,
2519 				    GFP_KERNEL);
2520 
2521 	/*
2522 	 * memory.high is breached and reclaim is unable to keep up. Throttle
2523 	 * allocators proactively to slow down excessive growth.
2524 	 */
2525 	penalty_jiffies = calculate_high_delay(memcg, nr_pages,
2526 					       mem_find_max_overage(memcg));
2527 
2528 	penalty_jiffies += calculate_high_delay(memcg, nr_pages,
2529 						swap_find_max_overage(memcg));
2530 
2531 	/*
2532 	 * Clamp the max delay per usermode return so as to still keep the
2533 	 * application moving forwards and also permit diagnostics, albeit
2534 	 * extremely slowly.
2535 	 */
2536 	penalty_jiffies = min(penalty_jiffies, MEMCG_MAX_HIGH_DELAY_JIFFIES);
2537 
2538 	/*
2539 	 * Don't sleep if the amount of jiffies this memcg owes us is so low
2540 	 * that it's not even worth doing, in an attempt to be nice to those who
2541 	 * go only a small amount over their memory.high value and maybe haven't
2542 	 * been aggressively reclaimed enough yet.
2543 	 */
2544 	if (penalty_jiffies <= HZ / 100)
2545 		goto out;
2546 
2547 	/*
2548 	 * If reclaim is making forward progress but we're still over
2549 	 * memory.high, we want to encourage that rather than doing allocator
2550 	 * throttling.
2551 	 */
2552 	if (nr_reclaimed || nr_retries--) {
2553 		in_retry = true;
2554 		goto retry_reclaim;
2555 	}
2556 
2557 	/*
2558 	 * If we exit early, we're guaranteed to die (since
2559 	 * schedule_timeout_killable sets TASK_KILLABLE). This means we don't
2560 	 * need to account for any ill-begotten jiffies to pay them off later.
2561 	 */
2562 	psi_memstall_enter(&pflags);
2563 	schedule_timeout_killable(penalty_jiffies);
2564 	psi_memstall_leave(&pflags);
2565 
2566 out:
2567 	css_put(&memcg->css);
2568 }
2569 
2570 static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
2571 			unsigned int nr_pages)
2572 {
2573 	unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages);
2574 	int nr_retries = MAX_RECLAIM_RETRIES;
2575 	struct mem_cgroup *mem_over_limit;
2576 	struct page_counter *counter;
2577 	unsigned long nr_reclaimed;
2578 	bool passed_oom = false;
2579 	bool may_swap = true;
2580 	bool drained = false;
2581 	unsigned long pflags;
2582 
2583 retry:
2584 	if (consume_stock(memcg, nr_pages))
2585 		return 0;
2586 
2587 	if (!do_memsw_account() ||
2588 	    page_counter_try_charge(&memcg->memsw, batch, &counter)) {
2589 		if (page_counter_try_charge(&memcg->memory, batch, &counter))
2590 			goto done_restock;
2591 		if (do_memsw_account())
2592 			page_counter_uncharge(&memcg->memsw, batch);
2593 		mem_over_limit = mem_cgroup_from_counter(counter, memory);
2594 	} else {
2595 		mem_over_limit = mem_cgroup_from_counter(counter, memsw);
2596 		may_swap = false;
2597 	}
2598 
2599 	if (batch > nr_pages) {
2600 		batch = nr_pages;
2601 		goto retry;
2602 	}
2603 
2604 	/*
2605 	 * Prevent unbounded recursion when reclaim operations need to
2606 	 * allocate memory. This might exceed the limits temporarily,
2607 	 * but we prefer facilitating memory reclaim and getting back
2608 	 * under the limit over triggering OOM kills in these cases.
2609 	 */
2610 	if (unlikely(current->flags & PF_MEMALLOC))
2611 		goto force;
2612 
2613 	if (unlikely(task_in_memcg_oom(current)))
2614 		goto nomem;
2615 
2616 	if (!gfpflags_allow_blocking(gfp_mask))
2617 		goto nomem;
2618 
2619 	memcg_memory_event(mem_over_limit, MEMCG_MAX);
2620 
2621 	psi_memstall_enter(&pflags);
2622 	nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages,
2623 						    gfp_mask, may_swap);
2624 	psi_memstall_leave(&pflags);
2625 
2626 	if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
2627 		goto retry;
2628 
2629 	if (!drained) {
2630 		drain_all_stock(mem_over_limit);
2631 		drained = true;
2632 		goto retry;
2633 	}
2634 
2635 	if (gfp_mask & __GFP_NORETRY)
2636 		goto nomem;
2637 	/*
2638 	 * Even though the limit is exceeded at this point, reclaim
2639 	 * may have been able to free some pages.  Retry the charge
2640 	 * before killing the task.
2641 	 *
2642 	 * Only for regular pages, though: huge pages are rather
2643 	 * unlikely to succeed so close to the limit, and we fall back
2644 	 * to regular pages anyway in case of failure.
2645 	 */
2646 	if (nr_reclaimed && nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER))
2647 		goto retry;
2648 	/*
2649 	 * At task move, charge accounts can be doubly counted. So, it's
2650 	 * better to wait until the end of task_move if something is going on.
2651 	 */
2652 	if (mem_cgroup_wait_acct_move(mem_over_limit))
2653 		goto retry;
2654 
2655 	if (nr_retries--)
2656 		goto retry;
2657 
2658 	if (gfp_mask & __GFP_RETRY_MAYFAIL)
2659 		goto nomem;
2660 
2661 	/* Avoid endless loop for tasks bypassed by the oom killer */
2662 	if (passed_oom && task_is_dying())
2663 		goto nomem;
2664 
2665 	/*
2666 	 * keep retrying as long as the memcg oom killer is able to make
2667 	 * a forward progress or bypass the charge if the oom killer
2668 	 * couldn't make any progress.
2669 	 */
2670 	if (mem_cgroup_oom(mem_over_limit, gfp_mask,
2671 			   get_order(nr_pages * PAGE_SIZE))) {
2672 		passed_oom = true;
2673 		nr_retries = MAX_RECLAIM_RETRIES;
2674 		goto retry;
2675 	}
2676 nomem:
2677 	/*
2678 	 * Memcg doesn't have a dedicated reserve for atomic
2679 	 * allocations. But like the global atomic pool, we need to
2680 	 * put the burden of reclaim on regular allocation requests
2681 	 * and let these go through as privileged allocations.
2682 	 */
2683 	if (!(gfp_mask & (__GFP_NOFAIL | __GFP_HIGH)))
2684 		return -ENOMEM;
2685 force:
2686 	/*
2687 	 * The allocation either can't fail or will lead to more memory
2688 	 * being freed very soon.  Allow memory usage go over the limit
2689 	 * temporarily by force charging it.
2690 	 */
2691 	page_counter_charge(&memcg->memory, nr_pages);
2692 	if (do_memsw_account())
2693 		page_counter_charge(&memcg->memsw, nr_pages);
2694 
2695 	return 0;
2696 
2697 done_restock:
2698 	if (batch > nr_pages)
2699 		refill_stock(memcg, batch - nr_pages);
2700 
2701 	/*
2702 	 * If the hierarchy is above the normal consumption range, schedule
2703 	 * reclaim on returning to userland.  We can perform reclaim here
2704 	 * if __GFP_RECLAIM but let's always punt for simplicity and so that
2705 	 * GFP_KERNEL can consistently be used during reclaim.  @memcg is
2706 	 * not recorded as it most likely matches current's and won't
2707 	 * change in the meantime.  As high limit is checked again before
2708 	 * reclaim, the cost of mismatch is negligible.
2709 	 */
2710 	do {
2711 		bool mem_high, swap_high;
2712 
2713 		mem_high = page_counter_read(&memcg->memory) >
2714 			READ_ONCE(memcg->memory.high);
2715 		swap_high = page_counter_read(&memcg->swap) >
2716 			READ_ONCE(memcg->swap.high);
2717 
2718 		/* Don't bother a random interrupted task */
2719 		if (!in_task()) {
2720 			if (mem_high) {
2721 				schedule_work(&memcg->high_work);
2722 				break;
2723 			}
2724 			continue;
2725 		}
2726 
2727 		if (mem_high || swap_high) {
2728 			/*
2729 			 * The allocating tasks in this cgroup will need to do
2730 			 * reclaim or be throttled to prevent further growth
2731 			 * of the memory or swap footprints.
2732 			 *
2733 			 * Target some best-effort fairness between the tasks,
2734 			 * and distribute reclaim work and delay penalties
2735 			 * based on how much each task is actually allocating.
2736 			 */
2737 			current->memcg_nr_pages_over_high += batch;
2738 			set_notify_resume(current);
2739 			break;
2740 		}
2741 	} while ((memcg = parent_mem_cgroup(memcg)));
2742 
2743 	if (current->memcg_nr_pages_over_high > MEMCG_CHARGE_BATCH &&
2744 	    !(current->flags & PF_MEMALLOC) &&
2745 	    gfpflags_allow_blocking(gfp_mask)) {
2746 		mem_cgroup_handle_over_high();
2747 	}
2748 	return 0;
2749 }
2750 
2751 static inline int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
2752 			     unsigned int nr_pages)
2753 {
2754 	if (mem_cgroup_is_root(memcg))
2755 		return 0;
2756 
2757 	return try_charge_memcg(memcg, gfp_mask, nr_pages);
2758 }
2759 
2760 static inline void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
2761 {
2762 	if (mem_cgroup_is_root(memcg))
2763 		return;
2764 
2765 	page_counter_uncharge(&memcg->memory, nr_pages);
2766 	if (do_memsw_account())
2767 		page_counter_uncharge(&memcg->memsw, nr_pages);
2768 }
2769 
2770 static void commit_charge(struct folio *folio, struct mem_cgroup *memcg)
2771 {
2772 	VM_BUG_ON_FOLIO(folio_memcg(folio), folio);
2773 	/*
2774 	 * Any of the following ensures page's memcg stability:
2775 	 *
2776 	 * - the page lock
2777 	 * - LRU isolation
2778 	 * - lock_page_memcg()
2779 	 * - exclusive reference
2780 	 */
2781 	folio->memcg_data = (unsigned long)memcg;
2782 }
2783 
2784 #ifdef CONFIG_MEMCG_KMEM
2785 /*
2786  * The allocated objcg pointers array is not accounted directly.
2787  * Moreover, it should not come from DMA buffer and is not readily
2788  * reclaimable. So those GFP bits should be masked off.
2789  */
2790 #define OBJCGS_CLEAR_MASK	(__GFP_DMA | __GFP_RECLAIMABLE | __GFP_ACCOUNT)
2791 
2792 /*
2793  * mod_objcg_mlstate() may be called with irq enabled, so
2794  * mod_memcg_lruvec_state() should be used.
2795  */
2796 static inline void mod_objcg_mlstate(struct obj_cgroup *objcg,
2797 				     struct pglist_data *pgdat,
2798 				     enum node_stat_item idx, int nr)
2799 {
2800 	struct mem_cgroup *memcg;
2801 	struct lruvec *lruvec;
2802 
2803 	rcu_read_lock();
2804 	memcg = obj_cgroup_memcg(objcg);
2805 	lruvec = mem_cgroup_lruvec(memcg, pgdat);
2806 	mod_memcg_lruvec_state(lruvec, idx, nr);
2807 	rcu_read_unlock();
2808 }
2809 
2810 int memcg_alloc_slab_cgroups(struct slab *slab, struct kmem_cache *s,
2811 				 gfp_t gfp, bool new_slab)
2812 {
2813 	unsigned int objects = objs_per_slab(s, slab);
2814 	unsigned long memcg_data;
2815 	void *vec;
2816 
2817 	gfp &= ~OBJCGS_CLEAR_MASK;
2818 	vec = kcalloc_node(objects, sizeof(struct obj_cgroup *), gfp,
2819 			   slab_nid(slab));
2820 	if (!vec)
2821 		return -ENOMEM;
2822 
2823 	memcg_data = (unsigned long) vec | MEMCG_DATA_OBJCGS;
2824 	if (new_slab) {
2825 		/*
2826 		 * If the slab is brand new and nobody can yet access its
2827 		 * memcg_data, no synchronization is required and memcg_data can
2828 		 * be simply assigned.
2829 		 */
2830 		slab->memcg_data = memcg_data;
2831 	} else if (cmpxchg(&slab->memcg_data, 0, memcg_data)) {
2832 		/*
2833 		 * If the slab is already in use, somebody can allocate and
2834 		 * assign obj_cgroups in parallel. In this case the existing
2835 		 * objcg vector should be reused.
2836 		 */
2837 		kfree(vec);
2838 		return 0;
2839 	}
2840 
2841 	kmemleak_not_leak(vec);
2842 	return 0;
2843 }
2844 
2845 /*
2846  * Returns a pointer to the memory cgroup to which the kernel object is charged.
2847  *
2848  * A passed kernel object can be a slab object or a generic kernel page, so
2849  * different mechanisms for getting the memory cgroup pointer should be used.
2850  * In certain cases (e.g. kernel stacks or large kmallocs with SLUB) the caller
2851  * can not know for sure how the kernel object is implemented.
2852  * mem_cgroup_from_obj() can be safely used in such cases.
2853  *
2854  * The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(),
2855  * cgroup_mutex, etc.
2856  */
2857 struct mem_cgroup *mem_cgroup_from_obj(void *p)
2858 {
2859 	struct folio *folio;
2860 
2861 	if (mem_cgroup_disabled())
2862 		return NULL;
2863 
2864 	folio = virt_to_folio(p);
2865 
2866 	/*
2867 	 * Slab objects are accounted individually, not per-page.
2868 	 * Memcg membership data for each individual object is saved in
2869 	 * slab->memcg_data.
2870 	 */
2871 	if (folio_test_slab(folio)) {
2872 		struct obj_cgroup **objcgs;
2873 		struct slab *slab;
2874 		unsigned int off;
2875 
2876 		slab = folio_slab(folio);
2877 		objcgs = slab_objcgs(slab);
2878 		if (!objcgs)
2879 			return NULL;
2880 
2881 		off = obj_to_index(slab->slab_cache, slab, p);
2882 		if (objcgs[off])
2883 			return obj_cgroup_memcg(objcgs[off]);
2884 
2885 		return NULL;
2886 	}
2887 
2888 	/*
2889 	 * page_memcg_check() is used here, because in theory we can encounter
2890 	 * a folio where the slab flag has been cleared already, but
2891 	 * slab->memcg_data has not been freed yet
2892 	 * page_memcg_check(page) will guarantee that a proper memory
2893 	 * cgroup pointer or NULL will be returned.
2894 	 */
2895 	return page_memcg_check(folio_page(folio, 0));
2896 }
2897 
2898 static struct obj_cgroup *__get_obj_cgroup_from_memcg(struct mem_cgroup *memcg)
2899 {
2900 	struct obj_cgroup *objcg = NULL;
2901 
2902 	for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) {
2903 		objcg = rcu_dereference(memcg->objcg);
2904 		if (objcg && obj_cgroup_tryget(objcg))
2905 			break;
2906 		objcg = NULL;
2907 	}
2908 	return objcg;
2909 }
2910 
2911 __always_inline struct obj_cgroup *get_obj_cgroup_from_current(void)
2912 {
2913 	struct obj_cgroup *objcg = NULL;
2914 	struct mem_cgroup *memcg;
2915 
2916 	if (memcg_kmem_bypass())
2917 		return NULL;
2918 
2919 	rcu_read_lock();
2920 	if (unlikely(active_memcg()))
2921 		memcg = active_memcg();
2922 	else
2923 		memcg = mem_cgroup_from_task(current);
2924 	objcg = __get_obj_cgroup_from_memcg(memcg);
2925 	rcu_read_unlock();
2926 	return objcg;
2927 }
2928 
2929 struct obj_cgroup *get_obj_cgroup_from_page(struct page *page)
2930 {
2931 	struct obj_cgroup *objcg;
2932 
2933 	if (!memcg_kmem_enabled() || memcg_kmem_bypass())
2934 		return NULL;
2935 
2936 	if (PageMemcgKmem(page)) {
2937 		objcg = __folio_objcg(page_folio(page));
2938 		obj_cgroup_get(objcg);
2939 	} else {
2940 		struct mem_cgroup *memcg;
2941 
2942 		rcu_read_lock();
2943 		memcg = __folio_memcg(page_folio(page));
2944 		if (memcg)
2945 			objcg = __get_obj_cgroup_from_memcg(memcg);
2946 		else
2947 			objcg = NULL;
2948 		rcu_read_unlock();
2949 	}
2950 	return objcg;
2951 }
2952 
2953 static void memcg_account_kmem(struct mem_cgroup *memcg, int nr_pages)
2954 {
2955 	mod_memcg_state(memcg, MEMCG_KMEM, nr_pages);
2956 	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
2957 		if (nr_pages > 0)
2958 			page_counter_charge(&memcg->kmem, nr_pages);
2959 		else
2960 			page_counter_uncharge(&memcg->kmem, -nr_pages);
2961 	}
2962 }
2963 
2964 
2965 /*
2966  * obj_cgroup_uncharge_pages: uncharge a number of kernel pages from a objcg
2967  * @objcg: object cgroup to uncharge
2968  * @nr_pages: number of pages to uncharge
2969  */
2970 static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
2971 				      unsigned int nr_pages)
2972 {
2973 	struct mem_cgroup *memcg;
2974 
2975 	memcg = get_mem_cgroup_from_objcg(objcg);
2976 
2977 	memcg_account_kmem(memcg, -nr_pages);
2978 	refill_stock(memcg, nr_pages);
2979 
2980 	css_put(&memcg->css);
2981 }
2982 
2983 /*
2984  * obj_cgroup_charge_pages: charge a number of kernel pages to a objcg
2985  * @objcg: object cgroup to charge
2986  * @gfp: reclaim mode
2987  * @nr_pages: number of pages to charge
2988  *
2989  * Returns 0 on success, an error code on failure.
2990  */
2991 static int obj_cgroup_charge_pages(struct obj_cgroup *objcg, gfp_t gfp,
2992 				   unsigned int nr_pages)
2993 {
2994 	struct mem_cgroup *memcg;
2995 	int ret;
2996 
2997 	memcg = get_mem_cgroup_from_objcg(objcg);
2998 
2999 	ret = try_charge_memcg(memcg, gfp, nr_pages);
3000 	if (ret)
3001 		goto out;
3002 
3003 	memcg_account_kmem(memcg, nr_pages);
3004 out:
3005 	css_put(&memcg->css);
3006 
3007 	return ret;
3008 }
3009 
3010 /**
3011  * __memcg_kmem_charge_page: charge a kmem page to the current memory cgroup
3012  * @page: page to charge
3013  * @gfp: reclaim mode
3014  * @order: allocation order
3015  *
3016  * Returns 0 on success, an error code on failure.
3017  */
3018 int __memcg_kmem_charge_page(struct page *page, gfp_t gfp, int order)
3019 {
3020 	struct obj_cgroup *objcg;
3021 	int ret = 0;
3022 
3023 	objcg = get_obj_cgroup_from_current();
3024 	if (objcg) {
3025 		ret = obj_cgroup_charge_pages(objcg, gfp, 1 << order);
3026 		if (!ret) {
3027 			page->memcg_data = (unsigned long)objcg |
3028 				MEMCG_DATA_KMEM;
3029 			return 0;
3030 		}
3031 		obj_cgroup_put(objcg);
3032 	}
3033 	return ret;
3034 }
3035 
3036 /**
3037  * __memcg_kmem_uncharge_page: uncharge a kmem page
3038  * @page: page to uncharge
3039  * @order: allocation order
3040  */
3041 void __memcg_kmem_uncharge_page(struct page *page, int order)
3042 {
3043 	struct folio *folio = page_folio(page);
3044 	struct obj_cgroup *objcg;
3045 	unsigned int nr_pages = 1 << order;
3046 
3047 	if (!folio_memcg_kmem(folio))
3048 		return;
3049 
3050 	objcg = __folio_objcg(folio);
3051 	obj_cgroup_uncharge_pages(objcg, nr_pages);
3052 	folio->memcg_data = 0;
3053 	obj_cgroup_put(objcg);
3054 }
3055 
3056 void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat,
3057 		     enum node_stat_item idx, int nr)
3058 {
3059 	struct memcg_stock_pcp *stock;
3060 	struct obj_cgroup *old = NULL;
3061 	unsigned long flags;
3062 	int *bytes;
3063 
3064 	local_lock_irqsave(&memcg_stock.stock_lock, flags);
3065 	stock = this_cpu_ptr(&memcg_stock);
3066 
3067 	/*
3068 	 * Save vmstat data in stock and skip vmstat array update unless
3069 	 * accumulating over a page of vmstat data or when pgdat or idx
3070 	 * changes.
3071 	 */
3072 	if (stock->cached_objcg != objcg) {
3073 		old = drain_obj_stock(stock);
3074 		obj_cgroup_get(objcg);
3075 		stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes)
3076 				? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;
3077 		stock->cached_objcg = objcg;
3078 		stock->cached_pgdat = pgdat;
3079 	} else if (stock->cached_pgdat != pgdat) {
3080 		/* Flush the existing cached vmstat data */
3081 		struct pglist_data *oldpg = stock->cached_pgdat;
3082 
3083 		if (stock->nr_slab_reclaimable_b) {
3084 			mod_objcg_mlstate(objcg, oldpg, NR_SLAB_RECLAIMABLE_B,
3085 					  stock->nr_slab_reclaimable_b);
3086 			stock->nr_slab_reclaimable_b = 0;
3087 		}
3088 		if (stock->nr_slab_unreclaimable_b) {
3089 			mod_objcg_mlstate(objcg, oldpg, NR_SLAB_UNRECLAIMABLE_B,
3090 					  stock->nr_slab_unreclaimable_b);
3091 			stock->nr_slab_unreclaimable_b = 0;
3092 		}
3093 		stock->cached_pgdat = pgdat;
3094 	}
3095 
3096 	bytes = (idx == NR_SLAB_RECLAIMABLE_B) ? &stock->nr_slab_reclaimable_b
3097 					       : &stock->nr_slab_unreclaimable_b;
3098 	/*
3099 	 * Even for large object >= PAGE_SIZE, the vmstat data will still be
3100 	 * cached locally at least once before pushing it out.
3101 	 */
3102 	if (!*bytes) {
3103 		*bytes = nr;
3104 		nr = 0;
3105 	} else {
3106 		*bytes += nr;
3107 		if (abs(*bytes) > PAGE_SIZE) {
3108 			nr = *bytes;
3109 			*bytes = 0;
3110 		} else {
3111 			nr = 0;
3112 		}
3113 	}
3114 	if (nr)
3115 		mod_objcg_mlstate(objcg, pgdat, idx, nr);
3116 
3117 	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
3118 	if (old)
3119 		obj_cgroup_put(old);
3120 }
3121 
3122 static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes)
3123 {
3124 	struct memcg_stock_pcp *stock;
3125 	unsigned long flags;
3126 	bool ret = false;
3127 
3128 	local_lock_irqsave(&memcg_stock.stock_lock, flags);
3129 
3130 	stock = this_cpu_ptr(&memcg_stock);
3131 	if (objcg == stock->cached_objcg && stock->nr_bytes >= nr_bytes) {
3132 		stock->nr_bytes -= nr_bytes;
3133 		ret = true;
3134 	}
3135 
3136 	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
3137 
3138 	return ret;
3139 }
3140 
3141 static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock)
3142 {
3143 	struct obj_cgroup *old = stock->cached_objcg;
3144 
3145 	if (!old)
3146 		return NULL;
3147 
3148 	if (stock->nr_bytes) {
3149 		unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT;
3150 		unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1);
3151 
3152 		if (nr_pages) {
3153 			struct mem_cgroup *memcg;
3154 
3155 			memcg = get_mem_cgroup_from_objcg(old);
3156 
3157 			memcg_account_kmem(memcg, -nr_pages);
3158 			__refill_stock(memcg, nr_pages);
3159 
3160 			css_put(&memcg->css);
3161 		}
3162 
3163 		/*
3164 		 * The leftover is flushed to the centralized per-memcg value.
3165 		 * On the next attempt to refill obj stock it will be moved
3166 		 * to a per-cpu stock (probably, on an other CPU), see
3167 		 * refill_obj_stock().
3168 		 *
3169 		 * How often it's flushed is a trade-off between the memory
3170 		 * limit enforcement accuracy and potential CPU contention,
3171 		 * so it might be changed in the future.
3172 		 */
3173 		atomic_add(nr_bytes, &old->nr_charged_bytes);
3174 		stock->nr_bytes = 0;
3175 	}
3176 
3177 	/*
3178 	 * Flush the vmstat data in current stock
3179 	 */
3180 	if (stock->nr_slab_reclaimable_b || stock->nr_slab_unreclaimable_b) {
3181 		if (stock->nr_slab_reclaimable_b) {
3182 			mod_objcg_mlstate(old, stock->cached_pgdat,
3183 					  NR_SLAB_RECLAIMABLE_B,
3184 					  stock->nr_slab_reclaimable_b);
3185 			stock->nr_slab_reclaimable_b = 0;
3186 		}
3187 		if (stock->nr_slab_unreclaimable_b) {
3188 			mod_objcg_mlstate(old, stock->cached_pgdat,
3189 					  NR_SLAB_UNRECLAIMABLE_B,
3190 					  stock->nr_slab_unreclaimable_b);
3191 			stock->nr_slab_unreclaimable_b = 0;
3192 		}
3193 		stock->cached_pgdat = NULL;
3194 	}
3195 
3196 	stock->cached_objcg = NULL;
3197 	/*
3198 	 * The `old' objects needs to be released by the caller via
3199 	 * obj_cgroup_put() outside of memcg_stock_pcp::stock_lock.
3200 	 */
3201 	return old;
3202 }
3203 
3204 static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
3205 				     struct mem_cgroup *root_memcg)
3206 {
3207 	struct mem_cgroup *memcg;
3208 
3209 	if (stock->cached_objcg) {
3210 		memcg = obj_cgroup_memcg(stock->cached_objcg);
3211 		if (memcg && mem_cgroup_is_descendant(memcg, root_memcg))
3212 			return true;
3213 	}
3214 
3215 	return false;
3216 }
3217 
3218 static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
3219 			     bool allow_uncharge)
3220 {
3221 	struct memcg_stock_pcp *stock;
3222 	struct obj_cgroup *old = NULL;
3223 	unsigned long flags;
3224 	unsigned int nr_pages = 0;
3225 
3226 	local_lock_irqsave(&memcg_stock.stock_lock, flags);
3227 
3228 	stock = this_cpu_ptr(&memcg_stock);
3229 	if (stock->cached_objcg != objcg) { /* reset if necessary */
3230 		old = drain_obj_stock(stock);
3231 		obj_cgroup_get(objcg);
3232 		stock->cached_objcg = objcg;
3233 		stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes)
3234 				? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;
3235 		allow_uncharge = true;	/* Allow uncharge when objcg changes */
3236 	}
3237 	stock->nr_bytes += nr_bytes;
3238 
3239 	if (allow_uncharge && (stock->nr_bytes > PAGE_SIZE)) {
3240 		nr_pages = stock->nr_bytes >> PAGE_SHIFT;
3241 		stock->nr_bytes &= (PAGE_SIZE - 1);
3242 	}
3243 
3244 	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
3245 	if (old)
3246 		obj_cgroup_put(old);
3247 
3248 	if (nr_pages)
3249 		obj_cgroup_uncharge_pages(objcg, nr_pages);
3250 }
3251 
3252 int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
3253 {
3254 	unsigned int nr_pages, nr_bytes;
3255 	int ret;
3256 
3257 	if (consume_obj_stock(objcg, size))
3258 		return 0;
3259 
3260 	/*
3261 	 * In theory, objcg->nr_charged_bytes can have enough
3262 	 * pre-charged bytes to satisfy the allocation. However,
3263 	 * flushing objcg->nr_charged_bytes requires two atomic
3264 	 * operations, and objcg->nr_charged_bytes can't be big.
3265 	 * The shared objcg->nr_charged_bytes can also become a
3266 	 * performance bottleneck if all tasks of the same memcg are
3267 	 * trying to update it. So it's better to ignore it and try
3268 	 * grab some new pages. The stock's nr_bytes will be flushed to
3269 	 * objcg->nr_charged_bytes later on when objcg changes.
3270 	 *
3271 	 * The stock's nr_bytes may contain enough pre-charged bytes
3272 	 * to allow one less page from being charged, but we can't rely
3273 	 * on the pre-charged bytes not being changed outside of
3274 	 * consume_obj_stock() or refill_obj_stock(). So ignore those
3275 	 * pre-charged bytes as well when charging pages. To avoid a
3276 	 * page uncharge right after a page charge, we set the
3277 	 * allow_uncharge flag to false when calling refill_obj_stock()
3278 	 * to temporarily allow the pre-charged bytes to exceed the page
3279 	 * size limit. The maximum reachable value of the pre-charged
3280 	 * bytes is (sizeof(object) + PAGE_SIZE - 2) if there is no data
3281 	 * race.
3282 	 */
3283 	nr_pages = size >> PAGE_SHIFT;
3284 	nr_bytes = size & (PAGE_SIZE - 1);
3285 
3286 	if (nr_bytes)
3287 		nr_pages += 1;
3288 
3289 	ret = obj_cgroup_charge_pages(objcg, gfp, nr_pages);
3290 	if (!ret && nr_bytes)
3291 		refill_obj_stock(objcg, PAGE_SIZE - nr_bytes, false);
3292 
3293 	return ret;
3294 }
3295 
3296 void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size)
3297 {
3298 	refill_obj_stock(objcg, size, true);
3299 }
3300 
3301 #endif /* CONFIG_MEMCG_KMEM */
3302 
3303 /*
3304  * Because page_memcg(head) is not set on tails, set it now.
3305  */
3306 void split_page_memcg(struct page *head, unsigned int nr)
3307 {
3308 	struct folio *folio = page_folio(head);
3309 	struct mem_cgroup *memcg = folio_memcg(folio);
3310 	int i;
3311 
3312 	if (mem_cgroup_disabled() || !memcg)
3313 		return;
3314 
3315 	for (i = 1; i < nr; i++)
3316 		folio_page(folio, i)->memcg_data = folio->memcg_data;
3317 
3318 	if (folio_memcg_kmem(folio))
3319 		obj_cgroup_get_many(__folio_objcg(folio), nr - 1);
3320 	else
3321 		css_get_many(&memcg->css, nr - 1);
3322 }
3323 
3324 #ifdef CONFIG_MEMCG_SWAP
3325 /**
3326  * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
3327  * @entry: swap entry to be moved
3328  * @from:  mem_cgroup which the entry is moved from
3329  * @to:  mem_cgroup which the entry is moved to
3330  *
3331  * It succeeds only when the swap_cgroup's record for this entry is the same
3332  * as the mem_cgroup's id of @from.
3333  *
3334  * Returns 0 on success, -EINVAL on failure.
3335  *
3336  * The caller must have charged to @to, IOW, called page_counter_charge() about
3337  * both res and memsw, and called css_get().
3338  */
3339 static int mem_cgroup_move_swap_account(swp_entry_t entry,
3340 				struct mem_cgroup *from, struct mem_cgroup *to)
3341 {
3342 	unsigned short old_id, new_id;
3343 
3344 	old_id = mem_cgroup_id(from);
3345 	new_id = mem_cgroup_id(to);
3346 
3347 	if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
3348 		mod_memcg_state(from, MEMCG_SWAP, -1);
3349 		mod_memcg_state(to, MEMCG_SWAP, 1);
3350 		return 0;
3351 	}
3352 	return -EINVAL;
3353 }
3354 #else
3355 static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
3356 				struct mem_cgroup *from, struct mem_cgroup *to)
3357 {
3358 	return -EINVAL;
3359 }
3360 #endif
3361 
3362 static DEFINE_MUTEX(memcg_max_mutex);
3363 
3364 static int mem_cgroup_resize_max(struct mem_cgroup *memcg,
3365 				 unsigned long max, bool memsw)
3366 {
3367 	bool enlarge = false;
3368 	bool drained = false;
3369 	int ret;
3370 	bool limits_invariant;
3371 	struct page_counter *counter = memsw ? &memcg->memsw : &memcg->memory;
3372 
3373 	do {
3374 		if (signal_pending(current)) {
3375 			ret = -EINTR;
3376 			break;
3377 		}
3378 
3379 		mutex_lock(&memcg_max_mutex);
3380 		/*
3381 		 * Make sure that the new limit (memsw or memory limit) doesn't
3382 		 * break our basic invariant rule memory.max <= memsw.max.
3383 		 */
3384 		limits_invariant = memsw ? max >= READ_ONCE(memcg->memory.max) :
3385 					   max <= memcg->memsw.max;
3386 		if (!limits_invariant) {
3387 			mutex_unlock(&memcg_max_mutex);
3388 			ret = -EINVAL;
3389 			break;
3390 		}
3391 		if (max > counter->max)
3392 			enlarge = true;
3393 		ret = page_counter_set_max(counter, max);
3394 		mutex_unlock(&memcg_max_mutex);
3395 
3396 		if (!ret)
3397 			break;
3398 
3399 		if (!drained) {
3400 			drain_all_stock(memcg);
3401 			drained = true;
3402 			continue;
3403 		}
3404 
3405 		if (!try_to_free_mem_cgroup_pages(memcg, 1,
3406 					GFP_KERNEL, !memsw)) {
3407 			ret = -EBUSY;
3408 			break;
3409 		}
3410 	} while (true);
3411 
3412 	if (!ret && enlarge)
3413 		memcg_oom_recover(memcg);
3414 
3415 	return ret;
3416 }
3417 
3418 unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
3419 					    gfp_t gfp_mask,
3420 					    unsigned long *total_scanned)
3421 {
3422 	unsigned long nr_reclaimed = 0;
3423 	struct mem_cgroup_per_node *mz, *next_mz = NULL;
3424 	unsigned long reclaimed;
3425 	int loop = 0;
3426 	struct mem_cgroup_tree_per_node *mctz;
3427 	unsigned long excess;
3428 
3429 	if (order > 0)
3430 		return 0;
3431 
3432 	mctz = soft_limit_tree.rb_tree_per_node[pgdat->node_id];
3433 
3434 	/*
3435 	 * Do not even bother to check the largest node if the root
3436 	 * is empty. Do it lockless to prevent lock bouncing. Races
3437 	 * are acceptable as soft limit is best effort anyway.
3438 	 */
3439 	if (!mctz || RB_EMPTY_ROOT(&mctz->rb_root))
3440 		return 0;
3441 
3442 	/*
3443 	 * This loop can run a while, specially if mem_cgroup's continuously
3444 	 * keep exceeding their soft limit and putting the system under
3445 	 * pressure
3446 	 */
3447 	do {
3448 		if (next_mz)
3449 			mz = next_mz;
3450 		else
3451 			mz = mem_cgroup_largest_soft_limit_node(mctz);
3452 		if (!mz)
3453 			break;
3454 
3455 		reclaimed = mem_cgroup_soft_reclaim(mz->memcg, pgdat,
3456 						    gfp_mask, total_scanned);
3457 		nr_reclaimed += reclaimed;
3458 		spin_lock_irq(&mctz->lock);
3459 
3460 		/*
3461 		 * If we failed to reclaim anything from this memory cgroup
3462 		 * it is time to move on to the next cgroup
3463 		 */
3464 		next_mz = NULL;
3465 		if (!reclaimed)
3466 			next_mz = __mem_cgroup_largest_soft_limit_node(mctz);
3467 
3468 		excess = soft_limit_excess(mz->memcg);
3469 		/*
3470 		 * One school of thought says that we should not add
3471 		 * back the node to the tree if reclaim returns 0.
3472 		 * But our reclaim could return 0, simply because due
3473 		 * to priority we are exposing a smaller subset of
3474 		 * memory to reclaim from. Consider this as a longer
3475 		 * term TODO.
3476 		 */
3477 		/* If excess == 0, no tree ops */
3478 		__mem_cgroup_insert_exceeded(mz, mctz, excess);
3479 		spin_unlock_irq(&mctz->lock);
3480 		css_put(&mz->memcg->css);
3481 		loop++;
3482 		/*
3483 		 * Could not reclaim anything and there are no more
3484 		 * mem cgroups to try or we seem to be looping without
3485 		 * reclaiming anything.
3486 		 */
3487 		if (!nr_reclaimed &&
3488 			(next_mz == NULL ||
3489 			loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
3490 			break;
3491 	} while (!nr_reclaimed);
3492 	if (next_mz)
3493 		css_put(&next_mz->memcg->css);
3494 	return nr_reclaimed;
3495 }
3496 
3497 /*
3498  * Reclaims as many pages from the given memcg as possible.
3499  *
3500  * Caller is responsible for holding css reference for memcg.
3501  */
3502 static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
3503 {
3504 	int nr_retries = MAX_RECLAIM_RETRIES;
3505 
3506 	/* we call try-to-free pages for make this cgroup empty */
3507 	lru_add_drain_all();
3508 
3509 	drain_all_stock(memcg);
3510 
3511 	/* try to free all pages in this cgroup */
3512 	while (nr_retries && page_counter_read(&memcg->memory)) {
3513 		if (signal_pending(current))
3514 			return -EINTR;
3515 
3516 		if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, true))
3517 			nr_retries--;
3518 	}
3519 
3520 	return 0;
3521 }
3522 
3523 static ssize_t mem_cgroup_force_empty_write(struct kernfs_open_file *of,
3524 					    char *buf, size_t nbytes,
3525 					    loff_t off)
3526 {
3527 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
3528 
3529 	if (mem_cgroup_is_root(memcg))
3530 		return -EINVAL;
3531 	return mem_cgroup_force_empty(memcg) ?: nbytes;
3532 }
3533 
3534 static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css,
3535 				     struct cftype *cft)
3536 {
3537 	return 1;
3538 }
3539 
3540 static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
3541 				      struct cftype *cft, u64 val)
3542 {
3543 	if (val == 1)
3544 		return 0;
3545 
3546 	pr_warn_once("Non-hierarchical mode is deprecated. "
3547 		     "Please report your usecase to linux-mm@kvack.org if you "
3548 		     "depend on this functionality.\n");
3549 
3550 	return -EINVAL;
3551 }
3552 
3553 static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
3554 {
3555 	unsigned long val;
3556 
3557 	if (mem_cgroup_is_root(memcg)) {
3558 		mem_cgroup_flush_stats();
3559 		val = memcg_page_state(memcg, NR_FILE_PAGES) +
3560 			memcg_page_state(memcg, NR_ANON_MAPPED);
3561 		if (swap)
3562 			val += memcg_page_state(memcg, MEMCG_SWAP);
3563 	} else {
3564 		if (!swap)
3565 			val = page_counter_read(&memcg->memory);
3566 		else
3567 			val = page_counter_read(&memcg->memsw);
3568 	}
3569 	return val;
3570 }
3571 
3572 enum {
3573 	RES_USAGE,
3574 	RES_LIMIT,
3575 	RES_MAX_USAGE,
3576 	RES_FAILCNT,
3577 	RES_SOFT_LIMIT,
3578 };
3579 
3580 static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
3581 			       struct cftype *cft)
3582 {
3583 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
3584 	struct page_counter *counter;
3585 
3586 	switch (MEMFILE_TYPE(cft->private)) {
3587 	case _MEM:
3588 		counter = &memcg->memory;
3589 		break;
3590 	case _MEMSWAP:
3591 		counter = &memcg->memsw;
3592 		break;
3593 	case _KMEM:
3594 		counter = &memcg->kmem;
3595 		break;
3596 	case _TCP:
3597 		counter = &memcg->tcpmem;
3598 		break;
3599 	default:
3600 		BUG();
3601 	}
3602 
3603 	switch (MEMFILE_ATTR(cft->private)) {
3604 	case RES_USAGE:
3605 		if (counter == &memcg->memory)
3606 			return (u64)mem_cgroup_usage(memcg, false) * PAGE_SIZE;
3607 		if (counter == &memcg->memsw)
3608 			return (u64)mem_cgroup_usage(memcg, true) * PAGE_SIZE;
3609 		return (u64)page_counter_read(counter) * PAGE_SIZE;
3610 	case RES_LIMIT:
3611 		return (u64)counter->max * PAGE_SIZE;
3612 	case RES_MAX_USAGE:
3613 		return (u64)counter->watermark * PAGE_SIZE;
3614 	case RES_FAILCNT:
3615 		return counter->failcnt;
3616 	case RES_SOFT_LIMIT:
3617 		return (u64)memcg->soft_limit * PAGE_SIZE;
3618 	default:
3619 		BUG();
3620 	}
3621 }
3622 
3623 #ifdef CONFIG_MEMCG_KMEM
3624 static int memcg_online_kmem(struct mem_cgroup *memcg)
3625 {
3626 	struct obj_cgroup *objcg;
3627 
3628 	if (cgroup_memory_nokmem)
3629 		return 0;
3630 
3631 	if (unlikely(mem_cgroup_is_root(memcg)))
3632 		return 0;
3633 
3634 	objcg = obj_cgroup_alloc();
3635 	if (!objcg)
3636 		return -ENOMEM;
3637 
3638 	objcg->memcg = memcg;
3639 	rcu_assign_pointer(memcg->objcg, objcg);
3640 
3641 	static_branch_enable(&memcg_kmem_enabled_key);
3642 
3643 	memcg->kmemcg_id = memcg->id.id;
3644 
3645 	return 0;
3646 }
3647 
3648 static void memcg_offline_kmem(struct mem_cgroup *memcg)
3649 {
3650 	struct mem_cgroup *parent;
3651 
3652 	if (cgroup_memory_nokmem)
3653 		return;
3654 
3655 	if (unlikely(mem_cgroup_is_root(memcg)))
3656 		return;
3657 
3658 	parent = parent_mem_cgroup(memcg);
3659 	if (!parent)
3660 		parent = root_mem_cgroup;
3661 
3662 	memcg_reparent_objcgs(memcg, parent);
3663 
3664 	/*
3665 	 * After we have finished memcg_reparent_objcgs(), all list_lrus
3666 	 * corresponding to this cgroup are guaranteed to remain empty.
3667 	 * The ordering is imposed by list_lru_node->lock taken by
3668 	 * memcg_reparent_list_lrus().
3669 	 */
3670 	memcg_reparent_list_lrus(memcg, parent);
3671 }
3672 #else
3673 static int memcg_online_kmem(struct mem_cgroup *memcg)
3674 {
3675 	return 0;
3676 }
3677 static void memcg_offline_kmem(struct mem_cgroup *memcg)
3678 {
3679 }
3680 #endif /* CONFIG_MEMCG_KMEM */
3681 
3682 static int memcg_update_tcp_max(struct mem_cgroup *memcg, unsigned long max)
3683 {
3684 	int ret;
3685 
3686 	mutex_lock(&memcg_max_mutex);
3687 
3688 	ret = page_counter_set_max(&memcg->tcpmem, max);
3689 	if (ret)
3690 		goto out;
3691 
3692 	if (!memcg->tcpmem_active) {
3693 		/*
3694 		 * The active flag needs to be written after the static_key
3695 		 * update. This is what guarantees that the socket activation
3696 		 * function is the last one to run. See mem_cgroup_sk_alloc()
3697 		 * for details, and note that we don't mark any socket as
3698 		 * belonging to this memcg until that flag is up.
3699 		 *
3700 		 * We need to do this, because static_keys will span multiple
3701 		 * sites, but we can't control their order. If we mark a socket
3702 		 * as accounted, but the accounting functions are not patched in
3703 		 * yet, we'll lose accounting.
3704 		 *
3705 		 * We never race with the readers in mem_cgroup_sk_alloc(),
3706 		 * because when this value change, the code to process it is not
3707 		 * patched in yet.
3708 		 */
3709 		static_branch_inc(&memcg_sockets_enabled_key);
3710 		memcg->tcpmem_active = true;
3711 	}
3712 out:
3713 	mutex_unlock(&memcg_max_mutex);
3714 	return ret;
3715 }
3716 
3717 /*
3718  * The user of this function is...
3719  * RES_LIMIT.
3720  */
3721 static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
3722 				char *buf, size_t nbytes, loff_t off)
3723 {
3724 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
3725 	unsigned long nr_pages;
3726 	int ret;
3727 
3728 	buf = strstrip(buf);
3729 	ret = page_counter_memparse(buf, "-1", &nr_pages);
3730 	if (ret)
3731 		return ret;
3732 
3733 	switch (MEMFILE_ATTR(of_cft(of)->private)) {
3734 	case RES_LIMIT:
3735 		if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
3736 			ret = -EINVAL;
3737 			break;
3738 		}
3739 		switch (MEMFILE_TYPE(of_cft(of)->private)) {
3740 		case _MEM:
3741 			ret = mem_cgroup_resize_max(memcg, nr_pages, false);
3742 			break;
3743 		case _MEMSWAP:
3744 			ret = mem_cgroup_resize_max(memcg, nr_pages, true);
3745 			break;
3746 		case _KMEM:
3747 			/* kmem.limit_in_bytes is deprecated. */
3748 			ret = -EOPNOTSUPP;
3749 			break;
3750 		case _TCP:
3751 			ret = memcg_update_tcp_max(memcg, nr_pages);
3752 			break;
3753 		}
3754 		break;
3755 	case RES_SOFT_LIMIT:
3756 		if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
3757 			ret = -EOPNOTSUPP;
3758 		} else {
3759 			memcg->soft_limit = nr_pages;
3760 			ret = 0;
3761 		}
3762 		break;
3763 	}
3764 	return ret ?: nbytes;
3765 }
3766 
3767 static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf,
3768 				size_t nbytes, loff_t off)
3769 {
3770 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
3771 	struct page_counter *counter;
3772 
3773 	switch (MEMFILE_TYPE(of_cft(of)->private)) {
3774 	case _MEM:
3775 		counter = &memcg->memory;
3776 		break;
3777 	case _MEMSWAP:
3778 		counter = &memcg->memsw;
3779 		break;
3780 	case _KMEM:
3781 		counter = &memcg->kmem;
3782 		break;
3783 	case _TCP:
3784 		counter = &memcg->tcpmem;
3785 		break;
3786 	default:
3787 		BUG();
3788 	}
3789 
3790 	switch (MEMFILE_ATTR(of_cft(of)->private)) {
3791 	case RES_MAX_USAGE:
3792 		page_counter_reset_watermark(counter);
3793 		break;
3794 	case RES_FAILCNT:
3795 		counter->failcnt = 0;
3796 		break;
3797 	default:
3798 		BUG();
3799 	}
3800 
3801 	return nbytes;
3802 }
3803 
3804 static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
3805 					struct cftype *cft)
3806 {
3807 	return mem_cgroup_from_css(css)->move_charge_at_immigrate;
3808 }
3809 
3810 #ifdef CONFIG_MMU
3811 static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
3812 					struct cftype *cft, u64 val)
3813 {
3814 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
3815 
3816 	if (val & ~MOVE_MASK)
3817 		return -EINVAL;
3818 
3819 	/*
3820 	 * No kind of locking is needed in here, because ->can_attach() will
3821 	 * check this value once in the beginning of the process, and then carry
3822 	 * on with stale data. This means that changes to this value will only
3823 	 * affect task migrations starting after the change.
3824 	 */
3825 	memcg->move_charge_at_immigrate = val;
3826 	return 0;
3827 }
3828 #else
3829 static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
3830 					struct cftype *cft, u64 val)
3831 {
3832 	return -ENOSYS;
3833 }
3834 #endif
3835 
3836 #ifdef CONFIG_NUMA
3837 
3838 #define LRU_ALL_FILE (BIT(LRU_INACTIVE_FILE) | BIT(LRU_ACTIVE_FILE))
3839 #define LRU_ALL_ANON (BIT(LRU_INACTIVE_ANON) | BIT(LRU_ACTIVE_ANON))
3840 #define LRU_ALL	     ((1 << NR_LRU_LISTS) - 1)
3841 
3842 static unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
3843 				int nid, unsigned int lru_mask, bool tree)
3844 {
3845 	struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
3846 	unsigned long nr = 0;
3847 	enum lru_list lru;
3848 
3849 	VM_BUG_ON((unsigned)nid >= nr_node_ids);
3850 
3851 	for_each_lru(lru) {
3852 		if (!(BIT(lru) & lru_mask))
3853 			continue;
3854 		if (tree)
3855 			nr += lruvec_page_state(lruvec, NR_LRU_BASE + lru);
3856 		else
3857 			nr += lruvec_page_state_local(lruvec, NR_LRU_BASE + lru);
3858 	}
3859 	return nr;
3860 }
3861 
3862 static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
3863 					     unsigned int lru_mask,
3864 					     bool tree)
3865 {
3866 	unsigned long nr = 0;
3867 	enum lru_list lru;
3868 
3869 	for_each_lru(lru) {
3870 		if (!(BIT(lru) & lru_mask))
3871 			continue;
3872 		if (tree)
3873 			nr += memcg_page_state(memcg, NR_LRU_BASE + lru);
3874 		else
3875 			nr += memcg_page_state_local(memcg, NR_LRU_BASE + lru);
3876 	}
3877 	return nr;
3878 }
3879 
3880 static int memcg_numa_stat_show(struct seq_file *m, void *v)
3881 {
3882 	struct numa_stat {
3883 		const char *name;
3884 		unsigned int lru_mask;
3885 	};
3886 
3887 	static const struct numa_stat stats[] = {
3888 		{ "total", LRU_ALL },
3889 		{ "file", LRU_ALL_FILE },
3890 		{ "anon", LRU_ALL_ANON },
3891 		{ "unevictable", BIT(LRU_UNEVICTABLE) },
3892 	};
3893 	const struct numa_stat *stat;
3894 	int nid;
3895 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
3896 
3897 	mem_cgroup_flush_stats();
3898 
3899 	for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
3900 		seq_printf(m, "%s=%lu", stat->name,
3901 			   mem_cgroup_nr_lru_pages(memcg, stat->lru_mask,
3902 						   false));
3903 		for_each_node_state(nid, N_MEMORY)
3904 			seq_printf(m, " N%d=%lu", nid,
3905 				   mem_cgroup_node_nr_lru_pages(memcg, nid,
3906 							stat->lru_mask, false));
3907 		seq_putc(m, '\n');
3908 	}
3909 
3910 	for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
3911 
3912 		seq_printf(m, "hierarchical_%s=%lu", stat->name,
3913 			   mem_cgroup_nr_lru_pages(memcg, stat->lru_mask,
3914 						   true));
3915 		for_each_node_state(nid, N_MEMORY)
3916 			seq_printf(m, " N%d=%lu", nid,
3917 				   mem_cgroup_node_nr_lru_pages(memcg, nid,
3918 							stat->lru_mask, true));
3919 		seq_putc(m, '\n');
3920 	}
3921 
3922 	return 0;
3923 }
3924 #endif /* CONFIG_NUMA */
3925 
3926 static const unsigned int memcg1_stats[] = {
3927 	NR_FILE_PAGES,
3928 	NR_ANON_MAPPED,
3929 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3930 	NR_ANON_THPS,
3931 #endif
3932 	NR_SHMEM,
3933 	NR_FILE_MAPPED,
3934 	NR_FILE_DIRTY,
3935 	NR_WRITEBACK,
3936 	MEMCG_SWAP,
3937 };
3938 
3939 static const char *const memcg1_stat_names[] = {
3940 	"cache",
3941 	"rss",
3942 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3943 	"rss_huge",
3944 #endif
3945 	"shmem",
3946 	"mapped_file",
3947 	"dirty",
3948 	"writeback",
3949 	"swap",
3950 };
3951 
3952 /* Universal VM events cgroup1 shows, original sort order */
3953 static const unsigned int memcg1_events[] = {
3954 	PGPGIN,
3955 	PGPGOUT,
3956 	PGFAULT,
3957 	PGMAJFAULT,
3958 };
3959 
3960 static int memcg_stat_show(struct seq_file *m, void *v)
3961 {
3962 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
3963 	unsigned long memory, memsw;
3964 	struct mem_cgroup *mi;
3965 	unsigned int i;
3966 
3967 	BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats));
3968 
3969 	mem_cgroup_flush_stats();
3970 
3971 	for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
3972 		unsigned long nr;
3973 
3974 		if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
3975 			continue;
3976 		nr = memcg_page_state_local(memcg, memcg1_stats[i]);
3977 		seq_printf(m, "%s %lu\n", memcg1_stat_names[i], nr * PAGE_SIZE);
3978 	}
3979 
3980 	for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
3981 		seq_printf(m, "%s %lu\n", vm_event_name(memcg1_events[i]),
3982 			   memcg_events_local(memcg, memcg1_events[i]));
3983 
3984 	for (i = 0; i < NR_LRU_LISTS; i++)
3985 		seq_printf(m, "%s %lu\n", lru_list_name(i),
3986 			   memcg_page_state_local(memcg, NR_LRU_BASE + i) *
3987 			   PAGE_SIZE);
3988 
3989 	/* Hierarchical information */
3990 	memory = memsw = PAGE_COUNTER_MAX;
3991 	for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) {
3992 		memory = min(memory, READ_ONCE(mi->memory.max));
3993 		memsw = min(memsw, READ_ONCE(mi->memsw.max));
3994 	}
3995 	seq_printf(m, "hierarchical_memory_limit %llu\n",
3996 		   (u64)memory * PAGE_SIZE);
3997 	if (do_memsw_account())
3998 		seq_printf(m, "hierarchical_memsw_limit %llu\n",
3999 			   (u64)memsw * PAGE_SIZE);
4000 
4001 	for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
4002 		unsigned long nr;
4003 
4004 		if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
4005 			continue;
4006 		nr = memcg_page_state(memcg, memcg1_stats[i]);
4007 		seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i],
4008 						(u64)nr * PAGE_SIZE);
4009 	}
4010 
4011 	for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
4012 		seq_printf(m, "total_%s %llu\n",
4013 			   vm_event_name(memcg1_events[i]),
4014 			   (u64)memcg_events(memcg, memcg1_events[i]));
4015 
4016 	for (i = 0; i < NR_LRU_LISTS; i++)
4017 		seq_printf(m, "total_%s %llu\n", lru_list_name(i),
4018 			   (u64)memcg_page_state(memcg, NR_LRU_BASE + i) *
4019 			   PAGE_SIZE);
4020 
4021 #ifdef CONFIG_DEBUG_VM
4022 	{
4023 		pg_data_t *pgdat;
4024 		struct mem_cgroup_per_node *mz;
4025 		unsigned long anon_cost = 0;
4026 		unsigned long file_cost = 0;
4027 
4028 		for_each_online_pgdat(pgdat) {
4029 			mz = memcg->nodeinfo[pgdat->node_id];
4030 
4031 			anon_cost += mz->lruvec.anon_cost;
4032 			file_cost += mz->lruvec.file_cost;
4033 		}
4034 		seq_printf(m, "anon_cost %lu\n", anon_cost);
4035 		seq_printf(m, "file_cost %lu\n", file_cost);
4036 	}
4037 #endif
4038 
4039 	return 0;
4040 }
4041 
4042 static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css,
4043 				      struct cftype *cft)
4044 {
4045 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
4046 
4047 	return mem_cgroup_swappiness(memcg);
4048 }
4049 
4050 static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
4051 				       struct cftype *cft, u64 val)
4052 {
4053 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
4054 
4055 	if (val > 200)
4056 		return -EINVAL;
4057 
4058 	if (!mem_cgroup_is_root(memcg))
4059 		memcg->swappiness = val;
4060 	else
4061 		vm_swappiness = val;
4062 
4063 	return 0;
4064 }
4065 
4066 static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
4067 {
4068 	struct mem_cgroup_threshold_ary *t;
4069 	unsigned long usage;
4070 	int i;
4071 
4072 	rcu_read_lock();
4073 	if (!swap)
4074 		t = rcu_dereference(memcg->thresholds.primary);
4075 	else
4076 		t = rcu_dereference(memcg->memsw_thresholds.primary);
4077 
4078 	if (!t)
4079 		goto unlock;
4080 
4081 	usage = mem_cgroup_usage(memcg, swap);
4082 
4083 	/*
4084 	 * current_threshold points to threshold just below or equal to usage.
4085 	 * If it's not true, a threshold was crossed after last
4086 	 * call of __mem_cgroup_threshold().
4087 	 */
4088 	i = t->current_threshold;
4089 
4090 	/*
4091 	 * Iterate backward over array of thresholds starting from
4092 	 * current_threshold and check if a threshold is crossed.
4093 	 * If none of thresholds below usage is crossed, we read
4094 	 * only one element of the array here.
4095 	 */
4096 	for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
4097 		eventfd_signal(t->entries[i].eventfd, 1);
4098 
4099 	/* i = current_threshold + 1 */
4100 	i++;
4101 
4102 	/*
4103 	 * Iterate forward over array of thresholds starting from
4104 	 * current_threshold+1 and check if a threshold is crossed.
4105 	 * If none of thresholds above usage is crossed, we read
4106 	 * only one element of the array here.
4107 	 */
4108 	for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
4109 		eventfd_signal(t->entries[i].eventfd, 1);
4110 
4111 	/* Update current_threshold */
4112 	t->current_threshold = i - 1;
4113 unlock:
4114 	rcu_read_unlock();
4115 }
4116 
4117 static void mem_cgroup_threshold(struct mem_cgroup *memcg)
4118 {
4119 	while (memcg) {
4120 		__mem_cgroup_threshold(memcg, false);
4121 		if (do_memsw_account())
4122 			__mem_cgroup_threshold(memcg, true);
4123 
4124 		memcg = parent_mem_cgroup(memcg);
4125 	}
4126 }
4127 
4128 static int compare_thresholds(const void *a, const void *b)
4129 {
4130 	const struct mem_cgroup_threshold *_a = a;
4131 	const struct mem_cgroup_threshold *_b = b;
4132 
4133 	if (_a->threshold > _b->threshold)
4134 		return 1;
4135 
4136 	if (_a->threshold < _b->threshold)
4137 		return -1;
4138 
4139 	return 0;
4140 }
4141 
4142 static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
4143 {
4144 	struct mem_cgroup_eventfd_list *ev;
4145 
4146 	spin_lock(&memcg_oom_lock);
4147 
4148 	list_for_each_entry(ev, &memcg->oom_notify, list)
4149 		eventfd_signal(ev->eventfd, 1);
4150 
4151 	spin_unlock(&memcg_oom_lock);
4152 	return 0;
4153 }
4154 
4155 static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
4156 {
4157 	struct mem_cgroup *iter;
4158 
4159 	for_each_mem_cgroup_tree(iter, memcg)
4160 		mem_cgroup_oom_notify_cb(iter);
4161 }
4162 
4163 static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
4164 	struct eventfd_ctx *eventfd, const char *args, enum res_type type)
4165 {
4166 	struct mem_cgroup_thresholds *thresholds;
4167 	struct mem_cgroup_threshold_ary *new;
4168 	unsigned long threshold;
4169 	unsigned long usage;
4170 	int i, size, ret;
4171 
4172 	ret = page_counter_memparse(args, "-1", &threshold);
4173 	if (ret)
4174 		return ret;
4175 
4176 	mutex_lock(&memcg->thresholds_lock);
4177 
4178 	if (type == _MEM) {
4179 		thresholds = &memcg->thresholds;
4180 		usage = mem_cgroup_usage(memcg, false);
4181 	} else if (type == _MEMSWAP) {
4182 		thresholds = &memcg->memsw_thresholds;
4183 		usage = mem_cgroup_usage(memcg, true);
4184 	} else
4185 		BUG();
4186 
4187 	/* Check if a threshold crossed before adding a new one */
4188 	if (thresholds->primary)
4189 		__mem_cgroup_threshold(memcg, type == _MEMSWAP);
4190 
4191 	size = thresholds->primary ? thresholds->primary->size + 1 : 1;
4192 
4193 	/* Allocate memory for new array of thresholds */
4194 	new = kmalloc(struct_size(new, entries, size), GFP_KERNEL);
4195 	if (!new) {
4196 		ret = -ENOMEM;
4197 		goto unlock;
4198 	}
4199 	new->size = size;
4200 
4201 	/* Copy thresholds (if any) to new array */
4202 	if (thresholds->primary)
4203 		memcpy(new->entries, thresholds->primary->entries,
4204 		       flex_array_size(new, entries, size - 1));
4205 
4206 	/* Add new threshold */
4207 	new->entries[size - 1].eventfd = eventfd;
4208 	new->entries[size - 1].threshold = threshold;
4209 
4210 	/* Sort thresholds. Registering of new threshold isn't time-critical */
4211 	sort(new->entries, size, sizeof(*new->entries),
4212 			compare_thresholds, NULL);
4213 
4214 	/* Find current threshold */
4215 	new->current_threshold = -1;
4216 	for (i = 0; i < size; i++) {
4217 		if (new->entries[i].threshold <= usage) {
4218 			/*
4219 			 * new->current_threshold will not be used until
4220 			 * rcu_assign_pointer(), so it's safe to increment
4221 			 * it here.
4222 			 */
4223 			++new->current_threshold;
4224 		} else
4225 			break;
4226 	}
4227 
4228 	/* Free old spare buffer and save old primary buffer as spare */
4229 	kfree(thresholds->spare);
4230 	thresholds->spare = thresholds->primary;
4231 
4232 	rcu_assign_pointer(thresholds->primary, new);
4233 
4234 	/* To be sure that nobody uses thresholds */
4235 	synchronize_rcu();
4236 
4237 unlock:
4238 	mutex_unlock(&memcg->thresholds_lock);
4239 
4240 	return ret;
4241 }
4242 
4243 static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
4244 	struct eventfd_ctx *eventfd, const char *args)
4245 {
4246 	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
4247 }
4248 
4249 static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
4250 	struct eventfd_ctx *eventfd, const char *args)
4251 {
4252 	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
4253 }
4254 
4255 static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
4256 	struct eventfd_ctx *eventfd, enum res_type type)
4257 {
4258 	struct mem_cgroup_thresholds *thresholds;
4259 	struct mem_cgroup_threshold_ary *new;
4260 	unsigned long usage;
4261 	int i, j, size, entries;
4262 
4263 	mutex_lock(&memcg->thresholds_lock);
4264 
4265 	if (type == _MEM) {
4266 		thresholds = &memcg->thresholds;
4267 		usage = mem_cgroup_usage(memcg, false);
4268 	} else if (type == _MEMSWAP) {
4269 		thresholds = &memcg->memsw_thresholds;
4270 		usage = mem_cgroup_usage(memcg, true);
4271 	} else
4272 		BUG();
4273 
4274 	if (!thresholds->primary)
4275 		goto unlock;
4276 
4277 	/* Check if a threshold crossed before removing */
4278 	__mem_cgroup_threshold(memcg, type == _MEMSWAP);
4279 
4280 	/* Calculate new number of threshold */
4281 	size = entries = 0;
4282 	for (i = 0; i < thresholds->primary->size; i++) {
4283 		if (thresholds->primary->entries[i].eventfd != eventfd)
4284 			size++;
4285 		else
4286 			entries++;
4287 	}
4288 
4289 	new = thresholds->spare;
4290 
4291 	/* If no items related to eventfd have been cleared, nothing to do */
4292 	if (!entries)
4293 		goto unlock;
4294 
4295 	/* Set thresholds array to NULL if we don't have thresholds */
4296 	if (!size) {
4297 		kfree(new);
4298 		new = NULL;
4299 		goto swap_buffers;
4300 	}
4301 
4302 	new->size = size;
4303 
4304 	/* Copy thresholds and find current threshold */
4305 	new->current_threshold = -1;
4306 	for (i = 0, j = 0; i < thresholds->primary->size; i++) {
4307 		if (thresholds->primary->entries[i].eventfd == eventfd)
4308 			continue;
4309 
4310 		new->entries[j] = thresholds->primary->entries[i];
4311 		if (new->entries[j].threshold <= usage) {
4312 			/*
4313 			 * new->current_threshold will not be used
4314 			 * until rcu_assign_pointer(), so it's safe to increment
4315 			 * it here.
4316 			 */
4317 			++new->current_threshold;
4318 		}
4319 		j++;
4320 	}
4321 
4322 swap_buffers:
4323 	/* Swap primary and spare array */
4324 	thresholds->spare = thresholds->primary;
4325 
4326 	rcu_assign_pointer(thresholds->primary, new);
4327 
4328 	/* To be sure that nobody uses thresholds */
4329 	synchronize_rcu();
4330 
4331 	/* If all events are unregistered, free the spare array */
4332 	if (!new) {
4333 		kfree(thresholds->spare);
4334 		thresholds->spare = NULL;
4335 	}
4336 unlock:
4337 	mutex_unlock(&memcg->thresholds_lock);
4338 }
4339 
4340 static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
4341 	struct eventfd_ctx *eventfd)
4342 {
4343 	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
4344 }
4345 
4346 static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
4347 	struct eventfd_ctx *eventfd)
4348 {
4349 	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
4350 }
4351 
4352 static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
4353 	struct eventfd_ctx *eventfd, const char *args)
4354 {
4355 	struct mem_cgroup_eventfd_list *event;
4356 
4357 	event = kmalloc(sizeof(*event),	GFP_KERNEL);
4358 	if (!event)
4359 		return -ENOMEM;
4360 
4361 	spin_lock(&memcg_oom_lock);
4362 
4363 	event->eventfd = eventfd;
4364 	list_add(&event->list, &memcg->oom_notify);
4365 
4366 	/* already in OOM ? */
4367 	if (memcg->under_oom)
4368 		eventfd_signal(eventfd, 1);
4369 	spin_unlock(&memcg_oom_lock);
4370 
4371 	return 0;
4372 }
4373 
4374 static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
4375 	struct eventfd_ctx *eventfd)
4376 {
4377 	struct mem_cgroup_eventfd_list *ev, *tmp;
4378 
4379 	spin_lock(&memcg_oom_lock);
4380 
4381 	list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
4382 		if (ev->eventfd == eventfd) {
4383 			list_del(&ev->list);
4384 			kfree(ev);
4385 		}
4386 	}
4387 
4388 	spin_unlock(&memcg_oom_lock);
4389 }
4390 
4391 static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
4392 {
4393 	struct mem_cgroup *memcg = mem_cgroup_from_seq(sf);
4394 
4395 	seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable);
4396 	seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom);
4397 	seq_printf(sf, "oom_kill %lu\n",
4398 		   atomic_long_read(&memcg->memory_events[MEMCG_OOM_KILL]));
4399 	return 0;
4400 }
4401 
4402 static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
4403 	struct cftype *cft, u64 val)
4404 {
4405 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
4406 
4407 	/* cannot set to root cgroup and only 0 and 1 are allowed */
4408 	if (mem_cgroup_is_root(memcg) || !((val == 0) || (val == 1)))
4409 		return -EINVAL;
4410 
4411 	memcg->oom_kill_disable = val;
4412 	if (!val)
4413 		memcg_oom_recover(memcg);
4414 
4415 	return 0;
4416 }
4417 
4418 #ifdef CONFIG_CGROUP_WRITEBACK
4419 
4420 #include <trace/events/writeback.h>
4421 
4422 static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp)
4423 {
4424 	return wb_domain_init(&memcg->cgwb_domain, gfp);
4425 }
4426 
4427 static void memcg_wb_domain_exit(struct mem_cgroup *memcg)
4428 {
4429 	wb_domain_exit(&memcg->cgwb_domain);
4430 }
4431 
4432 static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
4433 {
4434 	wb_domain_size_changed(&memcg->cgwb_domain);
4435 }
4436 
4437 struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb)
4438 {
4439 	struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
4440 
4441 	if (!memcg->css.parent)
4442 		return NULL;
4443 
4444 	return &memcg->cgwb_domain;
4445 }
4446 
4447 /**
4448  * mem_cgroup_wb_stats - retrieve writeback related stats from its memcg
4449  * @wb: bdi_writeback in question
4450  * @pfilepages: out parameter for number of file pages
4451  * @pheadroom: out parameter for number of allocatable pages according to memcg
4452  * @pdirty: out parameter for number of dirty pages
4453  * @pwriteback: out parameter for number of pages under writeback
4454  *
4455  * Determine the numbers of file, headroom, dirty, and writeback pages in
4456  * @wb's memcg.  File, dirty and writeback are self-explanatory.  Headroom
4457  * is a bit more involved.
4458  *
4459  * A memcg's headroom is "min(max, high) - used".  In the hierarchy, the
4460  * headroom is calculated as the lowest headroom of itself and the
4461  * ancestors.  Note that this doesn't consider the actual amount of
4462  * available memory in the system.  The caller should further cap
4463  * *@pheadroom accordingly.
4464  */
4465 void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages,
4466 			 unsigned long *pheadroom, unsigned long *pdirty,
4467 			 unsigned long *pwriteback)
4468 {
4469 	struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
4470 	struct mem_cgroup *parent;
4471 
4472 	mem_cgroup_flush_stats();
4473 
4474 	*pdirty = memcg_page_state(memcg, NR_FILE_DIRTY);
4475 	*pwriteback = memcg_page_state(memcg, NR_WRITEBACK);
4476 	*pfilepages = memcg_page_state(memcg, NR_INACTIVE_FILE) +
4477 			memcg_page_state(memcg, NR_ACTIVE_FILE);
4478 
4479 	*pheadroom = PAGE_COUNTER_MAX;
4480 	while ((parent = parent_mem_cgroup(memcg))) {
4481 		unsigned long ceiling = min(READ_ONCE(memcg->memory.max),
4482 					    READ_ONCE(memcg->memory.high));
4483 		unsigned long used = page_counter_read(&memcg->memory);
4484 
4485 		*pheadroom = min(*pheadroom, ceiling - min(ceiling, used));
4486 		memcg = parent;
4487 	}
4488 }
4489 
4490 /*
4491  * Foreign dirty flushing
4492  *
4493  * There's an inherent mismatch between memcg and writeback.  The former
4494  * tracks ownership per-page while the latter per-inode.  This was a
4495  * deliberate design decision because honoring per-page ownership in the
4496  * writeback path is complicated, may lead to higher CPU and IO overheads
4497  * and deemed unnecessary given that write-sharing an inode across
4498  * different cgroups isn't a common use-case.
4499  *
4500  * Combined with inode majority-writer ownership switching, this works well
4501  * enough in most cases but there are some pathological cases.  For
4502  * example, let's say there are two cgroups A and B which keep writing to
4503  * different but confined parts of the same inode.  B owns the inode and
4504  * A's memory is limited far below B's.  A's dirty ratio can rise enough to
4505  * trigger balance_dirty_pages() sleeps but B's can be low enough to avoid
4506  * triggering background writeback.  A will be slowed down without a way to
4507  * make writeback of the dirty pages happen.
4508  *
4509  * Conditions like the above can lead to a cgroup getting repeatedly and
4510  * severely throttled after making some progress after each
4511  * dirty_expire_interval while the underlying IO device is almost
4512  * completely idle.
4513  *
4514  * Solving this problem completely requires matching the ownership tracking
4515  * granularities between memcg and writeback in either direction.  However,
4516  * the more egregious behaviors can be avoided by simply remembering the
4517  * most recent foreign dirtying events and initiating remote flushes on
4518  * them when local writeback isn't enough to keep the memory clean enough.
4519  *
4520  * The following two functions implement such mechanism.  When a foreign
4521  * page - a page whose memcg and writeback ownerships don't match - is
4522  * dirtied, mem_cgroup_track_foreign_dirty() records the inode owning
4523  * bdi_writeback on the page owning memcg.  When balance_dirty_pages()
4524  * decides that the memcg needs to sleep due to high dirty ratio, it calls
4525  * mem_cgroup_flush_foreign() which queues writeback on the recorded
4526  * foreign bdi_writebacks which haven't expired.  Both the numbers of
4527  * recorded bdi_writebacks and concurrent in-flight foreign writebacks are
4528  * limited to MEMCG_CGWB_FRN_CNT.
4529  *
4530  * The mechanism only remembers IDs and doesn't hold any object references.
4531  * As being wrong occasionally doesn't matter, updates and accesses to the
4532  * records are lockless and racy.
4533  */
4534 void mem_cgroup_track_foreign_dirty_slowpath(struct folio *folio,
4535 					     struct bdi_writeback *wb)
4536 {
4537 	struct mem_cgroup *memcg = folio_memcg(folio);
4538 	struct memcg_cgwb_frn *frn;
4539 	u64 now = get_jiffies_64();
4540 	u64 oldest_at = now;
4541 	int oldest = -1;
4542 	int i;
4543 
4544 	trace_track_foreign_dirty(folio, wb);
4545 
4546 	/*
4547 	 * Pick the slot to use.  If there is already a slot for @wb, keep
4548 	 * using it.  If not replace the oldest one which isn't being
4549 	 * written out.
4550 	 */
4551 	for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++) {
4552 		frn = &memcg->cgwb_frn[i];
4553 		if (frn->bdi_id == wb->bdi->id &&
4554 		    frn->memcg_id == wb->memcg_css->id)
4555 			break;
4556 		if (time_before64(frn->at, oldest_at) &&
4557 		    atomic_read(&frn->done.cnt) == 1) {
4558 			oldest = i;
4559 			oldest_at = frn->at;
4560 		}
4561 	}
4562 
4563 	if (i < MEMCG_CGWB_FRN_CNT) {
4564 		/*
4565 		 * Re-using an existing one.  Update timestamp lazily to
4566 		 * avoid making the cacheline hot.  We want them to be
4567 		 * reasonably up-to-date and significantly shorter than
4568 		 * dirty_expire_interval as that's what expires the record.
4569 		 * Use the shorter of 1s and dirty_expire_interval / 8.
4570 		 */
4571 		unsigned long update_intv =
4572 			min_t(unsigned long, HZ,
4573 			      msecs_to_jiffies(dirty_expire_interval * 10) / 8);
4574 
4575 		if (time_before64(frn->at, now - update_intv))
4576 			frn->at = now;
4577 	} else if (oldest >= 0) {
4578 		/* replace the oldest free one */
4579 		frn = &memcg->cgwb_frn[oldest];
4580 		frn->bdi_id = wb->bdi->id;
4581 		frn->memcg_id = wb->memcg_css->id;
4582 		frn->at = now;
4583 	}
4584 }
4585 
4586 /* issue foreign writeback flushes for recorded foreign dirtying events */
4587 void mem_cgroup_flush_foreign(struct bdi_writeback *wb)
4588 {
4589 	struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
4590 	unsigned long intv = msecs_to_jiffies(dirty_expire_interval * 10);
4591 	u64 now = jiffies_64;
4592 	int i;
4593 
4594 	for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++) {
4595 		struct memcg_cgwb_frn *frn = &memcg->cgwb_frn[i];
4596 
4597 		/*
4598 		 * If the record is older than dirty_expire_interval,
4599 		 * writeback on it has already started.  No need to kick it
4600 		 * off again.  Also, don't start a new one if there's
4601 		 * already one in flight.
4602 		 */
4603 		if (time_after64(frn->at, now - intv) &&
4604 		    atomic_read(&frn->done.cnt) == 1) {
4605 			frn->at = 0;
4606 			trace_flush_foreign(wb, frn->bdi_id, frn->memcg_id);
4607 			cgroup_writeback_by_id(frn->bdi_id, frn->memcg_id,
4608 					       WB_REASON_FOREIGN_FLUSH,
4609 					       &frn->done);
4610 		}
4611 	}
4612 }
4613 
4614 #else	/* CONFIG_CGROUP_WRITEBACK */
4615 
4616 static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp)
4617 {
4618 	return 0;
4619 }
4620 
4621 static void memcg_wb_domain_exit(struct mem_cgroup *memcg)
4622 {
4623 }
4624 
4625 static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
4626 {
4627 }
4628 
4629 #endif	/* CONFIG_CGROUP_WRITEBACK */
4630 
4631 /*
4632  * DO NOT USE IN NEW FILES.
4633  *
4634  * "cgroup.event_control" implementation.
4635  *
4636  * This is way over-engineered.  It tries to support fully configurable
4637  * events for each user.  Such level of flexibility is completely
4638  * unnecessary especially in the light of the planned unified hierarchy.
4639  *
4640  * Please deprecate this and replace with something simpler if at all
4641  * possible.
4642  */
4643 
4644 /*
4645  * Unregister event and free resources.
4646  *
4647  * Gets called from workqueue.
4648  */
4649 static void memcg_event_remove(struct work_struct *work)
4650 {
4651 	struct mem_cgroup_event *event =
4652 		container_of(work, struct mem_cgroup_event, remove);
4653 	struct mem_cgroup *memcg = event->memcg;
4654 
4655 	remove_wait_queue(event->wqh, &event->wait);
4656 
4657 	event->unregister_event(memcg, event->eventfd);
4658 
4659 	/* Notify userspace the event is going away. */
4660 	eventfd_signal(event->eventfd, 1);
4661 
4662 	eventfd_ctx_put(event->eventfd);
4663 	kfree(event);
4664 	css_put(&memcg->css);
4665 }
4666 
4667 /*
4668  * Gets called on EPOLLHUP on eventfd when user closes it.
4669  *
4670  * Called with wqh->lock held and interrupts disabled.
4671  */
4672 static int memcg_event_wake(wait_queue_entry_t *wait, unsigned mode,
4673 			    int sync, void *key)
4674 {
4675 	struct mem_cgroup_event *event =
4676 		container_of(wait, struct mem_cgroup_event, wait);
4677 	struct mem_cgroup *memcg = event->memcg;
4678 	__poll_t flags = key_to_poll(key);
4679 
4680 	if (flags & EPOLLHUP) {
4681 		/*
4682 		 * If the event has been detached at cgroup removal, we
4683 		 * can simply return knowing the other side will cleanup
4684 		 * for us.
4685 		 *
4686 		 * We can't race against event freeing since the other
4687 		 * side will require wqh->lock via remove_wait_queue(),
4688 		 * which we hold.
4689 		 */
4690 		spin_lock(&memcg->event_list_lock);
4691 		if (!list_empty(&event->list)) {
4692 			list_del_init(&event->list);
4693 			/*
4694 			 * We are in atomic context, but cgroup_event_remove()
4695 			 * may sleep, so we have to call it in workqueue.
4696 			 */
4697 			schedule_work(&event->remove);
4698 		}
4699 		spin_unlock(&memcg->event_list_lock);
4700 	}
4701 
4702 	return 0;
4703 }
4704 
4705 static void memcg_event_ptable_queue_proc(struct file *file,
4706 		wait_queue_head_t *wqh, poll_table *pt)
4707 {
4708 	struct mem_cgroup_event *event =
4709 		container_of(pt, struct mem_cgroup_event, pt);
4710 
4711 	event->wqh = wqh;
4712 	add_wait_queue(wqh, &event->wait);
4713 }
4714 
4715 /*
4716  * DO NOT USE IN NEW FILES.
4717  *
4718  * Parse input and register new cgroup event handler.
4719  *
4720  * Input must be in format '<event_fd> <control_fd> <args>'.
4721  * Interpretation of args is defined by control file implementation.
4722  */
4723 static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
4724 					 char *buf, size_t nbytes, loff_t off)
4725 {
4726 	struct cgroup_subsys_state *css = of_css(of);
4727 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
4728 	struct mem_cgroup_event *event;
4729 	struct cgroup_subsys_state *cfile_css;
4730 	unsigned int efd, cfd;
4731 	struct fd efile;
4732 	struct fd cfile;
4733 	const char *name;
4734 	char *endp;
4735 	int ret;
4736 
4737 	if (IS_ENABLED(CONFIG_PREEMPT_RT))
4738 		return -EOPNOTSUPP;
4739 
4740 	buf = strstrip(buf);
4741 
4742 	efd = simple_strtoul(buf, &endp, 10);
4743 	if (*endp != ' ')
4744 		return -EINVAL;
4745 	buf = endp + 1;
4746 
4747 	cfd = simple_strtoul(buf, &endp, 10);
4748 	if ((*endp != ' ') && (*endp != '\0'))
4749 		return -EINVAL;
4750 	buf = endp + 1;
4751 
4752 	event = kzalloc(sizeof(*event), GFP_KERNEL);
4753 	if (!event)
4754 		return -ENOMEM;
4755 
4756 	event->memcg = memcg;
4757 	INIT_LIST_HEAD(&event->list);
4758 	init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc);
4759 	init_waitqueue_func_entry(&event->wait, memcg_event_wake);
4760 	INIT_WORK(&event->remove, memcg_event_remove);
4761 
4762 	efile = fdget(efd);
4763 	if (!efile.file) {
4764 		ret = -EBADF;
4765 		goto out_kfree;
4766 	}
4767 
4768 	event->eventfd = eventfd_ctx_fileget(efile.file);
4769 	if (IS_ERR(event->eventfd)) {
4770 		ret = PTR_ERR(event->eventfd);
4771 		goto out_put_efile;
4772 	}
4773 
4774 	cfile = fdget(cfd);
4775 	if (!cfile.file) {
4776 		ret = -EBADF;
4777 		goto out_put_eventfd;
4778 	}
4779 
4780 	/* the process need read permission on control file */
4781 	/* AV: shouldn't we check that it's been opened for read instead? */
4782 	ret = file_permission(cfile.file, MAY_READ);
4783 	if (ret < 0)
4784 		goto out_put_cfile;
4785 
4786 	/*
4787 	 * Determine the event callbacks and set them in @event.  This used
4788 	 * to be done via struct cftype but cgroup core no longer knows
4789 	 * about these events.  The following is crude but the whole thing
4790 	 * is for compatibility anyway.
4791 	 *
4792 	 * DO NOT ADD NEW FILES.
4793 	 */
4794 	name = cfile.file->f_path.dentry->d_name.name;
4795 
4796 	if (!strcmp(name, "memory.usage_in_bytes")) {
4797 		event->register_event = mem_cgroup_usage_register_event;
4798 		event->unregister_event = mem_cgroup_usage_unregister_event;
4799 	} else if (!strcmp(name, "memory.oom_control")) {
4800 		event->register_event = mem_cgroup_oom_register_event;
4801 		event->unregister_event = mem_cgroup_oom_unregister_event;
4802 	} else if (!strcmp(name, "memory.pressure_level")) {
4803 		event->register_event = vmpressure_register_event;
4804 		event->unregister_event = vmpressure_unregister_event;
4805 	} else if (!strcmp(name, "memory.memsw.usage_in_bytes")) {
4806 		event->register_event = memsw_cgroup_usage_register_event;
4807 		event->unregister_event = memsw_cgroup_usage_unregister_event;
4808 	} else {
4809 		ret = -EINVAL;
4810 		goto out_put_cfile;
4811 	}
4812 
4813 	/*
4814 	 * Verify @cfile should belong to @css.  Also, remaining events are
4815 	 * automatically removed on cgroup destruction but the removal is
4816 	 * asynchronous, so take an extra ref on @css.
4817 	 */
4818 	cfile_css = css_tryget_online_from_dir(cfile.file->f_path.dentry->d_parent,
4819 					       &memory_cgrp_subsys);
4820 	ret = -EINVAL;
4821 	if (IS_ERR(cfile_css))
4822 		goto out_put_cfile;
4823 	if (cfile_css != css) {
4824 		css_put(cfile_css);
4825 		goto out_put_cfile;
4826 	}
4827 
4828 	ret = event->register_event(memcg, event->eventfd, buf);
4829 	if (ret)
4830 		goto out_put_css;
4831 
4832 	vfs_poll(efile.file, &event->pt);
4833 
4834 	spin_lock_irq(&memcg->event_list_lock);
4835 	list_add(&event->list, &memcg->event_list);
4836 	spin_unlock_irq(&memcg->event_list_lock);
4837 
4838 	fdput(cfile);
4839 	fdput(efile);
4840 
4841 	return nbytes;
4842 
4843 out_put_css:
4844 	css_put(css);
4845 out_put_cfile:
4846 	fdput(cfile);
4847 out_put_eventfd:
4848 	eventfd_ctx_put(event->eventfd);
4849 out_put_efile:
4850 	fdput(efile);
4851 out_kfree:
4852 	kfree(event);
4853 
4854 	return ret;
4855 }
4856 
4857 #if defined(CONFIG_MEMCG_KMEM) && (defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG))
4858 static int mem_cgroup_slab_show(struct seq_file *m, void *p)
4859 {
4860 	/*
4861 	 * Deprecated.
4862 	 * Please, take a look at tools/cgroup/memcg_slabinfo.py .
4863 	 */
4864 	return 0;
4865 }
4866 #endif
4867 
4868 static struct cftype mem_cgroup_legacy_files[] = {
4869 	{
4870 		.name = "usage_in_bytes",
4871 		.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
4872 		.read_u64 = mem_cgroup_read_u64,
4873 	},
4874 	{
4875 		.name = "max_usage_in_bytes",
4876 		.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
4877 		.write = mem_cgroup_reset,
4878 		.read_u64 = mem_cgroup_read_u64,
4879 	},
4880 	{
4881 		.name = "limit_in_bytes",
4882 		.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
4883 		.write = mem_cgroup_write,
4884 		.read_u64 = mem_cgroup_read_u64,
4885 	},
4886 	{
4887 		.name = "soft_limit_in_bytes",
4888 		.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
4889 		.write = mem_cgroup_write,
4890 		.read_u64 = mem_cgroup_read_u64,
4891 	},
4892 	{
4893 		.name = "failcnt",
4894 		.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
4895 		.write = mem_cgroup_reset,
4896 		.read_u64 = mem_cgroup_read_u64,
4897 	},
4898 	{
4899 		.name = "stat",
4900 		.seq_show = memcg_stat_show,
4901 	},
4902 	{
4903 		.name = "force_empty",
4904 		.write = mem_cgroup_force_empty_write,
4905 	},
4906 	{
4907 		.name = "use_hierarchy",
4908 		.write_u64 = mem_cgroup_hierarchy_write,
4909 		.read_u64 = mem_cgroup_hierarchy_read,
4910 	},
4911 	{
4912 		.name = "cgroup.event_control",		/* XXX: for compat */
4913 		.write = memcg_write_event_control,
4914 		.flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE,
4915 	},
4916 	{
4917 		.name = "swappiness",
4918 		.read_u64 = mem_cgroup_swappiness_read,
4919 		.write_u64 = mem_cgroup_swappiness_write,
4920 	},
4921 	{
4922 		.name = "move_charge_at_immigrate",
4923 		.read_u64 = mem_cgroup_move_charge_read,
4924 		.write_u64 = mem_cgroup_move_charge_write,
4925 	},
4926 	{
4927 		.name = "oom_control",
4928 		.seq_show = mem_cgroup_oom_control_read,
4929 		.write_u64 = mem_cgroup_oom_control_write,
4930 	},
4931 	{
4932 		.name = "pressure_level",
4933 	},
4934 #ifdef CONFIG_NUMA
4935 	{
4936 		.name = "numa_stat",
4937 		.seq_show = memcg_numa_stat_show,
4938 	},
4939 #endif
4940 	{
4941 		.name = "kmem.limit_in_bytes",
4942 		.private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
4943 		.write = mem_cgroup_write,
4944 		.read_u64 = mem_cgroup_read_u64,
4945 	},
4946 	{
4947 		.name = "kmem.usage_in_bytes",
4948 		.private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
4949 		.read_u64 = mem_cgroup_read_u64,
4950 	},
4951 	{
4952 		.name = "kmem.failcnt",
4953 		.private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
4954 		.write = mem_cgroup_reset,
4955 		.read_u64 = mem_cgroup_read_u64,
4956 	},
4957 	{
4958 		.name = "kmem.max_usage_in_bytes",
4959 		.private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
4960 		.write = mem_cgroup_reset,
4961 		.read_u64 = mem_cgroup_read_u64,
4962 	},
4963 #if defined(CONFIG_MEMCG_KMEM) && \
4964 	(defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG))
4965 	{
4966 		.name = "kmem.slabinfo",
4967 		.seq_show = mem_cgroup_slab_show,
4968 	},
4969 #endif
4970 	{
4971 		.name = "kmem.tcp.limit_in_bytes",
4972 		.private = MEMFILE_PRIVATE(_TCP, RES_LIMIT),
4973 		.write = mem_cgroup_write,
4974 		.read_u64 = mem_cgroup_read_u64,
4975 	},
4976 	{
4977 		.name = "kmem.tcp.usage_in_bytes",
4978 		.private = MEMFILE_PRIVATE(_TCP, RES_USAGE),
4979 		.read_u64 = mem_cgroup_read_u64,
4980 	},
4981 	{
4982 		.name = "kmem.tcp.failcnt",
4983 		.private = MEMFILE_PRIVATE(_TCP, RES_FAILCNT),
4984 		.write = mem_cgroup_reset,
4985 		.read_u64 = mem_cgroup_read_u64,
4986 	},
4987 	{
4988 		.name = "kmem.tcp.max_usage_in_bytes",
4989 		.private = MEMFILE_PRIVATE(_TCP, RES_MAX_USAGE),
4990 		.write = mem_cgroup_reset,
4991 		.read_u64 = mem_cgroup_read_u64,
4992 	},
4993 	{ },	/* terminate */
4994 };
4995 
4996 /*
4997  * Private memory cgroup IDR
4998  *
4999  * Swap-out records and page cache shadow entries need to store memcg
5000  * references in constrained space, so we maintain an ID space that is
5001  * limited to 16 bit (MEM_CGROUP_ID_MAX), limiting the total number of
5002  * memory-controlled cgroups to 64k.
5003  *
5004  * However, there usually are many references to the offline CSS after
5005  * the cgroup has been destroyed, such as page cache or reclaimable
5006  * slab objects, that don't need to hang on to the ID. We want to keep
5007  * those dead CSS from occupying IDs, or we might quickly exhaust the
5008  * relatively small ID space and prevent the creation of new cgroups
5009  * even when there are much fewer than 64k cgroups - possibly none.
5010  *
5011  * Maintain a private 16-bit ID space for memcg, and allow the ID to
5012  * be freed and recycled when it's no longer needed, which is usually
5013  * when the CSS is offlined.
5014  *
5015  * The only exception to that are records of swapped out tmpfs/shmem
5016  * pages that need to be attributed to live ancestors on swapin. But
5017  * those references are manageable from userspace.
5018  */
5019 
5020 static DEFINE_IDR(mem_cgroup_idr);
5021 
5022 static void mem_cgroup_id_remove(struct mem_cgroup *memcg)
5023 {
5024 	if (memcg->id.id > 0) {
5025 		idr_remove(&mem_cgroup_idr, memcg->id.id);
5026 		memcg->id.id = 0;
5027 	}
5028 }
5029 
5030 static void __maybe_unused mem_cgroup_id_get_many(struct mem_cgroup *memcg,
5031 						  unsigned int n)
5032 {
5033 	refcount_add(n, &memcg->id.ref);
5034 }
5035 
5036 static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)
5037 {
5038 	if (refcount_sub_and_test(n, &memcg->id.ref)) {
5039 		mem_cgroup_id_remove(memcg);
5040 
5041 		/* Memcg ID pins CSS */
5042 		css_put(&memcg->css);
5043 	}
5044 }
5045 
5046 static inline void mem_cgroup_id_put(struct mem_cgroup *memcg)
5047 {
5048 	mem_cgroup_id_put_many(memcg, 1);
5049 }
5050 
5051 /**
5052  * mem_cgroup_from_id - look up a memcg from a memcg id
5053  * @id: the memcg id to look up
5054  *
5055  * Caller must hold rcu_read_lock().
5056  */
5057 struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
5058 {
5059 	WARN_ON_ONCE(!rcu_read_lock_held());
5060 	return idr_find(&mem_cgroup_idr, id);
5061 }
5062 
5063 static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
5064 {
5065 	struct mem_cgroup_per_node *pn;
5066 
5067 	pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, node);
5068 	if (!pn)
5069 		return 1;
5070 
5071 	pn->lruvec_stats_percpu = alloc_percpu_gfp(struct lruvec_stats_percpu,
5072 						   GFP_KERNEL_ACCOUNT);
5073 	if (!pn->lruvec_stats_percpu) {
5074 		kfree(pn);
5075 		return 1;
5076 	}
5077 
5078 	lruvec_init(&pn->lruvec);
5079 	pn->memcg = memcg;
5080 
5081 	memcg->nodeinfo[node] = pn;
5082 	return 0;
5083 }
5084 
5085 static void free_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
5086 {
5087 	struct mem_cgroup_per_node *pn = memcg->nodeinfo[node];
5088 
5089 	if (!pn)
5090 		return;
5091 
5092 	free_percpu(pn->lruvec_stats_percpu);
5093 	kfree(pn);
5094 }
5095 
5096 static void __mem_cgroup_free(struct mem_cgroup *memcg)
5097 {
5098 	int node;
5099 
5100 	for_each_node(node)
5101 		free_mem_cgroup_per_node_info(memcg, node);
5102 	free_percpu(memcg->vmstats_percpu);
5103 	kfree(memcg);
5104 }
5105 
5106 static void mem_cgroup_free(struct mem_cgroup *memcg)
5107 {
5108 	memcg_wb_domain_exit(memcg);
5109 	__mem_cgroup_free(memcg);
5110 }
5111 
5112 static struct mem_cgroup *mem_cgroup_alloc(void)
5113 {
5114 	struct mem_cgroup *memcg;
5115 	int node;
5116 	int __maybe_unused i;
5117 	long error = -ENOMEM;
5118 
5119 	memcg = kzalloc(struct_size(memcg, nodeinfo, nr_node_ids), GFP_KERNEL);
5120 	if (!memcg)
5121 		return ERR_PTR(error);
5122 
5123 	memcg->id.id = idr_alloc(&mem_cgroup_idr, NULL,
5124 				 1, MEM_CGROUP_ID_MAX + 1, GFP_KERNEL);
5125 	if (memcg->id.id < 0) {
5126 		error = memcg->id.id;
5127 		goto fail;
5128 	}
5129 
5130 	memcg->vmstats_percpu = alloc_percpu_gfp(struct memcg_vmstats_percpu,
5131 						 GFP_KERNEL_ACCOUNT);
5132 	if (!memcg->vmstats_percpu)
5133 		goto fail;
5134 
5135 	for_each_node(node)
5136 		if (alloc_mem_cgroup_per_node_info(memcg, node))
5137 			goto fail;
5138 
5139 	if (memcg_wb_domain_init(memcg, GFP_KERNEL))
5140 		goto fail;
5141 
5142 	INIT_WORK(&memcg->high_work, high_work_func);
5143 	INIT_LIST_HEAD(&memcg->oom_notify);
5144 	mutex_init(&memcg->thresholds_lock);
5145 	spin_lock_init(&memcg->move_lock);
5146 	vmpressure_init(&memcg->vmpressure);
5147 	INIT_LIST_HEAD(&memcg->event_list);
5148 	spin_lock_init(&memcg->event_list_lock);
5149 	memcg->socket_pressure = jiffies;
5150 #ifdef CONFIG_MEMCG_KMEM
5151 	memcg->kmemcg_id = -1;
5152 	INIT_LIST_HEAD(&memcg->objcg_list);
5153 #endif
5154 #ifdef CONFIG_CGROUP_WRITEBACK
5155 	INIT_LIST_HEAD(&memcg->cgwb_list);
5156 	for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++)
5157 		memcg->cgwb_frn[i].done =
5158 			__WB_COMPLETION_INIT(&memcg_cgwb_frn_waitq);
5159 #endif
5160 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
5161 	spin_lock_init(&memcg->deferred_split_queue.split_queue_lock);
5162 	INIT_LIST_HEAD(&memcg->deferred_split_queue.split_queue);
5163 	memcg->deferred_split_queue.split_queue_len = 0;
5164 #endif
5165 	idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
5166 	return memcg;
5167 fail:
5168 	mem_cgroup_id_remove(memcg);
5169 	__mem_cgroup_free(memcg);
5170 	return ERR_PTR(error);
5171 }
5172 
5173 static struct cgroup_subsys_state * __ref
5174 mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
5175 {
5176 	struct mem_cgroup *parent = mem_cgroup_from_css(parent_css);
5177 	struct mem_cgroup *memcg, *old_memcg;
5178 
5179 	old_memcg = set_active_memcg(parent);
5180 	memcg = mem_cgroup_alloc();
5181 	set_active_memcg(old_memcg);
5182 	if (IS_ERR(memcg))
5183 		return ERR_CAST(memcg);
5184 
5185 	page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX);
5186 	memcg->soft_limit = PAGE_COUNTER_MAX;
5187 #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
5188 	memcg->zswap_max = PAGE_COUNTER_MAX;
5189 #endif
5190 	page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX);
5191 	if (parent) {
5192 		memcg->swappiness = mem_cgroup_swappiness(parent);
5193 		memcg->oom_kill_disable = parent->oom_kill_disable;
5194 
5195 		page_counter_init(&memcg->memory, &parent->memory);
5196 		page_counter_init(&memcg->swap, &parent->swap);
5197 		page_counter_init(&memcg->kmem, &parent->kmem);
5198 		page_counter_init(&memcg->tcpmem, &parent->tcpmem);
5199 	} else {
5200 		page_counter_init(&memcg->memory, NULL);
5201 		page_counter_init(&memcg->swap, NULL);
5202 		page_counter_init(&memcg->kmem, NULL);
5203 		page_counter_init(&memcg->tcpmem, NULL);
5204 
5205 		root_mem_cgroup = memcg;
5206 		return &memcg->css;
5207 	}
5208 
5209 	if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
5210 		static_branch_inc(&memcg_sockets_enabled_key);
5211 
5212 	return &memcg->css;
5213 }
5214 
5215 static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
5216 {
5217 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
5218 
5219 	if (memcg_online_kmem(memcg))
5220 		goto remove_id;
5221 
5222 	/*
5223 	 * A memcg must be visible for expand_shrinker_info()
5224 	 * by the time the maps are allocated. So, we allocate maps
5225 	 * here, when for_each_mem_cgroup() can't skip it.
5226 	 */
5227 	if (alloc_shrinker_info(memcg))
5228 		goto offline_kmem;
5229 
5230 	/* Online state pins memcg ID, memcg ID pins CSS */
5231 	refcount_set(&memcg->id.ref, 1);
5232 	css_get(css);
5233 
5234 	if (unlikely(mem_cgroup_is_root(memcg)))
5235 		queue_delayed_work(system_unbound_wq, &stats_flush_dwork,
5236 				   2UL*HZ);
5237 	return 0;
5238 offline_kmem:
5239 	memcg_offline_kmem(memcg);
5240 remove_id:
5241 	mem_cgroup_id_remove(memcg);
5242 	return -ENOMEM;
5243 }
5244 
5245 static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
5246 {
5247 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
5248 	struct mem_cgroup_event *event, *tmp;
5249 
5250 	/*
5251 	 * Unregister events and notify userspace.
5252 	 * Notify userspace about cgroup removing only after rmdir of cgroup
5253 	 * directory to avoid race between userspace and kernelspace.
5254 	 */
5255 	spin_lock_irq(&memcg->event_list_lock);
5256 	list_for_each_entry_safe(event, tmp, &memcg->event_list, list) {
5257 		list_del_init(&event->list);
5258 		schedule_work(&event->remove);
5259 	}
5260 	spin_unlock_irq(&memcg->event_list_lock);
5261 
5262 	page_counter_set_min(&memcg->memory, 0);
5263 	page_counter_set_low(&memcg->memory, 0);
5264 
5265 	memcg_offline_kmem(memcg);
5266 	reparent_shrinker_deferred(memcg);
5267 	wb_memcg_offline(memcg);
5268 
5269 	drain_all_stock(memcg);
5270 
5271 	mem_cgroup_id_put(memcg);
5272 }
5273 
5274 static void mem_cgroup_css_released(struct cgroup_subsys_state *css)
5275 {
5276 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
5277 
5278 	invalidate_reclaim_iterators(memcg);
5279 }
5280 
5281 static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
5282 {
5283 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
5284 	int __maybe_unused i;
5285 
5286 #ifdef CONFIG_CGROUP_WRITEBACK
5287 	for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++)
5288 		wb_wait_for_completion(&memcg->cgwb_frn[i].done);
5289 #endif
5290 	if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
5291 		static_branch_dec(&memcg_sockets_enabled_key);
5292 
5293 	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && memcg->tcpmem_active)
5294 		static_branch_dec(&memcg_sockets_enabled_key);
5295 
5296 	vmpressure_cleanup(&memcg->vmpressure);
5297 	cancel_work_sync(&memcg->high_work);
5298 	mem_cgroup_remove_from_trees(memcg);
5299 	free_shrinker_info(memcg);
5300 	mem_cgroup_free(memcg);
5301 }
5302 
5303 /**
5304  * mem_cgroup_css_reset - reset the states of a mem_cgroup
5305  * @css: the target css
5306  *
5307  * Reset the states of the mem_cgroup associated with @css.  This is
5308  * invoked when the userland requests disabling on the default hierarchy
5309  * but the memcg is pinned through dependency.  The memcg should stop
5310  * applying policies and should revert to the vanilla state as it may be
5311  * made visible again.
5312  *
5313  * The current implementation only resets the essential configurations.
5314  * This needs to be expanded to cover all the visible parts.
5315  */
5316 static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
5317 {
5318 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
5319 
5320 	page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX);
5321 	page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX);
5322 	page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX);
5323 	page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX);
5324 	page_counter_set_min(&memcg->memory, 0);
5325 	page_counter_set_low(&memcg->memory, 0);
5326 	page_counter_set_high(&memcg->memory, PAGE_COUNTER_MAX);
5327 	memcg->soft_limit = PAGE_COUNTER_MAX;
5328 	page_counter_set_high(&memcg->swap, PAGE_COUNTER_MAX);
5329 	memcg_wb_domain_size_changed(memcg);
5330 }
5331 
5332 static void mem_cgroup_css_rstat_flush(struct cgroup_subsys_state *css, int cpu)
5333 {
5334 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
5335 	struct mem_cgroup *parent = parent_mem_cgroup(memcg);
5336 	struct memcg_vmstats_percpu *statc;
5337 	long delta, v;
5338 	int i, nid;
5339 
5340 	statc = per_cpu_ptr(memcg->vmstats_percpu, cpu);
5341 
5342 	for (i = 0; i < MEMCG_NR_STAT; i++) {
5343 		/*
5344 		 * Collect the aggregated propagation counts of groups
5345 		 * below us. We're in a per-cpu loop here and this is
5346 		 * a global counter, so the first cycle will get them.
5347 		 */
5348 		delta = memcg->vmstats.state_pending[i];
5349 		if (delta)
5350 			memcg->vmstats.state_pending[i] = 0;
5351 
5352 		/* Add CPU changes on this level since the last flush */
5353 		v = READ_ONCE(statc->state[i]);
5354 		if (v != statc->state_prev[i]) {
5355 			delta += v - statc->state_prev[i];
5356 			statc->state_prev[i] = v;
5357 		}
5358 
5359 		if (!delta)
5360 			continue;
5361 
5362 		/* Aggregate counts on this level and propagate upwards */
5363 		memcg->vmstats.state[i] += delta;
5364 		if (parent)
5365 			parent->vmstats.state_pending[i] += delta;
5366 	}
5367 
5368 	for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
5369 		delta = memcg->vmstats.events_pending[i];
5370 		if (delta)
5371 			memcg->vmstats.events_pending[i] = 0;
5372 
5373 		v = READ_ONCE(statc->events[i]);
5374 		if (v != statc->events_prev[i]) {
5375 			delta += v - statc->events_prev[i];
5376 			statc->events_prev[i] = v;
5377 		}
5378 
5379 		if (!delta)
5380 			continue;
5381 
5382 		memcg->vmstats.events[i] += delta;
5383 		if (parent)
5384 			parent->vmstats.events_pending[i] += delta;
5385 	}
5386 
5387 	for_each_node_state(nid, N_MEMORY) {
5388 		struct mem_cgroup_per_node *pn = memcg->nodeinfo[nid];
5389 		struct mem_cgroup_per_node *ppn = NULL;
5390 		struct lruvec_stats_percpu *lstatc;
5391 
5392 		if (parent)
5393 			ppn = parent->nodeinfo[nid];
5394 
5395 		lstatc = per_cpu_ptr(pn->lruvec_stats_percpu, cpu);
5396 
5397 		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
5398 			delta = pn->lruvec_stats.state_pending[i];
5399 			if (delta)
5400 				pn->lruvec_stats.state_pending[i] = 0;
5401 
5402 			v = READ_ONCE(lstatc->state[i]);
5403 			if (v != lstatc->state_prev[i]) {
5404 				delta += v - lstatc->state_prev[i];
5405 				lstatc->state_prev[i] = v;
5406 			}
5407 
5408 			if (!delta)
5409 				continue;
5410 
5411 			pn->lruvec_stats.state[i] += delta;
5412 			if (ppn)
5413 				ppn->lruvec_stats.state_pending[i] += delta;
5414 		}
5415 	}
5416 }
5417 
5418 #ifdef CONFIG_MMU
5419 /* Handlers for move charge at task migration. */
5420 static int mem_cgroup_do_precharge(unsigned long count)
5421 {
5422 	int ret;
5423 
5424 	/* Try a single bulk charge without reclaim first, kswapd may wake */
5425 	ret = try_charge(mc.to, GFP_KERNEL & ~__GFP_DIRECT_RECLAIM, count);
5426 	if (!ret) {
5427 		mc.precharge += count;
5428 		return ret;
5429 	}
5430 
5431 	/* Try charges one by one with reclaim, but do not retry */
5432 	while (count--) {
5433 		ret = try_charge(mc.to, GFP_KERNEL | __GFP_NORETRY, 1);
5434 		if (ret)
5435 			return ret;
5436 		mc.precharge++;
5437 		cond_resched();
5438 	}
5439 	return 0;
5440 }
5441 
5442 union mc_target {
5443 	struct page	*page;
5444 	swp_entry_t	ent;
5445 };
5446 
5447 enum mc_target_type {
5448 	MC_TARGET_NONE = 0,
5449 	MC_TARGET_PAGE,
5450 	MC_TARGET_SWAP,
5451 	MC_TARGET_DEVICE,
5452 };
5453 
5454 static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
5455 						unsigned long addr, pte_t ptent)
5456 {
5457 	struct page *page = vm_normal_page(vma, addr, ptent);
5458 
5459 	if (!page || !page_mapped(page))
5460 		return NULL;
5461 	if (PageAnon(page)) {
5462 		if (!(mc.flags & MOVE_ANON))
5463 			return NULL;
5464 	} else {
5465 		if (!(mc.flags & MOVE_FILE))
5466 			return NULL;
5467 	}
5468 	if (!get_page_unless_zero(page))
5469 		return NULL;
5470 
5471 	return page;
5472 }
5473 
5474 #if defined(CONFIG_SWAP) || defined(CONFIG_DEVICE_PRIVATE)
5475 static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
5476 			pte_t ptent, swp_entry_t *entry)
5477 {
5478 	struct page *page = NULL;
5479 	swp_entry_t ent = pte_to_swp_entry(ptent);
5480 
5481 	if (!(mc.flags & MOVE_ANON))
5482 		return NULL;
5483 
5484 	/*
5485 	 * Handle device private pages that are not accessible by the CPU, but
5486 	 * stored as special swap entries in the page table.
5487 	 */
5488 	if (is_device_private_entry(ent)) {
5489 		page = pfn_swap_entry_to_page(ent);
5490 		if (!get_page_unless_zero(page))
5491 			return NULL;
5492 		return page;
5493 	}
5494 
5495 	if (non_swap_entry(ent))
5496 		return NULL;
5497 
5498 	/*
5499 	 * Because lookup_swap_cache() updates some statistics counter,
5500 	 * we call find_get_page() with swapper_space directly.
5501 	 */
5502 	page = find_get_page(swap_address_space(ent), swp_offset(ent));
5503 	entry->val = ent.val;
5504 
5505 	return page;
5506 }
5507 #else
5508 static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
5509 			pte_t ptent, swp_entry_t *entry)
5510 {
5511 	return NULL;
5512 }
5513 #endif
5514 
5515 static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
5516 			unsigned long addr, pte_t ptent)
5517 {
5518 	if (!vma->vm_file) /* anonymous vma */
5519 		return NULL;
5520 	if (!(mc.flags & MOVE_FILE))
5521 		return NULL;
5522 
5523 	/* page is moved even if it's not RSS of this task(page-faulted). */
5524 	/* shmem/tmpfs may report page out on swap: account for that too. */
5525 	return find_get_incore_page(vma->vm_file->f_mapping,
5526 			linear_page_index(vma, addr));
5527 }
5528 
5529 /**
5530  * mem_cgroup_move_account - move account of the page
5531  * @page: the page
5532  * @compound: charge the page as compound or small page
5533  * @from: mem_cgroup which the page is moved from.
5534  * @to:	mem_cgroup which the page is moved to. @from != @to.
5535  *
5536  * The caller must make sure the page is not on LRU (isolate_page() is useful.)
5537  *
5538  * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
5539  * from old cgroup.
5540  */
5541 static int mem_cgroup_move_account(struct page *page,
5542 				   bool compound,
5543 				   struct mem_cgroup *from,
5544 				   struct mem_cgroup *to)
5545 {
5546 	struct folio *folio = page_folio(page);
5547 	struct lruvec *from_vec, *to_vec;
5548 	struct pglist_data *pgdat;
5549 	unsigned int nr_pages = compound ? folio_nr_pages(folio) : 1;
5550 	int nid, ret;
5551 
5552 	VM_BUG_ON(from == to);
5553 	VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
5554 	VM_BUG_ON(compound && !folio_test_large(folio));
5555 
5556 	/*
5557 	 * Prevent mem_cgroup_migrate() from looking at
5558 	 * page's memory cgroup of its source page while we change it.
5559 	 */
5560 	ret = -EBUSY;
5561 	if (!folio_trylock(folio))
5562 		goto out;
5563 
5564 	ret = -EINVAL;
5565 	if (folio_memcg(folio) != from)
5566 		goto out_unlock;
5567 
5568 	pgdat = folio_pgdat(folio);
5569 	from_vec = mem_cgroup_lruvec(from, pgdat);
5570 	to_vec = mem_cgroup_lruvec(to, pgdat);
5571 
5572 	folio_memcg_lock(folio);
5573 
5574 	if (folio_test_anon(folio)) {
5575 		if (folio_mapped(folio)) {
5576 			__mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages);
5577 			__mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages);
5578 			if (folio_test_transhuge(folio)) {
5579 				__mod_lruvec_state(from_vec, NR_ANON_THPS,
5580 						   -nr_pages);
5581 				__mod_lruvec_state(to_vec, NR_ANON_THPS,
5582 						   nr_pages);
5583 			}
5584 		}
5585 	} else {
5586 		__mod_lruvec_state(from_vec, NR_FILE_PAGES, -nr_pages);
5587 		__mod_lruvec_state(to_vec, NR_FILE_PAGES, nr_pages);
5588 
5589 		if (folio_test_swapbacked(folio)) {
5590 			__mod_lruvec_state(from_vec, NR_SHMEM, -nr_pages);
5591 			__mod_lruvec_state(to_vec, NR_SHMEM, nr_pages);
5592 		}
5593 
5594 		if (folio_mapped(folio)) {
5595 			__mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages);
5596 			__mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages);
5597 		}
5598 
5599 		if (folio_test_dirty(folio)) {
5600 			struct address_space *mapping = folio_mapping(folio);
5601 
5602 			if (mapping_can_writeback(mapping)) {
5603 				__mod_lruvec_state(from_vec, NR_FILE_DIRTY,
5604 						   -nr_pages);
5605 				__mod_lruvec_state(to_vec, NR_FILE_DIRTY,
5606 						   nr_pages);
5607 			}
5608 		}
5609 	}
5610 
5611 	if (folio_test_writeback(folio)) {
5612 		__mod_lruvec_state(from_vec, NR_WRITEBACK, -nr_pages);
5613 		__mod_lruvec_state(to_vec, NR_WRITEBACK, nr_pages);
5614 	}
5615 
5616 	/*
5617 	 * All state has been migrated, let's switch to the new memcg.
5618 	 *
5619 	 * It is safe to change page's memcg here because the page
5620 	 * is referenced, charged, isolated, and locked: we can't race
5621 	 * with (un)charging, migration, LRU putback, or anything else
5622 	 * that would rely on a stable page's memory cgroup.
5623 	 *
5624 	 * Note that lock_page_memcg is a memcg lock, not a page lock,
5625 	 * to save space. As soon as we switch page's memory cgroup to a
5626 	 * new memcg that isn't locked, the above state can change
5627 	 * concurrently again. Make sure we're truly done with it.
5628 	 */
5629 	smp_mb();
5630 
5631 	css_get(&to->css);
5632 	css_put(&from->css);
5633 
5634 	folio->memcg_data = (unsigned long)to;
5635 
5636 	__folio_memcg_unlock(from);
5637 
5638 	ret = 0;
5639 	nid = folio_nid(folio);
5640 
5641 	local_irq_disable();
5642 	mem_cgroup_charge_statistics(to, nr_pages);
5643 	memcg_check_events(to, nid);
5644 	mem_cgroup_charge_statistics(from, -nr_pages);
5645 	memcg_check_events(from, nid);
5646 	local_irq_enable();
5647 out_unlock:
5648 	folio_unlock(folio);
5649 out:
5650 	return ret;
5651 }
5652 
5653 /**
5654  * get_mctgt_type - get target type of moving charge
5655  * @vma: the vma the pte to be checked belongs
5656  * @addr: the address corresponding to the pte to be checked
5657  * @ptent: the pte to be checked
5658  * @target: the pointer the target page or swap ent will be stored(can be NULL)
5659  *
5660  * Returns
5661  *   0(MC_TARGET_NONE): if the pte is not a target for move charge.
5662  *   1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
5663  *     move charge. if @target is not NULL, the page is stored in target->page
5664  *     with extra refcnt got(Callers should handle it).
5665  *   2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
5666  *     target for charge migration. if @target is not NULL, the entry is stored
5667  *     in target->ent.
5668  *   3(MC_TARGET_DEVICE): like MC_TARGET_PAGE  but page is MEMORY_DEVICE_PRIVATE
5669  *     (so ZONE_DEVICE page and thus not on the lru).
5670  *     For now we such page is charge like a regular page would be as for all
5671  *     intent and purposes it is just special memory taking the place of a
5672  *     regular page.
5673  *
5674  *     See Documentations/vm/hmm.txt and include/linux/hmm.h
5675  *
5676  * Called with pte lock held.
5677  */
5678 
5679 static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
5680 		unsigned long addr, pte_t ptent, union mc_target *target)
5681 {
5682 	struct page *page = NULL;
5683 	enum mc_target_type ret = MC_TARGET_NONE;
5684 	swp_entry_t ent = { .val = 0 };
5685 
5686 	if (pte_present(ptent))
5687 		page = mc_handle_present_pte(vma, addr, ptent);
5688 	else if (pte_none_mostly(ptent))
5689 		/*
5690 		 * PTE markers should be treated as a none pte here, separated
5691 		 * from other swap handling below.
5692 		 */
5693 		page = mc_handle_file_pte(vma, addr, ptent);
5694 	else if (is_swap_pte(ptent))
5695 		page = mc_handle_swap_pte(vma, ptent, &ent);
5696 
5697 	if (!page && !ent.val)
5698 		return ret;
5699 	if (page) {
5700 		/*
5701 		 * Do only loose check w/o serialization.
5702 		 * mem_cgroup_move_account() checks the page is valid or
5703 		 * not under LRU exclusion.
5704 		 */
5705 		if (page_memcg(page) == mc.from) {
5706 			ret = MC_TARGET_PAGE;
5707 			if (is_device_private_page(page))
5708 				ret = MC_TARGET_DEVICE;
5709 			if (target)
5710 				target->page = page;
5711 		}
5712 		if (!ret || !target)
5713 			put_page(page);
5714 	}
5715 	/*
5716 	 * There is a swap entry and a page doesn't exist or isn't charged.
5717 	 * But we cannot move a tail-page in a THP.
5718 	 */
5719 	if (ent.val && !ret && (!page || !PageTransCompound(page)) &&
5720 	    mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) {
5721 		ret = MC_TARGET_SWAP;
5722 		if (target)
5723 			target->ent = ent;
5724 	}
5725 	return ret;
5726 }
5727 
5728 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
5729 /*
5730  * We don't consider PMD mapped swapping or file mapped pages because THP does
5731  * not support them for now.
5732  * Caller should make sure that pmd_trans_huge(pmd) is true.
5733  */
5734 static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
5735 		unsigned long addr, pmd_t pmd, union mc_target *target)
5736 {
5737 	struct page *page = NULL;
5738 	enum mc_target_type ret = MC_TARGET_NONE;
5739 
5740 	if (unlikely(is_swap_pmd(pmd))) {
5741 		VM_BUG_ON(thp_migration_supported() &&
5742 				  !is_pmd_migration_entry(pmd));
5743 		return ret;
5744 	}
5745 	page = pmd_page(pmd);
5746 	VM_BUG_ON_PAGE(!page || !PageHead(page), page);
5747 	if (!(mc.flags & MOVE_ANON))
5748 		return ret;
5749 	if (page_memcg(page) == mc.from) {
5750 		ret = MC_TARGET_PAGE;
5751 		if (target) {
5752 			get_page(page);
5753 			target->page = page;
5754 		}
5755 	}
5756 	return ret;
5757 }
5758 #else
5759 static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
5760 		unsigned long addr, pmd_t pmd, union mc_target *target)
5761 {
5762 	return MC_TARGET_NONE;
5763 }
5764 #endif
5765 
5766 static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
5767 					unsigned long addr, unsigned long end,
5768 					struct mm_walk *walk)
5769 {
5770 	struct vm_area_struct *vma = walk->vma;
5771 	pte_t *pte;
5772 	spinlock_t *ptl;
5773 
5774 	ptl = pmd_trans_huge_lock(pmd, vma);
5775 	if (ptl) {
5776 		/*
5777 		 * Note their can not be MC_TARGET_DEVICE for now as we do not
5778 		 * support transparent huge page with MEMORY_DEVICE_PRIVATE but
5779 		 * this might change.
5780 		 */
5781 		if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
5782 			mc.precharge += HPAGE_PMD_NR;
5783 		spin_unlock(ptl);
5784 		return 0;
5785 	}
5786 
5787 	if (pmd_trans_unstable(pmd))
5788 		return 0;
5789 	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
5790 	for (; addr != end; pte++, addr += PAGE_SIZE)
5791 		if (get_mctgt_type(vma, addr, *pte, NULL))
5792 			mc.precharge++;	/* increment precharge temporarily */
5793 	pte_unmap_unlock(pte - 1, ptl);
5794 	cond_resched();
5795 
5796 	return 0;
5797 }
5798 
5799 static const struct mm_walk_ops precharge_walk_ops = {
5800 	.pmd_entry	= mem_cgroup_count_precharge_pte_range,
5801 };
5802 
5803 static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
5804 {
5805 	unsigned long precharge;
5806 
5807 	mmap_read_lock(mm);
5808 	walk_page_range(mm, 0, mm->highest_vm_end, &precharge_walk_ops, NULL);
5809 	mmap_read_unlock(mm);
5810 
5811 	precharge = mc.precharge;
5812 	mc.precharge = 0;
5813 
5814 	return precharge;
5815 }
5816 
5817 static int mem_cgroup_precharge_mc(struct mm_struct *mm)
5818 {
5819 	unsigned long precharge = mem_cgroup_count_precharge(mm);
5820 
5821 	VM_BUG_ON(mc.moving_task);
5822 	mc.moving_task = current;
5823 	return mem_cgroup_do_precharge(precharge);
5824 }
5825 
5826 /* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
5827 static void __mem_cgroup_clear_mc(void)
5828 {
5829 	struct mem_cgroup *from = mc.from;
5830 	struct mem_cgroup *to = mc.to;
5831 
5832 	/* we must uncharge all the leftover precharges from mc.to */
5833 	if (mc.precharge) {
5834 		cancel_charge(mc.to, mc.precharge);
5835 		mc.precharge = 0;
5836 	}
5837 	/*
5838 	 * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
5839 	 * we must uncharge here.
5840 	 */
5841 	if (mc.moved_charge) {
5842 		cancel_charge(mc.from, mc.moved_charge);
5843 		mc.moved_charge = 0;
5844 	}
5845 	/* we must fixup refcnts and charges */
5846 	if (mc.moved_swap) {
5847 		/* uncharge swap account from the old cgroup */
5848 		if (!mem_cgroup_is_root(mc.from))
5849 			page_counter_uncharge(&mc.from->memsw, mc.moved_swap);
5850 
5851 		mem_cgroup_id_put_many(mc.from, mc.moved_swap);
5852 
5853 		/*
5854 		 * we charged both to->memory and to->memsw, so we
5855 		 * should uncharge to->memory.
5856 		 */
5857 		if (!mem_cgroup_is_root(mc.to))
5858 			page_counter_uncharge(&mc.to->memory, mc.moved_swap);
5859 
5860 		mc.moved_swap = 0;
5861 	}
5862 	memcg_oom_recover(from);
5863 	memcg_oom_recover(to);
5864 	wake_up_all(&mc.waitq);
5865 }
5866 
5867 static void mem_cgroup_clear_mc(void)
5868 {
5869 	struct mm_struct *mm = mc.mm;
5870 
5871 	/*
5872 	 * we must clear moving_task before waking up waiters at the end of
5873 	 * task migration.
5874 	 */
5875 	mc.moving_task = NULL;
5876 	__mem_cgroup_clear_mc();
5877 	spin_lock(&mc.lock);
5878 	mc.from = NULL;
5879 	mc.to = NULL;
5880 	mc.mm = NULL;
5881 	spin_unlock(&mc.lock);
5882 
5883 	mmput(mm);
5884 }
5885 
5886 static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
5887 {
5888 	struct cgroup_subsys_state *css;
5889 	struct mem_cgroup *memcg = NULL; /* unneeded init to make gcc happy */
5890 	struct mem_cgroup *from;
5891 	struct task_struct *leader, *p;
5892 	struct mm_struct *mm;
5893 	unsigned long move_flags;
5894 	int ret = 0;
5895 
5896 	/* charge immigration isn't supported on the default hierarchy */
5897 	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
5898 		return 0;
5899 
5900 	/*
5901 	 * Multi-process migrations only happen on the default hierarchy
5902 	 * where charge immigration is not used.  Perform charge
5903 	 * immigration if @tset contains a leader and whine if there are
5904 	 * multiple.
5905 	 */
5906 	p = NULL;
5907 	cgroup_taskset_for_each_leader(leader, css, tset) {
5908 		WARN_ON_ONCE(p);
5909 		p = leader;
5910 		memcg = mem_cgroup_from_css(css);
5911 	}
5912 	if (!p)
5913 		return 0;
5914 
5915 	/*
5916 	 * We are now committed to this value whatever it is. Changes in this
5917 	 * tunable will only affect upcoming migrations, not the current one.
5918 	 * So we need to save it, and keep it going.
5919 	 */
5920 	move_flags = READ_ONCE(memcg->move_charge_at_immigrate);
5921 	if (!move_flags)
5922 		return 0;
5923 
5924 	from = mem_cgroup_from_task(p);
5925 
5926 	VM_BUG_ON(from == memcg);
5927 
5928 	mm = get_task_mm(p);
5929 	if (!mm)
5930 		return 0;
5931 	/* We move charges only when we move a owner of the mm */
5932 	if (mm->owner == p) {
5933 		VM_BUG_ON(mc.from);
5934 		VM_BUG_ON(mc.to);
5935 		VM_BUG_ON(mc.precharge);
5936 		VM_BUG_ON(mc.moved_charge);
5937 		VM_BUG_ON(mc.moved_swap);
5938 
5939 		spin_lock(&mc.lock);
5940 		mc.mm = mm;
5941 		mc.from = from;
5942 		mc.to = memcg;
5943 		mc.flags = move_flags;
5944 		spin_unlock(&mc.lock);
5945 		/* We set mc.moving_task later */
5946 
5947 		ret = mem_cgroup_precharge_mc(mm);
5948 		if (ret)
5949 			mem_cgroup_clear_mc();
5950 	} else {
5951 		mmput(mm);
5952 	}
5953 	return ret;
5954 }
5955 
5956 static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
5957 {
5958 	if (mc.to)
5959 		mem_cgroup_clear_mc();
5960 }
5961 
5962 static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
5963 				unsigned long addr, unsigned long end,
5964 				struct mm_walk *walk)
5965 {
5966 	int ret = 0;
5967 	struct vm_area_struct *vma = walk->vma;
5968 	pte_t *pte;
5969 	spinlock_t *ptl;
5970 	enum mc_target_type target_type;
5971 	union mc_target target;
5972 	struct page *page;
5973 
5974 	ptl = pmd_trans_huge_lock(pmd, vma);
5975 	if (ptl) {
5976 		if (mc.precharge < HPAGE_PMD_NR) {
5977 			spin_unlock(ptl);
5978 			return 0;
5979 		}
5980 		target_type = get_mctgt_type_thp(vma, addr, *pmd, &target);
5981 		if (target_type == MC_TARGET_PAGE) {
5982 			page = target.page;
5983 			if (!isolate_lru_page(page)) {
5984 				if (!mem_cgroup_move_account(page, true,
5985 							     mc.from, mc.to)) {
5986 					mc.precharge -= HPAGE_PMD_NR;
5987 					mc.moved_charge += HPAGE_PMD_NR;
5988 				}
5989 				putback_lru_page(page);
5990 			}
5991 			put_page(page);
5992 		} else if (target_type == MC_TARGET_DEVICE) {
5993 			page = target.page;
5994 			if (!mem_cgroup_move_account(page, true,
5995 						     mc.from, mc.to)) {
5996 				mc.precharge -= HPAGE_PMD_NR;
5997 				mc.moved_charge += HPAGE_PMD_NR;
5998 			}
5999 			put_page(page);
6000 		}
6001 		spin_unlock(ptl);
6002 		return 0;
6003 	}
6004 
6005 	if (pmd_trans_unstable(pmd))
6006 		return 0;
6007 retry:
6008 	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
6009 	for (; addr != end; addr += PAGE_SIZE) {
6010 		pte_t ptent = *(pte++);
6011 		bool device = false;
6012 		swp_entry_t ent;
6013 
6014 		if (!mc.precharge)
6015 			break;
6016 
6017 		switch (get_mctgt_type(vma, addr, ptent, &target)) {
6018 		case MC_TARGET_DEVICE:
6019 			device = true;
6020 			fallthrough;
6021 		case MC_TARGET_PAGE:
6022 			page = target.page;
6023 			/*
6024 			 * We can have a part of the split pmd here. Moving it
6025 			 * can be done but it would be too convoluted so simply
6026 			 * ignore such a partial THP and keep it in original
6027 			 * memcg. There should be somebody mapping the head.
6028 			 */
6029 			if (PageTransCompound(page))
6030 				goto put;
6031 			if (!device && isolate_lru_page(page))
6032 				goto put;
6033 			if (!mem_cgroup_move_account(page, false,
6034 						mc.from, mc.to)) {
6035 				mc.precharge--;
6036 				/* we uncharge from mc.from later. */
6037 				mc.moved_charge++;
6038 			}
6039 			if (!device)
6040 				putback_lru_page(page);
6041 put:			/* get_mctgt_type() gets the page */
6042 			put_page(page);
6043 			break;
6044 		case MC_TARGET_SWAP:
6045 			ent = target.ent;
6046 			if (!mem_cgroup_move_swap_account(ent, mc.from, mc.to)) {
6047 				mc.precharge--;
6048 				mem_cgroup_id_get_many(mc.to, 1);
6049 				/* we fixup other refcnts and charges later. */
6050 				mc.moved_swap++;
6051 			}
6052 			break;
6053 		default:
6054 			break;
6055 		}
6056 	}
6057 	pte_unmap_unlock(pte - 1, ptl);
6058 	cond_resched();
6059 
6060 	if (addr != end) {
6061 		/*
6062 		 * We have consumed all precharges we got in can_attach().
6063 		 * We try charge one by one, but don't do any additional
6064 		 * charges to mc.to if we have failed in charge once in attach()
6065 		 * phase.
6066 		 */
6067 		ret = mem_cgroup_do_precharge(1);
6068 		if (!ret)
6069 			goto retry;
6070 	}
6071 
6072 	return ret;
6073 }
6074 
6075 static const struct mm_walk_ops charge_walk_ops = {
6076 	.pmd_entry	= mem_cgroup_move_charge_pte_range,
6077 };
6078 
6079 static void mem_cgroup_move_charge(void)
6080 {
6081 	lru_add_drain_all();
6082 	/*
6083 	 * Signal lock_page_memcg() to take the memcg's move_lock
6084 	 * while we're moving its pages to another memcg. Then wait
6085 	 * for already started RCU-only updates to finish.
6086 	 */
6087 	atomic_inc(&mc.from->moving_account);
6088 	synchronize_rcu();
6089 retry:
6090 	if (unlikely(!mmap_read_trylock(mc.mm))) {
6091 		/*
6092 		 * Someone who are holding the mmap_lock might be waiting in
6093 		 * waitq. So we cancel all extra charges, wake up all waiters,
6094 		 * and retry. Because we cancel precharges, we might not be able
6095 		 * to move enough charges, but moving charge is a best-effort
6096 		 * feature anyway, so it wouldn't be a big problem.
6097 		 */
6098 		__mem_cgroup_clear_mc();
6099 		cond_resched();
6100 		goto retry;
6101 	}
6102 	/*
6103 	 * When we have consumed all precharges and failed in doing
6104 	 * additional charge, the page walk just aborts.
6105 	 */
6106 	walk_page_range(mc.mm, 0, mc.mm->highest_vm_end, &charge_walk_ops,
6107 			NULL);
6108 
6109 	mmap_read_unlock(mc.mm);
6110 	atomic_dec(&mc.from->moving_account);
6111 }
6112 
6113 static void mem_cgroup_move_task(void)
6114 {
6115 	if (mc.to) {
6116 		mem_cgroup_move_charge();
6117 		mem_cgroup_clear_mc();
6118 	}
6119 }
6120 #else	/* !CONFIG_MMU */
6121 static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
6122 {
6123 	return 0;
6124 }
6125 static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
6126 {
6127 }
6128 static void mem_cgroup_move_task(void)
6129 {
6130 }
6131 #endif
6132 
6133 static int seq_puts_memcg_tunable(struct seq_file *m, unsigned long value)
6134 {
6135 	if (value == PAGE_COUNTER_MAX)
6136 		seq_puts(m, "max\n");
6137 	else
6138 		seq_printf(m, "%llu\n", (u64)value * PAGE_SIZE);
6139 
6140 	return 0;
6141 }
6142 
6143 static u64 memory_current_read(struct cgroup_subsys_state *css,
6144 			       struct cftype *cft)
6145 {
6146 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
6147 
6148 	return (u64)page_counter_read(&memcg->memory) * PAGE_SIZE;
6149 }
6150 
6151 static u64 memory_peak_read(struct cgroup_subsys_state *css,
6152 			    struct cftype *cft)
6153 {
6154 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
6155 
6156 	return (u64)memcg->memory.watermark * PAGE_SIZE;
6157 }
6158 
6159 static int memory_min_show(struct seq_file *m, void *v)
6160 {
6161 	return seq_puts_memcg_tunable(m,
6162 		READ_ONCE(mem_cgroup_from_seq(m)->memory.min));
6163 }
6164 
6165 static ssize_t memory_min_write(struct kernfs_open_file *of,
6166 				char *buf, size_t nbytes, loff_t off)
6167 {
6168 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
6169 	unsigned long min;
6170 	int err;
6171 
6172 	buf = strstrip(buf);
6173 	err = page_counter_memparse(buf, "max", &min);
6174 	if (err)
6175 		return err;
6176 
6177 	page_counter_set_min(&memcg->memory, min);
6178 
6179 	return nbytes;
6180 }
6181 
6182 static int memory_low_show(struct seq_file *m, void *v)
6183 {
6184 	return seq_puts_memcg_tunable(m,
6185 		READ_ONCE(mem_cgroup_from_seq(m)->memory.low));
6186 }
6187 
6188 static ssize_t memory_low_write(struct kernfs_open_file *of,
6189 				char *buf, size_t nbytes, loff_t off)
6190 {
6191 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
6192 	unsigned long low;
6193 	int err;
6194 
6195 	buf = strstrip(buf);
6196 	err = page_counter_memparse(buf, "max", &low);
6197 	if (err)
6198 		return err;
6199 
6200 	page_counter_set_low(&memcg->memory, low);
6201 
6202 	return nbytes;
6203 }
6204 
6205 static int memory_high_show(struct seq_file *m, void *v)
6206 {
6207 	return seq_puts_memcg_tunable(m,
6208 		READ_ONCE(mem_cgroup_from_seq(m)->memory.high));
6209 }
6210 
6211 static ssize_t memory_high_write(struct kernfs_open_file *of,
6212 				 char *buf, size_t nbytes, loff_t off)
6213 {
6214 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
6215 	unsigned int nr_retries = MAX_RECLAIM_RETRIES;
6216 	bool drained = false;
6217 	unsigned long high;
6218 	int err;
6219 
6220 	buf = strstrip(buf);
6221 	err = page_counter_memparse(buf, "max", &high);
6222 	if (err)
6223 		return err;
6224 
6225 	page_counter_set_high(&memcg->memory, high);
6226 
6227 	for (;;) {
6228 		unsigned long nr_pages = page_counter_read(&memcg->memory);
6229 		unsigned long reclaimed;
6230 
6231 		if (nr_pages <= high)
6232 			break;
6233 
6234 		if (signal_pending(current))
6235 			break;
6236 
6237 		if (!drained) {
6238 			drain_all_stock(memcg);
6239 			drained = true;
6240 			continue;
6241 		}
6242 
6243 		reclaimed = try_to_free_mem_cgroup_pages(memcg, nr_pages - high,
6244 							 GFP_KERNEL, true);
6245 
6246 		if (!reclaimed && !nr_retries--)
6247 			break;
6248 	}
6249 
6250 	memcg_wb_domain_size_changed(memcg);
6251 	return nbytes;
6252 }
6253 
6254 static int memory_max_show(struct seq_file *m, void *v)
6255 {
6256 	return seq_puts_memcg_tunable(m,
6257 		READ_ONCE(mem_cgroup_from_seq(m)->memory.max));
6258 }
6259 
6260 static ssize_t memory_max_write(struct kernfs_open_file *of,
6261 				char *buf, size_t nbytes, loff_t off)
6262 {
6263 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
6264 	unsigned int nr_reclaims = MAX_RECLAIM_RETRIES;
6265 	bool drained = false;
6266 	unsigned long max;
6267 	int err;
6268 
6269 	buf = strstrip(buf);
6270 	err = page_counter_memparse(buf, "max", &max);
6271 	if (err)
6272 		return err;
6273 
6274 	xchg(&memcg->memory.max, max);
6275 
6276 	for (;;) {
6277 		unsigned long nr_pages = page_counter_read(&memcg->memory);
6278 
6279 		if (nr_pages <= max)
6280 			break;
6281 
6282 		if (signal_pending(current))
6283 			break;
6284 
6285 		if (!drained) {
6286 			drain_all_stock(memcg);
6287 			drained = true;
6288 			continue;
6289 		}
6290 
6291 		if (nr_reclaims) {
6292 			if (!try_to_free_mem_cgroup_pages(memcg, nr_pages - max,
6293 							  GFP_KERNEL, true))
6294 				nr_reclaims--;
6295 			continue;
6296 		}
6297 
6298 		memcg_memory_event(memcg, MEMCG_OOM);
6299 		if (!mem_cgroup_out_of_memory(memcg, GFP_KERNEL, 0))
6300 			break;
6301 	}
6302 
6303 	memcg_wb_domain_size_changed(memcg);
6304 	return nbytes;
6305 }
6306 
6307 static void __memory_events_show(struct seq_file *m, atomic_long_t *events)
6308 {
6309 	seq_printf(m, "low %lu\n", atomic_long_read(&events[MEMCG_LOW]));
6310 	seq_printf(m, "high %lu\n", atomic_long_read(&events[MEMCG_HIGH]));
6311 	seq_printf(m, "max %lu\n", atomic_long_read(&events[MEMCG_MAX]));
6312 	seq_printf(m, "oom %lu\n", atomic_long_read(&events[MEMCG_OOM]));
6313 	seq_printf(m, "oom_kill %lu\n",
6314 		   atomic_long_read(&events[MEMCG_OOM_KILL]));
6315 	seq_printf(m, "oom_group_kill %lu\n",
6316 		   atomic_long_read(&events[MEMCG_OOM_GROUP_KILL]));
6317 }
6318 
6319 static int memory_events_show(struct seq_file *m, void *v)
6320 {
6321 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
6322 
6323 	__memory_events_show(m, memcg->memory_events);
6324 	return 0;
6325 }
6326 
6327 static int memory_events_local_show(struct seq_file *m, void *v)
6328 {
6329 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
6330 
6331 	__memory_events_show(m, memcg->memory_events_local);
6332 	return 0;
6333 }
6334 
6335 static int memory_stat_show(struct seq_file *m, void *v)
6336 {
6337 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
6338 	char *buf;
6339 
6340 	buf = memory_stat_format(memcg);
6341 	if (!buf)
6342 		return -ENOMEM;
6343 	seq_puts(m, buf);
6344 	kfree(buf);
6345 	return 0;
6346 }
6347 
6348 #ifdef CONFIG_NUMA
6349 static inline unsigned long lruvec_page_state_output(struct lruvec *lruvec,
6350 						     int item)
6351 {
6352 	return lruvec_page_state(lruvec, item) * memcg_page_state_unit(item);
6353 }
6354 
6355 static int memory_numa_stat_show(struct seq_file *m, void *v)
6356 {
6357 	int i;
6358 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
6359 
6360 	mem_cgroup_flush_stats();
6361 
6362 	for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
6363 		int nid;
6364 
6365 		if (memory_stats[i].idx >= NR_VM_NODE_STAT_ITEMS)
6366 			continue;
6367 
6368 		seq_printf(m, "%s", memory_stats[i].name);
6369 		for_each_node_state(nid, N_MEMORY) {
6370 			u64 size;
6371 			struct lruvec *lruvec;
6372 
6373 			lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
6374 			size = lruvec_page_state_output(lruvec,
6375 							memory_stats[i].idx);
6376 			seq_printf(m, " N%d=%llu", nid, size);
6377 		}
6378 		seq_putc(m, '\n');
6379 	}
6380 
6381 	return 0;
6382 }
6383 #endif
6384 
6385 static int memory_oom_group_show(struct seq_file *m, void *v)
6386 {
6387 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
6388 
6389 	seq_printf(m, "%d\n", memcg->oom_group);
6390 
6391 	return 0;
6392 }
6393 
6394 static ssize_t memory_oom_group_write(struct kernfs_open_file *of,
6395 				      char *buf, size_t nbytes, loff_t off)
6396 {
6397 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
6398 	int ret, oom_group;
6399 
6400 	buf = strstrip(buf);
6401 	if (!buf)
6402 		return -EINVAL;
6403 
6404 	ret = kstrtoint(buf, 0, &oom_group);
6405 	if (ret)
6406 		return ret;
6407 
6408 	if (oom_group != 0 && oom_group != 1)
6409 		return -EINVAL;
6410 
6411 	memcg->oom_group = oom_group;
6412 
6413 	return nbytes;
6414 }
6415 
6416 static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf,
6417 			      size_t nbytes, loff_t off)
6418 {
6419 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
6420 	unsigned int nr_retries = MAX_RECLAIM_RETRIES;
6421 	unsigned long nr_to_reclaim, nr_reclaimed = 0;
6422 	int err;
6423 
6424 	buf = strstrip(buf);
6425 	err = page_counter_memparse(buf, "", &nr_to_reclaim);
6426 	if (err)
6427 		return err;
6428 
6429 	while (nr_reclaimed < nr_to_reclaim) {
6430 		unsigned long reclaimed;
6431 
6432 		if (signal_pending(current))
6433 			return -EINTR;
6434 
6435 		/*
6436 		 * This is the final attempt, drain percpu lru caches in the
6437 		 * hope of introducing more evictable pages for
6438 		 * try_to_free_mem_cgroup_pages().
6439 		 */
6440 		if (!nr_retries)
6441 			lru_add_drain_all();
6442 
6443 		reclaimed = try_to_free_mem_cgroup_pages(memcg,
6444 						nr_to_reclaim - nr_reclaimed,
6445 						GFP_KERNEL, true);
6446 
6447 		if (!reclaimed && !nr_retries--)
6448 			return -EAGAIN;
6449 
6450 		nr_reclaimed += reclaimed;
6451 	}
6452 
6453 	return nbytes;
6454 }
6455 
6456 static struct cftype memory_files[] = {
6457 	{
6458 		.name = "current",
6459 		.flags = CFTYPE_NOT_ON_ROOT,
6460 		.read_u64 = memory_current_read,
6461 	},
6462 	{
6463 		.name = "peak",
6464 		.flags = CFTYPE_NOT_ON_ROOT,
6465 		.read_u64 = memory_peak_read,
6466 	},
6467 	{
6468 		.name = "min",
6469 		.flags = CFTYPE_NOT_ON_ROOT,
6470 		.seq_show = memory_min_show,
6471 		.write = memory_min_write,
6472 	},
6473 	{
6474 		.name = "low",
6475 		.flags = CFTYPE_NOT_ON_ROOT,
6476 		.seq_show = memory_low_show,
6477 		.write = memory_low_write,
6478 	},
6479 	{
6480 		.name = "high",
6481 		.flags = CFTYPE_NOT_ON_ROOT,
6482 		.seq_show = memory_high_show,
6483 		.write = memory_high_write,
6484 	},
6485 	{
6486 		.name = "max",
6487 		.flags = CFTYPE_NOT_ON_ROOT,
6488 		.seq_show = memory_max_show,
6489 		.write = memory_max_write,
6490 	},
6491 	{
6492 		.name = "events",
6493 		.flags = CFTYPE_NOT_ON_ROOT,
6494 		.file_offset = offsetof(struct mem_cgroup, events_file),
6495 		.seq_show = memory_events_show,
6496 	},
6497 	{
6498 		.name = "events.local",
6499 		.flags = CFTYPE_NOT_ON_ROOT,
6500 		.file_offset = offsetof(struct mem_cgroup, events_local_file),
6501 		.seq_show = memory_events_local_show,
6502 	},
6503 	{
6504 		.name = "stat",
6505 		.seq_show = memory_stat_show,
6506 	},
6507 #ifdef CONFIG_NUMA
6508 	{
6509 		.name = "numa_stat",
6510 		.seq_show = memory_numa_stat_show,
6511 	},
6512 #endif
6513 	{
6514 		.name = "oom.group",
6515 		.flags = CFTYPE_NOT_ON_ROOT | CFTYPE_NS_DELEGATABLE,
6516 		.seq_show = memory_oom_group_show,
6517 		.write = memory_oom_group_write,
6518 	},
6519 	{
6520 		.name = "reclaim",
6521 		.flags = CFTYPE_NS_DELEGATABLE,
6522 		.write = memory_reclaim,
6523 	},
6524 	{ }	/* terminate */
6525 };
6526 
6527 struct cgroup_subsys memory_cgrp_subsys = {
6528 	.css_alloc = mem_cgroup_css_alloc,
6529 	.css_online = mem_cgroup_css_online,
6530 	.css_offline = mem_cgroup_css_offline,
6531 	.css_released = mem_cgroup_css_released,
6532 	.css_free = mem_cgroup_css_free,
6533 	.css_reset = mem_cgroup_css_reset,
6534 	.css_rstat_flush = mem_cgroup_css_rstat_flush,
6535 	.can_attach = mem_cgroup_can_attach,
6536 	.cancel_attach = mem_cgroup_cancel_attach,
6537 	.post_attach = mem_cgroup_move_task,
6538 	.dfl_cftypes = memory_files,
6539 	.legacy_cftypes = mem_cgroup_legacy_files,
6540 	.early_init = 0,
6541 };
6542 
6543 /*
6544  * This function calculates an individual cgroup's effective
6545  * protection which is derived from its own memory.min/low, its
6546  * parent's and siblings' settings, as well as the actual memory
6547  * distribution in the tree.
6548  *
6549  * The following rules apply to the effective protection values:
6550  *
6551  * 1. At the first level of reclaim, effective protection is equal to
6552  *    the declared protection in memory.min and memory.low.
6553  *
6554  * 2. To enable safe delegation of the protection configuration, at
6555  *    subsequent levels the effective protection is capped to the
6556  *    parent's effective protection.
6557  *
6558  * 3. To make complex and dynamic subtrees easier to configure, the
6559  *    user is allowed to overcommit the declared protection at a given
6560  *    level. If that is the case, the parent's effective protection is
6561  *    distributed to the children in proportion to how much protection
6562  *    they have declared and how much of it they are utilizing.
6563  *
6564  *    This makes distribution proportional, but also work-conserving:
6565  *    if one cgroup claims much more protection than it uses memory,
6566  *    the unused remainder is available to its siblings.
6567  *
6568  * 4. Conversely, when the declared protection is undercommitted at a
6569  *    given level, the distribution of the larger parental protection
6570  *    budget is NOT proportional. A cgroup's protection from a sibling
6571  *    is capped to its own memory.min/low setting.
6572  *
6573  * 5. However, to allow protecting recursive subtrees from each other
6574  *    without having to declare each individual cgroup's fixed share
6575  *    of the ancestor's claim to protection, any unutilized -
6576  *    "floating" - protection from up the tree is distributed in
6577  *    proportion to each cgroup's *usage*. This makes the protection
6578  *    neutral wrt sibling cgroups and lets them compete freely over
6579  *    the shared parental protection budget, but it protects the
6580  *    subtree as a whole from neighboring subtrees.
6581  *
6582  * Note that 4. and 5. are not in conflict: 4. is about protecting
6583  * against immediate siblings whereas 5. is about protecting against
6584  * neighboring subtrees.
6585  */
6586 static unsigned long effective_protection(unsigned long usage,
6587 					  unsigned long parent_usage,
6588 					  unsigned long setting,
6589 					  unsigned long parent_effective,
6590 					  unsigned long siblings_protected)
6591 {
6592 	unsigned long protected;
6593 	unsigned long ep;
6594 
6595 	protected = min(usage, setting);
6596 	/*
6597 	 * If all cgroups at this level combined claim and use more
6598 	 * protection then what the parent affords them, distribute
6599 	 * shares in proportion to utilization.
6600 	 *
6601 	 * We are using actual utilization rather than the statically
6602 	 * claimed protection in order to be work-conserving: claimed
6603 	 * but unused protection is available to siblings that would
6604 	 * otherwise get a smaller chunk than what they claimed.
6605 	 */
6606 	if (siblings_protected > parent_effective)
6607 		return protected * parent_effective / siblings_protected;
6608 
6609 	/*
6610 	 * Ok, utilized protection of all children is within what the
6611 	 * parent affords them, so we know whatever this child claims
6612 	 * and utilizes is effectively protected.
6613 	 *
6614 	 * If there is unprotected usage beyond this value, reclaim
6615 	 * will apply pressure in proportion to that amount.
6616 	 *
6617 	 * If there is unutilized protection, the cgroup will be fully
6618 	 * shielded from reclaim, but we do return a smaller value for
6619 	 * protection than what the group could enjoy in theory. This
6620 	 * is okay. With the overcommit distribution above, effective
6621 	 * protection is always dependent on how memory is actually
6622 	 * consumed among the siblings anyway.
6623 	 */
6624 	ep = protected;
6625 
6626 	/*
6627 	 * If the children aren't claiming (all of) the protection
6628 	 * afforded to them by the parent, distribute the remainder in
6629 	 * proportion to the (unprotected) memory of each cgroup. That
6630 	 * way, cgroups that aren't explicitly prioritized wrt each
6631 	 * other compete freely over the allowance, but they are
6632 	 * collectively protected from neighboring trees.
6633 	 *
6634 	 * We're using unprotected memory for the weight so that if
6635 	 * some cgroups DO claim explicit protection, we don't protect
6636 	 * the same bytes twice.
6637 	 *
6638 	 * Check both usage and parent_usage against the respective
6639 	 * protected values. One should imply the other, but they
6640 	 * aren't read atomically - make sure the division is sane.
6641 	 */
6642 	if (!(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT))
6643 		return ep;
6644 	if (parent_effective > siblings_protected &&
6645 	    parent_usage > siblings_protected &&
6646 	    usage > protected) {
6647 		unsigned long unclaimed;
6648 
6649 		unclaimed = parent_effective - siblings_protected;
6650 		unclaimed *= usage - protected;
6651 		unclaimed /= parent_usage - siblings_protected;
6652 
6653 		ep += unclaimed;
6654 	}
6655 
6656 	return ep;
6657 }
6658 
6659 /**
6660  * mem_cgroup_calculate_protection - check if memory consumption is in the normal range
6661  * @root: the top ancestor of the sub-tree being checked
6662  * @memcg: the memory cgroup to check
6663  *
6664  * WARNING: This function is not stateless! It can only be used as part
6665  *          of a top-down tree iteration, not for isolated queries.
6666  */
6667 void mem_cgroup_calculate_protection(struct mem_cgroup *root,
6668 				     struct mem_cgroup *memcg)
6669 {
6670 	unsigned long usage, parent_usage;
6671 	struct mem_cgroup *parent;
6672 
6673 	if (mem_cgroup_disabled())
6674 		return;
6675 
6676 	if (!root)
6677 		root = root_mem_cgroup;
6678 
6679 	/*
6680 	 * Effective values of the reclaim targets are ignored so they
6681 	 * can be stale. Have a look at mem_cgroup_protection for more
6682 	 * details.
6683 	 * TODO: calculation should be more robust so that we do not need
6684 	 * that special casing.
6685 	 */
6686 	if (memcg == root)
6687 		return;
6688 
6689 	usage = page_counter_read(&memcg->memory);
6690 	if (!usage)
6691 		return;
6692 
6693 	parent = parent_mem_cgroup(memcg);
6694 
6695 	if (parent == root) {
6696 		memcg->memory.emin = READ_ONCE(memcg->memory.min);
6697 		memcg->memory.elow = READ_ONCE(memcg->memory.low);
6698 		return;
6699 	}
6700 
6701 	parent_usage = page_counter_read(&parent->memory);
6702 
6703 	WRITE_ONCE(memcg->memory.emin, effective_protection(usage, parent_usage,
6704 			READ_ONCE(memcg->memory.min),
6705 			READ_ONCE(parent->memory.emin),
6706 			atomic_long_read(&parent->memory.children_min_usage)));
6707 
6708 	WRITE_ONCE(memcg->memory.elow, effective_protection(usage, parent_usage,
6709 			READ_ONCE(memcg->memory.low),
6710 			READ_ONCE(parent->memory.elow),
6711 			atomic_long_read(&parent->memory.children_low_usage)));
6712 }
6713 
6714 static int charge_memcg(struct folio *folio, struct mem_cgroup *memcg,
6715 			gfp_t gfp)
6716 {
6717 	long nr_pages = folio_nr_pages(folio);
6718 	int ret;
6719 
6720 	ret = try_charge(memcg, gfp, nr_pages);
6721 	if (ret)
6722 		goto out;
6723 
6724 	css_get(&memcg->css);
6725 	commit_charge(folio, memcg);
6726 
6727 	local_irq_disable();
6728 	mem_cgroup_charge_statistics(memcg, nr_pages);
6729 	memcg_check_events(memcg, folio_nid(folio));
6730 	local_irq_enable();
6731 out:
6732 	return ret;
6733 }
6734 
6735 int __mem_cgroup_charge(struct folio *folio, struct mm_struct *mm, gfp_t gfp)
6736 {
6737 	struct mem_cgroup *memcg;
6738 	int ret;
6739 
6740 	memcg = get_mem_cgroup_from_mm(mm);
6741 	ret = charge_memcg(folio, memcg, gfp);
6742 	css_put(&memcg->css);
6743 
6744 	return ret;
6745 }
6746 
6747 /**
6748  * mem_cgroup_swapin_charge_page - charge a newly allocated page for swapin
6749  * @page: page to charge
6750  * @mm: mm context of the victim
6751  * @gfp: reclaim mode
6752  * @entry: swap entry for which the page is allocated
6753  *
6754  * This function charges a page allocated for swapin. Please call this before
6755  * adding the page to the swapcache.
6756  *
6757  * Returns 0 on success. Otherwise, an error code is returned.
6758  */
6759 int mem_cgroup_swapin_charge_page(struct page *page, struct mm_struct *mm,
6760 				  gfp_t gfp, swp_entry_t entry)
6761 {
6762 	struct folio *folio = page_folio(page);
6763 	struct mem_cgroup *memcg;
6764 	unsigned short id;
6765 	int ret;
6766 
6767 	if (mem_cgroup_disabled())
6768 		return 0;
6769 
6770 	id = lookup_swap_cgroup_id(entry);
6771 	rcu_read_lock();
6772 	memcg = mem_cgroup_from_id(id);
6773 	if (!memcg || !css_tryget_online(&memcg->css))
6774 		memcg = get_mem_cgroup_from_mm(mm);
6775 	rcu_read_unlock();
6776 
6777 	ret = charge_memcg(folio, memcg, gfp);
6778 
6779 	css_put(&memcg->css);
6780 	return ret;
6781 }
6782 
6783 /*
6784  * mem_cgroup_swapin_uncharge_swap - uncharge swap slot
6785  * @entry: swap entry for which the page is charged
6786  *
6787  * Call this function after successfully adding the charged page to swapcache.
6788  *
6789  * Note: This function assumes the page for which swap slot is being uncharged
6790  * is order 0 page.
6791  */
6792 void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry)
6793 {
6794 	/*
6795 	 * Cgroup1's unified memory+swap counter has been charged with the
6796 	 * new swapcache page, finish the transfer by uncharging the swap
6797 	 * slot. The swap slot would also get uncharged when it dies, but
6798 	 * it can stick around indefinitely and we'd count the page twice
6799 	 * the entire time.
6800 	 *
6801 	 * Cgroup2 has separate resource counters for memory and swap,
6802 	 * so this is a non-issue here. Memory and swap charge lifetimes
6803 	 * correspond 1:1 to page and swap slot lifetimes: we charge the
6804 	 * page to memory here, and uncharge swap when the slot is freed.
6805 	 */
6806 	if (!mem_cgroup_disabled() && do_memsw_account()) {
6807 		/*
6808 		 * The swap entry might not get freed for a long time,
6809 		 * let's not wait for it.  The page already received a
6810 		 * memory+swap charge, drop the swap entry duplicate.
6811 		 */
6812 		mem_cgroup_uncharge_swap(entry, 1);
6813 	}
6814 }
6815 
6816 struct uncharge_gather {
6817 	struct mem_cgroup *memcg;
6818 	unsigned long nr_memory;
6819 	unsigned long pgpgout;
6820 	unsigned long nr_kmem;
6821 	int nid;
6822 };
6823 
6824 static inline void uncharge_gather_clear(struct uncharge_gather *ug)
6825 {
6826 	memset(ug, 0, sizeof(*ug));
6827 }
6828 
6829 static void uncharge_batch(const struct uncharge_gather *ug)
6830 {
6831 	unsigned long flags;
6832 
6833 	if (ug->nr_memory) {
6834 		page_counter_uncharge(&ug->memcg->memory, ug->nr_memory);
6835 		if (do_memsw_account())
6836 			page_counter_uncharge(&ug->memcg->memsw, ug->nr_memory);
6837 		if (ug->nr_kmem)
6838 			memcg_account_kmem(ug->memcg, -ug->nr_kmem);
6839 		memcg_oom_recover(ug->memcg);
6840 	}
6841 
6842 	local_irq_save(flags);
6843 	__count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout);
6844 	__this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, ug->nr_memory);
6845 	memcg_check_events(ug->memcg, ug->nid);
6846 	local_irq_restore(flags);
6847 
6848 	/* drop reference from uncharge_folio */
6849 	css_put(&ug->memcg->css);
6850 }
6851 
6852 static void uncharge_folio(struct folio *folio, struct uncharge_gather *ug)
6853 {
6854 	long nr_pages;
6855 	struct mem_cgroup *memcg;
6856 	struct obj_cgroup *objcg;
6857 
6858 	VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
6859 
6860 	/*
6861 	 * Nobody should be changing or seriously looking at
6862 	 * folio memcg or objcg at this point, we have fully
6863 	 * exclusive access to the folio.
6864 	 */
6865 	if (folio_memcg_kmem(folio)) {
6866 		objcg = __folio_objcg(folio);
6867 		/*
6868 		 * This get matches the put at the end of the function and
6869 		 * kmem pages do not hold memcg references anymore.
6870 		 */
6871 		memcg = get_mem_cgroup_from_objcg(objcg);
6872 	} else {
6873 		memcg = __folio_memcg(folio);
6874 	}
6875 
6876 	if (!memcg)
6877 		return;
6878 
6879 	if (ug->memcg != memcg) {
6880 		if (ug->memcg) {
6881 			uncharge_batch(ug);
6882 			uncharge_gather_clear(ug);
6883 		}
6884 		ug->memcg = memcg;
6885 		ug->nid = folio_nid(folio);
6886 
6887 		/* pairs with css_put in uncharge_batch */
6888 		css_get(&memcg->css);
6889 	}
6890 
6891 	nr_pages = folio_nr_pages(folio);
6892 
6893 	if (folio_memcg_kmem(folio)) {
6894 		ug->nr_memory += nr_pages;
6895 		ug->nr_kmem += nr_pages;
6896 
6897 		folio->memcg_data = 0;
6898 		obj_cgroup_put(objcg);
6899 	} else {
6900 		/* LRU pages aren't accounted at the root level */
6901 		if (!mem_cgroup_is_root(memcg))
6902 			ug->nr_memory += nr_pages;
6903 		ug->pgpgout++;
6904 
6905 		folio->memcg_data = 0;
6906 	}
6907 
6908 	css_put(&memcg->css);
6909 }
6910 
6911 void __mem_cgroup_uncharge(struct folio *folio)
6912 {
6913 	struct uncharge_gather ug;
6914 
6915 	/* Don't touch folio->lru of any random page, pre-check: */
6916 	if (!folio_memcg(folio))
6917 		return;
6918 
6919 	uncharge_gather_clear(&ug);
6920 	uncharge_folio(folio, &ug);
6921 	uncharge_batch(&ug);
6922 }
6923 
6924 /**
6925  * __mem_cgroup_uncharge_list - uncharge a list of page
6926  * @page_list: list of pages to uncharge
6927  *
6928  * Uncharge a list of pages previously charged with
6929  * __mem_cgroup_charge().
6930  */
6931 void __mem_cgroup_uncharge_list(struct list_head *page_list)
6932 {
6933 	struct uncharge_gather ug;
6934 	struct folio *folio;
6935 
6936 	uncharge_gather_clear(&ug);
6937 	list_for_each_entry(folio, page_list, lru)
6938 		uncharge_folio(folio, &ug);
6939 	if (ug.memcg)
6940 		uncharge_batch(&ug);
6941 }
6942 
6943 /**
6944  * mem_cgroup_migrate - Charge a folio's replacement.
6945  * @old: Currently circulating folio.
6946  * @new: Replacement folio.
6947  *
6948  * Charge @new as a replacement folio for @old. @old will
6949  * be uncharged upon free.
6950  *
6951  * Both folios must be locked, @new->mapping must be set up.
6952  */
6953 void mem_cgroup_migrate(struct folio *old, struct folio *new)
6954 {
6955 	struct mem_cgroup *memcg;
6956 	long nr_pages = folio_nr_pages(new);
6957 	unsigned long flags;
6958 
6959 	VM_BUG_ON_FOLIO(!folio_test_locked(old), old);
6960 	VM_BUG_ON_FOLIO(!folio_test_locked(new), new);
6961 	VM_BUG_ON_FOLIO(folio_test_anon(old) != folio_test_anon(new), new);
6962 	VM_BUG_ON_FOLIO(folio_nr_pages(old) != nr_pages, new);
6963 
6964 	if (mem_cgroup_disabled())
6965 		return;
6966 
6967 	/* Page cache replacement: new folio already charged? */
6968 	if (folio_memcg(new))
6969 		return;
6970 
6971 	memcg = folio_memcg(old);
6972 	VM_WARN_ON_ONCE_FOLIO(!memcg, old);
6973 	if (!memcg)
6974 		return;
6975 
6976 	/* Force-charge the new page. The old one will be freed soon */
6977 	if (!mem_cgroup_is_root(memcg)) {
6978 		page_counter_charge(&memcg->memory, nr_pages);
6979 		if (do_memsw_account())
6980 			page_counter_charge(&memcg->memsw, nr_pages);
6981 	}
6982 
6983 	css_get(&memcg->css);
6984 	commit_charge(new, memcg);
6985 
6986 	local_irq_save(flags);
6987 	mem_cgroup_charge_statistics(memcg, nr_pages);
6988 	memcg_check_events(memcg, folio_nid(new));
6989 	local_irq_restore(flags);
6990 }
6991 
6992 DEFINE_STATIC_KEY_FALSE(memcg_sockets_enabled_key);
6993 EXPORT_SYMBOL(memcg_sockets_enabled_key);
6994 
6995 void mem_cgroup_sk_alloc(struct sock *sk)
6996 {
6997 	struct mem_cgroup *memcg;
6998 
6999 	if (!mem_cgroup_sockets_enabled)
7000 		return;
7001 
7002 	/* Do not associate the sock with unrelated interrupted task's memcg. */
7003 	if (!in_task())
7004 		return;
7005 
7006 	rcu_read_lock();
7007 	memcg = mem_cgroup_from_task(current);
7008 	if (memcg == root_mem_cgroup)
7009 		goto out;
7010 	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !memcg->tcpmem_active)
7011 		goto out;
7012 	if (css_tryget(&memcg->css))
7013 		sk->sk_memcg = memcg;
7014 out:
7015 	rcu_read_unlock();
7016 }
7017 
7018 void mem_cgroup_sk_free(struct sock *sk)
7019 {
7020 	if (sk->sk_memcg)
7021 		css_put(&sk->sk_memcg->css);
7022 }
7023 
7024 /**
7025  * mem_cgroup_charge_skmem - charge socket memory
7026  * @memcg: memcg to charge
7027  * @nr_pages: number of pages to charge
7028  * @gfp_mask: reclaim mode
7029  *
7030  * Charges @nr_pages to @memcg. Returns %true if the charge fit within
7031  * @memcg's configured limit, %false if it doesn't.
7032  */
7033 bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages,
7034 			     gfp_t gfp_mask)
7035 {
7036 	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
7037 		struct page_counter *fail;
7038 
7039 		if (page_counter_try_charge(&memcg->tcpmem, nr_pages, &fail)) {
7040 			memcg->tcpmem_pressure = 0;
7041 			return true;
7042 		}
7043 		memcg->tcpmem_pressure = 1;
7044 		if (gfp_mask & __GFP_NOFAIL) {
7045 			page_counter_charge(&memcg->tcpmem, nr_pages);
7046 			return true;
7047 		}
7048 		return false;
7049 	}
7050 
7051 	if (try_charge(memcg, gfp_mask, nr_pages) == 0) {
7052 		mod_memcg_state(memcg, MEMCG_SOCK, nr_pages);
7053 		return true;
7054 	}
7055 
7056 	return false;
7057 }
7058 
7059 /**
7060  * mem_cgroup_uncharge_skmem - uncharge socket memory
7061  * @memcg: memcg to uncharge
7062  * @nr_pages: number of pages to uncharge
7063  */
7064 void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
7065 {
7066 	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
7067 		page_counter_uncharge(&memcg->tcpmem, nr_pages);
7068 		return;
7069 	}
7070 
7071 	mod_memcg_state(memcg, MEMCG_SOCK, -nr_pages);
7072 
7073 	refill_stock(memcg, nr_pages);
7074 }
7075 
7076 static int __init cgroup_memory(char *s)
7077 {
7078 	char *token;
7079 
7080 	while ((token = strsep(&s, ",")) != NULL) {
7081 		if (!*token)
7082 			continue;
7083 		if (!strcmp(token, "nosocket"))
7084 			cgroup_memory_nosocket = true;
7085 		if (!strcmp(token, "nokmem"))
7086 			cgroup_memory_nokmem = true;
7087 	}
7088 	return 1;
7089 }
7090 __setup("cgroup.memory=", cgroup_memory);
7091 
7092 /*
7093  * subsys_initcall() for memory controller.
7094  *
7095  * Some parts like memcg_hotplug_cpu_dead() have to be initialized from this
7096  * context because of lock dependencies (cgroup_lock -> cpu hotplug) but
7097  * basically everything that doesn't depend on a specific mem_cgroup structure
7098  * should be initialized from here.
7099  */
7100 static int __init mem_cgroup_init(void)
7101 {
7102 	int cpu, node;
7103 
7104 	/*
7105 	 * Currently s32 type (can refer to struct batched_lruvec_stat) is
7106 	 * used for per-memcg-per-cpu caching of per-node statistics. In order
7107 	 * to work fine, we should make sure that the overfill threshold can't
7108 	 * exceed S32_MAX / PAGE_SIZE.
7109 	 */
7110 	BUILD_BUG_ON(MEMCG_CHARGE_BATCH > S32_MAX / PAGE_SIZE);
7111 
7112 	cpuhp_setup_state_nocalls(CPUHP_MM_MEMCQ_DEAD, "mm/memctrl:dead", NULL,
7113 				  memcg_hotplug_cpu_dead);
7114 
7115 	for_each_possible_cpu(cpu)
7116 		INIT_WORK(&per_cpu_ptr(&memcg_stock, cpu)->work,
7117 			  drain_local_stock);
7118 
7119 	for_each_node(node) {
7120 		struct mem_cgroup_tree_per_node *rtpn;
7121 
7122 		rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
7123 				    node_online(node) ? node : NUMA_NO_NODE);
7124 
7125 		rtpn->rb_root = RB_ROOT;
7126 		rtpn->rb_rightmost = NULL;
7127 		spin_lock_init(&rtpn->lock);
7128 		soft_limit_tree.rb_tree_per_node[node] = rtpn;
7129 	}
7130 
7131 	return 0;
7132 }
7133 subsys_initcall(mem_cgroup_init);
7134 
7135 #ifdef CONFIG_MEMCG_SWAP
7136 static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
7137 {
7138 	while (!refcount_inc_not_zero(&memcg->id.ref)) {
7139 		/*
7140 		 * The root cgroup cannot be destroyed, so it's refcount must
7141 		 * always be >= 1.
7142 		 */
7143 		if (WARN_ON_ONCE(memcg == root_mem_cgroup)) {
7144 			VM_BUG_ON(1);
7145 			break;
7146 		}
7147 		memcg = parent_mem_cgroup(memcg);
7148 		if (!memcg)
7149 			memcg = root_mem_cgroup;
7150 	}
7151 	return memcg;
7152 }
7153 
7154 /**
7155  * mem_cgroup_swapout - transfer a memsw charge to swap
7156  * @folio: folio whose memsw charge to transfer
7157  * @entry: swap entry to move the charge to
7158  *
7159  * Transfer the memsw charge of @folio to @entry.
7160  */
7161 void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
7162 {
7163 	struct mem_cgroup *memcg, *swap_memcg;
7164 	unsigned int nr_entries;
7165 	unsigned short oldid;
7166 
7167 	VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
7168 	VM_BUG_ON_FOLIO(folio_ref_count(folio), folio);
7169 
7170 	if (mem_cgroup_disabled())
7171 		return;
7172 
7173 	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
7174 		return;
7175 
7176 	memcg = folio_memcg(folio);
7177 
7178 	VM_WARN_ON_ONCE_FOLIO(!memcg, folio);
7179 	if (!memcg)
7180 		return;
7181 
7182 	/*
7183 	 * In case the memcg owning these pages has been offlined and doesn't
7184 	 * have an ID allocated to it anymore, charge the closest online
7185 	 * ancestor for the swap instead and transfer the memory+swap charge.
7186 	 */
7187 	swap_memcg = mem_cgroup_id_get_online(memcg);
7188 	nr_entries = folio_nr_pages(folio);
7189 	/* Get references for the tail pages, too */
7190 	if (nr_entries > 1)
7191 		mem_cgroup_id_get_many(swap_memcg, nr_entries - 1);
7192 	oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg),
7193 				   nr_entries);
7194 	VM_BUG_ON_FOLIO(oldid, folio);
7195 	mod_memcg_state(swap_memcg, MEMCG_SWAP, nr_entries);
7196 
7197 	folio->memcg_data = 0;
7198 
7199 	if (!mem_cgroup_is_root(memcg))
7200 		page_counter_uncharge(&memcg->memory, nr_entries);
7201 
7202 	if (!cgroup_memory_noswap && memcg != swap_memcg) {
7203 		if (!mem_cgroup_is_root(swap_memcg))
7204 			page_counter_charge(&swap_memcg->memsw, nr_entries);
7205 		page_counter_uncharge(&memcg->memsw, nr_entries);
7206 	}
7207 
7208 	/*
7209 	 * Interrupts should be disabled here because the caller holds the
7210 	 * i_pages lock which is taken with interrupts-off. It is
7211 	 * important here to have the interrupts disabled because it is the
7212 	 * only synchronisation we have for updating the per-CPU variables.
7213 	 */
7214 	memcg_stats_lock();
7215 	mem_cgroup_charge_statistics(memcg, -nr_entries);
7216 	memcg_stats_unlock();
7217 	memcg_check_events(memcg, folio_nid(folio));
7218 
7219 	css_put(&memcg->css);
7220 }
7221 
7222 /**
7223  * __mem_cgroup_try_charge_swap - try charging swap space for a folio
7224  * @folio: folio being added to swap
7225  * @entry: swap entry to charge
7226  *
7227  * Try to charge @folio's memcg for the swap space at @entry.
7228  *
7229  * Returns 0 on success, -ENOMEM on failure.
7230  */
7231 int __mem_cgroup_try_charge_swap(struct folio *folio, swp_entry_t entry)
7232 {
7233 	unsigned int nr_pages = folio_nr_pages(folio);
7234 	struct page_counter *counter;
7235 	struct mem_cgroup *memcg;
7236 	unsigned short oldid;
7237 
7238 	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
7239 		return 0;
7240 
7241 	memcg = folio_memcg(folio);
7242 
7243 	VM_WARN_ON_ONCE_FOLIO(!memcg, folio);
7244 	if (!memcg)
7245 		return 0;
7246 
7247 	if (!entry.val) {
7248 		memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
7249 		return 0;
7250 	}
7251 
7252 	memcg = mem_cgroup_id_get_online(memcg);
7253 
7254 	if (!cgroup_memory_noswap && !mem_cgroup_is_root(memcg) &&
7255 	    !page_counter_try_charge(&memcg->swap, nr_pages, &counter)) {
7256 		memcg_memory_event(memcg, MEMCG_SWAP_MAX);
7257 		memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
7258 		mem_cgroup_id_put(memcg);
7259 		return -ENOMEM;
7260 	}
7261 
7262 	/* Get references for the tail pages, too */
7263 	if (nr_pages > 1)
7264 		mem_cgroup_id_get_many(memcg, nr_pages - 1);
7265 	oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg), nr_pages);
7266 	VM_BUG_ON_FOLIO(oldid, folio);
7267 	mod_memcg_state(memcg, MEMCG_SWAP, nr_pages);
7268 
7269 	return 0;
7270 }
7271 
7272 /**
7273  * __mem_cgroup_uncharge_swap - uncharge swap space
7274  * @entry: swap entry to uncharge
7275  * @nr_pages: the amount of swap space to uncharge
7276  */
7277 void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
7278 {
7279 	struct mem_cgroup *memcg;
7280 	unsigned short id;
7281 
7282 	id = swap_cgroup_record(entry, 0, nr_pages);
7283 	rcu_read_lock();
7284 	memcg = mem_cgroup_from_id(id);
7285 	if (memcg) {
7286 		if (!cgroup_memory_noswap && !mem_cgroup_is_root(memcg)) {
7287 			if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
7288 				page_counter_uncharge(&memcg->swap, nr_pages);
7289 			else
7290 				page_counter_uncharge(&memcg->memsw, nr_pages);
7291 		}
7292 		mod_memcg_state(memcg, MEMCG_SWAP, -nr_pages);
7293 		mem_cgroup_id_put_many(memcg, nr_pages);
7294 	}
7295 	rcu_read_unlock();
7296 }
7297 
7298 long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
7299 {
7300 	long nr_swap_pages = get_nr_swap_pages();
7301 
7302 	if (cgroup_memory_noswap || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
7303 		return nr_swap_pages;
7304 	for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))
7305 		nr_swap_pages = min_t(long, nr_swap_pages,
7306 				      READ_ONCE(memcg->swap.max) -
7307 				      page_counter_read(&memcg->swap));
7308 	return nr_swap_pages;
7309 }
7310 
7311 bool mem_cgroup_swap_full(struct page *page)
7312 {
7313 	struct mem_cgroup *memcg;
7314 
7315 	VM_BUG_ON_PAGE(!PageLocked(page), page);
7316 
7317 	if (vm_swap_full())
7318 		return true;
7319 	if (cgroup_memory_noswap || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
7320 		return false;
7321 
7322 	memcg = page_memcg(page);
7323 	if (!memcg)
7324 		return false;
7325 
7326 	for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) {
7327 		unsigned long usage = page_counter_read(&memcg->swap);
7328 
7329 		if (usage * 2 >= READ_ONCE(memcg->swap.high) ||
7330 		    usage * 2 >= READ_ONCE(memcg->swap.max))
7331 			return true;
7332 	}
7333 
7334 	return false;
7335 }
7336 
7337 static int __init setup_swap_account(char *s)
7338 {
7339 	if (!strcmp(s, "1"))
7340 		cgroup_memory_noswap = false;
7341 	else if (!strcmp(s, "0"))
7342 		cgroup_memory_noswap = true;
7343 	return 1;
7344 }
7345 __setup("swapaccount=", setup_swap_account);
7346 
7347 static u64 swap_current_read(struct cgroup_subsys_state *css,
7348 			     struct cftype *cft)
7349 {
7350 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
7351 
7352 	return (u64)page_counter_read(&memcg->swap) * PAGE_SIZE;
7353 }
7354 
7355 static int swap_high_show(struct seq_file *m, void *v)
7356 {
7357 	return seq_puts_memcg_tunable(m,
7358 		READ_ONCE(mem_cgroup_from_seq(m)->swap.high));
7359 }
7360 
7361 static ssize_t swap_high_write(struct kernfs_open_file *of,
7362 			       char *buf, size_t nbytes, loff_t off)
7363 {
7364 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
7365 	unsigned long high;
7366 	int err;
7367 
7368 	buf = strstrip(buf);
7369 	err = page_counter_memparse(buf, "max", &high);
7370 	if (err)
7371 		return err;
7372 
7373 	page_counter_set_high(&memcg->swap, high);
7374 
7375 	return nbytes;
7376 }
7377 
7378 static int swap_max_show(struct seq_file *m, void *v)
7379 {
7380 	return seq_puts_memcg_tunable(m,
7381 		READ_ONCE(mem_cgroup_from_seq(m)->swap.max));
7382 }
7383 
7384 static ssize_t swap_max_write(struct kernfs_open_file *of,
7385 			      char *buf, size_t nbytes, loff_t off)
7386 {
7387 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
7388 	unsigned long max;
7389 	int err;
7390 
7391 	buf = strstrip(buf);
7392 	err = page_counter_memparse(buf, "max", &max);
7393 	if (err)
7394 		return err;
7395 
7396 	xchg(&memcg->swap.max, max);
7397 
7398 	return nbytes;
7399 }
7400 
7401 static int swap_events_show(struct seq_file *m, void *v)
7402 {
7403 	struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
7404 
7405 	seq_printf(m, "high %lu\n",
7406 		   atomic_long_read(&memcg->memory_events[MEMCG_SWAP_HIGH]));
7407 	seq_printf(m, "max %lu\n",
7408 		   atomic_long_read(&memcg->memory_events[MEMCG_SWAP_MAX]));
7409 	seq_printf(m, "fail %lu\n",
7410 		   atomic_long_read(&memcg->memory_events[MEMCG_SWAP_FAIL]));
7411 
7412 	return 0;
7413 }
7414 
7415 static struct cftype swap_files[] = {
7416 	{
7417 		.name = "swap.current",
7418 		.flags = CFTYPE_NOT_ON_ROOT,
7419 		.read_u64 = swap_current_read,
7420 	},
7421 	{
7422 		.name = "swap.high",
7423 		.flags = CFTYPE_NOT_ON_ROOT,
7424 		.seq_show = swap_high_show,
7425 		.write = swap_high_write,
7426 	},
7427 	{
7428 		.name = "swap.max",
7429 		.flags = CFTYPE_NOT_ON_ROOT,
7430 		.seq_show = swap_max_show,
7431 		.write = swap_max_write,
7432 	},
7433 	{
7434 		.name = "swap.events",
7435 		.flags = CFTYPE_NOT_ON_ROOT,
7436 		.file_offset = offsetof(struct mem_cgroup, swap_events_file),
7437 		.seq_show = swap_events_show,
7438 	},
7439 	{ }	/* terminate */
7440 };
7441 
7442 static struct cftype memsw_files[] = {
7443 	{
7444 		.name = "memsw.usage_in_bytes",
7445 		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
7446 		.read_u64 = mem_cgroup_read_u64,
7447 	},
7448 	{
7449 		.name = "memsw.max_usage_in_bytes",
7450 		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
7451 		.write = mem_cgroup_reset,
7452 		.read_u64 = mem_cgroup_read_u64,
7453 	},
7454 	{
7455 		.name = "memsw.limit_in_bytes",
7456 		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
7457 		.write = mem_cgroup_write,
7458 		.read_u64 = mem_cgroup_read_u64,
7459 	},
7460 	{
7461 		.name = "memsw.failcnt",
7462 		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
7463 		.write = mem_cgroup_reset,
7464 		.read_u64 = mem_cgroup_read_u64,
7465 	},
7466 	{ },	/* terminate */
7467 };
7468 
7469 #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
7470 /**
7471  * obj_cgroup_may_zswap - check if this cgroup can zswap
7472  * @objcg: the object cgroup
7473  *
7474  * Check if the hierarchical zswap limit has been reached.
7475  *
7476  * This doesn't check for specific headroom, and it is not atomic
7477  * either. But with zswap, the size of the allocation is only known
7478  * once compression has occured, and this optimistic pre-check avoids
7479  * spending cycles on compression when there is already no room left
7480  * or zswap is disabled altogether somewhere in the hierarchy.
7481  */
7482 bool obj_cgroup_may_zswap(struct obj_cgroup *objcg)
7483 {
7484 	struct mem_cgroup *memcg, *original_memcg;
7485 	bool ret = true;
7486 
7487 	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
7488 		return true;
7489 
7490 	original_memcg = get_mem_cgroup_from_objcg(objcg);
7491 	for (memcg = original_memcg; memcg != root_mem_cgroup;
7492 	     memcg = parent_mem_cgroup(memcg)) {
7493 		unsigned long max = READ_ONCE(memcg->zswap_max);
7494 		unsigned long pages;
7495 
7496 		if (max == PAGE_COUNTER_MAX)
7497 			continue;
7498 		if (max == 0) {
7499 			ret = false;
7500 			break;
7501 		}
7502 
7503 		cgroup_rstat_flush(memcg->css.cgroup);
7504 		pages = memcg_page_state(memcg, MEMCG_ZSWAP_B) / PAGE_SIZE;
7505 		if (pages < max)
7506 			continue;
7507 		ret = false;
7508 		break;
7509 	}
7510 	mem_cgroup_put(original_memcg);
7511 	return ret;
7512 }
7513 
7514 /**
7515  * obj_cgroup_charge_zswap - charge compression backend memory
7516  * @objcg: the object cgroup
7517  * @size: size of compressed object
7518  *
7519  * This forces the charge after obj_cgroup_may_swap() allowed
7520  * compression and storage in zwap for this cgroup to go ahead.
7521  */
7522 void obj_cgroup_charge_zswap(struct obj_cgroup *objcg, size_t size)
7523 {
7524 	struct mem_cgroup *memcg;
7525 
7526 	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
7527 		return;
7528 
7529 	VM_WARN_ON_ONCE(!(current->flags & PF_MEMALLOC));
7530 
7531 	/* PF_MEMALLOC context, charging must succeed */
7532 	if (obj_cgroup_charge(objcg, GFP_KERNEL, size))
7533 		VM_WARN_ON_ONCE(1);
7534 
7535 	rcu_read_lock();
7536 	memcg = obj_cgroup_memcg(objcg);
7537 	mod_memcg_state(memcg, MEMCG_ZSWAP_B, size);
7538 	mod_memcg_state(memcg, MEMCG_ZSWAPPED, 1);
7539 	rcu_read_unlock();
7540 }
7541 
7542 /**
7543  * obj_cgroup_uncharge_zswap - uncharge compression backend memory
7544  * @objcg: the object cgroup
7545  * @size: size of compressed object
7546  *
7547  * Uncharges zswap memory on page in.
7548  */
7549 void obj_cgroup_uncharge_zswap(struct obj_cgroup *objcg, size_t size)
7550 {
7551 	struct mem_cgroup *memcg;
7552 
7553 	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
7554 		return;
7555 
7556 	obj_cgroup_uncharge(objcg, size);
7557 
7558 	rcu_read_lock();
7559 	memcg = obj_cgroup_memcg(objcg);
7560 	mod_memcg_state(memcg, MEMCG_ZSWAP_B, -size);
7561 	mod_memcg_state(memcg, MEMCG_ZSWAPPED, -1);
7562 	rcu_read_unlock();
7563 }
7564 
7565 static u64 zswap_current_read(struct cgroup_subsys_state *css,
7566 			      struct cftype *cft)
7567 {
7568 	cgroup_rstat_flush(css->cgroup);
7569 	return memcg_page_state(mem_cgroup_from_css(css), MEMCG_ZSWAP_B);
7570 }
7571 
7572 static int zswap_max_show(struct seq_file *m, void *v)
7573 {
7574 	return seq_puts_memcg_tunable(m,
7575 		READ_ONCE(mem_cgroup_from_seq(m)->zswap_max));
7576 }
7577 
7578 static ssize_t zswap_max_write(struct kernfs_open_file *of,
7579 			       char *buf, size_t nbytes, loff_t off)
7580 {
7581 	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
7582 	unsigned long max;
7583 	int err;
7584 
7585 	buf = strstrip(buf);
7586 	err = page_counter_memparse(buf, "max", &max);
7587 	if (err)
7588 		return err;
7589 
7590 	xchg(&memcg->zswap_max, max);
7591 
7592 	return nbytes;
7593 }
7594 
7595 static struct cftype zswap_files[] = {
7596 	{
7597 		.name = "zswap.current",
7598 		.flags = CFTYPE_NOT_ON_ROOT,
7599 		.read_u64 = zswap_current_read,
7600 	},
7601 	{
7602 		.name = "zswap.max",
7603 		.flags = CFTYPE_NOT_ON_ROOT,
7604 		.seq_show = zswap_max_show,
7605 		.write = zswap_max_write,
7606 	},
7607 	{ }	/* terminate */
7608 };
7609 #endif /* CONFIG_MEMCG_KMEM && CONFIG_ZSWAP */
7610 
7611 /*
7612  * If mem_cgroup_swap_init() is implemented as a subsys_initcall()
7613  * instead of a core_initcall(), this could mean cgroup_memory_noswap still
7614  * remains set to false even when memcg is disabled via "cgroup_disable=memory"
7615  * boot parameter. This may result in premature OOPS inside
7616  * mem_cgroup_get_nr_swap_pages() function in corner cases.
7617  */
7618 static int __init mem_cgroup_swap_init(void)
7619 {
7620 	/* No memory control -> no swap control */
7621 	if (mem_cgroup_disabled())
7622 		cgroup_memory_noswap = true;
7623 
7624 	if (cgroup_memory_noswap)
7625 		return 0;
7626 
7627 	WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, swap_files));
7628 	WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys, memsw_files));
7629 #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
7630 	WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, zswap_files));
7631 #endif
7632 	return 0;
7633 }
7634 core_initcall(mem_cgroup_swap_init);
7635 
7636 #endif /* CONFIG_MEMCG_SWAP */
7637