xref: /openbmc/linux/mm/madvise.c (revision f59a3ee6)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *	linux/mm/madvise.c
4  *
5  * Copyright (C) 1999  Linus Torvalds
6  * Copyright (C) 2002  Christoph Hellwig
7  */
8 
9 #include <linux/mman.h>
10 #include <linux/pagemap.h>
11 #include <linux/syscalls.h>
12 #include <linux/mempolicy.h>
13 #include <linux/page-isolation.h>
14 #include <linux/page_idle.h>
15 #include <linux/userfaultfd_k.h>
16 #include <linux/hugetlb.h>
17 #include <linux/falloc.h>
18 #include <linux/fadvise.h>
19 #include <linux/sched.h>
20 #include <linux/sched/mm.h>
21 #include <linux/mm_inline.h>
22 #include <linux/string.h>
23 #include <linux/uio.h>
24 #include <linux/ksm.h>
25 #include <linux/fs.h>
26 #include <linux/file.h>
27 #include <linux/blkdev.h>
28 #include <linux/backing-dev.h>
29 #include <linux/pagewalk.h>
30 #include <linux/swap.h>
31 #include <linux/swapops.h>
32 #include <linux/shmem_fs.h>
33 #include <linux/mmu_notifier.h>
34 
35 #include <asm/tlb.h>
36 
37 #include "internal.h"
38 #include "swap.h"
39 
40 struct madvise_walk_private {
41 	struct mmu_gather *tlb;
42 	bool pageout;
43 };
44 
45 /*
46  * Any behaviour which results in changes to the vma->vm_flags needs to
47  * take mmap_lock for writing. Others, which simply traverse vmas, need
48  * to only take it for reading.
49  */
50 static int madvise_need_mmap_write(int behavior)
51 {
52 	switch (behavior) {
53 	case MADV_REMOVE:
54 	case MADV_WILLNEED:
55 	case MADV_DONTNEED:
56 	case MADV_DONTNEED_LOCKED:
57 	case MADV_COLD:
58 	case MADV_PAGEOUT:
59 	case MADV_FREE:
60 	case MADV_POPULATE_READ:
61 	case MADV_POPULATE_WRITE:
62 	case MADV_COLLAPSE:
63 		return 0;
64 	default:
65 		/* be safe, default to 1. list exceptions explicitly */
66 		return 1;
67 	}
68 }
69 
70 #ifdef CONFIG_ANON_VMA_NAME
71 struct anon_vma_name *anon_vma_name_alloc(const char *name)
72 {
73 	struct anon_vma_name *anon_name;
74 	size_t count;
75 
76 	/* Add 1 for NUL terminator at the end of the anon_name->name */
77 	count = strlen(name) + 1;
78 	anon_name = kmalloc(struct_size(anon_name, name, count), GFP_KERNEL);
79 	if (anon_name) {
80 		kref_init(&anon_name->kref);
81 		memcpy(anon_name->name, name, count);
82 	}
83 
84 	return anon_name;
85 }
86 
87 void anon_vma_name_free(struct kref *kref)
88 {
89 	struct anon_vma_name *anon_name =
90 			container_of(kref, struct anon_vma_name, kref);
91 	kfree(anon_name);
92 }
93 
94 struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
95 {
96 	mmap_assert_locked(vma->vm_mm);
97 
98 	if (vma->vm_file)
99 		return NULL;
100 
101 	return vma->anon_name;
102 }
103 
104 /* mmap_lock should be write-locked */
105 static int replace_anon_vma_name(struct vm_area_struct *vma,
106 				 struct anon_vma_name *anon_name)
107 {
108 	struct anon_vma_name *orig_name = anon_vma_name(vma);
109 
110 	if (!anon_name) {
111 		vma->anon_name = NULL;
112 		anon_vma_name_put(orig_name);
113 		return 0;
114 	}
115 
116 	if (anon_vma_name_eq(orig_name, anon_name))
117 		return 0;
118 
119 	vma->anon_name = anon_vma_name_reuse(anon_name);
120 	anon_vma_name_put(orig_name);
121 
122 	return 0;
123 }
124 #else /* CONFIG_ANON_VMA_NAME */
125 static int replace_anon_vma_name(struct vm_area_struct *vma,
126 				 struct anon_vma_name *anon_name)
127 {
128 	if (anon_name)
129 		return -EINVAL;
130 
131 	return 0;
132 }
133 #endif /* CONFIG_ANON_VMA_NAME */
134 /*
135  * Update the vm_flags on region of a vma, splitting it or merging it as
136  * necessary.  Must be called with mmap_sem held for writing;
137  * Caller should ensure anon_name stability by raising its refcount even when
138  * anon_name belongs to a valid vma because this function might free that vma.
139  */
140 static int madvise_update_vma(struct vm_area_struct *vma,
141 			      struct vm_area_struct **prev, unsigned long start,
142 			      unsigned long end, unsigned long new_flags,
143 			      struct anon_vma_name *anon_name)
144 {
145 	struct mm_struct *mm = vma->vm_mm;
146 	int error;
147 	pgoff_t pgoff;
148 
149 	if (new_flags == vma->vm_flags && anon_vma_name_eq(anon_vma_name(vma), anon_name)) {
150 		*prev = vma;
151 		return 0;
152 	}
153 
154 	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
155 	*prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
156 			  vma->vm_file, pgoff, vma_policy(vma),
157 			  vma->vm_userfaultfd_ctx, anon_name);
158 	if (*prev) {
159 		vma = *prev;
160 		goto success;
161 	}
162 
163 	*prev = vma;
164 
165 	if (start != vma->vm_start) {
166 		if (unlikely(mm->map_count >= sysctl_max_map_count))
167 			return -ENOMEM;
168 		error = __split_vma(mm, vma, start, 1);
169 		if (error)
170 			return error;
171 	}
172 
173 	if (end != vma->vm_end) {
174 		if (unlikely(mm->map_count >= sysctl_max_map_count))
175 			return -ENOMEM;
176 		error = __split_vma(mm, vma, end, 0);
177 		if (error)
178 			return error;
179 	}
180 
181 success:
182 	/*
183 	 * vm_flags is protected by the mmap_lock held in write mode.
184 	 */
185 	vma->vm_flags = new_flags;
186 	if (!vma->vm_file) {
187 		error = replace_anon_vma_name(vma, anon_name);
188 		if (error)
189 			return error;
190 	}
191 
192 	return 0;
193 }
194 
195 #ifdef CONFIG_SWAP
196 static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
197 	unsigned long end, struct mm_walk *walk)
198 {
199 	struct vm_area_struct *vma = walk->private;
200 	unsigned long index;
201 	struct swap_iocb *splug = NULL;
202 
203 	if (pmd_none_or_trans_huge_or_clear_bad(pmd))
204 		return 0;
205 
206 	for (index = start; index != end; index += PAGE_SIZE) {
207 		pte_t pte;
208 		swp_entry_t entry;
209 		struct page *page;
210 		spinlock_t *ptl;
211 		pte_t *ptep;
212 
213 		ptep = pte_offset_map_lock(vma->vm_mm, pmd, index, &ptl);
214 		pte = *ptep;
215 		pte_unmap_unlock(ptep, ptl);
216 
217 		if (!is_swap_pte(pte))
218 			continue;
219 		entry = pte_to_swp_entry(pte);
220 		if (unlikely(non_swap_entry(entry)))
221 			continue;
222 
223 		page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
224 					     vma, index, false, &splug);
225 		if (page)
226 			put_page(page);
227 	}
228 	swap_read_unplug(splug);
229 
230 	return 0;
231 }
232 
233 static const struct mm_walk_ops swapin_walk_ops = {
234 	.pmd_entry		= swapin_walk_pmd_entry,
235 };
236 
237 static void force_shm_swapin_readahead(struct vm_area_struct *vma,
238 		unsigned long start, unsigned long end,
239 		struct address_space *mapping)
240 {
241 	XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
242 	pgoff_t end_index = linear_page_index(vma, end + PAGE_SIZE - 1);
243 	struct page *page;
244 	struct swap_iocb *splug = NULL;
245 
246 	rcu_read_lock();
247 	xas_for_each(&xas, page, end_index) {
248 		swp_entry_t swap;
249 
250 		if (!xa_is_value(page))
251 			continue;
252 		swap = radix_to_swp_entry(page);
253 		/* There might be swapin error entries in shmem mapping. */
254 		if (non_swap_entry(swap))
255 			continue;
256 		xas_pause(&xas);
257 		rcu_read_unlock();
258 
259 		page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
260 					     NULL, 0, false, &splug);
261 		if (page)
262 			put_page(page);
263 
264 		rcu_read_lock();
265 	}
266 	rcu_read_unlock();
267 	swap_read_unplug(splug);
268 
269 	lru_add_drain();	/* Push any new pages onto the LRU now */
270 }
271 #endif		/* CONFIG_SWAP */
272 
273 /*
274  * Schedule all required I/O operations.  Do not wait for completion.
275  */
276 static long madvise_willneed(struct vm_area_struct *vma,
277 			     struct vm_area_struct **prev,
278 			     unsigned long start, unsigned long end)
279 {
280 	struct mm_struct *mm = vma->vm_mm;
281 	struct file *file = vma->vm_file;
282 	loff_t offset;
283 
284 	*prev = vma;
285 #ifdef CONFIG_SWAP
286 	if (!file) {
287 		walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
288 		lru_add_drain(); /* Push any new pages onto the LRU now */
289 		return 0;
290 	}
291 
292 	if (shmem_mapping(file->f_mapping)) {
293 		force_shm_swapin_readahead(vma, start, end,
294 					file->f_mapping);
295 		return 0;
296 	}
297 #else
298 	if (!file)
299 		return -EBADF;
300 #endif
301 
302 	if (IS_DAX(file_inode(file))) {
303 		/* no bad return value, but ignore advice */
304 		return 0;
305 	}
306 
307 	/*
308 	 * Filesystem's fadvise may need to take various locks.  We need to
309 	 * explicitly grab a reference because the vma (and hence the
310 	 * vma's reference to the file) can go away as soon as we drop
311 	 * mmap_lock.
312 	 */
313 	*prev = NULL;	/* tell sys_madvise we drop mmap_lock */
314 	get_file(file);
315 	offset = (loff_t)(start - vma->vm_start)
316 			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
317 	mmap_read_unlock(mm);
318 	vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
319 	fput(file);
320 	mmap_read_lock(mm);
321 	return 0;
322 }
323 
324 static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
325 				unsigned long addr, unsigned long end,
326 				struct mm_walk *walk)
327 {
328 	struct madvise_walk_private *private = walk->private;
329 	struct mmu_gather *tlb = private->tlb;
330 	bool pageout = private->pageout;
331 	struct mm_struct *mm = tlb->mm;
332 	struct vm_area_struct *vma = walk->vma;
333 	pte_t *orig_pte, *pte, ptent;
334 	spinlock_t *ptl;
335 	struct page *page = NULL;
336 	LIST_HEAD(page_list);
337 
338 	if (fatal_signal_pending(current))
339 		return -EINTR;
340 
341 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
342 	if (pmd_trans_huge(*pmd)) {
343 		pmd_t orig_pmd;
344 		unsigned long next = pmd_addr_end(addr, end);
345 
346 		tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
347 		ptl = pmd_trans_huge_lock(pmd, vma);
348 		if (!ptl)
349 			return 0;
350 
351 		orig_pmd = *pmd;
352 		if (is_huge_zero_pmd(orig_pmd))
353 			goto huge_unlock;
354 
355 		if (unlikely(!pmd_present(orig_pmd))) {
356 			VM_BUG_ON(thp_migration_supported() &&
357 					!is_pmd_migration_entry(orig_pmd));
358 			goto huge_unlock;
359 		}
360 
361 		page = pmd_page(orig_pmd);
362 
363 		/* Do not interfere with other mappings of this page */
364 		if (page_mapcount(page) != 1)
365 			goto huge_unlock;
366 
367 		if (next - addr != HPAGE_PMD_SIZE) {
368 			int err;
369 
370 			get_page(page);
371 			spin_unlock(ptl);
372 			lock_page(page);
373 			err = split_huge_page(page);
374 			unlock_page(page);
375 			put_page(page);
376 			if (!err)
377 				goto regular_page;
378 			return 0;
379 		}
380 
381 		if (pmd_young(orig_pmd)) {
382 			pmdp_invalidate(vma, addr, pmd);
383 			orig_pmd = pmd_mkold(orig_pmd);
384 
385 			set_pmd_at(mm, addr, pmd, orig_pmd);
386 			tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
387 		}
388 
389 		ClearPageReferenced(page);
390 		test_and_clear_page_young(page);
391 		if (pageout) {
392 			if (!isolate_lru_page(page)) {
393 				if (PageUnevictable(page))
394 					putback_lru_page(page);
395 				else
396 					list_add(&page->lru, &page_list);
397 			}
398 		} else
399 			deactivate_page(page);
400 huge_unlock:
401 		spin_unlock(ptl);
402 		if (pageout)
403 			reclaim_pages(&page_list);
404 		return 0;
405 	}
406 
407 regular_page:
408 	if (pmd_trans_unstable(pmd))
409 		return 0;
410 #endif
411 	tlb_change_page_size(tlb, PAGE_SIZE);
412 	orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
413 	flush_tlb_batched_pending(mm);
414 	arch_enter_lazy_mmu_mode();
415 	for (; addr < end; pte++, addr += PAGE_SIZE) {
416 		ptent = *pte;
417 
418 		if (pte_none(ptent))
419 			continue;
420 
421 		if (!pte_present(ptent))
422 			continue;
423 
424 		page = vm_normal_page(vma, addr, ptent);
425 		if (!page || is_zone_device_page(page))
426 			continue;
427 
428 		/*
429 		 * Creating a THP page is expensive so split it only if we
430 		 * are sure it's worth. Split it if we are only owner.
431 		 */
432 		if (PageTransCompound(page)) {
433 			if (page_mapcount(page) != 1)
434 				break;
435 			get_page(page);
436 			if (!trylock_page(page)) {
437 				put_page(page);
438 				break;
439 			}
440 			pte_unmap_unlock(orig_pte, ptl);
441 			if (split_huge_page(page)) {
442 				unlock_page(page);
443 				put_page(page);
444 				orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
445 				break;
446 			}
447 			unlock_page(page);
448 			put_page(page);
449 			orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
450 			pte--;
451 			addr -= PAGE_SIZE;
452 			continue;
453 		}
454 
455 		/*
456 		 * Do not interfere with other mappings of this page and
457 		 * non-LRU page.
458 		 */
459 		if (!PageLRU(page) || page_mapcount(page) != 1)
460 			continue;
461 
462 		VM_BUG_ON_PAGE(PageTransCompound(page), page);
463 
464 		if (pte_young(ptent)) {
465 			ptent = ptep_get_and_clear_full(mm, addr, pte,
466 							tlb->fullmm);
467 			ptent = pte_mkold(ptent);
468 			set_pte_at(mm, addr, pte, ptent);
469 			tlb_remove_tlb_entry(tlb, pte, addr);
470 		}
471 
472 		/*
473 		 * We are deactivating a page for accelerating reclaiming.
474 		 * VM couldn't reclaim the page unless we clear PG_young.
475 		 * As a side effect, it makes confuse idle-page tracking
476 		 * because they will miss recent referenced history.
477 		 */
478 		ClearPageReferenced(page);
479 		test_and_clear_page_young(page);
480 		if (pageout) {
481 			if (!isolate_lru_page(page)) {
482 				if (PageUnevictable(page))
483 					putback_lru_page(page);
484 				else
485 					list_add(&page->lru, &page_list);
486 			}
487 		} else
488 			deactivate_page(page);
489 	}
490 
491 	arch_leave_lazy_mmu_mode();
492 	pte_unmap_unlock(orig_pte, ptl);
493 	if (pageout)
494 		reclaim_pages(&page_list);
495 	cond_resched();
496 
497 	return 0;
498 }
499 
500 static const struct mm_walk_ops cold_walk_ops = {
501 	.pmd_entry = madvise_cold_or_pageout_pte_range,
502 };
503 
504 static void madvise_cold_page_range(struct mmu_gather *tlb,
505 			     struct vm_area_struct *vma,
506 			     unsigned long addr, unsigned long end)
507 {
508 	struct madvise_walk_private walk_private = {
509 		.pageout = false,
510 		.tlb = tlb,
511 	};
512 
513 	tlb_start_vma(tlb, vma);
514 	walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
515 	tlb_end_vma(tlb, vma);
516 }
517 
518 static inline bool can_madv_lru_vma(struct vm_area_struct *vma)
519 {
520 	return !(vma->vm_flags & (VM_LOCKED|VM_PFNMAP|VM_HUGETLB));
521 }
522 
523 static long madvise_cold(struct vm_area_struct *vma,
524 			struct vm_area_struct **prev,
525 			unsigned long start_addr, unsigned long end_addr)
526 {
527 	struct mm_struct *mm = vma->vm_mm;
528 	struct mmu_gather tlb;
529 
530 	*prev = vma;
531 	if (!can_madv_lru_vma(vma))
532 		return -EINVAL;
533 
534 	lru_add_drain();
535 	tlb_gather_mmu(&tlb, mm);
536 	madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
537 	tlb_finish_mmu(&tlb);
538 
539 	return 0;
540 }
541 
542 static void madvise_pageout_page_range(struct mmu_gather *tlb,
543 			     struct vm_area_struct *vma,
544 			     unsigned long addr, unsigned long end)
545 {
546 	struct madvise_walk_private walk_private = {
547 		.pageout = true,
548 		.tlb = tlb,
549 	};
550 
551 	tlb_start_vma(tlb, vma);
552 	walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
553 	tlb_end_vma(tlb, vma);
554 }
555 
556 static inline bool can_do_pageout(struct vm_area_struct *vma)
557 {
558 	if (vma_is_anonymous(vma))
559 		return true;
560 	if (!vma->vm_file)
561 		return false;
562 	/*
563 	 * paging out pagecache only for non-anonymous mappings that correspond
564 	 * to the files the calling process could (if tried) open for writing;
565 	 * otherwise we'd be including shared non-exclusive mappings, which
566 	 * opens a side channel.
567 	 */
568 	return inode_owner_or_capable(&init_user_ns,
569 				      file_inode(vma->vm_file)) ||
570 	       file_permission(vma->vm_file, MAY_WRITE) == 0;
571 }
572 
573 static long madvise_pageout(struct vm_area_struct *vma,
574 			struct vm_area_struct **prev,
575 			unsigned long start_addr, unsigned long end_addr)
576 {
577 	struct mm_struct *mm = vma->vm_mm;
578 	struct mmu_gather tlb;
579 
580 	*prev = vma;
581 	if (!can_madv_lru_vma(vma))
582 		return -EINVAL;
583 
584 	if (!can_do_pageout(vma))
585 		return 0;
586 
587 	lru_add_drain();
588 	tlb_gather_mmu(&tlb, mm);
589 	madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
590 	tlb_finish_mmu(&tlb);
591 
592 	return 0;
593 }
594 
595 static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
596 				unsigned long end, struct mm_walk *walk)
597 
598 {
599 	struct mmu_gather *tlb = walk->private;
600 	struct mm_struct *mm = tlb->mm;
601 	struct vm_area_struct *vma = walk->vma;
602 	spinlock_t *ptl;
603 	pte_t *orig_pte, *pte, ptent;
604 	struct folio *folio;
605 	struct page *page;
606 	int nr_swap = 0;
607 	unsigned long next;
608 
609 	next = pmd_addr_end(addr, end);
610 	if (pmd_trans_huge(*pmd))
611 		if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
612 			goto next;
613 
614 	if (pmd_trans_unstable(pmd))
615 		return 0;
616 
617 	tlb_change_page_size(tlb, PAGE_SIZE);
618 	orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
619 	flush_tlb_batched_pending(mm);
620 	arch_enter_lazy_mmu_mode();
621 	for (; addr != end; pte++, addr += PAGE_SIZE) {
622 		ptent = *pte;
623 
624 		if (pte_none(ptent))
625 			continue;
626 		/*
627 		 * If the pte has swp_entry, just clear page table to
628 		 * prevent swap-in which is more expensive rather than
629 		 * (page allocation + zeroing).
630 		 */
631 		if (!pte_present(ptent)) {
632 			swp_entry_t entry;
633 
634 			entry = pte_to_swp_entry(ptent);
635 			if (!non_swap_entry(entry)) {
636 				nr_swap--;
637 				free_swap_and_cache(entry);
638 				pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
639 			} else if (is_hwpoison_entry(entry) ||
640 				   is_swapin_error_entry(entry)) {
641 				pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
642 			}
643 			continue;
644 		}
645 
646 		page = vm_normal_page(vma, addr, ptent);
647 		if (!page || is_zone_device_page(page))
648 			continue;
649 		folio = page_folio(page);
650 
651 		/*
652 		 * If pmd isn't transhuge but the folio is large and
653 		 * is owned by only this process, split it and
654 		 * deactivate all pages.
655 		 */
656 		if (folio_test_large(folio)) {
657 			if (folio_mapcount(folio) != 1)
658 				goto out;
659 			folio_get(folio);
660 			if (!folio_trylock(folio)) {
661 				folio_put(folio);
662 				goto out;
663 			}
664 			pte_unmap_unlock(orig_pte, ptl);
665 			if (split_folio(folio)) {
666 				folio_unlock(folio);
667 				folio_put(folio);
668 				orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
669 				goto out;
670 			}
671 			folio_unlock(folio);
672 			folio_put(folio);
673 			orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
674 			pte--;
675 			addr -= PAGE_SIZE;
676 			continue;
677 		}
678 
679 		if (folio_test_swapcache(folio) || folio_test_dirty(folio)) {
680 			if (!folio_trylock(folio))
681 				continue;
682 			/*
683 			 * If folio is shared with others, we mustn't clear
684 			 * the folio's dirty flag.
685 			 */
686 			if (folio_mapcount(folio) != 1) {
687 				folio_unlock(folio);
688 				continue;
689 			}
690 
691 			if (folio_test_swapcache(folio) &&
692 			    !folio_free_swap(folio)) {
693 				folio_unlock(folio);
694 				continue;
695 			}
696 
697 			folio_clear_dirty(folio);
698 			folio_unlock(folio);
699 		}
700 
701 		if (pte_young(ptent) || pte_dirty(ptent)) {
702 			/*
703 			 * Some of architecture(ex, PPC) don't update TLB
704 			 * with set_pte_at and tlb_remove_tlb_entry so for
705 			 * the portability, remap the pte with old|clean
706 			 * after pte clearing.
707 			 */
708 			ptent = ptep_get_and_clear_full(mm, addr, pte,
709 							tlb->fullmm);
710 
711 			ptent = pte_mkold(ptent);
712 			ptent = pte_mkclean(ptent);
713 			set_pte_at(mm, addr, pte, ptent);
714 			tlb_remove_tlb_entry(tlb, pte, addr);
715 		}
716 		mark_page_lazyfree(&folio->page);
717 	}
718 out:
719 	if (nr_swap) {
720 		if (current->mm == mm)
721 			sync_mm_rss(mm);
722 
723 		add_mm_counter(mm, MM_SWAPENTS, nr_swap);
724 	}
725 	arch_leave_lazy_mmu_mode();
726 	pte_unmap_unlock(orig_pte, ptl);
727 	cond_resched();
728 next:
729 	return 0;
730 }
731 
732 static const struct mm_walk_ops madvise_free_walk_ops = {
733 	.pmd_entry		= madvise_free_pte_range,
734 };
735 
736 static int madvise_free_single_vma(struct vm_area_struct *vma,
737 			unsigned long start_addr, unsigned long end_addr)
738 {
739 	struct mm_struct *mm = vma->vm_mm;
740 	struct mmu_notifier_range range;
741 	struct mmu_gather tlb;
742 
743 	/* MADV_FREE works for only anon vma at the moment */
744 	if (!vma_is_anonymous(vma))
745 		return -EINVAL;
746 
747 	range.start = max(vma->vm_start, start_addr);
748 	if (range.start >= vma->vm_end)
749 		return -EINVAL;
750 	range.end = min(vma->vm_end, end_addr);
751 	if (range.end <= vma->vm_start)
752 		return -EINVAL;
753 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
754 				range.start, range.end);
755 
756 	lru_add_drain();
757 	tlb_gather_mmu(&tlb, mm);
758 	update_hiwater_rss(mm);
759 
760 	mmu_notifier_invalidate_range_start(&range);
761 	tlb_start_vma(&tlb, vma);
762 	walk_page_range(vma->vm_mm, range.start, range.end,
763 			&madvise_free_walk_ops, &tlb);
764 	tlb_end_vma(&tlb, vma);
765 	mmu_notifier_invalidate_range_end(&range);
766 	tlb_finish_mmu(&tlb);
767 
768 	return 0;
769 }
770 
771 /*
772  * Application no longer needs these pages.  If the pages are dirty,
773  * it's OK to just throw them away.  The app will be more careful about
774  * data it wants to keep.  Be sure to free swap resources too.  The
775  * zap_page_range call sets things up for shrink_active_list to actually free
776  * these pages later if no one else has touched them in the meantime,
777  * although we could add these pages to a global reuse list for
778  * shrink_active_list to pick up before reclaiming other pages.
779  *
780  * NB: This interface discards data rather than pushes it out to swap,
781  * as some implementations do.  This has performance implications for
782  * applications like large transactional databases which want to discard
783  * pages in anonymous maps after committing to backing store the data
784  * that was kept in them.  There is no reason to write this data out to
785  * the swap area if the application is discarding it.
786  *
787  * An interface that causes the system to free clean pages and flush
788  * dirty pages is already available as msync(MS_INVALIDATE).
789  */
790 static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
791 					unsigned long start, unsigned long end)
792 {
793 	zap_page_range(vma, start, end - start);
794 	return 0;
795 }
796 
797 static bool madvise_dontneed_free_valid_vma(struct vm_area_struct *vma,
798 					    unsigned long start,
799 					    unsigned long *end,
800 					    int behavior)
801 {
802 	if (!is_vm_hugetlb_page(vma)) {
803 		unsigned int forbidden = VM_PFNMAP;
804 
805 		if (behavior != MADV_DONTNEED_LOCKED)
806 			forbidden |= VM_LOCKED;
807 
808 		return !(vma->vm_flags & forbidden);
809 	}
810 
811 	if (behavior != MADV_DONTNEED && behavior != MADV_DONTNEED_LOCKED)
812 		return false;
813 	if (start & ~huge_page_mask(hstate_vma(vma)))
814 		return false;
815 
816 	/*
817 	 * Madvise callers expect the length to be rounded up to PAGE_SIZE
818 	 * boundaries, and may be unaware that this VMA uses huge pages.
819 	 * Avoid unexpected data loss by rounding down the number of
820 	 * huge pages freed.
821 	 */
822 	*end = ALIGN_DOWN(*end, huge_page_size(hstate_vma(vma)));
823 
824 	return true;
825 }
826 
827 static long madvise_dontneed_free(struct vm_area_struct *vma,
828 				  struct vm_area_struct **prev,
829 				  unsigned long start, unsigned long end,
830 				  int behavior)
831 {
832 	struct mm_struct *mm = vma->vm_mm;
833 
834 	*prev = vma;
835 	if (!madvise_dontneed_free_valid_vma(vma, start, &end, behavior))
836 		return -EINVAL;
837 
838 	if (start == end)
839 		return 0;
840 
841 	if (!userfaultfd_remove(vma, start, end)) {
842 		*prev = NULL; /* mmap_lock has been dropped, prev is stale */
843 
844 		mmap_read_lock(mm);
845 		vma = find_vma(mm, start);
846 		if (!vma)
847 			return -ENOMEM;
848 		if (start < vma->vm_start) {
849 			/*
850 			 * This "vma" under revalidation is the one
851 			 * with the lowest vma->vm_start where start
852 			 * is also < vma->vm_end. If start <
853 			 * vma->vm_start it means an hole materialized
854 			 * in the user address space within the
855 			 * virtual range passed to MADV_DONTNEED
856 			 * or MADV_FREE.
857 			 */
858 			return -ENOMEM;
859 		}
860 		/*
861 		 * Potential end adjustment for hugetlb vma is OK as
862 		 * the check below keeps end within vma.
863 		 */
864 		if (!madvise_dontneed_free_valid_vma(vma, start, &end,
865 						     behavior))
866 			return -EINVAL;
867 		if (end > vma->vm_end) {
868 			/*
869 			 * Don't fail if end > vma->vm_end. If the old
870 			 * vma was split while the mmap_lock was
871 			 * released the effect of the concurrent
872 			 * operation may not cause madvise() to
873 			 * have an undefined result. There may be an
874 			 * adjacent next vma that we'll walk
875 			 * next. userfaultfd_remove() will generate an
876 			 * UFFD_EVENT_REMOVE repetition on the
877 			 * end-vma->vm_end range, but the manager can
878 			 * handle a repetition fine.
879 			 */
880 			end = vma->vm_end;
881 		}
882 		VM_WARN_ON(start >= end);
883 	}
884 
885 	if (behavior == MADV_DONTNEED || behavior == MADV_DONTNEED_LOCKED)
886 		return madvise_dontneed_single_vma(vma, start, end);
887 	else if (behavior == MADV_FREE)
888 		return madvise_free_single_vma(vma, start, end);
889 	else
890 		return -EINVAL;
891 }
892 
893 static long madvise_populate(struct vm_area_struct *vma,
894 			     struct vm_area_struct **prev,
895 			     unsigned long start, unsigned long end,
896 			     int behavior)
897 {
898 	const bool write = behavior == MADV_POPULATE_WRITE;
899 	struct mm_struct *mm = vma->vm_mm;
900 	unsigned long tmp_end;
901 	int locked = 1;
902 	long pages;
903 
904 	*prev = vma;
905 
906 	while (start < end) {
907 		/*
908 		 * We might have temporarily dropped the lock. For example,
909 		 * our VMA might have been split.
910 		 */
911 		if (!vma || start >= vma->vm_end) {
912 			vma = vma_lookup(mm, start);
913 			if (!vma)
914 				return -ENOMEM;
915 		}
916 
917 		tmp_end = min_t(unsigned long, end, vma->vm_end);
918 		/* Populate (prefault) page tables readable/writable. */
919 		pages = faultin_vma_page_range(vma, start, tmp_end, write,
920 					       &locked);
921 		if (!locked) {
922 			mmap_read_lock(mm);
923 			locked = 1;
924 			*prev = NULL;
925 			vma = NULL;
926 		}
927 		if (pages < 0) {
928 			switch (pages) {
929 			case -EINTR:
930 				return -EINTR;
931 			case -EINVAL: /* Incompatible mappings / permissions. */
932 				return -EINVAL;
933 			case -EHWPOISON:
934 				return -EHWPOISON;
935 			case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
936 				return -EFAULT;
937 			default:
938 				pr_warn_once("%s: unhandled return value: %ld\n",
939 					     __func__, pages);
940 				fallthrough;
941 			case -ENOMEM:
942 				return -ENOMEM;
943 			}
944 		}
945 		start += pages * PAGE_SIZE;
946 	}
947 	return 0;
948 }
949 
950 /*
951  * Application wants to free up the pages and associated backing store.
952  * This is effectively punching a hole into the middle of a file.
953  */
954 static long madvise_remove(struct vm_area_struct *vma,
955 				struct vm_area_struct **prev,
956 				unsigned long start, unsigned long end)
957 {
958 	loff_t offset;
959 	int error;
960 	struct file *f;
961 	struct mm_struct *mm = vma->vm_mm;
962 
963 	*prev = NULL;	/* tell sys_madvise we drop mmap_lock */
964 
965 	if (vma->vm_flags & VM_LOCKED)
966 		return -EINVAL;
967 
968 	f = vma->vm_file;
969 
970 	if (!f || !f->f_mapping || !f->f_mapping->host) {
971 			return -EINVAL;
972 	}
973 
974 	if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
975 		return -EACCES;
976 
977 	offset = (loff_t)(start - vma->vm_start)
978 			+ ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
979 
980 	/*
981 	 * Filesystem's fallocate may need to take i_rwsem.  We need to
982 	 * explicitly grab a reference because the vma (and hence the
983 	 * vma's reference to the file) can go away as soon as we drop
984 	 * mmap_lock.
985 	 */
986 	get_file(f);
987 	if (userfaultfd_remove(vma, start, end)) {
988 		/* mmap_lock was not released by userfaultfd_remove() */
989 		mmap_read_unlock(mm);
990 	}
991 	error = vfs_fallocate(f,
992 				FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
993 				offset, end - start);
994 	fput(f);
995 	mmap_read_lock(mm);
996 	return error;
997 }
998 
999 /*
1000  * Apply an madvise behavior to a region of a vma.  madvise_update_vma
1001  * will handle splitting a vm area into separate areas, each area with its own
1002  * behavior.
1003  */
1004 static int madvise_vma_behavior(struct vm_area_struct *vma,
1005 				struct vm_area_struct **prev,
1006 				unsigned long start, unsigned long end,
1007 				unsigned long behavior)
1008 {
1009 	int error;
1010 	struct anon_vma_name *anon_name;
1011 	unsigned long new_flags = vma->vm_flags;
1012 
1013 	switch (behavior) {
1014 	case MADV_REMOVE:
1015 		return madvise_remove(vma, prev, start, end);
1016 	case MADV_WILLNEED:
1017 		return madvise_willneed(vma, prev, start, end);
1018 	case MADV_COLD:
1019 		return madvise_cold(vma, prev, start, end);
1020 	case MADV_PAGEOUT:
1021 		return madvise_pageout(vma, prev, start, end);
1022 	case MADV_FREE:
1023 	case MADV_DONTNEED:
1024 	case MADV_DONTNEED_LOCKED:
1025 		return madvise_dontneed_free(vma, prev, start, end, behavior);
1026 	case MADV_POPULATE_READ:
1027 	case MADV_POPULATE_WRITE:
1028 		return madvise_populate(vma, prev, start, end, behavior);
1029 	case MADV_NORMAL:
1030 		new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
1031 		break;
1032 	case MADV_SEQUENTIAL:
1033 		new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
1034 		break;
1035 	case MADV_RANDOM:
1036 		new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
1037 		break;
1038 	case MADV_DONTFORK:
1039 		new_flags |= VM_DONTCOPY;
1040 		break;
1041 	case MADV_DOFORK:
1042 		if (vma->vm_flags & VM_IO)
1043 			return -EINVAL;
1044 		new_flags &= ~VM_DONTCOPY;
1045 		break;
1046 	case MADV_WIPEONFORK:
1047 		/* MADV_WIPEONFORK is only supported on anonymous memory. */
1048 		if (vma->vm_file || vma->vm_flags & VM_SHARED)
1049 			return -EINVAL;
1050 		new_flags |= VM_WIPEONFORK;
1051 		break;
1052 	case MADV_KEEPONFORK:
1053 		new_flags &= ~VM_WIPEONFORK;
1054 		break;
1055 	case MADV_DONTDUMP:
1056 		new_flags |= VM_DONTDUMP;
1057 		break;
1058 	case MADV_DODUMP:
1059 		if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL)
1060 			return -EINVAL;
1061 		new_flags &= ~VM_DONTDUMP;
1062 		break;
1063 	case MADV_MERGEABLE:
1064 	case MADV_UNMERGEABLE:
1065 		error = ksm_madvise(vma, start, end, behavior, &new_flags);
1066 		if (error)
1067 			goto out;
1068 		break;
1069 	case MADV_HUGEPAGE:
1070 	case MADV_NOHUGEPAGE:
1071 		error = hugepage_madvise(vma, &new_flags, behavior);
1072 		if (error)
1073 			goto out;
1074 		break;
1075 	case MADV_COLLAPSE:
1076 		return madvise_collapse(vma, prev, start, end);
1077 	}
1078 
1079 	anon_name = anon_vma_name(vma);
1080 	anon_vma_name_get(anon_name);
1081 	error = madvise_update_vma(vma, prev, start, end, new_flags,
1082 				   anon_name);
1083 	anon_vma_name_put(anon_name);
1084 
1085 out:
1086 	/*
1087 	 * madvise() returns EAGAIN if kernel resources, such as
1088 	 * slab, are temporarily unavailable.
1089 	 */
1090 	if (error == -ENOMEM)
1091 		error = -EAGAIN;
1092 	return error;
1093 }
1094 
1095 #ifdef CONFIG_MEMORY_FAILURE
1096 /*
1097  * Error injection support for memory error handling.
1098  */
1099 static int madvise_inject_error(int behavior,
1100 		unsigned long start, unsigned long end)
1101 {
1102 	unsigned long size;
1103 
1104 	if (!capable(CAP_SYS_ADMIN))
1105 		return -EPERM;
1106 
1107 
1108 	for (; start < end; start += size) {
1109 		unsigned long pfn;
1110 		struct page *page;
1111 		int ret;
1112 
1113 		ret = get_user_pages_fast(start, 1, 0, &page);
1114 		if (ret != 1)
1115 			return ret;
1116 		pfn = page_to_pfn(page);
1117 
1118 		/*
1119 		 * When soft offlining hugepages, after migrating the page
1120 		 * we dissolve it, therefore in the second loop "page" will
1121 		 * no longer be a compound page.
1122 		 */
1123 		size = page_size(compound_head(page));
1124 
1125 		if (behavior == MADV_SOFT_OFFLINE) {
1126 			pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
1127 				 pfn, start);
1128 			ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
1129 		} else {
1130 			pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
1131 				 pfn, start);
1132 			ret = memory_failure(pfn, MF_COUNT_INCREASED | MF_SW_SIMULATED);
1133 			if (ret == -EOPNOTSUPP)
1134 				ret = 0;
1135 		}
1136 
1137 		if (ret)
1138 			return ret;
1139 	}
1140 
1141 	return 0;
1142 }
1143 #endif
1144 
1145 static bool
1146 madvise_behavior_valid(int behavior)
1147 {
1148 	switch (behavior) {
1149 	case MADV_DOFORK:
1150 	case MADV_DONTFORK:
1151 	case MADV_NORMAL:
1152 	case MADV_SEQUENTIAL:
1153 	case MADV_RANDOM:
1154 	case MADV_REMOVE:
1155 	case MADV_WILLNEED:
1156 	case MADV_DONTNEED:
1157 	case MADV_DONTNEED_LOCKED:
1158 	case MADV_FREE:
1159 	case MADV_COLD:
1160 	case MADV_PAGEOUT:
1161 	case MADV_POPULATE_READ:
1162 	case MADV_POPULATE_WRITE:
1163 #ifdef CONFIG_KSM
1164 	case MADV_MERGEABLE:
1165 	case MADV_UNMERGEABLE:
1166 #endif
1167 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1168 	case MADV_HUGEPAGE:
1169 	case MADV_NOHUGEPAGE:
1170 	case MADV_COLLAPSE:
1171 #endif
1172 	case MADV_DONTDUMP:
1173 	case MADV_DODUMP:
1174 	case MADV_WIPEONFORK:
1175 	case MADV_KEEPONFORK:
1176 #ifdef CONFIG_MEMORY_FAILURE
1177 	case MADV_SOFT_OFFLINE:
1178 	case MADV_HWPOISON:
1179 #endif
1180 		return true;
1181 
1182 	default:
1183 		return false;
1184 	}
1185 }
1186 
1187 static bool process_madvise_behavior_valid(int behavior)
1188 {
1189 	switch (behavior) {
1190 	case MADV_COLD:
1191 	case MADV_PAGEOUT:
1192 	case MADV_WILLNEED:
1193 	case MADV_COLLAPSE:
1194 		return true;
1195 	default:
1196 		return false;
1197 	}
1198 }
1199 
1200 /*
1201  * Walk the vmas in range [start,end), and call the visit function on each one.
1202  * The visit function will get start and end parameters that cover the overlap
1203  * between the current vma and the original range.  Any unmapped regions in the
1204  * original range will result in this function returning -ENOMEM while still
1205  * calling the visit function on all of the existing vmas in the range.
1206  * Must be called with the mmap_lock held for reading or writing.
1207  */
1208 static
1209 int madvise_walk_vmas(struct mm_struct *mm, unsigned long start,
1210 		      unsigned long end, unsigned long arg,
1211 		      int (*visit)(struct vm_area_struct *vma,
1212 				   struct vm_area_struct **prev, unsigned long start,
1213 				   unsigned long end, unsigned long arg))
1214 {
1215 	struct vm_area_struct *vma;
1216 	struct vm_area_struct *prev;
1217 	unsigned long tmp;
1218 	int unmapped_error = 0;
1219 
1220 	/*
1221 	 * If the interval [start,end) covers some unmapped address
1222 	 * ranges, just ignore them, but return -ENOMEM at the end.
1223 	 * - different from the way of handling in mlock etc.
1224 	 */
1225 	vma = find_vma_prev(mm, start, &prev);
1226 	if (vma && start > vma->vm_start)
1227 		prev = vma;
1228 
1229 	for (;;) {
1230 		int error;
1231 
1232 		/* Still start < end. */
1233 		if (!vma)
1234 			return -ENOMEM;
1235 
1236 		/* Here start < (end|vma->vm_end). */
1237 		if (start < vma->vm_start) {
1238 			unmapped_error = -ENOMEM;
1239 			start = vma->vm_start;
1240 			if (start >= end)
1241 				break;
1242 		}
1243 
1244 		/* Here vma->vm_start <= start < (end|vma->vm_end) */
1245 		tmp = vma->vm_end;
1246 		if (end < tmp)
1247 			tmp = end;
1248 
1249 		/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
1250 		error = visit(vma, &prev, start, tmp, arg);
1251 		if (error)
1252 			return error;
1253 		start = tmp;
1254 		if (prev && start < prev->vm_end)
1255 			start = prev->vm_end;
1256 		if (start >= end)
1257 			break;
1258 		if (prev)
1259 			vma = find_vma(mm, prev->vm_end);
1260 		else	/* madvise_remove dropped mmap_lock */
1261 			vma = find_vma(mm, start);
1262 	}
1263 
1264 	return unmapped_error;
1265 }
1266 
1267 #ifdef CONFIG_ANON_VMA_NAME
1268 static int madvise_vma_anon_name(struct vm_area_struct *vma,
1269 				 struct vm_area_struct **prev,
1270 				 unsigned long start, unsigned long end,
1271 				 unsigned long anon_name)
1272 {
1273 	int error;
1274 
1275 	/* Only anonymous mappings can be named */
1276 	if (vma->vm_file)
1277 		return -EBADF;
1278 
1279 	error = madvise_update_vma(vma, prev, start, end, vma->vm_flags,
1280 				   (struct anon_vma_name *)anon_name);
1281 
1282 	/*
1283 	 * madvise() returns EAGAIN if kernel resources, such as
1284 	 * slab, are temporarily unavailable.
1285 	 */
1286 	if (error == -ENOMEM)
1287 		error = -EAGAIN;
1288 	return error;
1289 }
1290 
1291 int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
1292 			  unsigned long len_in, struct anon_vma_name *anon_name)
1293 {
1294 	unsigned long end;
1295 	unsigned long len;
1296 
1297 	if (start & ~PAGE_MASK)
1298 		return -EINVAL;
1299 	len = (len_in + ~PAGE_MASK) & PAGE_MASK;
1300 
1301 	/* Check to see whether len was rounded up from small -ve to zero */
1302 	if (len_in && !len)
1303 		return -EINVAL;
1304 
1305 	end = start + len;
1306 	if (end < start)
1307 		return -EINVAL;
1308 
1309 	if (end == start)
1310 		return 0;
1311 
1312 	return madvise_walk_vmas(mm, start, end, (unsigned long)anon_name,
1313 				 madvise_vma_anon_name);
1314 }
1315 #endif /* CONFIG_ANON_VMA_NAME */
1316 /*
1317  * The madvise(2) system call.
1318  *
1319  * Applications can use madvise() to advise the kernel how it should
1320  * handle paging I/O in this VM area.  The idea is to help the kernel
1321  * use appropriate read-ahead and caching techniques.  The information
1322  * provided is advisory only, and can be safely disregarded by the
1323  * kernel without affecting the correct operation of the application.
1324  *
1325  * behavior values:
1326  *  MADV_NORMAL - the default behavior is to read clusters.  This
1327  *		results in some read-ahead and read-behind.
1328  *  MADV_RANDOM - the system should read the minimum amount of data
1329  *		on any access, since it is unlikely that the appli-
1330  *		cation will need more than what it asks for.
1331  *  MADV_SEQUENTIAL - pages in the given range will probably be accessed
1332  *		once, so they can be aggressively read ahead, and
1333  *		can be freed soon after they are accessed.
1334  *  MADV_WILLNEED - the application is notifying the system to read
1335  *		some pages ahead.
1336  *  MADV_DONTNEED - the application is finished with the given range,
1337  *		so the kernel can free resources associated with it.
1338  *  MADV_FREE - the application marks pages in the given range as lazy free,
1339  *		where actual purges are postponed until memory pressure happens.
1340  *  MADV_REMOVE - the application wants to free up the given range of
1341  *		pages and associated backing store.
1342  *  MADV_DONTFORK - omit this area from child's address space when forking:
1343  *		typically, to avoid COWing pages pinned by get_user_pages().
1344  *  MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
1345  *  MADV_WIPEONFORK - present the child process with zero-filled memory in this
1346  *              range after a fork.
1347  *  MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
1348  *  MADV_HWPOISON - trigger memory error handler as if the given memory range
1349  *		were corrupted by unrecoverable hardware memory failure.
1350  *  MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
1351  *  MADV_MERGEABLE - the application recommends that KSM try to merge pages in
1352  *		this area with pages of identical content from other such areas.
1353  *  MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
1354  *  MADV_HUGEPAGE - the application wants to back the given range by transparent
1355  *		huge pages in the future. Existing pages might be coalesced and
1356  *		new pages might be allocated as THP.
1357  *  MADV_NOHUGEPAGE - mark the given range as not worth being backed by
1358  *		transparent huge pages so the existing pages will not be
1359  *		coalesced into THP and new pages will not be allocated as THP.
1360  *  MADV_COLLAPSE - synchronously coalesce pages into new THP.
1361  *  MADV_DONTDUMP - the application wants to prevent pages in the given range
1362  *		from being included in its core dump.
1363  *  MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
1364  *  MADV_COLD - the application is not expected to use this memory soon,
1365  *		deactivate pages in this range so that they can be reclaimed
1366  *		easily if memory pressure happens.
1367  *  MADV_PAGEOUT - the application is not expected to use this memory soon,
1368  *		page out the pages in this range immediately.
1369  *  MADV_POPULATE_READ - populate (prefault) page tables readable by
1370  *		triggering read faults if required
1371  *  MADV_POPULATE_WRITE - populate (prefault) page tables writable by
1372  *		triggering write faults if required
1373  *
1374  * return values:
1375  *  zero    - success
1376  *  -EINVAL - start + len < 0, start is not page-aligned,
1377  *		"behavior" is not a valid value, or application
1378  *		is attempting to release locked or shared pages,
1379  *		or the specified address range includes file, Huge TLB,
1380  *		MAP_SHARED or VMPFNMAP range.
1381  *  -ENOMEM - addresses in the specified range are not currently
1382  *		mapped, or are outside the AS of the process.
1383  *  -EIO    - an I/O error occurred while paging in data.
1384  *  -EBADF  - map exists, but area maps something that isn't a file.
1385  *  -EAGAIN - a kernel resource was temporarily unavailable.
1386  */
1387 int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior)
1388 {
1389 	unsigned long end;
1390 	int error;
1391 	int write;
1392 	size_t len;
1393 	struct blk_plug plug;
1394 
1395 	start = untagged_addr(start);
1396 
1397 	if (!madvise_behavior_valid(behavior))
1398 		return -EINVAL;
1399 
1400 	if (!PAGE_ALIGNED(start))
1401 		return -EINVAL;
1402 	len = PAGE_ALIGN(len_in);
1403 
1404 	/* Check to see whether len was rounded up from small -ve to zero */
1405 	if (len_in && !len)
1406 		return -EINVAL;
1407 
1408 	end = start + len;
1409 	if (end < start)
1410 		return -EINVAL;
1411 
1412 	if (end == start)
1413 		return 0;
1414 
1415 #ifdef CONFIG_MEMORY_FAILURE
1416 	if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
1417 		return madvise_inject_error(behavior, start, start + len_in);
1418 #endif
1419 
1420 	write = madvise_need_mmap_write(behavior);
1421 	if (write) {
1422 		if (mmap_write_lock_killable(mm))
1423 			return -EINTR;
1424 	} else {
1425 		mmap_read_lock(mm);
1426 	}
1427 
1428 	blk_start_plug(&plug);
1429 	error = madvise_walk_vmas(mm, start, end, behavior,
1430 			madvise_vma_behavior);
1431 	blk_finish_plug(&plug);
1432 	if (write)
1433 		mmap_write_unlock(mm);
1434 	else
1435 		mmap_read_unlock(mm);
1436 
1437 	return error;
1438 }
1439 
1440 SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
1441 {
1442 	return do_madvise(current->mm, start, len_in, behavior);
1443 }
1444 
1445 SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
1446 		size_t, vlen, int, behavior, unsigned int, flags)
1447 {
1448 	ssize_t ret;
1449 	struct iovec iovstack[UIO_FASTIOV], iovec;
1450 	struct iovec *iov = iovstack;
1451 	struct iov_iter iter;
1452 	struct task_struct *task;
1453 	struct mm_struct *mm;
1454 	size_t total_len;
1455 	unsigned int f_flags;
1456 
1457 	if (flags != 0) {
1458 		ret = -EINVAL;
1459 		goto out;
1460 	}
1461 
1462 	ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
1463 	if (ret < 0)
1464 		goto out;
1465 
1466 	task = pidfd_get_task(pidfd, &f_flags);
1467 	if (IS_ERR(task)) {
1468 		ret = PTR_ERR(task);
1469 		goto free_iov;
1470 	}
1471 
1472 	if (!process_madvise_behavior_valid(behavior)) {
1473 		ret = -EINVAL;
1474 		goto release_task;
1475 	}
1476 
1477 	/* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
1478 	mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
1479 	if (IS_ERR_OR_NULL(mm)) {
1480 		ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
1481 		goto release_task;
1482 	}
1483 
1484 	/*
1485 	 * Require CAP_SYS_NICE for influencing process performance. Note that
1486 	 * only non-destructive hints are currently supported.
1487 	 */
1488 	if (!capable(CAP_SYS_NICE)) {
1489 		ret = -EPERM;
1490 		goto release_mm;
1491 	}
1492 
1493 	total_len = iov_iter_count(&iter);
1494 
1495 	while (iov_iter_count(&iter)) {
1496 		iovec = iov_iter_iovec(&iter);
1497 		ret = do_madvise(mm, (unsigned long)iovec.iov_base,
1498 					iovec.iov_len, behavior);
1499 		if (ret < 0)
1500 			break;
1501 		iov_iter_advance(&iter, iovec.iov_len);
1502 	}
1503 
1504 	ret = (total_len - iov_iter_count(&iter)) ? : ret;
1505 
1506 release_mm:
1507 	mmput(mm);
1508 release_task:
1509 	put_task_struct(task);
1510 free_iov:
1511 	kfree(iov);
1512 out:
1513 	return ret;
1514 }
1515