xref: /openbmc/linux/mm/memory.c (revision 495311927ffbe3604e915aeafdf03325e9925b9d)
1 /*
2  *  linux/mm/memory.c
3  *
4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
5  */
6 
7 /*
8  * demand-loading started 01.12.91 - seems it is high on the list of
9  * things wanted, and it should be easy to implement. - Linus
10  */
11 
12 /*
13  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14  * pages started 02.12.91, seems to work. - Linus.
15  *
16  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17  * would have taken more than the 6M I have free, but it worked well as
18  * far as I could see.
19  *
20  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21  */
22 
23 /*
24  * Real VM (paging to/from disk) started 18.12.91. Much more work and
25  * thought has to go into this. Oh, well..
26  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
27  *		Found it. Everything seems to work now.
28  * 20.12.91  -  Ok, making the swap-device changeable like the root.
29  */
30 
31 /*
32  * 05.04.94  -  Multi-page memory management added for v1.1.
33  * 		Idea by Alex Bligh (alex@cconcepts.co.uk)
34  *
35  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
36  *		(Gerhard.Wichert@pdb.siemens.de)
37  *
38  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39  */
40 
41 #include <linux/kernel_stat.h>
42 #include <linux/mm.h>
43 #include <linux/hugetlb.h>
44 #include <linux/mman.h>
45 #include <linux/swap.h>
46 #include <linux/highmem.h>
47 #include <linux/pagemap.h>
48 #include <linux/ksm.h>
49 #include <linux/rmap.h>
50 #include <linux/module.h>
51 #include <linux/delayacct.h>
52 #include <linux/init.h>
53 #include <linux/writeback.h>
54 #include <linux/memcontrol.h>
55 #include <linux/mmu_notifier.h>
56 #include <linux/kallsyms.h>
57 #include <linux/swapops.h>
58 #include <linux/elf.h>
59 #include <linux/gfp.h>
60 
61 #include <asm/io.h>
62 #include <asm/pgalloc.h>
63 #include <asm/uaccess.h>
64 #include <asm/tlb.h>
65 #include <asm/tlbflush.h>
66 #include <asm/pgtable.h>
67 
68 #include "internal.h"
69 
70 #ifndef CONFIG_NEED_MULTIPLE_NODES
71 /* use the per-pgdat data instead for discontigmem - mbligh */
72 unsigned long max_mapnr;
73 struct page *mem_map;
74 
75 EXPORT_SYMBOL(max_mapnr);
76 EXPORT_SYMBOL(mem_map);
77 #endif
78 
79 unsigned long num_physpages;
80 /*
81  * A number of key systems in x86 including ioremap() rely on the assumption
82  * that high_memory defines the upper bound on direct map memory, then end
83  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
84  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
85  * and ZONE_HIGHMEM.
86  */
87 void * high_memory;
88 
89 EXPORT_SYMBOL(num_physpages);
90 EXPORT_SYMBOL(high_memory);
91 
92 /*
93  * Randomize the address space (stacks, mmaps, brk, etc.).
94  *
95  * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
96  *   as ancient (libc5 based) binaries can segfault. )
97  */
98 int randomize_va_space __read_mostly =
99 #ifdef CONFIG_COMPAT_BRK
100 					1;
101 #else
102 					2;
103 #endif
104 
105 static int __init disable_randmaps(char *s)
106 {
107 	randomize_va_space = 0;
108 	return 1;
109 }
110 __setup("norandmaps", disable_randmaps);
111 
112 unsigned long zero_pfn __read_mostly;
113 unsigned long highest_memmap_pfn __read_mostly;
114 
115 /*
116  * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
117  */
118 static int __init init_zero_pfn(void)
119 {
120 	zero_pfn = page_to_pfn(ZERO_PAGE(0));
121 	return 0;
122 }
123 core_initcall(init_zero_pfn);
124 
125 
126 #if defined(SPLIT_RSS_COUNTING)
127 
128 static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
129 {
130 	int i;
131 
132 	for (i = 0; i < NR_MM_COUNTERS; i++) {
133 		if (task->rss_stat.count[i]) {
134 			add_mm_counter(mm, i, task->rss_stat.count[i]);
135 			task->rss_stat.count[i] = 0;
136 		}
137 	}
138 	task->rss_stat.events = 0;
139 }
140 
141 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
142 {
143 	struct task_struct *task = current;
144 
145 	if (likely(task->mm == mm))
146 		task->rss_stat.count[member] += val;
147 	else
148 		add_mm_counter(mm, member, val);
149 }
150 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
151 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
152 
153 /* sync counter once per 64 page faults */
154 #define TASK_RSS_EVENTS_THRESH	(64)
155 static void check_sync_rss_stat(struct task_struct *task)
156 {
157 	if (unlikely(task != current))
158 		return;
159 	if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
160 		__sync_task_rss_stat(task, task->mm);
161 }
162 
163 unsigned long get_mm_counter(struct mm_struct *mm, int member)
164 {
165 	long val = 0;
166 
167 	/*
168 	 * Don't use task->mm here...for avoiding to use task_get_mm()..
169 	 * The caller must guarantee task->mm is not invalid.
170 	 */
171 	val = atomic_long_read(&mm->rss_stat.count[member]);
172 	/*
173 	 * counter is updated in asynchronous manner and may go to minus.
174 	 * But it's never be expected number for users.
175 	 */
176 	if (val < 0)
177 		return 0;
178 	return (unsigned long)val;
179 }
180 
181 void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
182 {
183 	__sync_task_rss_stat(task, mm);
184 }
185 #else
186 
187 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
188 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
189 
190 static void check_sync_rss_stat(struct task_struct *task)
191 {
192 }
193 
194 #endif
195 
196 /*
197  * If a p?d_bad entry is found while walking page tables, report
198  * the error, before resetting entry to p?d_none.  Usually (but
199  * very seldom) called out from the p?d_none_or_clear_bad macros.
200  */
201 
202 void pgd_clear_bad(pgd_t *pgd)
203 {
204 	pgd_ERROR(*pgd);
205 	pgd_clear(pgd);
206 }
207 
208 void pud_clear_bad(pud_t *pud)
209 {
210 	pud_ERROR(*pud);
211 	pud_clear(pud);
212 }
213 
214 void pmd_clear_bad(pmd_t *pmd)
215 {
216 	pmd_ERROR(*pmd);
217 	pmd_clear(pmd);
218 }
219 
220 /*
221  * Note: this doesn't free the actual pages themselves. That
222  * has been handled earlier when unmapping all the memory regions.
223  */
224 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
225 			   unsigned long addr)
226 {
227 	pgtable_t token = pmd_pgtable(*pmd);
228 	pmd_clear(pmd);
229 	pte_free_tlb(tlb, token, addr);
230 	tlb->mm->nr_ptes--;
231 }
232 
233 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
234 				unsigned long addr, unsigned long end,
235 				unsigned long floor, unsigned long ceiling)
236 {
237 	pmd_t *pmd;
238 	unsigned long next;
239 	unsigned long start;
240 
241 	start = addr;
242 	pmd = pmd_offset(pud, addr);
243 	do {
244 		next = pmd_addr_end(addr, end);
245 		if (pmd_none_or_clear_bad(pmd))
246 			continue;
247 		free_pte_range(tlb, pmd, addr);
248 	} while (pmd++, addr = next, addr != end);
249 
250 	start &= PUD_MASK;
251 	if (start < floor)
252 		return;
253 	if (ceiling) {
254 		ceiling &= PUD_MASK;
255 		if (!ceiling)
256 			return;
257 	}
258 	if (end - 1 > ceiling - 1)
259 		return;
260 
261 	pmd = pmd_offset(pud, start);
262 	pud_clear(pud);
263 	pmd_free_tlb(tlb, pmd, start);
264 }
265 
266 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
267 				unsigned long addr, unsigned long end,
268 				unsigned long floor, unsigned long ceiling)
269 {
270 	pud_t *pud;
271 	unsigned long next;
272 	unsigned long start;
273 
274 	start = addr;
275 	pud = pud_offset(pgd, addr);
276 	do {
277 		next = pud_addr_end(addr, end);
278 		if (pud_none_or_clear_bad(pud))
279 			continue;
280 		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
281 	} while (pud++, addr = next, addr != end);
282 
283 	start &= PGDIR_MASK;
284 	if (start < floor)
285 		return;
286 	if (ceiling) {
287 		ceiling &= PGDIR_MASK;
288 		if (!ceiling)
289 			return;
290 	}
291 	if (end - 1 > ceiling - 1)
292 		return;
293 
294 	pud = pud_offset(pgd, start);
295 	pgd_clear(pgd);
296 	pud_free_tlb(tlb, pud, start);
297 }
298 
299 /*
300  * This function frees user-level page tables of a process.
301  *
302  * Must be called with pagetable lock held.
303  */
304 void free_pgd_range(struct mmu_gather *tlb,
305 			unsigned long addr, unsigned long end,
306 			unsigned long floor, unsigned long ceiling)
307 {
308 	pgd_t *pgd;
309 	unsigned long next;
310 
311 	/*
312 	 * The next few lines have given us lots of grief...
313 	 *
314 	 * Why are we testing PMD* at this top level?  Because often
315 	 * there will be no work to do at all, and we'd prefer not to
316 	 * go all the way down to the bottom just to discover that.
317 	 *
318 	 * Why all these "- 1"s?  Because 0 represents both the bottom
319 	 * of the address space and the top of it (using -1 for the
320 	 * top wouldn't help much: the masks would do the wrong thing).
321 	 * The rule is that addr 0 and floor 0 refer to the bottom of
322 	 * the address space, but end 0 and ceiling 0 refer to the top
323 	 * Comparisons need to use "end - 1" and "ceiling - 1" (though
324 	 * that end 0 case should be mythical).
325 	 *
326 	 * Wherever addr is brought up or ceiling brought down, we must
327 	 * be careful to reject "the opposite 0" before it confuses the
328 	 * subsequent tests.  But what about where end is brought down
329 	 * by PMD_SIZE below? no, end can't go down to 0 there.
330 	 *
331 	 * Whereas we round start (addr) and ceiling down, by different
332 	 * masks at different levels, in order to test whether a table
333 	 * now has no other vmas using it, so can be freed, we don't
334 	 * bother to round floor or end up - the tests don't need that.
335 	 */
336 
337 	addr &= PMD_MASK;
338 	if (addr < floor) {
339 		addr += PMD_SIZE;
340 		if (!addr)
341 			return;
342 	}
343 	if (ceiling) {
344 		ceiling &= PMD_MASK;
345 		if (!ceiling)
346 			return;
347 	}
348 	if (end - 1 > ceiling - 1)
349 		end -= PMD_SIZE;
350 	if (addr > end - 1)
351 		return;
352 
353 	pgd = pgd_offset(tlb->mm, addr);
354 	do {
355 		next = pgd_addr_end(addr, end);
356 		if (pgd_none_or_clear_bad(pgd))
357 			continue;
358 		free_pud_range(tlb, pgd, addr, next, floor, ceiling);
359 	} while (pgd++, addr = next, addr != end);
360 }
361 
362 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
363 		unsigned long floor, unsigned long ceiling)
364 {
365 	while (vma) {
366 		struct vm_area_struct *next = vma->vm_next;
367 		unsigned long addr = vma->vm_start;
368 
369 		/*
370 		 * Hide vma from rmap and truncate_pagecache before freeing
371 		 * pgtables
372 		 */
373 		unlink_anon_vmas(vma);
374 		unlink_file_vma(vma);
375 
376 		if (is_vm_hugetlb_page(vma)) {
377 			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
378 				floor, next? next->vm_start: ceiling);
379 		} else {
380 			/*
381 			 * Optimization: gather nearby vmas into one call down
382 			 */
383 			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
384 			       && !is_vm_hugetlb_page(next)) {
385 				vma = next;
386 				next = vma->vm_next;
387 				unlink_anon_vmas(vma);
388 				unlink_file_vma(vma);
389 			}
390 			free_pgd_range(tlb, addr, vma->vm_end,
391 				floor, next? next->vm_start: ceiling);
392 		}
393 		vma = next;
394 	}
395 }
396 
397 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
398 {
399 	pgtable_t new = pte_alloc_one(mm, address);
400 	if (!new)
401 		return -ENOMEM;
402 
403 	/*
404 	 * Ensure all pte setup (eg. pte page lock and page clearing) are
405 	 * visible before the pte is made visible to other CPUs by being
406 	 * put into page tables.
407 	 *
408 	 * The other side of the story is the pointer chasing in the page
409 	 * table walking code (when walking the page table without locking;
410 	 * ie. most of the time). Fortunately, these data accesses consist
411 	 * of a chain of data-dependent loads, meaning most CPUs (alpha
412 	 * being the notable exception) will already guarantee loads are
413 	 * seen in-order. See the alpha page table accessors for the
414 	 * smp_read_barrier_depends() barriers in page table walking code.
415 	 */
416 	smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
417 
418 	spin_lock(&mm->page_table_lock);
419 	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
420 		mm->nr_ptes++;
421 		pmd_populate(mm, pmd, new);
422 		new = NULL;
423 	}
424 	spin_unlock(&mm->page_table_lock);
425 	if (new)
426 		pte_free(mm, new);
427 	return 0;
428 }
429 
430 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
431 {
432 	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
433 	if (!new)
434 		return -ENOMEM;
435 
436 	smp_wmb(); /* See comment in __pte_alloc */
437 
438 	spin_lock(&init_mm.page_table_lock);
439 	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
440 		pmd_populate_kernel(&init_mm, pmd, new);
441 		new = NULL;
442 	}
443 	spin_unlock(&init_mm.page_table_lock);
444 	if (new)
445 		pte_free_kernel(&init_mm, new);
446 	return 0;
447 }
448 
449 static inline void init_rss_vec(int *rss)
450 {
451 	memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
452 }
453 
454 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
455 {
456 	int i;
457 
458 	if (current->mm == mm)
459 		sync_mm_rss(current, mm);
460 	for (i = 0; i < NR_MM_COUNTERS; i++)
461 		if (rss[i])
462 			add_mm_counter(mm, i, rss[i]);
463 }
464 
465 /*
466  * This function is called to print an error when a bad pte
467  * is found. For example, we might have a PFN-mapped pte in
468  * a region that doesn't allow it.
469  *
470  * The calling function must still handle the error.
471  */
472 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
473 			  pte_t pte, struct page *page)
474 {
475 	pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
476 	pud_t *pud = pud_offset(pgd, addr);
477 	pmd_t *pmd = pmd_offset(pud, addr);
478 	struct address_space *mapping;
479 	pgoff_t index;
480 	static unsigned long resume;
481 	static unsigned long nr_shown;
482 	static unsigned long nr_unshown;
483 
484 	/*
485 	 * Allow a burst of 60 reports, then keep quiet for that minute;
486 	 * or allow a steady drip of one report per second.
487 	 */
488 	if (nr_shown == 60) {
489 		if (time_before(jiffies, resume)) {
490 			nr_unshown++;
491 			return;
492 		}
493 		if (nr_unshown) {
494 			printk(KERN_ALERT
495 				"BUG: Bad page map: %lu messages suppressed\n",
496 				nr_unshown);
497 			nr_unshown = 0;
498 		}
499 		nr_shown = 0;
500 	}
501 	if (nr_shown++ == 0)
502 		resume = jiffies + 60 * HZ;
503 
504 	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
505 	index = linear_page_index(vma, addr);
506 
507 	printk(KERN_ALERT
508 		"BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
509 		current->comm,
510 		(long long)pte_val(pte), (long long)pmd_val(*pmd));
511 	if (page)
512 		dump_page(page);
513 	printk(KERN_ALERT
514 		"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
515 		(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
516 	/*
517 	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
518 	 */
519 	if (vma->vm_ops)
520 		print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
521 				(unsigned long)vma->vm_ops->fault);
522 	if (vma->vm_file && vma->vm_file->f_op)
523 		print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
524 				(unsigned long)vma->vm_file->f_op->mmap);
525 	dump_stack();
526 	add_taint(TAINT_BAD_PAGE);
527 }
528 
529 static inline int is_cow_mapping(unsigned int flags)
530 {
531 	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
532 }
533 
534 #ifndef is_zero_pfn
535 static inline int is_zero_pfn(unsigned long pfn)
536 {
537 	return pfn == zero_pfn;
538 }
539 #endif
540 
541 #ifndef my_zero_pfn
542 static inline unsigned long my_zero_pfn(unsigned long addr)
543 {
544 	return zero_pfn;
545 }
546 #endif
547 
548 /*
549  * vm_normal_page -- This function gets the "struct page" associated with a pte.
550  *
551  * "Special" mappings do not wish to be associated with a "struct page" (either
552  * it doesn't exist, or it exists but they don't want to touch it). In this
553  * case, NULL is returned here. "Normal" mappings do have a struct page.
554  *
555  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
556  * pte bit, in which case this function is trivial. Secondly, an architecture
557  * may not have a spare pte bit, which requires a more complicated scheme,
558  * described below.
559  *
560  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
561  * special mapping (even if there are underlying and valid "struct pages").
562  * COWed pages of a VM_PFNMAP are always normal.
563  *
564  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
565  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
566  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
567  * mapping will always honor the rule
568  *
569  *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
570  *
571  * And for normal mappings this is false.
572  *
573  * This restricts such mappings to be a linear translation from virtual address
574  * to pfn. To get around this restriction, we allow arbitrary mappings so long
575  * as the vma is not a COW mapping; in that case, we know that all ptes are
576  * special (because none can have been COWed).
577  *
578  *
579  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
580  *
581  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
582  * page" backing, however the difference is that _all_ pages with a struct
583  * page (that is, those where pfn_valid is true) are refcounted and considered
584  * normal pages by the VM. The disadvantage is that pages are refcounted
585  * (which can be slower and simply not an option for some PFNMAP users). The
586  * advantage is that we don't have to follow the strict linearity rule of
587  * PFNMAP mappings in order to support COWable mappings.
588  *
589  */
590 #ifdef __HAVE_ARCH_PTE_SPECIAL
591 # define HAVE_PTE_SPECIAL 1
592 #else
593 # define HAVE_PTE_SPECIAL 0
594 #endif
595 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
596 				pte_t pte)
597 {
598 	unsigned long pfn = pte_pfn(pte);
599 
600 	if (HAVE_PTE_SPECIAL) {
601 		if (likely(!pte_special(pte)))
602 			goto check_pfn;
603 		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
604 			return NULL;
605 		if (!is_zero_pfn(pfn))
606 			print_bad_pte(vma, addr, pte, NULL);
607 		return NULL;
608 	}
609 
610 	/* !HAVE_PTE_SPECIAL case follows: */
611 
612 	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
613 		if (vma->vm_flags & VM_MIXEDMAP) {
614 			if (!pfn_valid(pfn))
615 				return NULL;
616 			goto out;
617 		} else {
618 			unsigned long off;
619 			off = (addr - vma->vm_start) >> PAGE_SHIFT;
620 			if (pfn == vma->vm_pgoff + off)
621 				return NULL;
622 			if (!is_cow_mapping(vma->vm_flags))
623 				return NULL;
624 		}
625 	}
626 
627 	if (is_zero_pfn(pfn))
628 		return NULL;
629 check_pfn:
630 	if (unlikely(pfn > highest_memmap_pfn)) {
631 		print_bad_pte(vma, addr, pte, NULL);
632 		return NULL;
633 	}
634 
635 	/*
636 	 * NOTE! We still have PageReserved() pages in the page tables.
637 	 * eg. VDSO mappings can cause them to exist.
638 	 */
639 out:
640 	return pfn_to_page(pfn);
641 }
642 
643 /*
644  * copy one vm_area from one task to the other. Assumes the page tables
645  * already present in the new task to be cleared in the whole range
646  * covered by this vma.
647  */
648 
649 static inline unsigned long
650 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
651 		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
652 		unsigned long addr, int *rss)
653 {
654 	unsigned long vm_flags = vma->vm_flags;
655 	pte_t pte = *src_pte;
656 	struct page *page;
657 
658 	/* pte contains position in swap or file, so copy. */
659 	if (unlikely(!pte_present(pte))) {
660 		if (!pte_file(pte)) {
661 			swp_entry_t entry = pte_to_swp_entry(pte);
662 
663 			if (swap_duplicate(entry) < 0)
664 				return entry.val;
665 
666 			/* make sure dst_mm is on swapoff's mmlist. */
667 			if (unlikely(list_empty(&dst_mm->mmlist))) {
668 				spin_lock(&mmlist_lock);
669 				if (list_empty(&dst_mm->mmlist))
670 					list_add(&dst_mm->mmlist,
671 						 &src_mm->mmlist);
672 				spin_unlock(&mmlist_lock);
673 			}
674 			if (likely(!non_swap_entry(entry)))
675 				rss[MM_SWAPENTS]++;
676 			else if (is_write_migration_entry(entry) &&
677 					is_cow_mapping(vm_flags)) {
678 				/*
679 				 * COW mappings require pages in both parent
680 				 * and child to be set to read.
681 				 */
682 				make_migration_entry_read(&entry);
683 				pte = swp_entry_to_pte(entry);
684 				set_pte_at(src_mm, addr, src_pte, pte);
685 			}
686 		}
687 		goto out_set_pte;
688 	}
689 
690 	/*
691 	 * If it's a COW mapping, write protect it both
692 	 * in the parent and the child
693 	 */
694 	if (is_cow_mapping(vm_flags)) {
695 		ptep_set_wrprotect(src_mm, addr, src_pte);
696 		pte = pte_wrprotect(pte);
697 	}
698 
699 	/*
700 	 * If it's a shared mapping, mark it clean in
701 	 * the child
702 	 */
703 	if (vm_flags & VM_SHARED)
704 		pte = pte_mkclean(pte);
705 	pte = pte_mkold(pte);
706 
707 	page = vm_normal_page(vma, addr, pte);
708 	if (page) {
709 		get_page(page);
710 		page_dup_rmap(page);
711 		if (PageAnon(page))
712 			rss[MM_ANONPAGES]++;
713 		else
714 			rss[MM_FILEPAGES]++;
715 	}
716 
717 out_set_pte:
718 	set_pte_at(dst_mm, addr, dst_pte, pte);
719 	return 0;
720 }
721 
722 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
723 		pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
724 		unsigned long addr, unsigned long end)
725 {
726 	pte_t *orig_src_pte, *orig_dst_pte;
727 	pte_t *src_pte, *dst_pte;
728 	spinlock_t *src_ptl, *dst_ptl;
729 	int progress = 0;
730 	int rss[NR_MM_COUNTERS];
731 	swp_entry_t entry = (swp_entry_t){0};
732 
733 again:
734 	init_rss_vec(rss);
735 
736 	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
737 	if (!dst_pte)
738 		return -ENOMEM;
739 	src_pte = pte_offset_map_nested(src_pmd, addr);
740 	src_ptl = pte_lockptr(src_mm, src_pmd);
741 	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
742 	orig_src_pte = src_pte;
743 	orig_dst_pte = dst_pte;
744 	arch_enter_lazy_mmu_mode();
745 
746 	do {
747 		/*
748 		 * We are holding two locks at this point - either of them
749 		 * could generate latencies in another task on another CPU.
750 		 */
751 		if (progress >= 32) {
752 			progress = 0;
753 			if (need_resched() ||
754 			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
755 				break;
756 		}
757 		if (pte_none(*src_pte)) {
758 			progress++;
759 			continue;
760 		}
761 		entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
762 							vma, addr, rss);
763 		if (entry.val)
764 			break;
765 		progress += 8;
766 	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
767 
768 	arch_leave_lazy_mmu_mode();
769 	spin_unlock(src_ptl);
770 	pte_unmap_nested(orig_src_pte);
771 	add_mm_rss_vec(dst_mm, rss);
772 	pte_unmap_unlock(orig_dst_pte, dst_ptl);
773 	cond_resched();
774 
775 	if (entry.val) {
776 		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
777 			return -ENOMEM;
778 		progress = 0;
779 	}
780 	if (addr != end)
781 		goto again;
782 	return 0;
783 }
784 
785 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
786 		pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
787 		unsigned long addr, unsigned long end)
788 {
789 	pmd_t *src_pmd, *dst_pmd;
790 	unsigned long next;
791 
792 	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
793 	if (!dst_pmd)
794 		return -ENOMEM;
795 	src_pmd = pmd_offset(src_pud, addr);
796 	do {
797 		next = pmd_addr_end(addr, end);
798 		if (pmd_none_or_clear_bad(src_pmd))
799 			continue;
800 		if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
801 						vma, addr, next))
802 			return -ENOMEM;
803 	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
804 	return 0;
805 }
806 
807 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
808 		pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
809 		unsigned long addr, unsigned long end)
810 {
811 	pud_t *src_pud, *dst_pud;
812 	unsigned long next;
813 
814 	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
815 	if (!dst_pud)
816 		return -ENOMEM;
817 	src_pud = pud_offset(src_pgd, addr);
818 	do {
819 		next = pud_addr_end(addr, end);
820 		if (pud_none_or_clear_bad(src_pud))
821 			continue;
822 		if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
823 						vma, addr, next))
824 			return -ENOMEM;
825 	} while (dst_pud++, src_pud++, addr = next, addr != end);
826 	return 0;
827 }
828 
829 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
830 		struct vm_area_struct *vma)
831 {
832 	pgd_t *src_pgd, *dst_pgd;
833 	unsigned long next;
834 	unsigned long addr = vma->vm_start;
835 	unsigned long end = vma->vm_end;
836 	int ret;
837 
838 	/*
839 	 * Don't copy ptes where a page fault will fill them correctly.
840 	 * Fork becomes much lighter when there are big shared or private
841 	 * readonly mappings. The tradeoff is that copy_page_range is more
842 	 * efficient than faulting.
843 	 */
844 	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
845 		if (!vma->anon_vma)
846 			return 0;
847 	}
848 
849 	if (is_vm_hugetlb_page(vma))
850 		return copy_hugetlb_page_range(dst_mm, src_mm, vma);
851 
852 	if (unlikely(is_pfn_mapping(vma))) {
853 		/*
854 		 * We do not free on error cases below as remove_vma
855 		 * gets called on error from higher level routine
856 		 */
857 		ret = track_pfn_vma_copy(vma);
858 		if (ret)
859 			return ret;
860 	}
861 
862 	/*
863 	 * We need to invalidate the secondary MMU mappings only when
864 	 * there could be a permission downgrade on the ptes of the
865 	 * parent mm. And a permission downgrade will only happen if
866 	 * is_cow_mapping() returns true.
867 	 */
868 	if (is_cow_mapping(vma->vm_flags))
869 		mmu_notifier_invalidate_range_start(src_mm, addr, end);
870 
871 	ret = 0;
872 	dst_pgd = pgd_offset(dst_mm, addr);
873 	src_pgd = pgd_offset(src_mm, addr);
874 	do {
875 		next = pgd_addr_end(addr, end);
876 		if (pgd_none_or_clear_bad(src_pgd))
877 			continue;
878 		if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
879 					    vma, addr, next))) {
880 			ret = -ENOMEM;
881 			break;
882 		}
883 	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
884 
885 	if (is_cow_mapping(vma->vm_flags))
886 		mmu_notifier_invalidate_range_end(src_mm,
887 						  vma->vm_start, end);
888 	return ret;
889 }
890 
891 static unsigned long zap_pte_range(struct mmu_gather *tlb,
892 				struct vm_area_struct *vma, pmd_t *pmd,
893 				unsigned long addr, unsigned long end,
894 				long *zap_work, struct zap_details *details)
895 {
896 	struct mm_struct *mm = tlb->mm;
897 	pte_t *pte;
898 	spinlock_t *ptl;
899 	int rss[NR_MM_COUNTERS];
900 
901 	init_rss_vec(rss);
902 
903 	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
904 	arch_enter_lazy_mmu_mode();
905 	do {
906 		pte_t ptent = *pte;
907 		if (pte_none(ptent)) {
908 			(*zap_work)--;
909 			continue;
910 		}
911 
912 		(*zap_work) -= PAGE_SIZE;
913 
914 		if (pte_present(ptent)) {
915 			struct page *page;
916 
917 			page = vm_normal_page(vma, addr, ptent);
918 			if (unlikely(details) && page) {
919 				/*
920 				 * unmap_shared_mapping_pages() wants to
921 				 * invalidate cache without truncating:
922 				 * unmap shared but keep private pages.
923 				 */
924 				if (details->check_mapping &&
925 				    details->check_mapping != page->mapping)
926 					continue;
927 				/*
928 				 * Each page->index must be checked when
929 				 * invalidating or truncating nonlinear.
930 				 */
931 				if (details->nonlinear_vma &&
932 				    (page->index < details->first_index ||
933 				     page->index > details->last_index))
934 					continue;
935 			}
936 			ptent = ptep_get_and_clear_full(mm, addr, pte,
937 							tlb->fullmm);
938 			tlb_remove_tlb_entry(tlb, pte, addr);
939 			if (unlikely(!page))
940 				continue;
941 			if (unlikely(details) && details->nonlinear_vma
942 			    && linear_page_index(details->nonlinear_vma,
943 						addr) != page->index)
944 				set_pte_at(mm, addr, pte,
945 					   pgoff_to_pte(page->index));
946 			if (PageAnon(page))
947 				rss[MM_ANONPAGES]--;
948 			else {
949 				if (pte_dirty(ptent))
950 					set_page_dirty(page);
951 				if (pte_young(ptent) &&
952 				    likely(!VM_SequentialReadHint(vma)))
953 					mark_page_accessed(page);
954 				rss[MM_FILEPAGES]--;
955 			}
956 			page_remove_rmap(page);
957 			if (unlikely(page_mapcount(page) < 0))
958 				print_bad_pte(vma, addr, ptent, page);
959 			tlb_remove_page(tlb, page);
960 			continue;
961 		}
962 		/*
963 		 * If details->check_mapping, we leave swap entries;
964 		 * if details->nonlinear_vma, we leave file entries.
965 		 */
966 		if (unlikely(details))
967 			continue;
968 		if (pte_file(ptent)) {
969 			if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
970 				print_bad_pte(vma, addr, ptent, NULL);
971 		} else {
972 			swp_entry_t entry = pte_to_swp_entry(ptent);
973 
974 			if (!non_swap_entry(entry))
975 				rss[MM_SWAPENTS]--;
976 			if (unlikely(!free_swap_and_cache(entry)))
977 				print_bad_pte(vma, addr, ptent, NULL);
978 		}
979 		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
980 	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
981 
982 	add_mm_rss_vec(mm, rss);
983 	arch_leave_lazy_mmu_mode();
984 	pte_unmap_unlock(pte - 1, ptl);
985 
986 	return addr;
987 }
988 
989 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
990 				struct vm_area_struct *vma, pud_t *pud,
991 				unsigned long addr, unsigned long end,
992 				long *zap_work, struct zap_details *details)
993 {
994 	pmd_t *pmd;
995 	unsigned long next;
996 
997 	pmd = pmd_offset(pud, addr);
998 	do {
999 		next = pmd_addr_end(addr, end);
1000 		if (pmd_none_or_clear_bad(pmd)) {
1001 			(*zap_work)--;
1002 			continue;
1003 		}
1004 		next = zap_pte_range(tlb, vma, pmd, addr, next,
1005 						zap_work, details);
1006 	} while (pmd++, addr = next, (addr != end && *zap_work > 0));
1007 
1008 	return addr;
1009 }
1010 
1011 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1012 				struct vm_area_struct *vma, pgd_t *pgd,
1013 				unsigned long addr, unsigned long end,
1014 				long *zap_work, struct zap_details *details)
1015 {
1016 	pud_t *pud;
1017 	unsigned long next;
1018 
1019 	pud = pud_offset(pgd, addr);
1020 	do {
1021 		next = pud_addr_end(addr, end);
1022 		if (pud_none_or_clear_bad(pud)) {
1023 			(*zap_work)--;
1024 			continue;
1025 		}
1026 		next = zap_pmd_range(tlb, vma, pud, addr, next,
1027 						zap_work, details);
1028 	} while (pud++, addr = next, (addr != end && *zap_work > 0));
1029 
1030 	return addr;
1031 }
1032 
1033 static unsigned long unmap_page_range(struct mmu_gather *tlb,
1034 				struct vm_area_struct *vma,
1035 				unsigned long addr, unsigned long end,
1036 				long *zap_work, struct zap_details *details)
1037 {
1038 	pgd_t *pgd;
1039 	unsigned long next;
1040 
1041 	if (details && !details->check_mapping && !details->nonlinear_vma)
1042 		details = NULL;
1043 
1044 	BUG_ON(addr >= end);
1045 	mem_cgroup_uncharge_start();
1046 	tlb_start_vma(tlb, vma);
1047 	pgd = pgd_offset(vma->vm_mm, addr);
1048 	do {
1049 		next = pgd_addr_end(addr, end);
1050 		if (pgd_none_or_clear_bad(pgd)) {
1051 			(*zap_work)--;
1052 			continue;
1053 		}
1054 		next = zap_pud_range(tlb, vma, pgd, addr, next,
1055 						zap_work, details);
1056 	} while (pgd++, addr = next, (addr != end && *zap_work > 0));
1057 	tlb_end_vma(tlb, vma);
1058 	mem_cgroup_uncharge_end();
1059 
1060 	return addr;
1061 }
1062 
1063 #ifdef CONFIG_PREEMPT
1064 # define ZAP_BLOCK_SIZE	(8 * PAGE_SIZE)
1065 #else
1066 /* No preempt: go for improved straight-line efficiency */
1067 # define ZAP_BLOCK_SIZE	(1024 * PAGE_SIZE)
1068 #endif
1069 
1070 /**
1071  * unmap_vmas - unmap a range of memory covered by a list of vma's
1072  * @tlbp: address of the caller's struct mmu_gather
1073  * @vma: the starting vma
1074  * @start_addr: virtual address at which to start unmapping
1075  * @end_addr: virtual address at which to end unmapping
1076  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
1077  * @details: details of nonlinear truncation or shared cache invalidation
1078  *
1079  * Returns the end address of the unmapping (restart addr if interrupted).
1080  *
1081  * Unmap all pages in the vma list.
1082  *
1083  * We aim to not hold locks for too long (for scheduling latency reasons).
1084  * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
1085  * return the ending mmu_gather to the caller.
1086  *
1087  * Only addresses between `start' and `end' will be unmapped.
1088  *
1089  * The VMA list must be sorted in ascending virtual address order.
1090  *
1091  * unmap_vmas() assumes that the caller will flush the whole unmapped address
1092  * range after unmap_vmas() returns.  So the only responsibility here is to
1093  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1094  * drops the lock and schedules.
1095  */
1096 unsigned long unmap_vmas(struct mmu_gather **tlbp,
1097 		struct vm_area_struct *vma, unsigned long start_addr,
1098 		unsigned long end_addr, unsigned long *nr_accounted,
1099 		struct zap_details *details)
1100 {
1101 	long zap_work = ZAP_BLOCK_SIZE;
1102 	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
1103 	int tlb_start_valid = 0;
1104 	unsigned long start = start_addr;
1105 	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
1106 	int fullmm = (*tlbp)->fullmm;
1107 	struct mm_struct *mm = vma->vm_mm;
1108 
1109 	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1110 	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
1111 		unsigned long end;
1112 
1113 		start = max(vma->vm_start, start_addr);
1114 		if (start >= vma->vm_end)
1115 			continue;
1116 		end = min(vma->vm_end, end_addr);
1117 		if (end <= vma->vm_start)
1118 			continue;
1119 
1120 		if (vma->vm_flags & VM_ACCOUNT)
1121 			*nr_accounted += (end - start) >> PAGE_SHIFT;
1122 
1123 		if (unlikely(is_pfn_mapping(vma)))
1124 			untrack_pfn_vma(vma, 0, 0);
1125 
1126 		while (start != end) {
1127 			if (!tlb_start_valid) {
1128 				tlb_start = start;
1129 				tlb_start_valid = 1;
1130 			}
1131 
1132 			if (unlikely(is_vm_hugetlb_page(vma))) {
1133 				/*
1134 				 * It is undesirable to test vma->vm_file as it
1135 				 * should be non-null for valid hugetlb area.
1136 				 * However, vm_file will be NULL in the error
1137 				 * cleanup path of do_mmap_pgoff. When
1138 				 * hugetlbfs ->mmap method fails,
1139 				 * do_mmap_pgoff() nullifies vma->vm_file
1140 				 * before calling this function to clean up.
1141 				 * Since no pte has actually been setup, it is
1142 				 * safe to do nothing in this case.
1143 				 */
1144 				if (vma->vm_file) {
1145 					unmap_hugepage_range(vma, start, end, NULL);
1146 					zap_work -= (end - start) /
1147 					pages_per_huge_page(hstate_vma(vma));
1148 				}
1149 
1150 				start = end;
1151 			} else
1152 				start = unmap_page_range(*tlbp, vma,
1153 						start, end, &zap_work, details);
1154 
1155 			if (zap_work > 0) {
1156 				BUG_ON(start != end);
1157 				break;
1158 			}
1159 
1160 			tlb_finish_mmu(*tlbp, tlb_start, start);
1161 
1162 			if (need_resched() ||
1163 				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
1164 				if (i_mmap_lock) {
1165 					*tlbp = NULL;
1166 					goto out;
1167 				}
1168 				cond_resched();
1169 			}
1170 
1171 			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
1172 			tlb_start_valid = 0;
1173 			zap_work = ZAP_BLOCK_SIZE;
1174 		}
1175 	}
1176 out:
1177 	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1178 	return start;	/* which is now the end (or restart) address */
1179 }
1180 
1181 /**
1182  * zap_page_range - remove user pages in a given range
1183  * @vma: vm_area_struct holding the applicable pages
1184  * @address: starting address of pages to zap
1185  * @size: number of bytes to zap
1186  * @details: details of nonlinear truncation or shared cache invalidation
1187  */
1188 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1189 		unsigned long size, struct zap_details *details)
1190 {
1191 	struct mm_struct *mm = vma->vm_mm;
1192 	struct mmu_gather *tlb;
1193 	unsigned long end = address + size;
1194 	unsigned long nr_accounted = 0;
1195 
1196 	lru_add_drain();
1197 	tlb = tlb_gather_mmu(mm, 0);
1198 	update_hiwater_rss(mm);
1199 	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1200 	if (tlb)
1201 		tlb_finish_mmu(tlb, address, end);
1202 	return end;
1203 }
1204 
1205 /**
1206  * zap_vma_ptes - remove ptes mapping the vma
1207  * @vma: vm_area_struct holding ptes to be zapped
1208  * @address: starting address of pages to zap
1209  * @size: number of bytes to zap
1210  *
1211  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1212  *
1213  * The entire address range must be fully contained within the vma.
1214  *
1215  * Returns 0 if successful.
1216  */
1217 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1218 		unsigned long size)
1219 {
1220 	if (address < vma->vm_start || address + size > vma->vm_end ||
1221 	    		!(vma->vm_flags & VM_PFNMAP))
1222 		return -1;
1223 	zap_page_range(vma, address, size, NULL);
1224 	return 0;
1225 }
1226 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1227 
1228 /**
1229  * follow_page - look up a page descriptor from a user-virtual address
1230  * @vma: vm_area_struct mapping @address
1231  * @address: virtual address to look up
1232  * @flags: flags modifying lookup behaviour
1233  *
1234  * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1235  *
1236  * Returns the mapped (struct page *), %NULL if no mapping exists, or
1237  * an error pointer if there is a mapping to something not represented
1238  * by a page descriptor (see also vm_normal_page()).
1239  */
1240 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1241 			unsigned int flags)
1242 {
1243 	pgd_t *pgd;
1244 	pud_t *pud;
1245 	pmd_t *pmd;
1246 	pte_t *ptep, pte;
1247 	spinlock_t *ptl;
1248 	struct page *page;
1249 	struct mm_struct *mm = vma->vm_mm;
1250 
1251 	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1252 	if (!IS_ERR(page)) {
1253 		BUG_ON(flags & FOLL_GET);
1254 		goto out;
1255 	}
1256 
1257 	page = NULL;
1258 	pgd = pgd_offset(mm, address);
1259 	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1260 		goto no_page_table;
1261 
1262 	pud = pud_offset(pgd, address);
1263 	if (pud_none(*pud))
1264 		goto no_page_table;
1265 	if (pud_huge(*pud)) {
1266 		BUG_ON(flags & FOLL_GET);
1267 		page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1268 		goto out;
1269 	}
1270 	if (unlikely(pud_bad(*pud)))
1271 		goto no_page_table;
1272 
1273 	pmd = pmd_offset(pud, address);
1274 	if (pmd_none(*pmd))
1275 		goto no_page_table;
1276 	if (pmd_huge(*pmd)) {
1277 		BUG_ON(flags & FOLL_GET);
1278 		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1279 		goto out;
1280 	}
1281 	if (unlikely(pmd_bad(*pmd)))
1282 		goto no_page_table;
1283 
1284 	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1285 
1286 	pte = *ptep;
1287 	if (!pte_present(pte))
1288 		goto no_page;
1289 	if ((flags & FOLL_WRITE) && !pte_write(pte))
1290 		goto unlock;
1291 
1292 	page = vm_normal_page(vma, address, pte);
1293 	if (unlikely(!page)) {
1294 		if ((flags & FOLL_DUMP) ||
1295 		    !is_zero_pfn(pte_pfn(pte)))
1296 			goto bad_page;
1297 		page = pte_page(pte);
1298 	}
1299 
1300 	if (flags & FOLL_GET)
1301 		get_page(page);
1302 	if (flags & FOLL_TOUCH) {
1303 		if ((flags & FOLL_WRITE) &&
1304 		    !pte_dirty(pte) && !PageDirty(page))
1305 			set_page_dirty(page);
1306 		/*
1307 		 * pte_mkyoung() would be more correct here, but atomic care
1308 		 * is needed to avoid losing the dirty bit: it is easier to use
1309 		 * mark_page_accessed().
1310 		 */
1311 		mark_page_accessed(page);
1312 	}
1313 unlock:
1314 	pte_unmap_unlock(ptep, ptl);
1315 out:
1316 	return page;
1317 
1318 bad_page:
1319 	pte_unmap_unlock(ptep, ptl);
1320 	return ERR_PTR(-EFAULT);
1321 
1322 no_page:
1323 	pte_unmap_unlock(ptep, ptl);
1324 	if (!pte_none(pte))
1325 		return page;
1326 
1327 no_page_table:
1328 	/*
1329 	 * When core dumping an enormous anonymous area that nobody
1330 	 * has touched so far, we don't want to allocate unnecessary pages or
1331 	 * page tables.  Return error instead of NULL to skip handle_mm_fault,
1332 	 * then get_dump_page() will return NULL to leave a hole in the dump.
1333 	 * But we can only make this optimization where a hole would surely
1334 	 * be zero-filled if handle_mm_fault() actually did handle it.
1335 	 */
1336 	if ((flags & FOLL_DUMP) &&
1337 	    (!vma->vm_ops || !vma->vm_ops->fault))
1338 		return ERR_PTR(-EFAULT);
1339 	return page;
1340 }
1341 
1342 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1343 		     unsigned long start, int nr_pages, unsigned int gup_flags,
1344 		     struct page **pages, struct vm_area_struct **vmas)
1345 {
1346 	int i;
1347 	unsigned long vm_flags;
1348 
1349 	if (nr_pages <= 0)
1350 		return 0;
1351 
1352 	VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1353 
1354 	/*
1355 	 * Require read or write permissions.
1356 	 * If FOLL_FORCE is set, we only require the "MAY" flags.
1357 	 */
1358 	vm_flags  = (gup_flags & FOLL_WRITE) ?
1359 			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1360 	vm_flags &= (gup_flags & FOLL_FORCE) ?
1361 			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1362 	i = 0;
1363 
1364 	do {
1365 		struct vm_area_struct *vma;
1366 
1367 		vma = find_extend_vma(mm, start);
1368 		if (!vma && in_gate_area(tsk, start)) {
1369 			unsigned long pg = start & PAGE_MASK;
1370 			struct vm_area_struct *gate_vma = get_gate_vma(tsk);
1371 			pgd_t *pgd;
1372 			pud_t *pud;
1373 			pmd_t *pmd;
1374 			pte_t *pte;
1375 
1376 			/* user gate pages are read-only */
1377 			if (gup_flags & FOLL_WRITE)
1378 				return i ? : -EFAULT;
1379 			if (pg > TASK_SIZE)
1380 				pgd = pgd_offset_k(pg);
1381 			else
1382 				pgd = pgd_offset_gate(mm, pg);
1383 			BUG_ON(pgd_none(*pgd));
1384 			pud = pud_offset(pgd, pg);
1385 			BUG_ON(pud_none(*pud));
1386 			pmd = pmd_offset(pud, pg);
1387 			if (pmd_none(*pmd))
1388 				return i ? : -EFAULT;
1389 			pte = pte_offset_map(pmd, pg);
1390 			if (pte_none(*pte)) {
1391 				pte_unmap(pte);
1392 				return i ? : -EFAULT;
1393 			}
1394 			if (pages) {
1395 				struct page *page;
1396 
1397 				page = vm_normal_page(gate_vma, start, *pte);
1398 				if (!page) {
1399 					if (!(gup_flags & FOLL_DUMP) &&
1400 					     is_zero_pfn(pte_pfn(*pte)))
1401 						page = pte_page(*pte);
1402 					else {
1403 						pte_unmap(pte);
1404 						return i ? : -EFAULT;
1405 					}
1406 				}
1407 				pages[i] = page;
1408 				get_page(page);
1409 			}
1410 			pte_unmap(pte);
1411 			if (vmas)
1412 				vmas[i] = gate_vma;
1413 			i++;
1414 			start += PAGE_SIZE;
1415 			nr_pages--;
1416 			continue;
1417 		}
1418 
1419 		if (!vma ||
1420 		    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1421 		    !(vm_flags & vma->vm_flags))
1422 			return i ? : -EFAULT;
1423 
1424 		if (is_vm_hugetlb_page(vma)) {
1425 			i = follow_hugetlb_page(mm, vma, pages, vmas,
1426 					&start, &nr_pages, i, gup_flags);
1427 			continue;
1428 		}
1429 
1430 		do {
1431 			struct page *page;
1432 			unsigned int foll_flags = gup_flags;
1433 
1434 			/*
1435 			 * If we have a pending SIGKILL, don't keep faulting
1436 			 * pages and potentially allocating memory.
1437 			 */
1438 			if (unlikely(fatal_signal_pending(current)))
1439 				return i ? i : -ERESTARTSYS;
1440 
1441 			cond_resched();
1442 			while (!(page = follow_page(vma, start, foll_flags))) {
1443 				int ret;
1444 
1445 				ret = handle_mm_fault(mm, vma, start,
1446 					(foll_flags & FOLL_WRITE) ?
1447 					FAULT_FLAG_WRITE : 0);
1448 
1449 				if (ret & VM_FAULT_ERROR) {
1450 					if (ret & VM_FAULT_OOM)
1451 						return i ? i : -ENOMEM;
1452 					if (ret &
1453 					    (VM_FAULT_HWPOISON|VM_FAULT_SIGBUS))
1454 						return i ? i : -EFAULT;
1455 					BUG();
1456 				}
1457 				if (ret & VM_FAULT_MAJOR)
1458 					tsk->maj_flt++;
1459 				else
1460 					tsk->min_flt++;
1461 
1462 				/*
1463 				 * The VM_FAULT_WRITE bit tells us that
1464 				 * do_wp_page has broken COW when necessary,
1465 				 * even if maybe_mkwrite decided not to set
1466 				 * pte_write. We can thus safely do subsequent
1467 				 * page lookups as if they were reads. But only
1468 				 * do so when looping for pte_write is futile:
1469 				 * in some cases userspace may also be wanting
1470 				 * to write to the gotten user page, which a
1471 				 * read fault here might prevent (a readonly
1472 				 * page might get reCOWed by userspace write).
1473 				 */
1474 				if ((ret & VM_FAULT_WRITE) &&
1475 				    !(vma->vm_flags & VM_WRITE))
1476 					foll_flags &= ~FOLL_WRITE;
1477 
1478 				cond_resched();
1479 			}
1480 			if (IS_ERR(page))
1481 				return i ? i : PTR_ERR(page);
1482 			if (pages) {
1483 				pages[i] = page;
1484 
1485 				flush_anon_page(vma, page, start);
1486 				flush_dcache_page(page);
1487 			}
1488 			if (vmas)
1489 				vmas[i] = vma;
1490 			i++;
1491 			start += PAGE_SIZE;
1492 			nr_pages--;
1493 		} while (nr_pages && start < vma->vm_end);
1494 	} while (nr_pages);
1495 	return i;
1496 }
1497 
1498 /**
1499  * get_user_pages() - pin user pages in memory
1500  * @tsk:	task_struct of target task
1501  * @mm:		mm_struct of target mm
1502  * @start:	starting user address
1503  * @nr_pages:	number of pages from start to pin
1504  * @write:	whether pages will be written to by the caller
1505  * @force:	whether to force write access even if user mapping is
1506  *		readonly. This will result in the page being COWed even
1507  *		in MAP_SHARED mappings. You do not want this.
1508  * @pages:	array that receives pointers to the pages pinned.
1509  *		Should be at least nr_pages long. Or NULL, if caller
1510  *		only intends to ensure the pages are faulted in.
1511  * @vmas:	array of pointers to vmas corresponding to each page.
1512  *		Or NULL if the caller does not require them.
1513  *
1514  * Returns number of pages pinned. This may be fewer than the number
1515  * requested. If nr_pages is 0 or negative, returns 0. If no pages
1516  * were pinned, returns -errno. Each page returned must be released
1517  * with a put_page() call when it is finished with. vmas will only
1518  * remain valid while mmap_sem is held.
1519  *
1520  * Must be called with mmap_sem held for read or write.
1521  *
1522  * get_user_pages walks a process's page tables and takes a reference to
1523  * each struct page that each user address corresponds to at a given
1524  * instant. That is, it takes the page that would be accessed if a user
1525  * thread accesses the given user virtual address at that instant.
1526  *
1527  * This does not guarantee that the page exists in the user mappings when
1528  * get_user_pages returns, and there may even be a completely different
1529  * page there in some cases (eg. if mmapped pagecache has been invalidated
1530  * and subsequently re faulted). However it does guarantee that the page
1531  * won't be freed completely. And mostly callers simply care that the page
1532  * contains data that was valid *at some point in time*. Typically, an IO
1533  * or similar operation cannot guarantee anything stronger anyway because
1534  * locks can't be held over the syscall boundary.
1535  *
1536  * If write=0, the page must not be written to. If the page is written to,
1537  * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1538  * after the page is finished with, and before put_page is called.
1539  *
1540  * get_user_pages is typically used for fewer-copy IO operations, to get a
1541  * handle on the memory by some means other than accesses via the user virtual
1542  * addresses. The pages may be submitted for DMA to devices or accessed via
1543  * their kernel linear mapping (via the kmap APIs). Care should be taken to
1544  * use the correct cache flushing APIs.
1545  *
1546  * See also get_user_pages_fast, for performance critical applications.
1547  */
1548 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1549 		unsigned long start, int nr_pages, int write, int force,
1550 		struct page **pages, struct vm_area_struct **vmas)
1551 {
1552 	int flags = FOLL_TOUCH;
1553 
1554 	if (pages)
1555 		flags |= FOLL_GET;
1556 	if (write)
1557 		flags |= FOLL_WRITE;
1558 	if (force)
1559 		flags |= FOLL_FORCE;
1560 
1561 	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
1562 }
1563 EXPORT_SYMBOL(get_user_pages);
1564 
1565 /**
1566  * get_dump_page() - pin user page in memory while writing it to core dump
1567  * @addr: user address
1568  *
1569  * Returns struct page pointer of user page pinned for dump,
1570  * to be freed afterwards by page_cache_release() or put_page().
1571  *
1572  * Returns NULL on any kind of failure - a hole must then be inserted into
1573  * the corefile, to preserve alignment with its headers; and also returns
1574  * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1575  * allowing a hole to be left in the corefile to save diskspace.
1576  *
1577  * Called without mmap_sem, but after all other threads have been killed.
1578  */
1579 #ifdef CONFIG_ELF_CORE
1580 struct page *get_dump_page(unsigned long addr)
1581 {
1582 	struct vm_area_struct *vma;
1583 	struct page *page;
1584 
1585 	if (__get_user_pages(current, current->mm, addr, 1,
1586 			FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma) < 1)
1587 		return NULL;
1588 	flush_cache_page(vma, addr, page_to_pfn(page));
1589 	return page;
1590 }
1591 #endif /* CONFIG_ELF_CORE */
1592 
1593 pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
1594 			spinlock_t **ptl)
1595 {
1596 	pgd_t * pgd = pgd_offset(mm, addr);
1597 	pud_t * pud = pud_alloc(mm, pgd, addr);
1598 	if (pud) {
1599 		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1600 		if (pmd)
1601 			return pte_alloc_map_lock(mm, pmd, addr, ptl);
1602 	}
1603 	return NULL;
1604 }
1605 
1606 /*
1607  * This is the old fallback for page remapping.
1608  *
1609  * For historical reasons, it only allows reserved pages. Only
1610  * old drivers should use this, and they needed to mark their
1611  * pages reserved for the old functions anyway.
1612  */
1613 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1614 			struct page *page, pgprot_t prot)
1615 {
1616 	struct mm_struct *mm = vma->vm_mm;
1617 	int retval;
1618 	pte_t *pte;
1619 	spinlock_t *ptl;
1620 
1621 	retval = -EINVAL;
1622 	if (PageAnon(page))
1623 		goto out;
1624 	retval = -ENOMEM;
1625 	flush_dcache_page(page);
1626 	pte = get_locked_pte(mm, addr, &ptl);
1627 	if (!pte)
1628 		goto out;
1629 	retval = -EBUSY;
1630 	if (!pte_none(*pte))
1631 		goto out_unlock;
1632 
1633 	/* Ok, finally just insert the thing.. */
1634 	get_page(page);
1635 	inc_mm_counter_fast(mm, MM_FILEPAGES);
1636 	page_add_file_rmap(page);
1637 	set_pte_at(mm, addr, pte, mk_pte(page, prot));
1638 
1639 	retval = 0;
1640 	pte_unmap_unlock(pte, ptl);
1641 	return retval;
1642 out_unlock:
1643 	pte_unmap_unlock(pte, ptl);
1644 out:
1645 	return retval;
1646 }
1647 
1648 /**
1649  * vm_insert_page - insert single page into user vma
1650  * @vma: user vma to map to
1651  * @addr: target user address of this page
1652  * @page: source kernel page
1653  *
1654  * This allows drivers to insert individual pages they've allocated
1655  * into a user vma.
1656  *
1657  * The page has to be a nice clean _individual_ kernel allocation.
1658  * If you allocate a compound page, you need to have marked it as
1659  * such (__GFP_COMP), or manually just split the page up yourself
1660  * (see split_page()).
1661  *
1662  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1663  * took an arbitrary page protection parameter. This doesn't allow
1664  * that. Your vma protection will have to be set up correctly, which
1665  * means that if you want a shared writable mapping, you'd better
1666  * ask for a shared writable mapping!
1667  *
1668  * The page does not need to be reserved.
1669  */
1670 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1671 			struct page *page)
1672 {
1673 	if (addr < vma->vm_start || addr >= vma->vm_end)
1674 		return -EFAULT;
1675 	if (!page_count(page))
1676 		return -EINVAL;
1677 	vma->vm_flags |= VM_INSERTPAGE;
1678 	return insert_page(vma, addr, page, vma->vm_page_prot);
1679 }
1680 EXPORT_SYMBOL(vm_insert_page);
1681 
1682 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1683 			unsigned long pfn, pgprot_t prot)
1684 {
1685 	struct mm_struct *mm = vma->vm_mm;
1686 	int retval;
1687 	pte_t *pte, entry;
1688 	spinlock_t *ptl;
1689 
1690 	retval = -ENOMEM;
1691 	pte = get_locked_pte(mm, addr, &ptl);
1692 	if (!pte)
1693 		goto out;
1694 	retval = -EBUSY;
1695 	if (!pte_none(*pte))
1696 		goto out_unlock;
1697 
1698 	/* Ok, finally just insert the thing.. */
1699 	entry = pte_mkspecial(pfn_pte(pfn, prot));
1700 	set_pte_at(mm, addr, pte, entry);
1701 	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1702 
1703 	retval = 0;
1704 out_unlock:
1705 	pte_unmap_unlock(pte, ptl);
1706 out:
1707 	return retval;
1708 }
1709 
1710 /**
1711  * vm_insert_pfn - insert single pfn into user vma
1712  * @vma: user vma to map to
1713  * @addr: target user address of this page
1714  * @pfn: source kernel pfn
1715  *
1716  * Similar to vm_inert_page, this allows drivers to insert individual pages
1717  * they've allocated into a user vma. Same comments apply.
1718  *
1719  * This function should only be called from a vm_ops->fault handler, and
1720  * in that case the handler should return NULL.
1721  *
1722  * vma cannot be a COW mapping.
1723  *
1724  * As this is called only for pages that do not currently exist, we
1725  * do not need to flush old virtual caches or the TLB.
1726  */
1727 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1728 			unsigned long pfn)
1729 {
1730 	int ret;
1731 	pgprot_t pgprot = vma->vm_page_prot;
1732 	/*
1733 	 * Technically, architectures with pte_special can avoid all these
1734 	 * restrictions (same for remap_pfn_range).  However we would like
1735 	 * consistency in testing and feature parity among all, so we should
1736 	 * try to keep these invariants in place for everybody.
1737 	 */
1738 	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1739 	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1740 						(VM_PFNMAP|VM_MIXEDMAP));
1741 	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1742 	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1743 
1744 	if (addr < vma->vm_start || addr >= vma->vm_end)
1745 		return -EFAULT;
1746 	if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1747 		return -EINVAL;
1748 
1749 	ret = insert_pfn(vma, addr, pfn, pgprot);
1750 
1751 	if (ret)
1752 		untrack_pfn_vma(vma, pfn, PAGE_SIZE);
1753 
1754 	return ret;
1755 }
1756 EXPORT_SYMBOL(vm_insert_pfn);
1757 
1758 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1759 			unsigned long pfn)
1760 {
1761 	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1762 
1763 	if (addr < vma->vm_start || addr >= vma->vm_end)
1764 		return -EFAULT;
1765 
1766 	/*
1767 	 * If we don't have pte special, then we have to use the pfn_valid()
1768 	 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1769 	 * refcount the page if pfn_valid is true (hence insert_page rather
1770 	 * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
1771 	 * without pte special, it would there be refcounted as a normal page.
1772 	 */
1773 	if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
1774 		struct page *page;
1775 
1776 		page = pfn_to_page(pfn);
1777 		return insert_page(vma, addr, page, vma->vm_page_prot);
1778 	}
1779 	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
1780 }
1781 EXPORT_SYMBOL(vm_insert_mixed);
1782 
1783 /*
1784  * maps a range of physical memory into the requested pages. the old
1785  * mappings are removed. any references to nonexistent pages results
1786  * in null mappings (currently treated as "copy-on-access")
1787  */
1788 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1789 			unsigned long addr, unsigned long end,
1790 			unsigned long pfn, pgprot_t prot)
1791 {
1792 	pte_t *pte;
1793 	spinlock_t *ptl;
1794 
1795 	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1796 	if (!pte)
1797 		return -ENOMEM;
1798 	arch_enter_lazy_mmu_mode();
1799 	do {
1800 		BUG_ON(!pte_none(*pte));
1801 		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1802 		pfn++;
1803 	} while (pte++, addr += PAGE_SIZE, addr != end);
1804 	arch_leave_lazy_mmu_mode();
1805 	pte_unmap_unlock(pte - 1, ptl);
1806 	return 0;
1807 }
1808 
1809 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1810 			unsigned long addr, unsigned long end,
1811 			unsigned long pfn, pgprot_t prot)
1812 {
1813 	pmd_t *pmd;
1814 	unsigned long next;
1815 
1816 	pfn -= addr >> PAGE_SHIFT;
1817 	pmd = pmd_alloc(mm, pud, addr);
1818 	if (!pmd)
1819 		return -ENOMEM;
1820 	do {
1821 		next = pmd_addr_end(addr, end);
1822 		if (remap_pte_range(mm, pmd, addr, next,
1823 				pfn + (addr >> PAGE_SHIFT), prot))
1824 			return -ENOMEM;
1825 	} while (pmd++, addr = next, addr != end);
1826 	return 0;
1827 }
1828 
1829 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1830 			unsigned long addr, unsigned long end,
1831 			unsigned long pfn, pgprot_t prot)
1832 {
1833 	pud_t *pud;
1834 	unsigned long next;
1835 
1836 	pfn -= addr >> PAGE_SHIFT;
1837 	pud = pud_alloc(mm, pgd, addr);
1838 	if (!pud)
1839 		return -ENOMEM;
1840 	do {
1841 		next = pud_addr_end(addr, end);
1842 		if (remap_pmd_range(mm, pud, addr, next,
1843 				pfn + (addr >> PAGE_SHIFT), prot))
1844 			return -ENOMEM;
1845 	} while (pud++, addr = next, addr != end);
1846 	return 0;
1847 }
1848 
1849 /**
1850  * remap_pfn_range - remap kernel memory to userspace
1851  * @vma: user vma to map to
1852  * @addr: target user address to start at
1853  * @pfn: physical address of kernel memory
1854  * @size: size of map area
1855  * @prot: page protection flags for this mapping
1856  *
1857  *  Note: this is only safe if the mm semaphore is held when called.
1858  */
1859 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1860 		    unsigned long pfn, unsigned long size, pgprot_t prot)
1861 {
1862 	pgd_t *pgd;
1863 	unsigned long next;
1864 	unsigned long end = addr + PAGE_ALIGN(size);
1865 	struct mm_struct *mm = vma->vm_mm;
1866 	int err;
1867 
1868 	/*
1869 	 * Physically remapped pages are special. Tell the
1870 	 * rest of the world about it:
1871 	 *   VM_IO tells people not to look at these pages
1872 	 *	(accesses can have side effects).
1873 	 *   VM_RESERVED is specified all over the place, because
1874 	 *	in 2.4 it kept swapout's vma scan off this vma; but
1875 	 *	in 2.6 the LRU scan won't even find its pages, so this
1876 	 *	flag means no more than count its pages in reserved_vm,
1877 	 * 	and omit it from core dump, even when VM_IO turned off.
1878 	 *   VM_PFNMAP tells the core MM that the base pages are just
1879 	 *	raw PFN mappings, and do not have a "struct page" associated
1880 	 *	with them.
1881 	 *
1882 	 * There's a horrible special case to handle copy-on-write
1883 	 * behaviour that some programs depend on. We mark the "original"
1884 	 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1885 	 */
1886 	if (addr == vma->vm_start && end == vma->vm_end) {
1887 		vma->vm_pgoff = pfn;
1888 		vma->vm_flags |= VM_PFN_AT_MMAP;
1889 	} else if (is_cow_mapping(vma->vm_flags))
1890 		return -EINVAL;
1891 
1892 	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1893 
1894 	err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
1895 	if (err) {
1896 		/*
1897 		 * To indicate that track_pfn related cleanup is not
1898 		 * needed from higher level routine calling unmap_vmas
1899 		 */
1900 		vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
1901 		vma->vm_flags &= ~VM_PFN_AT_MMAP;
1902 		return -EINVAL;
1903 	}
1904 
1905 	BUG_ON(addr >= end);
1906 	pfn -= addr >> PAGE_SHIFT;
1907 	pgd = pgd_offset(mm, addr);
1908 	flush_cache_range(vma, addr, end);
1909 	do {
1910 		next = pgd_addr_end(addr, end);
1911 		err = remap_pud_range(mm, pgd, addr, next,
1912 				pfn + (addr >> PAGE_SHIFT), prot);
1913 		if (err)
1914 			break;
1915 	} while (pgd++, addr = next, addr != end);
1916 
1917 	if (err)
1918 		untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
1919 
1920 	return err;
1921 }
1922 EXPORT_SYMBOL(remap_pfn_range);
1923 
1924 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1925 				     unsigned long addr, unsigned long end,
1926 				     pte_fn_t fn, void *data)
1927 {
1928 	pte_t *pte;
1929 	int err;
1930 	pgtable_t token;
1931 	spinlock_t *uninitialized_var(ptl);
1932 
1933 	pte = (mm == &init_mm) ?
1934 		pte_alloc_kernel(pmd, addr) :
1935 		pte_alloc_map_lock(mm, pmd, addr, &ptl);
1936 	if (!pte)
1937 		return -ENOMEM;
1938 
1939 	BUG_ON(pmd_huge(*pmd));
1940 
1941 	arch_enter_lazy_mmu_mode();
1942 
1943 	token = pmd_pgtable(*pmd);
1944 
1945 	do {
1946 		err = fn(pte++, token, addr, data);
1947 		if (err)
1948 			break;
1949 	} while (addr += PAGE_SIZE, addr != end);
1950 
1951 	arch_leave_lazy_mmu_mode();
1952 
1953 	if (mm != &init_mm)
1954 		pte_unmap_unlock(pte-1, ptl);
1955 	return err;
1956 }
1957 
1958 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
1959 				     unsigned long addr, unsigned long end,
1960 				     pte_fn_t fn, void *data)
1961 {
1962 	pmd_t *pmd;
1963 	unsigned long next;
1964 	int err;
1965 
1966 	BUG_ON(pud_huge(*pud));
1967 
1968 	pmd = pmd_alloc(mm, pud, addr);
1969 	if (!pmd)
1970 		return -ENOMEM;
1971 	do {
1972 		next = pmd_addr_end(addr, end);
1973 		err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1974 		if (err)
1975 			break;
1976 	} while (pmd++, addr = next, addr != end);
1977 	return err;
1978 }
1979 
1980 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
1981 				     unsigned long addr, unsigned long end,
1982 				     pte_fn_t fn, void *data)
1983 {
1984 	pud_t *pud;
1985 	unsigned long next;
1986 	int err;
1987 
1988 	pud = pud_alloc(mm, pgd, addr);
1989 	if (!pud)
1990 		return -ENOMEM;
1991 	do {
1992 		next = pud_addr_end(addr, end);
1993 		err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1994 		if (err)
1995 			break;
1996 	} while (pud++, addr = next, addr != end);
1997 	return err;
1998 }
1999 
2000 /*
2001  * Scan a region of virtual memory, filling in page tables as necessary
2002  * and calling a provided function on each leaf page table.
2003  */
2004 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2005 			unsigned long size, pte_fn_t fn, void *data)
2006 {
2007 	pgd_t *pgd;
2008 	unsigned long next;
2009 	unsigned long end = addr + size;
2010 	int err;
2011 
2012 	BUG_ON(addr >= end);
2013 	pgd = pgd_offset(mm, addr);
2014 	do {
2015 		next = pgd_addr_end(addr, end);
2016 		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2017 		if (err)
2018 			break;
2019 	} while (pgd++, addr = next, addr != end);
2020 
2021 	return err;
2022 }
2023 EXPORT_SYMBOL_GPL(apply_to_page_range);
2024 
2025 /*
2026  * handle_pte_fault chooses page fault handler according to an entry
2027  * which was read non-atomically.  Before making any commitment, on
2028  * those architectures or configurations (e.g. i386 with PAE) which
2029  * might give a mix of unmatched parts, do_swap_page and do_file_page
2030  * must check under lock before unmapping the pte and proceeding
2031  * (but do_wp_page is only called after already making such a check;
2032  * and do_anonymous_page and do_no_page can safely check later on).
2033  */
2034 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2035 				pte_t *page_table, pte_t orig_pte)
2036 {
2037 	int same = 1;
2038 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2039 	if (sizeof(pte_t) > sizeof(unsigned long)) {
2040 		spinlock_t *ptl = pte_lockptr(mm, pmd);
2041 		spin_lock(ptl);
2042 		same = pte_same(*page_table, orig_pte);
2043 		spin_unlock(ptl);
2044 	}
2045 #endif
2046 	pte_unmap(page_table);
2047 	return same;
2048 }
2049 
2050 /*
2051  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
2052  * servicing faults for write access.  In the normal case, do always want
2053  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
2054  * that do not have writing enabled, when used by access_process_vm.
2055  */
2056 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
2057 {
2058 	if (likely(vma->vm_flags & VM_WRITE))
2059 		pte = pte_mkwrite(pte);
2060 	return pte;
2061 }
2062 
2063 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2064 {
2065 	/*
2066 	 * If the source page was a PFN mapping, we don't have
2067 	 * a "struct page" for it. We do a best-effort copy by
2068 	 * just copying from the original user address. If that
2069 	 * fails, we just zero-fill it. Live with it.
2070 	 */
2071 	if (unlikely(!src)) {
2072 		void *kaddr = kmap_atomic(dst, KM_USER0);
2073 		void __user *uaddr = (void __user *)(va & PAGE_MASK);
2074 
2075 		/*
2076 		 * This really shouldn't fail, because the page is there
2077 		 * in the page tables. But it might just be unreadable,
2078 		 * in which case we just give up and fill the result with
2079 		 * zeroes.
2080 		 */
2081 		if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2082 			memset(kaddr, 0, PAGE_SIZE);
2083 		kunmap_atomic(kaddr, KM_USER0);
2084 		flush_dcache_page(dst);
2085 	} else
2086 		copy_user_highpage(dst, src, va, vma);
2087 }
2088 
2089 /*
2090  * This routine handles present pages, when users try to write
2091  * to a shared page. It is done by copying the page to a new address
2092  * and decrementing the shared-page counter for the old page.
2093  *
2094  * Note that this routine assumes that the protection checks have been
2095  * done by the caller (the low-level page fault routine in most cases).
2096  * Thus we can safely just mark it writable once we've done any necessary
2097  * COW.
2098  *
2099  * We also mark the page dirty at this point even though the page will
2100  * change only once the write actually happens. This avoids a few races,
2101  * and potentially makes it more efficient.
2102  *
2103  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2104  * but allow concurrent faults), with pte both mapped and locked.
2105  * We return with mmap_sem still held, but pte unmapped and unlocked.
2106  */
2107 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2108 		unsigned long address, pte_t *page_table, pmd_t *pmd,
2109 		spinlock_t *ptl, pte_t orig_pte)
2110 {
2111 	struct page *old_page, *new_page;
2112 	pte_t entry;
2113 	int reuse = 0, ret = 0;
2114 	int page_mkwrite = 0;
2115 	struct page *dirty_page = NULL;
2116 
2117 	old_page = vm_normal_page(vma, address, orig_pte);
2118 	if (!old_page) {
2119 		/*
2120 		 * VM_MIXEDMAP !pfn_valid() case
2121 		 *
2122 		 * We should not cow pages in a shared writeable mapping.
2123 		 * Just mark the pages writable as we can't do any dirty
2124 		 * accounting on raw pfn maps.
2125 		 */
2126 		if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2127 				     (VM_WRITE|VM_SHARED))
2128 			goto reuse;
2129 		goto gotten;
2130 	}
2131 
2132 	/*
2133 	 * Take out anonymous pages first, anonymous shared vmas are
2134 	 * not dirty accountable.
2135 	 */
2136 	if (PageAnon(old_page) && !PageKsm(old_page)) {
2137 		if (!trylock_page(old_page)) {
2138 			page_cache_get(old_page);
2139 			pte_unmap_unlock(page_table, ptl);
2140 			lock_page(old_page);
2141 			page_table = pte_offset_map_lock(mm, pmd, address,
2142 							 &ptl);
2143 			if (!pte_same(*page_table, orig_pte)) {
2144 				unlock_page(old_page);
2145 				page_cache_release(old_page);
2146 				goto unlock;
2147 			}
2148 			page_cache_release(old_page);
2149 		}
2150 		reuse = reuse_swap_page(old_page);
2151 		if (reuse)
2152 			/*
2153 			 * The page is all ours.  Move it to our anon_vma so
2154 			 * the rmap code will not search our parent or siblings.
2155 			 * Protected against the rmap code by the page lock.
2156 			 */
2157 			page_move_anon_rmap(old_page, vma, address);
2158 		unlock_page(old_page);
2159 	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2160 					(VM_WRITE|VM_SHARED))) {
2161 		/*
2162 		 * Only catch write-faults on shared writable pages,
2163 		 * read-only shared pages can get COWed by
2164 		 * get_user_pages(.write=1, .force=1).
2165 		 */
2166 		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2167 			struct vm_fault vmf;
2168 			int tmp;
2169 
2170 			vmf.virtual_address = (void __user *)(address &
2171 								PAGE_MASK);
2172 			vmf.pgoff = old_page->index;
2173 			vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2174 			vmf.page = old_page;
2175 
2176 			/*
2177 			 * Notify the address space that the page is about to
2178 			 * become writable so that it can prohibit this or wait
2179 			 * for the page to get into an appropriate state.
2180 			 *
2181 			 * We do this without the lock held, so that it can
2182 			 * sleep if it needs to.
2183 			 */
2184 			page_cache_get(old_page);
2185 			pte_unmap_unlock(page_table, ptl);
2186 
2187 			tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2188 			if (unlikely(tmp &
2189 					(VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2190 				ret = tmp;
2191 				goto unwritable_page;
2192 			}
2193 			if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2194 				lock_page(old_page);
2195 				if (!old_page->mapping) {
2196 					ret = 0; /* retry the fault */
2197 					unlock_page(old_page);
2198 					goto unwritable_page;
2199 				}
2200 			} else
2201 				VM_BUG_ON(!PageLocked(old_page));
2202 
2203 			/*
2204 			 * Since we dropped the lock we need to revalidate
2205 			 * the PTE as someone else may have changed it.  If
2206 			 * they did, we just return, as we can count on the
2207 			 * MMU to tell us if they didn't also make it writable.
2208 			 */
2209 			page_table = pte_offset_map_lock(mm, pmd, address,
2210 							 &ptl);
2211 			if (!pte_same(*page_table, orig_pte)) {
2212 				unlock_page(old_page);
2213 				page_cache_release(old_page);
2214 				goto unlock;
2215 			}
2216 
2217 			page_mkwrite = 1;
2218 		}
2219 		dirty_page = old_page;
2220 		get_page(dirty_page);
2221 		reuse = 1;
2222 	}
2223 
2224 	if (reuse) {
2225 reuse:
2226 		flush_cache_page(vma, address, pte_pfn(orig_pte));
2227 		entry = pte_mkyoung(orig_pte);
2228 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2229 		if (ptep_set_access_flags(vma, address, page_table, entry,1))
2230 			update_mmu_cache(vma, address, page_table);
2231 		ret |= VM_FAULT_WRITE;
2232 		goto unlock;
2233 	}
2234 
2235 	/*
2236 	 * Ok, we need to copy. Oh, well..
2237 	 */
2238 	page_cache_get(old_page);
2239 gotten:
2240 	pte_unmap_unlock(page_table, ptl);
2241 
2242 	if (unlikely(anon_vma_prepare(vma)))
2243 		goto oom;
2244 
2245 	if (is_zero_pfn(pte_pfn(orig_pte))) {
2246 		new_page = alloc_zeroed_user_highpage_movable(vma, address);
2247 		if (!new_page)
2248 			goto oom;
2249 	} else {
2250 		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2251 		if (!new_page)
2252 			goto oom;
2253 		cow_user_page(new_page, old_page, address, vma);
2254 	}
2255 	__SetPageUptodate(new_page);
2256 
2257 	/*
2258 	 * Don't let another task, with possibly unlocked vma,
2259 	 * keep the mlocked page.
2260 	 */
2261 	if ((vma->vm_flags & VM_LOCKED) && old_page) {
2262 		lock_page(old_page);	/* for LRU manipulation */
2263 		clear_page_mlock(old_page);
2264 		unlock_page(old_page);
2265 	}
2266 
2267 	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2268 		goto oom_free_new;
2269 
2270 	/*
2271 	 * Re-check the pte - we dropped the lock
2272 	 */
2273 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2274 	if (likely(pte_same(*page_table, orig_pte))) {
2275 		if (old_page) {
2276 			if (!PageAnon(old_page)) {
2277 				dec_mm_counter_fast(mm, MM_FILEPAGES);
2278 				inc_mm_counter_fast(mm, MM_ANONPAGES);
2279 			}
2280 		} else
2281 			inc_mm_counter_fast(mm, MM_ANONPAGES);
2282 		flush_cache_page(vma, address, pte_pfn(orig_pte));
2283 		entry = mk_pte(new_page, vma->vm_page_prot);
2284 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2285 		/*
2286 		 * Clear the pte entry and flush it first, before updating the
2287 		 * pte with the new entry. This will avoid a race condition
2288 		 * seen in the presence of one thread doing SMC and another
2289 		 * thread doing COW.
2290 		 */
2291 		ptep_clear_flush(vma, address, page_table);
2292 		page_add_new_anon_rmap(new_page, vma, address);
2293 		/*
2294 		 * We call the notify macro here because, when using secondary
2295 		 * mmu page tables (such as kvm shadow page tables), we want the
2296 		 * new page to be mapped directly into the secondary page table.
2297 		 */
2298 		set_pte_at_notify(mm, address, page_table, entry);
2299 		update_mmu_cache(vma, address, page_table);
2300 		if (old_page) {
2301 			/*
2302 			 * Only after switching the pte to the new page may
2303 			 * we remove the mapcount here. Otherwise another
2304 			 * process may come and find the rmap count decremented
2305 			 * before the pte is switched to the new page, and
2306 			 * "reuse" the old page writing into it while our pte
2307 			 * here still points into it and can be read by other
2308 			 * threads.
2309 			 *
2310 			 * The critical issue is to order this
2311 			 * page_remove_rmap with the ptp_clear_flush above.
2312 			 * Those stores are ordered by (if nothing else,)
2313 			 * the barrier present in the atomic_add_negative
2314 			 * in page_remove_rmap.
2315 			 *
2316 			 * Then the TLB flush in ptep_clear_flush ensures that
2317 			 * no process can access the old page before the
2318 			 * decremented mapcount is visible. And the old page
2319 			 * cannot be reused until after the decremented
2320 			 * mapcount is visible. So transitively, TLBs to
2321 			 * old page will be flushed before it can be reused.
2322 			 */
2323 			page_remove_rmap(old_page);
2324 		}
2325 
2326 		/* Free the old page.. */
2327 		new_page = old_page;
2328 		ret |= VM_FAULT_WRITE;
2329 	} else
2330 		mem_cgroup_uncharge_page(new_page);
2331 
2332 	if (new_page)
2333 		page_cache_release(new_page);
2334 	if (old_page)
2335 		page_cache_release(old_page);
2336 unlock:
2337 	pte_unmap_unlock(page_table, ptl);
2338 	if (dirty_page) {
2339 		/*
2340 		 * Yes, Virginia, this is actually required to prevent a race
2341 		 * with clear_page_dirty_for_io() from clearing the page dirty
2342 		 * bit after it clear all dirty ptes, but before a racing
2343 		 * do_wp_page installs a dirty pte.
2344 		 *
2345 		 * do_no_page is protected similarly.
2346 		 */
2347 		if (!page_mkwrite) {
2348 			wait_on_page_locked(dirty_page);
2349 			set_page_dirty_balance(dirty_page, page_mkwrite);
2350 		}
2351 		put_page(dirty_page);
2352 		if (page_mkwrite) {
2353 			struct address_space *mapping = dirty_page->mapping;
2354 
2355 			set_page_dirty(dirty_page);
2356 			unlock_page(dirty_page);
2357 			page_cache_release(dirty_page);
2358 			if (mapping)	{
2359 				/*
2360 				 * Some device drivers do not set page.mapping
2361 				 * but still dirty their pages
2362 				 */
2363 				balance_dirty_pages_ratelimited(mapping);
2364 			}
2365 		}
2366 
2367 		/* file_update_time outside page_lock */
2368 		if (vma->vm_file)
2369 			file_update_time(vma->vm_file);
2370 	}
2371 	return ret;
2372 oom_free_new:
2373 	page_cache_release(new_page);
2374 oom:
2375 	if (old_page) {
2376 		if (page_mkwrite) {
2377 			unlock_page(old_page);
2378 			page_cache_release(old_page);
2379 		}
2380 		page_cache_release(old_page);
2381 	}
2382 	return VM_FAULT_OOM;
2383 
2384 unwritable_page:
2385 	page_cache_release(old_page);
2386 	return ret;
2387 }
2388 
2389 /*
2390  * Helper functions for unmap_mapping_range().
2391  *
2392  * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
2393  *
2394  * We have to restart searching the prio_tree whenever we drop the lock,
2395  * since the iterator is only valid while the lock is held, and anyway
2396  * a later vma might be split and reinserted earlier while lock dropped.
2397  *
2398  * The list of nonlinear vmas could be handled more efficiently, using
2399  * a placeholder, but handle it in the same way until a need is shown.
2400  * It is important to search the prio_tree before nonlinear list: a vma
2401  * may become nonlinear and be shifted from prio_tree to nonlinear list
2402  * while the lock is dropped; but never shifted from list to prio_tree.
2403  *
2404  * In order to make forward progress despite restarting the search,
2405  * vm_truncate_count is used to mark a vma as now dealt with, so we can
2406  * quickly skip it next time around.  Since the prio_tree search only
2407  * shows us those vmas affected by unmapping the range in question, we
2408  * can't efficiently keep all vmas in step with mapping->truncate_count:
2409  * so instead reset them all whenever it wraps back to 0 (then go to 1).
2410  * mapping->truncate_count and vma->vm_truncate_count are protected by
2411  * i_mmap_lock.
2412  *
2413  * In order to make forward progress despite repeatedly restarting some
2414  * large vma, note the restart_addr from unmap_vmas when it breaks out:
2415  * and restart from that address when we reach that vma again.  It might
2416  * have been split or merged, shrunk or extended, but never shifted: so
2417  * restart_addr remains valid so long as it remains in the vma's range.
2418  * unmap_mapping_range forces truncate_count to leap over page-aligned
2419  * values so we can save vma's restart_addr in its truncate_count field.
2420  */
2421 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
2422 
2423 static void reset_vma_truncate_counts(struct address_space *mapping)
2424 {
2425 	struct vm_area_struct *vma;
2426 	struct prio_tree_iter iter;
2427 
2428 	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
2429 		vma->vm_truncate_count = 0;
2430 	list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
2431 		vma->vm_truncate_count = 0;
2432 }
2433 
2434 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
2435 		unsigned long start_addr, unsigned long end_addr,
2436 		struct zap_details *details)
2437 {
2438 	unsigned long restart_addr;
2439 	int need_break;
2440 
2441 	/*
2442 	 * files that support invalidating or truncating portions of the
2443 	 * file from under mmaped areas must have their ->fault function
2444 	 * return a locked page (and set VM_FAULT_LOCKED in the return).
2445 	 * This provides synchronisation against concurrent unmapping here.
2446 	 */
2447 
2448 again:
2449 	restart_addr = vma->vm_truncate_count;
2450 	if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
2451 		start_addr = restart_addr;
2452 		if (start_addr >= end_addr) {
2453 			/* Top of vma has been split off since last time */
2454 			vma->vm_truncate_count = details->truncate_count;
2455 			return 0;
2456 		}
2457 	}
2458 
2459 	restart_addr = zap_page_range(vma, start_addr,
2460 					end_addr - start_addr, details);
2461 	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
2462 
2463 	if (restart_addr >= end_addr) {
2464 		/* We have now completed this vma: mark it so */
2465 		vma->vm_truncate_count = details->truncate_count;
2466 		if (!need_break)
2467 			return 0;
2468 	} else {
2469 		/* Note restart_addr in vma's truncate_count field */
2470 		vma->vm_truncate_count = restart_addr;
2471 		if (!need_break)
2472 			goto again;
2473 	}
2474 
2475 	spin_unlock(details->i_mmap_lock);
2476 	cond_resched();
2477 	spin_lock(details->i_mmap_lock);
2478 	return -EINTR;
2479 }
2480 
2481 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2482 					    struct zap_details *details)
2483 {
2484 	struct vm_area_struct *vma;
2485 	struct prio_tree_iter iter;
2486 	pgoff_t vba, vea, zba, zea;
2487 
2488 restart:
2489 	vma_prio_tree_foreach(vma, &iter, root,
2490 			details->first_index, details->last_index) {
2491 		/* Skip quickly over those we have already dealt with */
2492 		if (vma->vm_truncate_count == details->truncate_count)
2493 			continue;
2494 
2495 		vba = vma->vm_pgoff;
2496 		vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2497 		/* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2498 		zba = details->first_index;
2499 		if (zba < vba)
2500 			zba = vba;
2501 		zea = details->last_index;
2502 		if (zea > vea)
2503 			zea = vea;
2504 
2505 		if (unmap_mapping_range_vma(vma,
2506 			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2507 			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2508 				details) < 0)
2509 			goto restart;
2510 	}
2511 }
2512 
2513 static inline void unmap_mapping_range_list(struct list_head *head,
2514 					    struct zap_details *details)
2515 {
2516 	struct vm_area_struct *vma;
2517 
2518 	/*
2519 	 * In nonlinear VMAs there is no correspondence between virtual address
2520 	 * offset and file offset.  So we must perform an exhaustive search
2521 	 * across *all* the pages in each nonlinear VMA, not just the pages
2522 	 * whose virtual address lies outside the file truncation point.
2523 	 */
2524 restart:
2525 	list_for_each_entry(vma, head, shared.vm_set.list) {
2526 		/* Skip quickly over those we have already dealt with */
2527 		if (vma->vm_truncate_count == details->truncate_count)
2528 			continue;
2529 		details->nonlinear_vma = vma;
2530 		if (unmap_mapping_range_vma(vma, vma->vm_start,
2531 					vma->vm_end, details) < 0)
2532 			goto restart;
2533 	}
2534 }
2535 
2536 /**
2537  * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2538  * @mapping: the address space containing mmaps to be unmapped.
2539  * @holebegin: byte in first page to unmap, relative to the start of
2540  * the underlying file.  This will be rounded down to a PAGE_SIZE
2541  * boundary.  Note that this is different from truncate_pagecache(), which
2542  * must keep the partial page.  In contrast, we must get rid of
2543  * partial pages.
2544  * @holelen: size of prospective hole in bytes.  This will be rounded
2545  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2546  * end of the file.
2547  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2548  * but 0 when invalidating pagecache, don't throw away private data.
2549  */
2550 void unmap_mapping_range(struct address_space *mapping,
2551 		loff_t const holebegin, loff_t const holelen, int even_cows)
2552 {
2553 	struct zap_details details;
2554 	pgoff_t hba = holebegin >> PAGE_SHIFT;
2555 	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2556 
2557 	/* Check for overflow. */
2558 	if (sizeof(holelen) > sizeof(hlen)) {
2559 		long long holeend =
2560 			(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2561 		if (holeend & ~(long long)ULONG_MAX)
2562 			hlen = ULONG_MAX - hba + 1;
2563 	}
2564 
2565 	details.check_mapping = even_cows? NULL: mapping;
2566 	details.nonlinear_vma = NULL;
2567 	details.first_index = hba;
2568 	details.last_index = hba + hlen - 1;
2569 	if (details.last_index < details.first_index)
2570 		details.last_index = ULONG_MAX;
2571 	details.i_mmap_lock = &mapping->i_mmap_lock;
2572 
2573 	spin_lock(&mapping->i_mmap_lock);
2574 
2575 	/* Protect against endless unmapping loops */
2576 	mapping->truncate_count++;
2577 	if (unlikely(is_restart_addr(mapping->truncate_count))) {
2578 		if (mapping->truncate_count == 0)
2579 			reset_vma_truncate_counts(mapping);
2580 		mapping->truncate_count++;
2581 	}
2582 	details.truncate_count = mapping->truncate_count;
2583 
2584 	if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2585 		unmap_mapping_range_tree(&mapping->i_mmap, &details);
2586 	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2587 		unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2588 	spin_unlock(&mapping->i_mmap_lock);
2589 }
2590 EXPORT_SYMBOL(unmap_mapping_range);
2591 
2592 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
2593 {
2594 	struct address_space *mapping = inode->i_mapping;
2595 
2596 	/*
2597 	 * If the underlying filesystem is not going to provide
2598 	 * a way to truncate a range of blocks (punch a hole) -
2599 	 * we should return failure right now.
2600 	 */
2601 	if (!inode->i_op->truncate_range)
2602 		return -ENOSYS;
2603 
2604 	mutex_lock(&inode->i_mutex);
2605 	down_write(&inode->i_alloc_sem);
2606 	unmap_mapping_range(mapping, offset, (end - offset), 1);
2607 	truncate_inode_pages_range(mapping, offset, end);
2608 	unmap_mapping_range(mapping, offset, (end - offset), 1);
2609 	inode->i_op->truncate_range(inode, offset, end);
2610 	up_write(&inode->i_alloc_sem);
2611 	mutex_unlock(&inode->i_mutex);
2612 
2613 	return 0;
2614 }
2615 
2616 /*
2617  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2618  * but allow concurrent faults), and pte mapped but not yet locked.
2619  * We return with mmap_sem still held, but pte unmapped and unlocked.
2620  */
2621 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2622 		unsigned long address, pte_t *page_table, pmd_t *pmd,
2623 		unsigned int flags, pte_t orig_pte)
2624 {
2625 	spinlock_t *ptl;
2626 	struct page *page;
2627 	swp_entry_t entry;
2628 	pte_t pte;
2629 	struct mem_cgroup *ptr = NULL;
2630 	int exclusive = 0;
2631 	int ret = 0;
2632 
2633 	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2634 		goto out;
2635 
2636 	entry = pte_to_swp_entry(orig_pte);
2637 	if (unlikely(non_swap_entry(entry))) {
2638 		if (is_migration_entry(entry)) {
2639 			migration_entry_wait(mm, pmd, address);
2640 		} else if (is_hwpoison_entry(entry)) {
2641 			ret = VM_FAULT_HWPOISON;
2642 		} else {
2643 			print_bad_pte(vma, address, orig_pte, NULL);
2644 			ret = VM_FAULT_SIGBUS;
2645 		}
2646 		goto out;
2647 	}
2648 	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2649 	page = lookup_swap_cache(entry);
2650 	if (!page) {
2651 		grab_swap_token(mm); /* Contend for token _before_ read-in */
2652 		page = swapin_readahead(entry,
2653 					GFP_HIGHUSER_MOVABLE, vma, address);
2654 		if (!page) {
2655 			/*
2656 			 * Back out if somebody else faulted in this pte
2657 			 * while we released the pte lock.
2658 			 */
2659 			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2660 			if (likely(pte_same(*page_table, orig_pte)))
2661 				ret = VM_FAULT_OOM;
2662 			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2663 			goto unlock;
2664 		}
2665 
2666 		/* Had to read the page from swap area: Major fault */
2667 		ret = VM_FAULT_MAJOR;
2668 		count_vm_event(PGMAJFAULT);
2669 	} else if (PageHWPoison(page)) {
2670 		/*
2671 		 * hwpoisoned dirty swapcache pages are kept for killing
2672 		 * owner processes (which may be unknown at hwpoison time)
2673 		 */
2674 		ret = VM_FAULT_HWPOISON;
2675 		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2676 		goto out_release;
2677 	}
2678 
2679 	lock_page(page);
2680 	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2681 
2682 	page = ksm_might_need_to_copy(page, vma, address);
2683 	if (!page) {
2684 		ret = VM_FAULT_OOM;
2685 		goto out;
2686 	}
2687 
2688 	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2689 		ret = VM_FAULT_OOM;
2690 		goto out_page;
2691 	}
2692 
2693 	/*
2694 	 * Back out if somebody else already faulted in this pte.
2695 	 */
2696 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2697 	if (unlikely(!pte_same(*page_table, orig_pte)))
2698 		goto out_nomap;
2699 
2700 	if (unlikely(!PageUptodate(page))) {
2701 		ret = VM_FAULT_SIGBUS;
2702 		goto out_nomap;
2703 	}
2704 
2705 	/*
2706 	 * The page isn't present yet, go ahead with the fault.
2707 	 *
2708 	 * Be careful about the sequence of operations here.
2709 	 * To get its accounting right, reuse_swap_page() must be called
2710 	 * while the page is counted on swap but not yet in mapcount i.e.
2711 	 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2712 	 * must be called after the swap_free(), or it will never succeed.
2713 	 * Because delete_from_swap_page() may be called by reuse_swap_page(),
2714 	 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2715 	 * in page->private. In this case, a record in swap_cgroup  is silently
2716 	 * discarded at swap_free().
2717 	 */
2718 
2719 	inc_mm_counter_fast(mm, MM_ANONPAGES);
2720 	dec_mm_counter_fast(mm, MM_SWAPENTS);
2721 	pte = mk_pte(page, vma->vm_page_prot);
2722 	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2723 		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2724 		flags &= ~FAULT_FLAG_WRITE;
2725 		ret |= VM_FAULT_WRITE;
2726 		exclusive = 1;
2727 	}
2728 	flush_icache_page(vma, page);
2729 	set_pte_at(mm, address, page_table, pte);
2730 	do_page_add_anon_rmap(page, vma, address, exclusive);
2731 	/* It's better to call commit-charge after rmap is established */
2732 	mem_cgroup_commit_charge_swapin(page, ptr);
2733 
2734 	swap_free(entry);
2735 	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2736 		try_to_free_swap(page);
2737 	unlock_page(page);
2738 
2739 	if (flags & FAULT_FLAG_WRITE) {
2740 		ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2741 		if (ret & VM_FAULT_ERROR)
2742 			ret &= VM_FAULT_ERROR;
2743 		goto out;
2744 	}
2745 
2746 	/* No need to invalidate - it was non-present before */
2747 	update_mmu_cache(vma, address, page_table);
2748 unlock:
2749 	pte_unmap_unlock(page_table, ptl);
2750 out:
2751 	return ret;
2752 out_nomap:
2753 	mem_cgroup_cancel_charge_swapin(ptr);
2754 	pte_unmap_unlock(page_table, ptl);
2755 out_page:
2756 	unlock_page(page);
2757 out_release:
2758 	page_cache_release(page);
2759 	return ret;
2760 }
2761 
2762 /*
2763  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2764  * but allow concurrent faults), and pte mapped but not yet locked.
2765  * We return with mmap_sem still held, but pte unmapped and unlocked.
2766  */
2767 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2768 		unsigned long address, pte_t *page_table, pmd_t *pmd,
2769 		unsigned int flags)
2770 {
2771 	struct page *page;
2772 	spinlock_t *ptl;
2773 	pte_t entry;
2774 
2775 	if (!(flags & FAULT_FLAG_WRITE)) {
2776 		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
2777 						vma->vm_page_prot));
2778 		ptl = pte_lockptr(mm, pmd);
2779 		spin_lock(ptl);
2780 		if (!pte_none(*page_table))
2781 			goto unlock;
2782 		goto setpte;
2783 	}
2784 
2785 	/* Allocate our own private page. */
2786 	pte_unmap(page_table);
2787 
2788 	if (unlikely(anon_vma_prepare(vma)))
2789 		goto oom;
2790 	page = alloc_zeroed_user_highpage_movable(vma, address);
2791 	if (!page)
2792 		goto oom;
2793 	__SetPageUptodate(page);
2794 
2795 	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
2796 		goto oom_free_page;
2797 
2798 	entry = mk_pte(page, vma->vm_page_prot);
2799 	if (vma->vm_flags & VM_WRITE)
2800 		entry = pte_mkwrite(pte_mkdirty(entry));
2801 
2802 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2803 	if (!pte_none(*page_table))
2804 		goto release;
2805 
2806 	inc_mm_counter_fast(mm, MM_ANONPAGES);
2807 	page_add_new_anon_rmap(page, vma, address);
2808 setpte:
2809 	set_pte_at(mm, address, page_table, entry);
2810 
2811 	/* No need to invalidate - it was non-present before */
2812 	update_mmu_cache(vma, address, page_table);
2813 unlock:
2814 	pte_unmap_unlock(page_table, ptl);
2815 	return 0;
2816 release:
2817 	mem_cgroup_uncharge_page(page);
2818 	page_cache_release(page);
2819 	goto unlock;
2820 oom_free_page:
2821 	page_cache_release(page);
2822 oom:
2823 	return VM_FAULT_OOM;
2824 }
2825 
2826 /*
2827  * __do_fault() tries to create a new page mapping. It aggressively
2828  * tries to share with existing pages, but makes a separate copy if
2829  * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
2830  * the next page fault.
2831  *
2832  * As this is called only for pages that do not currently exist, we
2833  * do not need to flush old virtual caches or the TLB.
2834  *
2835  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2836  * but allow concurrent faults), and pte neither mapped nor locked.
2837  * We return with mmap_sem still held, but pte unmapped and unlocked.
2838  */
2839 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2840 		unsigned long address, pmd_t *pmd,
2841 		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2842 {
2843 	pte_t *page_table;
2844 	spinlock_t *ptl;
2845 	struct page *page;
2846 	pte_t entry;
2847 	int anon = 0;
2848 	int charged = 0;
2849 	struct page *dirty_page = NULL;
2850 	struct vm_fault vmf;
2851 	int ret;
2852 	int page_mkwrite = 0;
2853 
2854 	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2855 	vmf.pgoff = pgoff;
2856 	vmf.flags = flags;
2857 	vmf.page = NULL;
2858 
2859 	ret = vma->vm_ops->fault(vma, &vmf);
2860 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2861 		return ret;
2862 
2863 	if (unlikely(PageHWPoison(vmf.page))) {
2864 		if (ret & VM_FAULT_LOCKED)
2865 			unlock_page(vmf.page);
2866 		return VM_FAULT_HWPOISON;
2867 	}
2868 
2869 	/*
2870 	 * For consistency in subsequent calls, make the faulted page always
2871 	 * locked.
2872 	 */
2873 	if (unlikely(!(ret & VM_FAULT_LOCKED)))
2874 		lock_page(vmf.page);
2875 	else
2876 		VM_BUG_ON(!PageLocked(vmf.page));
2877 
2878 	/*
2879 	 * Should we do an early C-O-W break?
2880 	 */
2881 	page = vmf.page;
2882 	if (flags & FAULT_FLAG_WRITE) {
2883 		if (!(vma->vm_flags & VM_SHARED)) {
2884 			anon = 1;
2885 			if (unlikely(anon_vma_prepare(vma))) {
2886 				ret = VM_FAULT_OOM;
2887 				goto out;
2888 			}
2889 			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
2890 						vma, address);
2891 			if (!page) {
2892 				ret = VM_FAULT_OOM;
2893 				goto out;
2894 			}
2895 			if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
2896 				ret = VM_FAULT_OOM;
2897 				page_cache_release(page);
2898 				goto out;
2899 			}
2900 			charged = 1;
2901 			/*
2902 			 * Don't let another task, with possibly unlocked vma,
2903 			 * keep the mlocked page.
2904 			 */
2905 			if (vma->vm_flags & VM_LOCKED)
2906 				clear_page_mlock(vmf.page);
2907 			copy_user_highpage(page, vmf.page, address, vma);
2908 			__SetPageUptodate(page);
2909 		} else {
2910 			/*
2911 			 * If the page will be shareable, see if the backing
2912 			 * address space wants to know that the page is about
2913 			 * to become writable
2914 			 */
2915 			if (vma->vm_ops->page_mkwrite) {
2916 				int tmp;
2917 
2918 				unlock_page(page);
2919 				vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2920 				tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2921 				if (unlikely(tmp &
2922 					  (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2923 					ret = tmp;
2924 					goto unwritable_page;
2925 				}
2926 				if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2927 					lock_page(page);
2928 					if (!page->mapping) {
2929 						ret = 0; /* retry the fault */
2930 						unlock_page(page);
2931 						goto unwritable_page;
2932 					}
2933 				} else
2934 					VM_BUG_ON(!PageLocked(page));
2935 				page_mkwrite = 1;
2936 			}
2937 		}
2938 
2939 	}
2940 
2941 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2942 
2943 	/*
2944 	 * This silly early PAGE_DIRTY setting removes a race
2945 	 * due to the bad i386 page protection. But it's valid
2946 	 * for other architectures too.
2947 	 *
2948 	 * Note that if FAULT_FLAG_WRITE is set, we either now have
2949 	 * an exclusive copy of the page, or this is a shared mapping,
2950 	 * so we can make it writable and dirty to avoid having to
2951 	 * handle that later.
2952 	 */
2953 	/* Only go through if we didn't race with anybody else... */
2954 	if (likely(pte_same(*page_table, orig_pte))) {
2955 		flush_icache_page(vma, page);
2956 		entry = mk_pte(page, vma->vm_page_prot);
2957 		if (flags & FAULT_FLAG_WRITE)
2958 			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2959 		if (anon) {
2960 			inc_mm_counter_fast(mm, MM_ANONPAGES);
2961 			page_add_new_anon_rmap(page, vma, address);
2962 		} else {
2963 			inc_mm_counter_fast(mm, MM_FILEPAGES);
2964 			page_add_file_rmap(page);
2965 			if (flags & FAULT_FLAG_WRITE) {
2966 				dirty_page = page;
2967 				get_page(dirty_page);
2968 			}
2969 		}
2970 		set_pte_at(mm, address, page_table, entry);
2971 
2972 		/* no need to invalidate: a not-present page won't be cached */
2973 		update_mmu_cache(vma, address, page_table);
2974 	} else {
2975 		if (charged)
2976 			mem_cgroup_uncharge_page(page);
2977 		if (anon)
2978 			page_cache_release(page);
2979 		else
2980 			anon = 1; /* no anon but release faulted_page */
2981 	}
2982 
2983 	pte_unmap_unlock(page_table, ptl);
2984 
2985 out:
2986 	if (dirty_page) {
2987 		struct address_space *mapping = page->mapping;
2988 
2989 		if (set_page_dirty(dirty_page))
2990 			page_mkwrite = 1;
2991 		unlock_page(dirty_page);
2992 		put_page(dirty_page);
2993 		if (page_mkwrite && mapping) {
2994 			/*
2995 			 * Some device drivers do not set page.mapping but still
2996 			 * dirty their pages
2997 			 */
2998 			balance_dirty_pages_ratelimited(mapping);
2999 		}
3000 
3001 		/* file_update_time outside page_lock */
3002 		if (vma->vm_file)
3003 			file_update_time(vma->vm_file);
3004 	} else {
3005 		unlock_page(vmf.page);
3006 		if (anon)
3007 			page_cache_release(vmf.page);
3008 	}
3009 
3010 	return ret;
3011 
3012 unwritable_page:
3013 	page_cache_release(page);
3014 	return ret;
3015 }
3016 
3017 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3018 		unsigned long address, pte_t *page_table, pmd_t *pmd,
3019 		unsigned int flags, pte_t orig_pte)
3020 {
3021 	pgoff_t pgoff = (((address & PAGE_MASK)
3022 			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3023 
3024 	pte_unmap(page_table);
3025 	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3026 }
3027 
3028 /*
3029  * Fault of a previously existing named mapping. Repopulate the pte
3030  * from the encoded file_pte if possible. This enables swappable
3031  * nonlinear vmas.
3032  *
3033  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3034  * but allow concurrent faults), and pte mapped but not yet locked.
3035  * We return with mmap_sem still held, but pte unmapped and unlocked.
3036  */
3037 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3038 		unsigned long address, pte_t *page_table, pmd_t *pmd,
3039 		unsigned int flags, pte_t orig_pte)
3040 {
3041 	pgoff_t pgoff;
3042 
3043 	flags |= FAULT_FLAG_NONLINEAR;
3044 
3045 	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3046 		return 0;
3047 
3048 	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3049 		/*
3050 		 * Page table corrupted: show pte and kill process.
3051 		 */
3052 		print_bad_pte(vma, address, orig_pte, NULL);
3053 		return VM_FAULT_SIGBUS;
3054 	}
3055 
3056 	pgoff = pte_to_pgoff(orig_pte);
3057 	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3058 }
3059 
3060 /*
3061  * These routines also need to handle stuff like marking pages dirty
3062  * and/or accessed for architectures that don't do it in hardware (most
3063  * RISC architectures).  The early dirtying is also good on the i386.
3064  *
3065  * There is also a hook called "update_mmu_cache()" that architectures
3066  * with external mmu caches can use to update those (ie the Sparc or
3067  * PowerPC hashed page tables that act as extended TLBs).
3068  *
3069  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3070  * but allow concurrent faults), and pte mapped but not yet locked.
3071  * We return with mmap_sem still held, but pte unmapped and unlocked.
3072  */
3073 static inline int handle_pte_fault(struct mm_struct *mm,
3074 		struct vm_area_struct *vma, unsigned long address,
3075 		pte_t *pte, pmd_t *pmd, unsigned int flags)
3076 {
3077 	pte_t entry;
3078 	spinlock_t *ptl;
3079 
3080 	entry = *pte;
3081 	if (!pte_present(entry)) {
3082 		if (pte_none(entry)) {
3083 			if (vma->vm_ops) {
3084 				if (likely(vma->vm_ops->fault))
3085 					return do_linear_fault(mm, vma, address,
3086 						pte, pmd, flags, entry);
3087 			}
3088 			return do_anonymous_page(mm, vma, address,
3089 						 pte, pmd, flags);
3090 		}
3091 		if (pte_file(entry))
3092 			return do_nonlinear_fault(mm, vma, address,
3093 					pte, pmd, flags, entry);
3094 		return do_swap_page(mm, vma, address,
3095 					pte, pmd, flags, entry);
3096 	}
3097 
3098 	ptl = pte_lockptr(mm, pmd);
3099 	spin_lock(ptl);
3100 	if (unlikely(!pte_same(*pte, entry)))
3101 		goto unlock;
3102 	if (flags & FAULT_FLAG_WRITE) {
3103 		if (!pte_write(entry))
3104 			return do_wp_page(mm, vma, address,
3105 					pte, pmd, ptl, entry);
3106 		entry = pte_mkdirty(entry);
3107 	}
3108 	entry = pte_mkyoung(entry);
3109 	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3110 		update_mmu_cache(vma, address, pte);
3111 	} else {
3112 		/*
3113 		 * This is needed only for protection faults but the arch code
3114 		 * is not yet telling us if this is a protection fault or not.
3115 		 * This still avoids useless tlb flushes for .text page faults
3116 		 * with threads.
3117 		 */
3118 		if (flags & FAULT_FLAG_WRITE)
3119 			flush_tlb_page(vma, address);
3120 	}
3121 unlock:
3122 	pte_unmap_unlock(pte, ptl);
3123 	return 0;
3124 }
3125 
3126 /*
3127  * By the time we get here, we already hold the mm semaphore
3128  */
3129 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3130 		unsigned long address, unsigned int flags)
3131 {
3132 	pgd_t *pgd;
3133 	pud_t *pud;
3134 	pmd_t *pmd;
3135 	pte_t *pte;
3136 
3137 	__set_current_state(TASK_RUNNING);
3138 
3139 	count_vm_event(PGFAULT);
3140 
3141 	/* do counter updates before entering really critical section. */
3142 	check_sync_rss_stat(current);
3143 
3144 	if (unlikely(is_vm_hugetlb_page(vma)))
3145 		return hugetlb_fault(mm, vma, address, flags);
3146 
3147 	pgd = pgd_offset(mm, address);
3148 	pud = pud_alloc(mm, pgd, address);
3149 	if (!pud)
3150 		return VM_FAULT_OOM;
3151 	pmd = pmd_alloc(mm, pud, address);
3152 	if (!pmd)
3153 		return VM_FAULT_OOM;
3154 	pte = pte_alloc_map(mm, pmd, address);
3155 	if (!pte)
3156 		return VM_FAULT_OOM;
3157 
3158 	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3159 }
3160 
3161 #ifndef __PAGETABLE_PUD_FOLDED
3162 /*
3163  * Allocate page upper directory.
3164  * We've already handled the fast-path in-line.
3165  */
3166 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3167 {
3168 	pud_t *new = pud_alloc_one(mm, address);
3169 	if (!new)
3170 		return -ENOMEM;
3171 
3172 	smp_wmb(); /* See comment in __pte_alloc */
3173 
3174 	spin_lock(&mm->page_table_lock);
3175 	if (pgd_present(*pgd))		/* Another has populated it */
3176 		pud_free(mm, new);
3177 	else
3178 		pgd_populate(mm, pgd, new);
3179 	spin_unlock(&mm->page_table_lock);
3180 	return 0;
3181 }
3182 #endif /* __PAGETABLE_PUD_FOLDED */
3183 
3184 #ifndef __PAGETABLE_PMD_FOLDED
3185 /*
3186  * Allocate page middle directory.
3187  * We've already handled the fast-path in-line.
3188  */
3189 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3190 {
3191 	pmd_t *new = pmd_alloc_one(mm, address);
3192 	if (!new)
3193 		return -ENOMEM;
3194 
3195 	smp_wmb(); /* See comment in __pte_alloc */
3196 
3197 	spin_lock(&mm->page_table_lock);
3198 #ifndef __ARCH_HAS_4LEVEL_HACK
3199 	if (pud_present(*pud))		/* Another has populated it */
3200 		pmd_free(mm, new);
3201 	else
3202 		pud_populate(mm, pud, new);
3203 #else
3204 	if (pgd_present(*pud))		/* Another has populated it */
3205 		pmd_free(mm, new);
3206 	else
3207 		pgd_populate(mm, pud, new);
3208 #endif /* __ARCH_HAS_4LEVEL_HACK */
3209 	spin_unlock(&mm->page_table_lock);
3210 	return 0;
3211 }
3212 #endif /* __PAGETABLE_PMD_FOLDED */
3213 
3214 int make_pages_present(unsigned long addr, unsigned long end)
3215 {
3216 	int ret, len, write;
3217 	struct vm_area_struct * vma;
3218 
3219 	vma = find_vma(current->mm, addr);
3220 	if (!vma)
3221 		return -ENOMEM;
3222 	write = (vma->vm_flags & VM_WRITE) != 0;
3223 	BUG_ON(addr >= end);
3224 	BUG_ON(end > vma->vm_end);
3225 	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3226 	ret = get_user_pages(current, current->mm, addr,
3227 			len, write, 0, NULL, NULL);
3228 	if (ret < 0)
3229 		return ret;
3230 	return ret == len ? 0 : -EFAULT;
3231 }
3232 
3233 #if !defined(__HAVE_ARCH_GATE_AREA)
3234 
3235 #if defined(AT_SYSINFO_EHDR)
3236 static struct vm_area_struct gate_vma;
3237 
3238 static int __init gate_vma_init(void)
3239 {
3240 	gate_vma.vm_mm = NULL;
3241 	gate_vma.vm_start = FIXADDR_USER_START;
3242 	gate_vma.vm_end = FIXADDR_USER_END;
3243 	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3244 	gate_vma.vm_page_prot = __P101;
3245 	/*
3246 	 * Make sure the vDSO gets into every core dump.
3247 	 * Dumping its contents makes post-mortem fully interpretable later
3248 	 * without matching up the same kernel and hardware config to see
3249 	 * what PC values meant.
3250 	 */
3251 	gate_vma.vm_flags |= VM_ALWAYSDUMP;
3252 	return 0;
3253 }
3254 __initcall(gate_vma_init);
3255 #endif
3256 
3257 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
3258 {
3259 #ifdef AT_SYSINFO_EHDR
3260 	return &gate_vma;
3261 #else
3262 	return NULL;
3263 #endif
3264 }
3265 
3266 int in_gate_area_no_task(unsigned long addr)
3267 {
3268 #ifdef AT_SYSINFO_EHDR
3269 	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3270 		return 1;
3271 #endif
3272 	return 0;
3273 }
3274 
3275 #endif	/* __HAVE_ARCH_GATE_AREA */
3276 
3277 static int follow_pte(struct mm_struct *mm, unsigned long address,
3278 		pte_t **ptepp, spinlock_t **ptlp)
3279 {
3280 	pgd_t *pgd;
3281 	pud_t *pud;
3282 	pmd_t *pmd;
3283 	pte_t *ptep;
3284 
3285 	pgd = pgd_offset(mm, address);
3286 	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3287 		goto out;
3288 
3289 	pud = pud_offset(pgd, address);
3290 	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3291 		goto out;
3292 
3293 	pmd = pmd_offset(pud, address);
3294 	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3295 		goto out;
3296 
3297 	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
3298 	if (pmd_huge(*pmd))
3299 		goto out;
3300 
3301 	ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3302 	if (!ptep)
3303 		goto out;
3304 	if (!pte_present(*ptep))
3305 		goto unlock;
3306 	*ptepp = ptep;
3307 	return 0;
3308 unlock:
3309 	pte_unmap_unlock(ptep, *ptlp);
3310 out:
3311 	return -EINVAL;
3312 }
3313 
3314 /**
3315  * follow_pfn - look up PFN at a user virtual address
3316  * @vma: memory mapping
3317  * @address: user virtual address
3318  * @pfn: location to store found PFN
3319  *
3320  * Only IO mappings and raw PFN mappings are allowed.
3321  *
3322  * Returns zero and the pfn at @pfn on success, -ve otherwise.
3323  */
3324 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3325 	unsigned long *pfn)
3326 {
3327 	int ret = -EINVAL;
3328 	spinlock_t *ptl;
3329 	pte_t *ptep;
3330 
3331 	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3332 		return ret;
3333 
3334 	ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3335 	if (ret)
3336 		return ret;
3337 	*pfn = pte_pfn(*ptep);
3338 	pte_unmap_unlock(ptep, ptl);
3339 	return 0;
3340 }
3341 EXPORT_SYMBOL(follow_pfn);
3342 
3343 #ifdef CONFIG_HAVE_IOREMAP_PROT
3344 int follow_phys(struct vm_area_struct *vma,
3345 		unsigned long address, unsigned int flags,
3346 		unsigned long *prot, resource_size_t *phys)
3347 {
3348 	int ret = -EINVAL;
3349 	pte_t *ptep, pte;
3350 	spinlock_t *ptl;
3351 
3352 	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3353 		goto out;
3354 
3355 	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3356 		goto out;
3357 	pte = *ptep;
3358 
3359 	if ((flags & FOLL_WRITE) && !pte_write(pte))
3360 		goto unlock;
3361 
3362 	*prot = pgprot_val(pte_pgprot(pte));
3363 	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3364 
3365 	ret = 0;
3366 unlock:
3367 	pte_unmap_unlock(ptep, ptl);
3368 out:
3369 	return ret;
3370 }
3371 
3372 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3373 			void *buf, int len, int write)
3374 {
3375 	resource_size_t phys_addr;
3376 	unsigned long prot = 0;
3377 	void __iomem *maddr;
3378 	int offset = addr & (PAGE_SIZE-1);
3379 
3380 	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3381 		return -EINVAL;
3382 
3383 	maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3384 	if (write)
3385 		memcpy_toio(maddr + offset, buf, len);
3386 	else
3387 		memcpy_fromio(buf, maddr + offset, len);
3388 	iounmap(maddr);
3389 
3390 	return len;
3391 }
3392 #endif
3393 
3394 /*
3395  * Access another process' address space.
3396  * Source/target buffer must be kernel space,
3397  * Do not walk the page table directly, use get_user_pages
3398  */
3399 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
3400 {
3401 	struct mm_struct *mm;
3402 	struct vm_area_struct *vma;
3403 	void *old_buf = buf;
3404 
3405 	mm = get_task_mm(tsk);
3406 	if (!mm)
3407 		return 0;
3408 
3409 	down_read(&mm->mmap_sem);
3410 	/* ignore errors, just check how much was successfully transferred */
3411 	while (len) {
3412 		int bytes, ret, offset;
3413 		void *maddr;
3414 		struct page *page = NULL;
3415 
3416 		ret = get_user_pages(tsk, mm, addr, 1,
3417 				write, 1, &page, &vma);
3418 		if (ret <= 0) {
3419 			/*
3420 			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
3421 			 * we can access using slightly different code.
3422 			 */
3423 #ifdef CONFIG_HAVE_IOREMAP_PROT
3424 			vma = find_vma(mm, addr);
3425 			if (!vma)
3426 				break;
3427 			if (vma->vm_ops && vma->vm_ops->access)
3428 				ret = vma->vm_ops->access(vma, addr, buf,
3429 							  len, write);
3430 			if (ret <= 0)
3431 #endif
3432 				break;
3433 			bytes = ret;
3434 		} else {
3435 			bytes = len;
3436 			offset = addr & (PAGE_SIZE-1);
3437 			if (bytes > PAGE_SIZE-offset)
3438 				bytes = PAGE_SIZE-offset;
3439 
3440 			maddr = kmap(page);
3441 			if (write) {
3442 				copy_to_user_page(vma, page, addr,
3443 						  maddr + offset, buf, bytes);
3444 				set_page_dirty_lock(page);
3445 			} else {
3446 				copy_from_user_page(vma, page, addr,
3447 						    buf, maddr + offset, bytes);
3448 			}
3449 			kunmap(page);
3450 			page_cache_release(page);
3451 		}
3452 		len -= bytes;
3453 		buf += bytes;
3454 		addr += bytes;
3455 	}
3456 	up_read(&mm->mmap_sem);
3457 	mmput(mm);
3458 
3459 	return buf - old_buf;
3460 }
3461 
3462 /*
3463  * Print the name of a VMA.
3464  */
3465 void print_vma_addr(char *prefix, unsigned long ip)
3466 {
3467 	struct mm_struct *mm = current->mm;
3468 	struct vm_area_struct *vma;
3469 
3470 	/*
3471 	 * Do not print if we are in atomic
3472 	 * contexts (in exception stacks, etc.):
3473 	 */
3474 	if (preempt_count())
3475 		return;
3476 
3477 	down_read(&mm->mmap_sem);
3478 	vma = find_vma(mm, ip);
3479 	if (vma && vma->vm_file) {
3480 		struct file *f = vma->vm_file;
3481 		char *buf = (char *)__get_free_page(GFP_KERNEL);
3482 		if (buf) {
3483 			char *p, *s;
3484 
3485 			p = d_path(&f->f_path, buf, PAGE_SIZE);
3486 			if (IS_ERR(p))
3487 				p = "?";
3488 			s = strrchr(p, '/');
3489 			if (s)
3490 				p = s+1;
3491 			printk("%s%s[%lx+%lx]", prefix, p,
3492 					vma->vm_start,
3493 					vma->vm_end - vma->vm_start);
3494 			free_page((unsigned long)buf);
3495 		}
3496 	}
3497 	up_read(&current->mm->mmap_sem);
3498 }
3499 
3500 #ifdef CONFIG_PROVE_LOCKING
3501 void might_fault(void)
3502 {
3503 	/*
3504 	 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3505 	 * holding the mmap_sem, this is safe because kernel memory doesn't
3506 	 * get paged out, therefore we'll never actually fault, and the
3507 	 * below annotations will generate false positives.
3508 	 */
3509 	if (segment_eq(get_fs(), KERNEL_DS))
3510 		return;
3511 
3512 	might_sleep();
3513 	/*
3514 	 * it would be nicer only to annotate paths which are not under
3515 	 * pagefault_disable, however that requires a larger audit and
3516 	 * providing helpers like get_user_atomic.
3517 	 */
3518 	if (!in_atomic() && current->mm)
3519 		might_lock_read(&current->mm->mmap_sem);
3520 }
3521 EXPORT_SYMBOL(might_fault);
3522 #endif
3523