mm: fix memory.c incorrect kernel-doc
[linux-2.6.git] / mm / memory.c
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, struct vm_area_struct *vma,
398                 pmd_t *pmd, unsigned long address)
399 {
400         pgtable_t new = pte_alloc_one(mm, address);
401         int wait_split_huge_page;
402         if (!new)
403                 return -ENOMEM;
404
405         /*
406          * Ensure all pte setup (eg. pte page lock and page clearing) are
407          * visible before the pte is made visible to other CPUs by being
408          * put into page tables.
409          *
410          * The other side of the story is the pointer chasing in the page
411          * table walking code (when walking the page table without locking;
412          * ie. most of the time). Fortunately, these data accesses consist
413          * of a chain of data-dependent loads, meaning most CPUs (alpha
414          * being the notable exception) will already guarantee loads are
415          * seen in-order. See the alpha page table accessors for the
416          * smp_read_barrier_depends() barriers in page table walking code.
417          */
418         smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
419
420         spin_lock(&mm->page_table_lock);
421         wait_split_huge_page = 0;
422         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
423                 mm->nr_ptes++;
424                 pmd_populate(mm, pmd, new);
425                 new = NULL;
426         } else if (unlikely(pmd_trans_splitting(*pmd)))
427                 wait_split_huge_page = 1;
428         spin_unlock(&mm->page_table_lock);
429         if (new)
430                 pte_free(mm, new);
431         if (wait_split_huge_page)
432                 wait_split_huge_page(vma->anon_vma, pmd);
433         return 0;
434 }
435
436 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
437 {
438         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
439         if (!new)
440                 return -ENOMEM;
441
442         smp_wmb(); /* See comment in __pte_alloc */
443
444         spin_lock(&init_mm.page_table_lock);
445         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
446                 pmd_populate_kernel(&init_mm, pmd, new);
447                 new = NULL;
448         } else
449                 VM_BUG_ON(pmd_trans_splitting(*pmd));
450         spin_unlock(&init_mm.page_table_lock);
451         if (new)
452                 pte_free_kernel(&init_mm, new);
453         return 0;
454 }
455
456 static inline void init_rss_vec(int *rss)
457 {
458         memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
459 }
460
461 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
462 {
463         int i;
464
465         if (current->mm == mm)
466                 sync_mm_rss(current, mm);
467         for (i = 0; i < NR_MM_COUNTERS; i++)
468                 if (rss[i])
469                         add_mm_counter(mm, i, rss[i]);
470 }
471
472 /*
473  * This function is called to print an error when a bad pte
474  * is found. For example, we might have a PFN-mapped pte in
475  * a region that doesn't allow it.
476  *
477  * The calling function must still handle the error.
478  */
479 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
480                           pte_t pte, struct page *page)
481 {
482         pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
483         pud_t *pud = pud_offset(pgd, addr);
484         pmd_t *pmd = pmd_offset(pud, addr);
485         struct address_space *mapping;
486         pgoff_t index;
487         static unsigned long resume;
488         static unsigned long nr_shown;
489         static unsigned long nr_unshown;
490
491         /*
492          * Allow a burst of 60 reports, then keep quiet for that minute;
493          * or allow a steady drip of one report per second.
494          */
495         if (nr_shown == 60) {
496                 if (time_before(jiffies, resume)) {
497                         nr_unshown++;
498                         return;
499                 }
500                 if (nr_unshown) {
501                         printk(KERN_ALERT
502                                 "BUG: Bad page map: %lu messages suppressed\n",
503                                 nr_unshown);
504                         nr_unshown = 0;
505                 }
506                 nr_shown = 0;
507         }
508         if (nr_shown++ == 0)
509                 resume = jiffies + 60 * HZ;
510
511         mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
512         index = linear_page_index(vma, addr);
513
514         printk(KERN_ALERT
515                 "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
516                 current->comm,
517                 (long long)pte_val(pte), (long long)pmd_val(*pmd));
518         if (page)
519                 dump_page(page);
520         printk(KERN_ALERT
521                 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
522                 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
523         /*
524          * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
525          */
526         if (vma->vm_ops)
527                 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
528                                 (unsigned long)vma->vm_ops->fault);
529         if (vma->vm_file && vma->vm_file->f_op)
530                 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
531                                 (unsigned long)vma->vm_file->f_op->mmap);
532         dump_stack();
533         add_taint(TAINT_BAD_PAGE);
534 }
535
536 static inline int is_cow_mapping(unsigned int flags)
537 {
538         return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
539 }
540
541 #ifndef is_zero_pfn
542 static inline int is_zero_pfn(unsigned long pfn)
543 {
544         return pfn == zero_pfn;
545 }
546 #endif
547
548 #ifndef my_zero_pfn
549 static inline unsigned long my_zero_pfn(unsigned long addr)
550 {
551         return zero_pfn;
552 }
553 #endif
554
555 /*
556  * vm_normal_page -- This function gets the "struct page" associated with a pte.
557  *
558  * "Special" mappings do not wish to be associated with a "struct page" (either
559  * it doesn't exist, or it exists but they don't want to touch it). In this
560  * case, NULL is returned here. "Normal" mappings do have a struct page.
561  *
562  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
563  * pte bit, in which case this function is trivial. Secondly, an architecture
564  * may not have a spare pte bit, which requires a more complicated scheme,
565  * described below.
566  *
567  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
568  * special mapping (even if there are underlying and valid "struct pages").
569  * COWed pages of a VM_PFNMAP are always normal.
570  *
571  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
572  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
573  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
574  * mapping will always honor the rule
575  *
576  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
577  *
578  * And for normal mappings this is false.
579  *
580  * This restricts such mappings to be a linear translation from virtual address
581  * to pfn. To get around this restriction, we allow arbitrary mappings so long
582  * as the vma is not a COW mapping; in that case, we know that all ptes are
583  * special (because none can have been COWed).
584  *
585  *
586  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
587  *
588  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
589  * page" backing, however the difference is that _all_ pages with a struct
590  * page (that is, those where pfn_valid is true) are refcounted and considered
591  * normal pages by the VM. The disadvantage is that pages are refcounted
592  * (which can be slower and simply not an option for some PFNMAP users). The
593  * advantage is that we don't have to follow the strict linearity rule of
594  * PFNMAP mappings in order to support COWable mappings.
595  *
596  */
597 #ifdef __HAVE_ARCH_PTE_SPECIAL
598 # define HAVE_PTE_SPECIAL 1
599 #else
600 # define HAVE_PTE_SPECIAL 0
601 #endif
602 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
603                                 pte_t pte)
604 {
605         unsigned long pfn = pte_pfn(pte);
606
607         if (HAVE_PTE_SPECIAL) {
608                 if (likely(!pte_special(pte)))
609                         goto check_pfn;
610                 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
611                         return NULL;
612                 if (!is_zero_pfn(pfn))
613                         print_bad_pte(vma, addr, pte, NULL);
614                 return NULL;
615         }
616
617         /* !HAVE_PTE_SPECIAL case follows: */
618
619         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
620                 if (vma->vm_flags & VM_MIXEDMAP) {
621                         if (!pfn_valid(pfn))
622                                 return NULL;
623                         goto out;
624                 } else {
625                         unsigned long off;
626                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
627                         if (pfn == vma->vm_pgoff + off)
628                                 return NULL;
629                         if (!is_cow_mapping(vma->vm_flags))
630                                 return NULL;
631                 }
632         }
633
634         if (is_zero_pfn(pfn))
635                 return NULL;
636 check_pfn:
637         if (unlikely(pfn > highest_memmap_pfn)) {
638                 print_bad_pte(vma, addr, pte, NULL);
639                 return NULL;
640         }
641
642         /*
643          * NOTE! We still have PageReserved() pages in the page tables.
644          * eg. VDSO mappings can cause them to exist.
645          */
646 out:
647         return pfn_to_page(pfn);
648 }
649
650 /*
651  * copy one vm_area from one task to the other. Assumes the page tables
652  * already present in the new task to be cleared in the whole range
653  * covered by this vma.
654  */
655
656 static inline unsigned long
657 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
658                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
659                 unsigned long addr, int *rss)
660 {
661         unsigned long vm_flags = vma->vm_flags;
662         pte_t pte = *src_pte;
663         struct page *page;
664
665         /* pte contains position in swap or file, so copy. */
666         if (unlikely(!pte_present(pte))) {
667                 if (!pte_file(pte)) {
668                         swp_entry_t entry = pte_to_swp_entry(pte);
669
670                         if (swap_duplicate(entry) < 0)
671                                 return entry.val;
672
673                         /* make sure dst_mm is on swapoff's mmlist. */
674                         if (unlikely(list_empty(&dst_mm->mmlist))) {
675                                 spin_lock(&mmlist_lock);
676                                 if (list_empty(&dst_mm->mmlist))
677                                         list_add(&dst_mm->mmlist,
678                                                  &src_mm->mmlist);
679                                 spin_unlock(&mmlist_lock);
680                         }
681                         if (likely(!non_swap_entry(entry)))
682                                 rss[MM_SWAPENTS]++;
683                         else if (is_write_migration_entry(entry) &&
684                                         is_cow_mapping(vm_flags)) {
685                                 /*
686                                  * COW mappings require pages in both parent
687                                  * and child to be set to read.
688                                  */
689                                 make_migration_entry_read(&entry);
690                                 pte = swp_entry_to_pte(entry);
691                                 set_pte_at(src_mm, addr, src_pte, pte);
692                         }
693                 }
694                 goto out_set_pte;
695         }
696
697         /*
698          * If it's a COW mapping, write protect it both
699          * in the parent and the child
700          */
701         if (is_cow_mapping(vm_flags)) {
702                 ptep_set_wrprotect(src_mm, addr, src_pte);
703                 pte = pte_wrprotect(pte);
704         }
705
706         /*
707          * If it's a shared mapping, mark it clean in
708          * the child
709          */
710         if (vm_flags & VM_SHARED)
711                 pte = pte_mkclean(pte);
712         pte = pte_mkold(pte);
713
714         page = vm_normal_page(vma, addr, pte);
715         if (page) {
716                 get_page(page);
717                 page_dup_rmap(page);
718                 if (PageAnon(page))
719                         rss[MM_ANONPAGES]++;
720                 else
721                         rss[MM_FILEPAGES]++;
722         }
723
724 out_set_pte:
725         set_pte_at(dst_mm, addr, dst_pte, pte);
726         return 0;
727 }
728
729 int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
730                    pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
731                    unsigned long addr, unsigned long end)
732 {
733         pte_t *orig_src_pte, *orig_dst_pte;
734         pte_t *src_pte, *dst_pte;
735         spinlock_t *src_ptl, *dst_ptl;
736         int progress = 0;
737         int rss[NR_MM_COUNTERS];
738         swp_entry_t entry = (swp_entry_t){0};
739
740 again:
741         init_rss_vec(rss);
742
743         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
744         if (!dst_pte)
745                 return -ENOMEM;
746         src_pte = pte_offset_map(src_pmd, addr);
747         src_ptl = pte_lockptr(src_mm, src_pmd);
748         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
749         orig_src_pte = src_pte;
750         orig_dst_pte = dst_pte;
751         arch_enter_lazy_mmu_mode();
752
753         do {
754                 /*
755                  * We are holding two locks at this point - either of them
756                  * could generate latencies in another task on another CPU.
757                  */
758                 if (progress >= 32) {
759                         progress = 0;
760                         if (need_resched() ||
761                             spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
762                                 break;
763                 }
764                 if (pte_none(*src_pte)) {
765                         progress++;
766                         continue;
767                 }
768                 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
769                                                         vma, addr, rss);
770                 if (entry.val)
771                         break;
772                 progress += 8;
773         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
774
775         arch_leave_lazy_mmu_mode();
776         spin_unlock(src_ptl);
777         pte_unmap(orig_src_pte);
778         add_mm_rss_vec(dst_mm, rss);
779         pte_unmap_unlock(orig_dst_pte, dst_ptl);
780         cond_resched();
781
782         if (entry.val) {
783                 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
784                         return -ENOMEM;
785                 progress = 0;
786         }
787         if (addr != end)
788                 goto again;
789         return 0;
790 }
791
792 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
793                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
794                 unsigned long addr, unsigned long end)
795 {
796         pmd_t *src_pmd, *dst_pmd;
797         unsigned long next;
798
799         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
800         if (!dst_pmd)
801                 return -ENOMEM;
802         src_pmd = pmd_offset(src_pud, addr);
803         do {
804                 next = pmd_addr_end(addr, end);
805                 if (pmd_trans_huge(*src_pmd)) {
806                         int err;
807                         VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
808                         err = copy_huge_pmd(dst_mm, src_mm,
809                                             dst_pmd, src_pmd, addr, vma);
810                         if (err == -ENOMEM)
811                                 return -ENOMEM;
812                         if (!err)
813                                 continue;
814                         /* fall through */
815                 }
816                 if (pmd_none_or_clear_bad(src_pmd))
817                         continue;
818                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
819                                                 vma, addr, next))
820                         return -ENOMEM;
821         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
822         return 0;
823 }
824
825 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
826                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
827                 unsigned long addr, unsigned long end)
828 {
829         pud_t *src_pud, *dst_pud;
830         unsigned long next;
831
832         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
833         if (!dst_pud)
834                 return -ENOMEM;
835         src_pud = pud_offset(src_pgd, addr);
836         do {
837                 next = pud_addr_end(addr, end);
838                 if (pud_none_or_clear_bad(src_pud))
839                         continue;
840                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
841                                                 vma, addr, next))
842                         return -ENOMEM;
843         } while (dst_pud++, src_pud++, addr = next, addr != end);
844         return 0;
845 }
846
847 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
848                 struct vm_area_struct *vma)
849 {
850         pgd_t *src_pgd, *dst_pgd;
851         unsigned long next;
852         unsigned long addr = vma->vm_start;
853         unsigned long end = vma->vm_end;
854         int ret;
855
856         /*
857          * Don't copy ptes where a page fault will fill them correctly.
858          * Fork becomes much lighter when there are big shared or private
859          * readonly mappings. The tradeoff is that copy_page_range is more
860          * efficient than faulting.
861          */
862         if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
863                 if (!vma->anon_vma)
864                         return 0;
865         }
866
867         if (is_vm_hugetlb_page(vma))
868                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
869
870         if (unlikely(is_pfn_mapping(vma))) {
871                 /*
872                  * We do not free on error cases below as remove_vma
873                  * gets called on error from higher level routine
874                  */
875                 ret = track_pfn_vma_copy(vma);
876                 if (ret)
877                         return ret;
878         }
879
880         /*
881          * We need to invalidate the secondary MMU mappings only when
882          * there could be a permission downgrade on the ptes of the
883          * parent mm. And a permission downgrade will only happen if
884          * is_cow_mapping() returns true.
885          */
886         if (is_cow_mapping(vma->vm_flags))
887                 mmu_notifier_invalidate_range_start(src_mm, addr, end);
888
889         ret = 0;
890         dst_pgd = pgd_offset(dst_mm, addr);
891         src_pgd = pgd_offset(src_mm, addr);
892         do {
893                 next = pgd_addr_end(addr, end);
894                 if (pgd_none_or_clear_bad(src_pgd))
895                         continue;
896                 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
897                                             vma, addr, next))) {
898                         ret = -ENOMEM;
899                         break;
900                 }
901         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
902
903         if (is_cow_mapping(vma->vm_flags))
904                 mmu_notifier_invalidate_range_end(src_mm,
905                                                   vma->vm_start, end);
906         return ret;
907 }
908
909 static unsigned long zap_pte_range(struct mmu_gather *tlb,
910                                 struct vm_area_struct *vma, pmd_t *pmd,
911                                 unsigned long addr, unsigned long end,
912                                 long *zap_work, struct zap_details *details)
913 {
914         struct mm_struct *mm = tlb->mm;
915         pte_t *pte;
916         spinlock_t *ptl;
917         int rss[NR_MM_COUNTERS];
918
919         init_rss_vec(rss);
920
921         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
922         arch_enter_lazy_mmu_mode();
923         do {
924                 pte_t ptent = *pte;
925                 if (pte_none(ptent)) {
926                         (*zap_work)--;
927                         continue;
928                 }
929
930                 (*zap_work) -= PAGE_SIZE;
931
932                 if (pte_present(ptent)) {
933                         struct page *page;
934
935                         page = vm_normal_page(vma, addr, ptent);
936                         if (unlikely(details) && page) {
937                                 /*
938                                  * unmap_shared_mapping_pages() wants to
939                                  * invalidate cache without truncating:
940                                  * unmap shared but keep private pages.
941                                  */
942                                 if (details->check_mapping &&
943                                     details->check_mapping != page->mapping)
944                                         continue;
945                                 /*
946                                  * Each page->index must be checked when
947                                  * invalidating or truncating nonlinear.
948                                  */
949                                 if (details->nonlinear_vma &&
950                                     (page->index < details->first_index ||
951                                      page->index > details->last_index))
952                                         continue;
953                         }
954                         ptent = ptep_get_and_clear_full(mm, addr, pte,
955                                                         tlb->fullmm);
956                         tlb_remove_tlb_entry(tlb, pte, addr);
957                         if (unlikely(!page))
958                                 continue;
959                         if (unlikely(details) && details->nonlinear_vma
960                             && linear_page_index(details->nonlinear_vma,
961                                                 addr) != page->index)
962                                 set_pte_at(mm, addr, pte,
963                                            pgoff_to_pte(page->index));
964                         if (PageAnon(page))
965                                 rss[MM_ANONPAGES]--;
966                         else {
967                                 if (pte_dirty(ptent))
968                                         set_page_dirty(page);
969                                 if (pte_young(ptent) &&
970                                     likely(!VM_SequentialReadHint(vma)))
971                                         mark_page_accessed(page);
972                                 rss[MM_FILEPAGES]--;
973                         }
974                         page_remove_rmap(page);
975                         if (unlikely(page_mapcount(page) < 0))
976                                 print_bad_pte(vma, addr, ptent, page);
977                         tlb_remove_page(tlb, page);
978                         continue;
979                 }
980                 /*
981                  * If details->check_mapping, we leave swap entries;
982                  * if details->nonlinear_vma, we leave file entries.
983                  */
984                 if (unlikely(details))
985                         continue;
986                 if (pte_file(ptent)) {
987                         if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
988                                 print_bad_pte(vma, addr, ptent, NULL);
989                 } else {
990                         swp_entry_t entry = pte_to_swp_entry(ptent);
991
992                         if (!non_swap_entry(entry))
993                                 rss[MM_SWAPENTS]--;
994                         if (unlikely(!free_swap_and_cache(entry)))
995                                 print_bad_pte(vma, addr, ptent, NULL);
996                 }
997                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
998         } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
999
1000         add_mm_rss_vec(mm, rss);
1001         arch_leave_lazy_mmu_mode();
1002         pte_unmap_unlock(pte - 1, ptl);
1003
1004         return addr;
1005 }
1006
1007 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1008                                 struct vm_area_struct *vma, pud_t *pud,
1009                                 unsigned long addr, unsigned long end,
1010                                 long *zap_work, struct zap_details *details)
1011 {
1012         pmd_t *pmd;
1013         unsigned long next;
1014
1015         pmd = pmd_offset(pud, addr);
1016         do {
1017                 next = pmd_addr_end(addr, end);
1018                 if (pmd_trans_huge(*pmd)) {
1019                         if (next-addr != HPAGE_PMD_SIZE) {
1020                                 VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
1021                                 split_huge_page_pmd(vma->vm_mm, pmd);
1022                         } else if (zap_huge_pmd(tlb, vma, pmd)) {
1023                                 (*zap_work)--;
1024                                 continue;
1025                         }
1026                         /* fall through */
1027                 }
1028                 if (pmd_none_or_clear_bad(pmd)) {
1029                         (*zap_work)--;
1030                         continue;
1031                 }
1032                 next = zap_pte_range(tlb, vma, pmd, addr, next,
1033                                                 zap_work, details);
1034         } while (pmd++, addr = next, (addr != end && *zap_work > 0));
1035
1036         return addr;
1037 }
1038
1039 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1040                                 struct vm_area_struct *vma, pgd_t *pgd,
1041                                 unsigned long addr, unsigned long end,
1042                                 long *zap_work, struct zap_details *details)
1043 {
1044         pud_t *pud;
1045         unsigned long next;
1046
1047         pud = pud_offset(pgd, addr);
1048         do {
1049                 next = pud_addr_end(addr, end);
1050                 if (pud_none_or_clear_bad(pud)) {
1051                         (*zap_work)--;
1052                         continue;
1053                 }
1054                 next = zap_pmd_range(tlb, vma, pud, addr, next,
1055                                                 zap_work, details);
1056         } while (pud++, addr = next, (addr != end && *zap_work > 0));
1057
1058         return addr;
1059 }
1060
1061 static unsigned long unmap_page_range(struct mmu_gather *tlb,
1062                                 struct vm_area_struct *vma,
1063                                 unsigned long addr, unsigned long end,
1064                                 long *zap_work, struct zap_details *details)
1065 {
1066         pgd_t *pgd;
1067         unsigned long next;
1068
1069         if (details && !details->check_mapping && !details->nonlinear_vma)
1070                 details = NULL;
1071
1072         BUG_ON(addr >= end);
1073         mem_cgroup_uncharge_start();
1074         tlb_start_vma(tlb, vma);
1075         pgd = pgd_offset(vma->vm_mm, addr);
1076         do {
1077                 next = pgd_addr_end(addr, end);
1078                 if (pgd_none_or_clear_bad(pgd)) {
1079                         (*zap_work)--;
1080                         continue;
1081                 }
1082                 next = zap_pud_range(tlb, vma, pgd, addr, next,
1083                                                 zap_work, details);
1084         } while (pgd++, addr = next, (addr != end && *zap_work > 0));
1085         tlb_end_vma(tlb, vma);
1086         mem_cgroup_uncharge_end();
1087
1088         return addr;
1089 }
1090
1091 #ifdef CONFIG_PREEMPT
1092 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
1093 #else
1094 /* No preempt: go for improved straight-line efficiency */
1095 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
1096 #endif
1097
1098 /**
1099  * unmap_vmas - unmap a range of memory covered by a list of vma's
1100  * @tlbp: address of the caller's struct mmu_gather
1101  * @vma: the starting vma
1102  * @start_addr: virtual address at which to start unmapping
1103  * @end_addr: virtual address at which to end unmapping
1104  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
1105  * @details: details of nonlinear truncation or shared cache invalidation
1106  *
1107  * Returns the end address of the unmapping (restart addr if interrupted).
1108  *
1109  * Unmap all pages in the vma list.
1110  *
1111  * We aim to not hold locks for too long (for scheduling latency reasons).
1112  * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
1113  * return the ending mmu_gather to the caller.
1114  *
1115  * Only addresses between `start' and `end' will be unmapped.
1116  *
1117  * The VMA list must be sorted in ascending virtual address order.
1118  *
1119  * unmap_vmas() assumes that the caller will flush the whole unmapped address
1120  * range after unmap_vmas() returns.  So the only responsibility here is to
1121  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1122  * drops the lock and schedules.
1123  */
1124 unsigned long unmap_vmas(struct mmu_gather **tlbp,
1125                 struct vm_area_struct *vma, unsigned long start_addr,
1126                 unsigned long end_addr, unsigned long *nr_accounted,
1127                 struct zap_details *details)
1128 {
1129         long zap_work = ZAP_BLOCK_SIZE;
1130         unsigned long tlb_start = 0;    /* For tlb_finish_mmu */
1131         int tlb_start_valid = 0;
1132         unsigned long start = start_addr;
1133         spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
1134         int fullmm = (*tlbp)->fullmm;
1135         struct mm_struct *mm = vma->vm_mm;
1136
1137         mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1138         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
1139                 unsigned long end;
1140
1141                 start = max(vma->vm_start, start_addr);
1142                 if (start >= vma->vm_end)
1143                         continue;
1144                 end = min(vma->vm_end, end_addr);
1145                 if (end <= vma->vm_start)
1146                         continue;
1147
1148                 if (vma->vm_flags & VM_ACCOUNT)
1149                         *nr_accounted += (end - start) >> PAGE_SHIFT;
1150
1151                 if (unlikely(is_pfn_mapping(vma)))
1152                         untrack_pfn_vma(vma, 0, 0);
1153
1154                 while (start != end) {
1155                         if (!tlb_start_valid) {
1156                                 tlb_start = start;
1157                                 tlb_start_valid = 1;
1158                         }
1159
1160                         if (unlikely(is_vm_hugetlb_page(vma))) {
1161                                 /*
1162                                  * It is undesirable to test vma->vm_file as it
1163                                  * should be non-null for valid hugetlb area.
1164                                  * However, vm_file will be NULL in the error
1165                                  * cleanup path of do_mmap_pgoff. When
1166                                  * hugetlbfs ->mmap method fails,
1167                                  * do_mmap_pgoff() nullifies vma->vm_file
1168                                  * before calling this function to clean up.
1169                                  * Since no pte has actually been setup, it is
1170                                  * safe to do nothing in this case.
1171                                  */
1172                                 if (vma->vm_file) {
1173                                         unmap_hugepage_range(vma, start, end, NULL);
1174                                         zap_work -= (end - start) /
1175                                         pages_per_huge_page(hstate_vma(vma));
1176                                 }
1177
1178                                 start = end;
1179                         } else
1180                                 start = unmap_page_range(*tlbp, vma,
1181                                                 start, end, &zap_work, details);
1182
1183                         if (zap_work > 0) {
1184                                 BUG_ON(start != end);
1185                                 break;
1186                         }
1187
1188                         tlb_finish_mmu(*tlbp, tlb_start, start);
1189
1190                         if (need_resched() ||
1191                                 (i_mmap_lock && spin_needbreak(i_mmap_lock))) {
1192                                 if (i_mmap_lock) {
1193                                         *tlbp = NULL;
1194                                         goto out;
1195                                 }
1196                                 cond_resched();
1197                         }
1198
1199                         *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
1200                         tlb_start_valid = 0;
1201                         zap_work = ZAP_BLOCK_SIZE;
1202                 }
1203         }
1204 out:
1205         mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1206         return start;   /* which is now the end (or restart) address */
1207 }
1208
1209 /**
1210  * zap_page_range - remove user pages in a given range
1211  * @vma: vm_area_struct holding the applicable pages
1212  * @address: starting address of pages to zap
1213  * @size: number of bytes to zap
1214  * @details: details of nonlinear truncation or shared cache invalidation
1215  */
1216 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1217                 unsigned long size, struct zap_details *details)
1218 {
1219         struct mm_struct *mm = vma->vm_mm;
1220         struct mmu_gather *tlb;
1221         unsigned long end = address + size;
1222         unsigned long nr_accounted = 0;
1223
1224         lru_add_drain();
1225         tlb = tlb_gather_mmu(mm, 0);
1226         update_hiwater_rss(mm);
1227         end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1228         if (tlb)
1229                 tlb_finish_mmu(tlb, address, end);
1230         return end;
1231 }
1232
1233 /**
1234  * zap_vma_ptes - remove ptes mapping the vma
1235  * @vma: vm_area_struct holding ptes to be zapped
1236  * @address: starting address of pages to zap
1237  * @size: number of bytes to zap
1238  *
1239  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1240  *
1241  * The entire address range must be fully contained within the vma.
1242  *
1243  * Returns 0 if successful.
1244  */
1245 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1246                 unsigned long size)
1247 {
1248         if (address < vma->vm_start || address + size > vma->vm_end ||
1249                         !(vma->vm_flags & VM_PFNMAP))
1250                 return -1;
1251         zap_page_range(vma, address, size, NULL);
1252         return 0;
1253 }
1254 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1255
1256 /**
1257  * follow_page - look up a page descriptor from a user-virtual address
1258  * @vma: vm_area_struct mapping @address
1259  * @address: virtual address to look up
1260  * @flags: flags modifying lookup behaviour
1261  *
1262  * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1263  *
1264  * Returns the mapped (struct page *), %NULL if no mapping exists, or
1265  * an error pointer if there is a mapping to something not represented
1266  * by a page descriptor (see also vm_normal_page()).
1267  */
1268 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1269                         unsigned int flags)
1270 {
1271         pgd_t *pgd;
1272         pud_t *pud;
1273         pmd_t *pmd;
1274         pte_t *ptep, pte;
1275         spinlock_t *ptl;
1276         struct page *page;
1277         struct mm_struct *mm = vma->vm_mm;
1278
1279         page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1280         if (!IS_ERR(page)) {
1281                 BUG_ON(flags & FOLL_GET);
1282                 goto out;
1283         }
1284
1285         page = NULL;
1286         pgd = pgd_offset(mm, address);
1287         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1288                 goto no_page_table;
1289
1290         pud = pud_offset(pgd, address);
1291         if (pud_none(*pud))
1292                 goto no_page_table;
1293         if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1294                 BUG_ON(flags & FOLL_GET);
1295                 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1296                 goto out;
1297         }
1298         if (unlikely(pud_bad(*pud)))
1299                 goto no_page_table;
1300
1301         pmd = pmd_offset(pud, address);
1302         if (pmd_none(*pmd))
1303                 goto no_page_table;
1304         if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1305                 BUG_ON(flags & FOLL_GET);
1306                 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1307                 goto out;
1308         }
1309         if (pmd_trans_huge(*pmd)) {
1310                 if (flags & FOLL_SPLIT) {
1311                         split_huge_page_pmd(mm, pmd);
1312                         goto split_fallthrough;
1313                 }
1314                 spin_lock(&mm->page_table_lock);
1315                 if (likely(pmd_trans_huge(*pmd))) {
1316                         if (unlikely(pmd_trans_splitting(*pmd))) {
1317                                 spin_unlock(&mm->page_table_lock);
1318                                 wait_split_huge_page(vma->anon_vma, pmd);
1319                         } else {
1320                                 page = follow_trans_huge_pmd(mm, address,
1321                                                              pmd, flags);
1322                                 spin_unlock(&mm->page_table_lock);
1323                                 goto out;
1324                         }
1325                 } else
1326                         spin_unlock(&mm->page_table_lock);
1327                 /* fall through */
1328         }
1329 split_fallthrough:
1330         if (unlikely(pmd_bad(*pmd)))
1331                 goto no_page_table;
1332
1333         ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1334
1335         pte = *ptep;
1336         if (!pte_present(pte))
1337                 goto no_page;
1338         if ((flags & FOLL_WRITE) && !pte_write(pte))
1339                 goto unlock;
1340
1341         page = vm_normal_page(vma, address, pte);
1342         if (unlikely(!page)) {
1343                 if ((flags & FOLL_DUMP) ||
1344                     !is_zero_pfn(pte_pfn(pte)))
1345                         goto bad_page;
1346                 page = pte_page(pte);
1347         }
1348
1349         if (flags & FOLL_GET)
1350                 get_page(page);
1351         if (flags & FOLL_TOUCH) {
1352                 if ((flags & FOLL_WRITE) &&
1353                     !pte_dirty(pte) && !PageDirty(page))
1354                         set_page_dirty(page);
1355                 /*
1356                  * pte_mkyoung() would be more correct here, but atomic care
1357                  * is needed to avoid losing the dirty bit: it is easier to use
1358                  * mark_page_accessed().
1359                  */
1360                 mark_page_accessed(page);
1361         }
1362         if (flags & FOLL_MLOCK) {
1363                 /*
1364                  * The preliminary mapping check is mainly to avoid the
1365                  * pointless overhead of lock_page on the ZERO_PAGE
1366                  * which might bounce very badly if there is contention.
1367                  *
1368                  * If the page is already locked, we don't need to
1369                  * handle it now - vmscan will handle it later if and
1370                  * when it attempts to reclaim the page.
1371                  */
1372                 if (page->mapping && trylock_page(page)) {
1373                         lru_add_drain();  /* push cached pages to LRU */
1374                         /*
1375                          * Because we lock page here and migration is
1376                          * blocked by the pte's page reference, we need
1377                          * only check for file-cache page truncation.
1378                          */
1379                         if (page->mapping)
1380                                 mlock_vma_page(page);
1381                         unlock_page(page);
1382                 }
1383         }
1384 unlock:
1385         pte_unmap_unlock(ptep, ptl);
1386 out:
1387         return page;
1388
1389 bad_page:
1390         pte_unmap_unlock(ptep, ptl);
1391         return ERR_PTR(-EFAULT);
1392
1393 no_page:
1394         pte_unmap_unlock(ptep, ptl);
1395         if (!pte_none(pte))
1396                 return page;
1397
1398 no_page_table:
1399         /*
1400          * When core dumping an enormous anonymous area that nobody
1401          * has touched so far, we don't want to allocate unnecessary pages or
1402          * page tables.  Return error instead of NULL to skip handle_mm_fault,
1403          * then get_dump_page() will return NULL to leave a hole in the dump.
1404          * But we can only make this optimization where a hole would surely
1405          * be zero-filled if handle_mm_fault() actually did handle it.
1406          */
1407         if ((flags & FOLL_DUMP) &&
1408             (!vma->vm_ops || !vma->vm_ops->fault))
1409                 return ERR_PTR(-EFAULT);
1410         return page;
1411 }
1412
1413 /**
1414  * __get_user_pages() - pin user pages in memory
1415  * @tsk:        task_struct of target task
1416  * @mm:         mm_struct of target mm
1417  * @start:      starting user address
1418  * @nr_pages:   number of pages from start to pin
1419  * @gup_flags:  flags modifying pin behaviour
1420  * @pages:      array that receives pointers to the pages pinned.
1421  *              Should be at least nr_pages long. Or NULL, if caller
1422  *              only intends to ensure the pages are faulted in.
1423  * @vmas:       array of pointers to vmas corresponding to each page.
1424  *              Or NULL if the caller does not require them.
1425  * @nonblocking: whether waiting for disk IO or mmap_sem contention
1426  *
1427  * Returns number of pages pinned. This may be fewer than the number
1428  * requested. If nr_pages is 0 or negative, returns 0. If no pages
1429  * were pinned, returns -errno. Each page returned must be released
1430  * with a put_page() call when it is finished with. vmas will only
1431  * remain valid while mmap_sem is held.
1432  *
1433  * Must be called with mmap_sem held for read or write.
1434  *
1435  * __get_user_pages walks a process's page tables and takes a reference to
1436  * each struct page that each user address corresponds to at a given
1437  * instant. That is, it takes the page that would be accessed if a user
1438  * thread accesses the given user virtual address at that instant.
1439  *
1440  * This does not guarantee that the page exists in the user mappings when
1441  * __get_user_pages returns, and there may even be a completely different
1442  * page there in some cases (eg. if mmapped pagecache has been invalidated
1443  * and subsequently re faulted). However it does guarantee that the page
1444  * won't be freed completely. And mostly callers simply care that the page
1445  * contains data that was valid *at some point in time*. Typically, an IO
1446  * or similar operation cannot guarantee anything stronger anyway because
1447  * locks can't be held over the syscall boundary.
1448  *
1449  * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1450  * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1451  * appropriate) must be called after the page is finished with, and
1452  * before put_page is called.
1453  *
1454  * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1455  * or mmap_sem contention, and if waiting is needed to pin all pages,
1456  * *@nonblocking will be set to 0.
1457  *
1458  * In most cases, get_user_pages or get_user_pages_fast should be used
1459  * instead of __get_user_pages. __get_user_pages should be used only if
1460  * you need some special @gup_flags.
1461  */
1462 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1463                      unsigned long start, int nr_pages, unsigned int gup_flags,
1464                      struct page **pages, struct vm_area_struct **vmas,
1465                      int *nonblocking)
1466 {
1467         int i;
1468         unsigned long vm_flags;
1469
1470         if (nr_pages <= 0)
1471                 return 0;
1472
1473         VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1474
1475         /* 
1476          * Require read or write permissions.
1477          * If FOLL_FORCE is set, we only require the "MAY" flags.
1478          */
1479         vm_flags  = (gup_flags & FOLL_WRITE) ?
1480                         (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1481         vm_flags &= (gup_flags & FOLL_FORCE) ?
1482                         (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1483         i = 0;
1484
1485         do {
1486                 struct vm_area_struct *vma;
1487
1488                 vma = find_extend_vma(mm, start);
1489                 if (!vma && in_gate_area(mm, start)) {
1490                         unsigned long pg = start & PAGE_MASK;
1491                         struct vm_area_struct *gate_vma = get_gate_vma(mm);
1492                         pgd_t *pgd;
1493                         pud_t *pud;
1494                         pmd_t *pmd;
1495                         pte_t *pte;
1496
1497                         /* user gate pages are read-only */
1498                         if (gup_flags & FOLL_WRITE)
1499                                 return i ? : -EFAULT;
1500                         if (pg > TASK_SIZE)
1501                                 pgd = pgd_offset_k(pg);
1502                         else
1503                                 pgd = pgd_offset_gate(mm, pg);
1504                         BUG_ON(pgd_none(*pgd));
1505                         pud = pud_offset(pgd, pg);
1506                         BUG_ON(pud_none(*pud));
1507                         pmd = pmd_offset(pud, pg);
1508                         if (pmd_none(*pmd))
1509                                 return i ? : -EFAULT;
1510                         VM_BUG_ON(pmd_trans_huge(*pmd));
1511                         pte = pte_offset_map(pmd, pg);
1512                         if (pte_none(*pte)) {
1513                                 pte_unmap(pte);
1514                                 return i ? : -EFAULT;
1515                         }
1516                         if (pages) {
1517                                 struct page *page;
1518
1519                                 page = vm_normal_page(gate_vma, start, *pte);
1520                                 if (!page) {
1521                                         if (!(gup_flags & FOLL_DUMP) &&
1522                                              is_zero_pfn(pte_pfn(*pte)))
1523                                                 page = pte_page(*pte);
1524                                         else {
1525                                                 pte_unmap(pte);
1526                                                 return i ? : -EFAULT;
1527                                         }
1528                                 }
1529                                 pages[i] = page;
1530                                 get_page(page);
1531                         }
1532                         pte_unmap(pte);
1533                         if (vmas)
1534                                 vmas[i] = gate_vma;
1535                         i++;
1536                         start += PAGE_SIZE;
1537                         nr_pages--;
1538                         continue;
1539                 }
1540
1541                 if (!vma ||
1542                     (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1543                     !(vm_flags & vma->vm_flags))
1544                         return i ? : -EFAULT;
1545
1546                 if (is_vm_hugetlb_page(vma)) {
1547                         i = follow_hugetlb_page(mm, vma, pages, vmas,
1548                                         &start, &nr_pages, i, gup_flags);
1549                         continue;
1550                 }
1551
1552                 do {
1553                         struct page *page;
1554                         unsigned int foll_flags = gup_flags;
1555
1556                         /*
1557                          * If we have a pending SIGKILL, don't keep faulting
1558                          * pages and potentially allocating memory.
1559                          */
1560                         if (unlikely(fatal_signal_pending(current)))
1561                                 return i ? i : -ERESTARTSYS;
1562
1563                         cond_resched();
1564                         while (!(page = follow_page(vma, start, foll_flags))) {
1565                                 int ret;
1566                                 unsigned int fault_flags = 0;
1567
1568                                 if (foll_flags & FOLL_WRITE)
1569                                         fault_flags |= FAULT_FLAG_WRITE;
1570                                 if (nonblocking)
1571                                         fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1572                                 if (foll_flags & FOLL_NOWAIT)
1573                                         fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1574
1575                                 ret = handle_mm_fault(mm, vma, start,
1576                                                         fault_flags);
1577
1578                                 if (ret & VM_FAULT_ERROR) {
1579                                         if (ret & VM_FAULT_OOM)
1580                                                 return i ? i : -ENOMEM;
1581                                         if (ret & (VM_FAULT_HWPOISON |
1582                                                    VM_FAULT_HWPOISON_LARGE)) {
1583                                                 if (i)
1584                                                         return i;
1585                                                 else if (gup_flags & FOLL_HWPOISON)
1586                                                         return -EHWPOISON;
1587                                                 else
1588                                                         return -EFAULT;
1589                                         }
1590                                         if (ret & VM_FAULT_SIGBUS)
1591                                                 return i ? i : -EFAULT;
1592                                         BUG();
1593                                 }
1594
1595                                 if (tsk) {
1596                                         if (ret & VM_FAULT_MAJOR)
1597                                                 tsk->maj_flt++;
1598                                         else
1599                                                 tsk->min_flt++;
1600                                 }
1601
1602                                 if (ret & VM_FAULT_RETRY) {
1603                                         if (nonblocking)
1604                                                 *nonblocking = 0;
1605                                         return i;
1606                                 }
1607
1608                                 /*
1609                                  * The VM_FAULT_WRITE bit tells us that
1610                                  * do_wp_page has broken COW when necessary,
1611                                  * even if maybe_mkwrite decided not to set
1612                                  * pte_write. We can thus safely do subsequent
1613                                  * page lookups as if they were reads. But only
1614                                  * do so when looping for pte_write is futile:
1615                                  * in some cases userspace may also be wanting
1616                                  * to write to the gotten user page, which a
1617                                  * read fault here might prevent (a readonly
1618                                  * page might get reCOWed by userspace write).
1619                                  */
1620                                 if ((ret & VM_FAULT_WRITE) &&
1621                                     !(vma->vm_flags & VM_WRITE))
1622                                         foll_flags &= ~FOLL_WRITE;
1623
1624                                 cond_resched();
1625                         }
1626                         if (IS_ERR(page))
1627                                 return i ? i : PTR_ERR(page);
1628                         if (pages) {
1629                                 pages[i] = page;
1630
1631                                 flush_anon_page(vma, page, start);
1632                                 flush_dcache_page(page);
1633                         }
1634                         if (vmas)
1635                                 vmas[i] = vma;
1636                         i++;
1637                         start += PAGE_SIZE;
1638                         nr_pages--;
1639                 } while (nr_pages && start < vma->vm_end);
1640         } while (nr_pages);
1641         return i;
1642 }
1643 EXPORT_SYMBOL(__get_user_pages);
1644
1645 /**
1646  * get_user_pages() - pin user pages in memory
1647  * @tsk:        the task_struct to use for page fault accounting, or
1648  *              NULL if faults are not to be recorded.
1649  * @mm:         mm_struct of target mm
1650  * @start:      starting user address
1651  * @nr_pages:   number of pages from start to pin
1652  * @write:      whether pages will be written to by the caller
1653  * @force:      whether to force write access even if user mapping is
1654  *              readonly. This will result in the page being COWed even
1655  *              in MAP_SHARED mappings. You do not want this.
1656  * @pages:      array that receives pointers to the pages pinned.
1657  *              Should be at least nr_pages long. Or NULL, if caller
1658  *              only intends to ensure the pages are faulted in.
1659  * @vmas:       array of pointers to vmas corresponding to each page.
1660  *              Or NULL if the caller does not require them.
1661  *
1662  * Returns number of pages pinned. This may be fewer than the number
1663  * requested. If nr_pages is 0 or negative, returns 0. If no pages
1664  * were pinned, returns -errno. Each page returned must be released
1665  * with a put_page() call when it is finished with. vmas will only
1666  * remain valid while mmap_sem is held.
1667  *
1668  * Must be called with mmap_sem held for read or write.
1669  *
1670  * get_user_pages walks a process's page tables and takes a reference to
1671  * each struct page that each user address corresponds to at a given
1672  * instant. That is, it takes the page that would be accessed if a user
1673  * thread accesses the given user virtual address at that instant.
1674  *
1675  * This does not guarantee that the page exists in the user mappings when
1676  * get_user_pages returns, and there may even be a completely different
1677  * page there in some cases (eg. if mmapped pagecache has been invalidated
1678  * and subsequently re faulted). However it does guarantee that the page
1679  * won't be freed completely. And mostly callers simply care that the page
1680  * contains data that was valid *at some point in time*. Typically, an IO
1681  * or similar operation cannot guarantee anything stronger anyway because
1682  * locks can't be held over the syscall boundary.
1683  *
1684  * If write=0, the page must not be written to. If the page is written to,
1685  * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1686  * after the page is finished with, and before put_page is called.
1687  *
1688  * get_user_pages is typically used for fewer-copy IO operations, to get a
1689  * handle on the memory by some means other than accesses via the user virtual
1690  * addresses. The pages may be submitted for DMA to devices or accessed via
1691  * their kernel linear mapping (via the kmap APIs). Care should be taken to
1692  * use the correct cache flushing APIs.
1693  *
1694  * See also get_user_pages_fast, for performance critical applications.
1695  */
1696 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1697                 unsigned long start, int nr_pages, int write, int force,
1698                 struct page **pages, struct vm_area_struct **vmas)
1699 {
1700         int flags = FOLL_TOUCH;
1701
1702         if (pages)
1703                 flags |= FOLL_GET;
1704         if (write)
1705                 flags |= FOLL_WRITE;
1706         if (force)
1707                 flags |= FOLL_FORCE;
1708
1709         return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
1710                                 NULL);
1711 }
1712 EXPORT_SYMBOL(get_user_pages);
1713
1714 /**
1715  * get_dump_page() - pin user page in memory while writing it to core dump
1716  * @addr: user address
1717  *
1718  * Returns struct page pointer of user page pinned for dump,
1719  * to be freed afterwards by page_cache_release() or put_page().
1720  *
1721  * Returns NULL on any kind of failure - a hole must then be inserted into
1722  * the corefile, to preserve alignment with its headers; and also returns
1723  * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1724  * allowing a hole to be left in the corefile to save diskspace.
1725  *
1726  * Called without mmap_sem, but after all other threads have been killed.
1727  */
1728 #ifdef CONFIG_ELF_CORE
1729 struct page *get_dump_page(unsigned long addr)
1730 {
1731         struct vm_area_struct *vma;
1732         struct page *page;
1733
1734         if (__get_user_pages(current, current->mm, addr, 1,
1735                              FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
1736                              NULL) < 1)
1737                 return NULL;
1738         flush_cache_page(vma, addr, page_to_pfn(page));
1739         return page;
1740 }
1741 #endif /* CONFIG_ELF_CORE */
1742
1743 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1744                         spinlock_t **ptl)
1745 {
1746         pgd_t * pgd = pgd_offset(mm, addr);
1747         pud_t * pud = pud_alloc(mm, pgd, addr);
1748         if (pud) {
1749                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1750                 if (pmd) {
1751                         VM_BUG_ON(pmd_trans_huge(*pmd));
1752                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1753                 }
1754         }
1755         return NULL;
1756 }
1757
1758 /*
1759  * This is the old fallback for page remapping.
1760  *
1761  * For historical reasons, it only allows reserved pages. Only
1762  * old drivers should use this, and they needed to mark their
1763  * pages reserved for the old functions anyway.
1764  */
1765 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1766                         struct page *page, pgprot_t prot)
1767 {
1768         struct mm_struct *mm = vma->vm_mm;
1769         int retval;
1770         pte_t *pte;
1771         spinlock_t *ptl;
1772
1773         retval = -EINVAL;
1774         if (PageAnon(page))
1775                 goto out;
1776         retval = -ENOMEM;
1777         flush_dcache_page(page);
1778         pte = get_locked_pte(mm, addr, &ptl);
1779         if (!pte)
1780                 goto out;
1781         retval = -EBUSY;
1782         if (!pte_none(*pte))
1783                 goto out_unlock;
1784
1785         /* Ok, finally just insert the thing.. */
1786         get_page(page);
1787         inc_mm_counter_fast(mm, MM_FILEPAGES);
1788         page_add_file_rmap(page);
1789         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1790
1791         retval = 0;
1792         pte_unmap_unlock(pte, ptl);
1793         return retval;
1794 out_unlock:
1795         pte_unmap_unlock(pte, ptl);
1796 out:
1797         return retval;
1798 }
1799
1800 /**
1801  * vm_insert_page - insert single page into user vma
1802  * @vma: user vma to map to
1803  * @addr: target user address of this page
1804  * @page: source kernel page
1805  *
1806  * This allows drivers to insert individual pages they've allocated
1807  * into a user vma.
1808  *
1809  * The page has to be a nice clean _individual_ kernel allocation.
1810  * If you allocate a compound page, you need to have marked it as
1811  * such (__GFP_COMP), or manually just split the page up yourself
1812  * (see split_page()).
1813  *
1814  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1815  * took an arbitrary page protection parameter. This doesn't allow
1816  * that. Your vma protection will have to be set up correctly, which
1817  * means that if you want a shared writable mapping, you'd better
1818  * ask for a shared writable mapping!
1819  *
1820  * The page does not need to be reserved.
1821  */
1822 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1823                         struct page *page)
1824 {
1825         if (addr < vma->vm_start || addr >= vma->vm_end)
1826                 return -EFAULT;
1827         if (!page_count(page))
1828                 return -EINVAL;
1829         vma->vm_flags |= VM_INSERTPAGE;
1830         return insert_page(vma, addr, page, vma->vm_page_prot);
1831 }
1832 EXPORT_SYMBOL(vm_insert_page);
1833
1834 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1835                         unsigned long pfn, pgprot_t prot)
1836 {
1837         struct mm_struct *mm = vma->vm_mm;
1838         int retval;
1839         pte_t *pte, entry;
1840         spinlock_t *ptl;
1841
1842         retval = -ENOMEM;
1843         pte = get_locked_pte(mm, addr, &ptl);
1844         if (!pte)
1845                 goto out;
1846         retval = -EBUSY;
1847         if (!pte_none(*pte))
1848                 goto out_unlock;
1849
1850         /* Ok, finally just insert the thing.. */
1851         entry = pte_mkspecial(pfn_pte(pfn, prot));
1852         set_pte_at(mm, addr, pte, entry);
1853         update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1854
1855         retval = 0;
1856 out_unlock:
1857         pte_unmap_unlock(pte, ptl);
1858 out:
1859         return retval;
1860 }
1861
1862 /**
1863  * vm_insert_pfn - insert single pfn into user vma
1864  * @vma: user vma to map to
1865  * @addr: target user address of this page
1866  * @pfn: source kernel pfn
1867  *
1868  * Similar to vm_inert_page, this allows drivers to insert individual pages
1869  * they've allocated into a user vma. Same comments apply.
1870  *
1871  * This function should only be called from a vm_ops->fault handler, and
1872  * in that case the handler should return NULL.
1873  *
1874  * vma cannot be a COW mapping.
1875  *
1876  * As this is called only for pages that do not currently exist, we
1877  * do not need to flush old virtual caches or the TLB.
1878  */
1879 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1880                         unsigned long pfn)
1881 {
1882         int ret;
1883         pgprot_t pgprot = vma->vm_page_prot;
1884         /*
1885          * Technically, architectures with pte_special can avoid all these
1886          * restrictions (same for remap_pfn_range).  However we would like
1887          * consistency in testing and feature parity among all, so we should
1888          * try to keep these invariants in place for everybody.
1889          */
1890         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1891         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1892                                                 (VM_PFNMAP|VM_MIXEDMAP));
1893         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1894         BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1895
1896         if (addr < vma->vm_start || addr >= vma->vm_end)
1897                 return -EFAULT;
1898         if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1899                 return -EINVAL;
1900
1901         ret = insert_pfn(vma, addr, pfn, pgprot);
1902
1903         if (ret)
1904                 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
1905
1906         return ret;
1907 }
1908 EXPORT_SYMBOL(vm_insert_pfn);
1909
1910 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1911                         unsigned long pfn)
1912 {
1913         BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1914
1915         if (addr < vma->vm_start || addr >= vma->vm_end)
1916                 return -EFAULT;
1917
1918         /*
1919          * If we don't have pte special, then we have to use the pfn_valid()
1920          * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1921          * refcount the page if pfn_valid is true (hence insert_page rather
1922          * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
1923          * without pte special, it would there be refcounted as a normal page.
1924          */
1925         if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
1926                 struct page *page;
1927
1928                 page = pfn_to_page(pfn);
1929                 return insert_page(vma, addr, page, vma->vm_page_prot);
1930         }
1931         return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
1932 }
1933 EXPORT_SYMBOL(vm_insert_mixed);
1934
1935 /*
1936  * maps a range of physical memory into the requested pages. the old
1937  * mappings are removed. any references to nonexistent pages results
1938  * in null mappings (currently treated as "copy-on-access")
1939  */
1940 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1941                         unsigned long addr, unsigned long end,
1942                         unsigned long pfn, pgprot_t prot)
1943 {
1944         pte_t *pte;
1945         spinlock_t *ptl;
1946
1947         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1948         if (!pte)
1949                 return -ENOMEM;
1950         arch_enter_lazy_mmu_mode();
1951         do {
1952                 BUG_ON(!pte_none(*pte));
1953                 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1954                 pfn++;
1955         } while (pte++, addr += PAGE_SIZE, addr != end);
1956         arch_leave_lazy_mmu_mode();
1957         pte_unmap_unlock(pte - 1, ptl);
1958         return 0;
1959 }
1960
1961 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1962                         unsigned long addr, unsigned long end,
1963                         unsigned long pfn, pgprot_t prot)
1964 {
1965         pmd_t *pmd;
1966         unsigned long next;
1967
1968         pfn -= addr >> PAGE_SHIFT;
1969         pmd = pmd_alloc(mm, pud, addr);
1970         if (!pmd)
1971                 return -ENOMEM;
1972         VM_BUG_ON(pmd_trans_huge(*pmd));
1973         do {
1974                 next = pmd_addr_end(addr, end);
1975                 if (remap_pte_range(mm, pmd, addr, next,
1976                                 pfn + (addr >> PAGE_SHIFT), prot))
1977                         return -ENOMEM;
1978         } while (pmd++, addr = next, addr != end);
1979         return 0;
1980 }
1981
1982 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1983                         unsigned long addr, unsigned long end,
1984                         unsigned long pfn, pgprot_t prot)
1985 {
1986         pud_t *pud;
1987         unsigned long next;
1988
1989         pfn -= addr >> PAGE_SHIFT;
1990         pud = pud_alloc(mm, pgd, addr);
1991         if (!pud)
1992                 return -ENOMEM;
1993         do {
1994                 next = pud_addr_end(addr, end);
1995                 if (remap_pmd_range(mm, pud, addr, next,
1996                                 pfn + (addr >> PAGE_SHIFT), prot))
1997                         return -ENOMEM;
1998         } while (pud++, addr = next, addr != end);
1999         return 0;
2000 }
2001
2002 /**
2003  * remap_pfn_range - remap kernel memory to userspace
2004  * @vma: user vma to map to
2005  * @addr: target user address to start at
2006  * @pfn: physical address of kernel memory
2007  * @size: size of map area
2008  * @prot: page protection flags for this mapping
2009  *
2010  *  Note: this is only safe if the mm semaphore is held when called.
2011  */
2012 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2013                     unsigned long pfn, unsigned long size, pgprot_t prot)
2014 {
2015         pgd_t *pgd;
2016         unsigned long next;
2017         unsigned long end = addr + PAGE_ALIGN(size);
2018         struct mm_struct *mm = vma->vm_mm;
2019         int err;
2020
2021         /*
2022          * Physically remapped pages are special. Tell the
2023          * rest of the world about it:
2024          *   VM_IO tells people not to look at these pages
2025          *      (accesses can have side effects).
2026          *   VM_RESERVED is specified all over the place, because
2027          *      in 2.4 it kept swapout's vma scan off this vma; but
2028          *      in 2.6 the LRU scan won't even find its pages, so this
2029          *      flag means no more than count its pages in reserved_vm,
2030          *      and omit it from core dump, even when VM_IO turned off.
2031          *   VM_PFNMAP tells the core MM that the base pages are just
2032          *      raw PFN mappings, and do not have a "struct page" associated
2033          *      with them.
2034          *
2035          * There's a horrible special case to handle copy-on-write
2036          * behaviour that some programs depend on. We mark the "original"
2037          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2038          */
2039         if (addr == vma->vm_start && end == vma->vm_end) {
2040                 vma->vm_pgoff = pfn;
2041                 vma->vm_flags |= VM_PFN_AT_MMAP;
2042         } else if (is_cow_mapping(vma->vm_flags))
2043                 return -EINVAL;
2044
2045         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
2046
2047         err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
2048         if (err) {
2049                 /*
2050                  * To indicate that track_pfn related cleanup is not
2051                  * needed from higher level routine calling unmap_vmas
2052                  */
2053                 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
2054                 vma->vm_flags &= ~VM_PFN_AT_MMAP;
2055                 return -EINVAL;
2056         }
2057
2058         BUG_ON(addr >= end);
2059         pfn -= addr >> PAGE_SHIFT;
2060         pgd = pgd_offset(mm, addr);
2061         flush_cache_range(vma, addr, end);
2062         do {
2063                 next = pgd_addr_end(addr, end);
2064                 err = remap_pud_range(mm, pgd, addr, next,
2065                                 pfn + (addr >> PAGE_SHIFT), prot);
2066                 if (err)
2067                         break;
2068         } while (pgd++, addr = next, addr != end);
2069
2070         if (err)
2071                 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
2072
2073         return err;
2074 }
2075 EXPORT_SYMBOL(remap_pfn_range);
2076
2077 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2078                                      unsigned long addr, unsigned long end,
2079                                      pte_fn_t fn, void *data)
2080 {
2081         pte_t *pte;
2082         int err;
2083         pgtable_t token;
2084         spinlock_t *uninitialized_var(ptl);
2085
2086         pte = (mm == &init_mm) ?
2087                 pte_alloc_kernel(pmd, addr) :
2088                 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2089         if (!pte)
2090                 return -ENOMEM;
2091
2092         BUG_ON(pmd_huge(*pmd));
2093
2094         arch_enter_lazy_mmu_mode();
2095
2096         token = pmd_pgtable(*pmd);
2097
2098         do {
2099                 err = fn(pte++, token, addr, data);
2100                 if (err)
2101                         break;
2102         } while (addr += PAGE_SIZE, addr != end);
2103
2104         arch_leave_lazy_mmu_mode();
2105
2106         if (mm != &init_mm)
2107                 pte_unmap_unlock(pte-1, ptl);
2108         return err;
2109 }
2110
2111 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2112                                      unsigned long addr, unsigned long end,
2113                                      pte_fn_t fn, void *data)
2114 {
2115         pmd_t *pmd;
2116         unsigned long next;
2117         int err;
2118
2119         BUG_ON(pud_huge(*pud));
2120
2121         pmd = pmd_alloc(mm, pud, addr);
2122         if (!pmd)
2123                 return -ENOMEM;
2124         do {
2125                 next = pmd_addr_end(addr, end);
2126                 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2127                 if (err)
2128                         break;
2129         } while (pmd++, addr = next, addr != end);
2130         return err;
2131 }
2132
2133 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2134                                      unsigned long addr, unsigned long end,
2135                                      pte_fn_t fn, void *data)
2136 {
2137         pud_t *pud;
2138         unsigned long next;
2139         int err;
2140
2141         pud = pud_alloc(mm, pgd, addr);
2142         if (!pud)
2143                 return -ENOMEM;
2144         do {
2145                 next = pud_addr_end(addr, end);
2146                 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2147                 if (err)
2148                         break;
2149         } while (pud++, addr = next, addr != end);
2150         return err;
2151 }
2152
2153 /*
2154  * Scan a region of virtual memory, filling in page tables as necessary
2155  * and calling a provided function on each leaf page table.
2156  */
2157 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2158                         unsigned long size, pte_fn_t fn, void *data)
2159 {
2160         pgd_t *pgd;
2161         unsigned long next;
2162         unsigned long end = addr + size;
2163         int err;
2164
2165         BUG_ON(addr >= end);
2166         pgd = pgd_offset(mm, addr);
2167         do {
2168                 next = pgd_addr_end(addr, end);
2169                 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2170                 if (err)
2171                         break;
2172         } while (pgd++, addr = next, addr != end);
2173
2174         return err;
2175 }
2176 EXPORT_SYMBOL_GPL(apply_to_page_range);
2177
2178 /*
2179  * handle_pte_fault chooses page fault handler according to an entry
2180  * which was read non-atomically.  Before making any commitment, on
2181  * those architectures or configurations (e.g. i386 with PAE) which
2182  * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2183  * must check under lock before unmapping the pte and proceeding
2184  * (but do_wp_page is only called after already making such a check;
2185  * and do_anonymous_page can safely check later on).
2186  */
2187 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2188                                 pte_t *page_table, pte_t orig_pte)
2189 {
2190         int same = 1;
2191 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2192         if (sizeof(pte_t) > sizeof(unsigned long)) {
2193                 spinlock_t *ptl = pte_lockptr(mm, pmd);
2194                 spin_lock(ptl);
2195                 same = pte_same(*page_table, orig_pte);
2196                 spin_unlock(ptl);
2197         }
2198 #endif
2199         pte_unmap(page_table);
2200         return same;
2201 }
2202
2203 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2204 {
2205         /*
2206          * If the source page was a PFN mapping, we don't have
2207          * a "struct page" for it. We do a best-effort copy by
2208          * just copying from the original user address. If that
2209          * fails, we just zero-fill it. Live with it.
2210          */
2211         if (unlikely(!src)) {
2212                 void *kaddr = kmap_atomic(dst, KM_USER0);
2213                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2214
2215                 /*
2216                  * This really shouldn't fail, because the page is there
2217                  * in the page tables. But it might just be unreadable,
2218                  * in which case we just give up and fill the result with
2219                  * zeroes.
2220                  */
2221                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2222                         clear_page(kaddr);
2223                 kunmap_atomic(kaddr, KM_USER0);
2224                 flush_dcache_page(dst);
2225         } else
2226                 copy_user_highpage(dst, src, va, vma);
2227 }
2228
2229 /*
2230  * This routine handles present pages, when users try to write
2231  * to a shared page. It is done by copying the page to a new address
2232  * and decrementing the shared-page counter for the old page.
2233  *
2234  * Note that this routine assumes that the protection checks have been
2235  * done by the caller (the low-level page fault routine in most cases).
2236  * Thus we can safely just mark it writable once we've done any necessary
2237  * COW.
2238  *
2239  * We also mark the page dirty at this point even though the page will
2240  * change only once the write actually happens. This avoids a few races,
2241  * and potentially makes it more efficient.
2242  *
2243  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2244  * but allow concurrent faults), with pte both mapped and locked.
2245  * We return with mmap_sem still held, but pte unmapped and unlocked.
2246  */
2247 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2248                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2249                 spinlock_t *ptl, pte_t orig_pte)
2250         __releases(ptl)
2251 {
2252         struct page *old_page, *new_page;
2253         pte_t entry;
2254         int ret = 0;
2255         int page_mkwrite = 0;
2256         struct page *dirty_page = NULL;
2257
2258         old_page = vm_normal_page(vma, address, orig_pte);
2259         if (!old_page) {
2260                 /*
2261                  * VM_MIXEDMAP !pfn_valid() case
2262                  *
2263                  * We should not cow pages in a shared writeable mapping.
2264                  * Just mark the pages writable as we can't do any dirty
2265                  * accounting on raw pfn maps.
2266                  */
2267                 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2268                                      (VM_WRITE|VM_SHARED))
2269                         goto reuse;
2270                 goto gotten;
2271         }
2272
2273         /*
2274          * Take out anonymous pages first, anonymous shared vmas are
2275          * not dirty accountable.
2276          */
2277         if (PageAnon(old_page) && !PageKsm(old_page)) {
2278                 if (!trylock_page(old_page)) {
2279                         page_cache_get(old_page);
2280                         pte_unmap_unlock(page_table, ptl);
2281                         lock_page(old_page);
2282                         page_table = pte_offset_map_lock(mm, pmd, address,
2283                                                          &ptl);
2284                         if (!pte_same(*page_table, orig_pte)) {
2285                                 unlock_page(old_page);
2286                                 goto unlock;
2287                         }
2288                         page_cache_release(old_page);
2289                 }
2290                 if (reuse_swap_page(old_page)) {
2291                         /*
2292                          * The page is all ours.  Move it to our anon_vma so
2293                          * the rmap code will not search our parent or siblings.
2294                          * Protected against the rmap code by the page lock.
2295                          */
2296                         page_move_anon_rmap(old_page, vma, address);
2297                         unlock_page(old_page);
2298                         goto reuse;
2299                 }
2300                 unlock_page(old_page);
2301         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2302                                         (VM_WRITE|VM_SHARED))) {
2303                 /*
2304                  * Only catch write-faults on shared writable pages,
2305                  * read-only shared pages can get COWed by
2306                  * get_user_pages(.write=1, .force=1).
2307                  */
2308                 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2309                         struct vm_fault vmf;
2310                         int tmp;
2311
2312                         vmf.virtual_address = (void __user *)(address &
2313                                                                 PAGE_MASK);
2314                         vmf.pgoff = old_page->index;
2315                         vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2316                         vmf.page = old_page;
2317
2318                         /*
2319                          * Notify the address space that the page is about to
2320                          * become writable so that it can prohibit this or wait
2321                          * for the page to get into an appropriate state.
2322                          *
2323                          * We do this without the lock held, so that it can
2324                          * sleep if it needs to.
2325                          */
2326                         page_cache_get(old_page);
2327                         pte_unmap_unlock(page_table, ptl);
2328
2329                         tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2330                         if (unlikely(tmp &
2331                                         (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2332                                 ret = tmp;
2333                                 goto unwritable_page;
2334                         }
2335                         if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2336                                 lock_page(old_page);
2337                                 if (!old_page->mapping) {
2338                                         ret = 0; /* retry the fault */
2339                                         unlock_page(old_page);
2340                                         goto unwritable_page;
2341                                 }
2342                         } else
2343                                 VM_BUG_ON(!PageLocked(old_page));
2344
2345                         /*
2346                          * Since we dropped the lock we need to revalidate
2347                          * the PTE as someone else may have changed it.  If
2348                          * they did, we just return, as we can count on the
2349                          * MMU to tell us if they didn't also make it writable.
2350                          */
2351                         page_table = pte_offset_map_lock(mm, pmd, address,
2352                                                          &ptl);
2353                         if (!pte_same(*page_table, orig_pte)) {
2354                                 unlock_page(old_page);
2355                                 goto unlock;
2356                         }
2357
2358                         page_mkwrite = 1;
2359                 }
2360                 dirty_page = old_page;
2361                 get_page(dirty_page);
2362
2363 reuse:
2364                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2365                 entry = pte_mkyoung(orig_pte);
2366                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2367                 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2368                         update_mmu_cache(vma, address, page_table);
2369                 pte_unmap_unlock(page_table, ptl);
2370                 ret |= VM_FAULT_WRITE;
2371
2372                 if (!dirty_page)
2373                         return ret;
2374
2375                 /*
2376                  * Yes, Virginia, this is actually required to prevent a race
2377                  * with clear_page_dirty_for_io() from clearing the page dirty
2378                  * bit after it clear all dirty ptes, but before a racing
2379                  * do_wp_page installs a dirty pte.
2380                  *
2381                  * __do_fault is protected similarly.
2382                  */
2383                 if (!page_mkwrite) {
2384                         wait_on_page_locked(dirty_page);
2385                         set_page_dirty_balance(dirty_page, page_mkwrite);
2386                 }
2387                 put_page(dirty_page);
2388                 if (page_mkwrite) {
2389                         struct address_space *mapping = dirty_page->mapping;
2390
2391                         set_page_dirty(dirty_page);
2392                         unlock_page(dirty_page);
2393                         page_cache_release(dirty_page);
2394                         if (mapping)    {
2395                                 /*
2396                                  * Some device drivers do not set page.mapping
2397                                  * but still dirty their pages
2398                                  */
2399                                 balance_dirty_pages_ratelimited(mapping);
2400                         }
2401                 }
2402
2403                 /* file_update_time outside page_lock */
2404                 if (vma->vm_file)
2405                         file_update_time(vma->vm_file);
2406
2407                 return ret;
2408         }
2409
2410         /*
2411          * Ok, we need to copy. Oh, well..
2412          */
2413         page_cache_get(old_page);
2414 gotten:
2415         pte_unmap_unlock(page_table, ptl);
2416
2417         if (unlikely(anon_vma_prepare(vma)))
2418                 goto oom;
2419
2420         if (is_zero_pfn(pte_pfn(orig_pte))) {
2421                 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2422                 if (!new_page)
2423                         goto oom;
2424         } else {
2425                 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2426                 if (!new_page)
2427                         goto oom;
2428                 cow_user_page(new_page, old_page, address, vma);
2429         }
2430         __SetPageUptodate(new_page);
2431
2432         if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2433                 goto oom_free_new;
2434
2435         /*
2436          * Re-check the pte - we dropped the lock
2437          */
2438         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2439         if (likely(pte_same(*page_table, orig_pte))) {
2440                 if (old_page) {
2441                         if (!PageAnon(old_page)) {
2442                                 dec_mm_counter_fast(mm, MM_FILEPAGES);
2443                                 inc_mm_counter_fast(mm, MM_ANONPAGES);
2444                         }
2445                 } else
2446                         inc_mm_counter_fast(mm, MM_ANONPAGES);
2447                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2448                 entry = mk_pte(new_page, vma->vm_page_prot);
2449                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2450                 /*
2451                  * Clear the pte entry and flush it first, before updating the
2452                  * pte with the new entry. This will avoid a race condition
2453                  * seen in the presence of one thread doing SMC and another
2454                  * thread doing COW.
2455                  */
2456                 ptep_clear_flush(vma, address, page_table);
2457                 page_add_new_anon_rmap(new_page, vma, address);
2458                 /*
2459                  * We call the notify macro here because, when using secondary
2460                  * mmu page tables (such as kvm shadow page tables), we want the
2461                  * new page to be mapped directly into the secondary page table.
2462                  */
2463                 set_pte_at_notify(mm, address, page_table, entry);
2464                 update_mmu_cache(vma, address, page_table);
2465                 if (old_page) {
2466                         /*
2467                          * Only after switching the pte to the new page may
2468                          * we remove the mapcount here. Otherwise another
2469                          * process may come and find the rmap count decremented
2470                          * before the pte is switched to the new page, and
2471                          * "reuse" the old page writing into it while our pte
2472                          * here still points into it and can be read by other
2473                          * threads.
2474                          *
2475                          * The critical issue is to order this
2476                          * page_remove_rmap with the ptp_clear_flush above.
2477                          * Those stores are ordered by (if nothing else,)
2478                          * the barrier present in the atomic_add_negative
2479                          * in page_remove_rmap.
2480                          *
2481                          * Then the TLB flush in ptep_clear_flush ensures that
2482                          * no process can access the old page before the
2483                          * decremented mapcount is visible. And the old page
2484                          * cannot be reused until after the decremented
2485                          * mapcount is visible. So transitively, TLBs to
2486                          * old page will be flushed before it can be reused.
2487                          */
2488                         page_remove_rmap(old_page);
2489                 }
2490
2491                 /* Free the old page.. */
2492                 new_page = old_page;
2493                 ret |= VM_FAULT_WRITE;
2494         } else
2495                 mem_cgroup_uncharge_page(new_page);
2496
2497         if (new_page)
2498                 page_cache_release(new_page);
2499 unlock:
2500         pte_unmap_unlock(page_table, ptl);
2501         if (old_page) {
2502                 /*
2503                  * Don't let another task, with possibly unlocked vma,
2504                  * keep the mlocked page.
2505                  */
2506                 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2507                         lock_page(old_page);    /* LRU manipulation */
2508                         munlock_vma_page(old_page);
2509                         unlock_page(old_page);
2510                 }
2511                 page_cache_release(old_page);
2512         }
2513         return ret;
2514 oom_free_new:
2515         page_cache_release(new_page);
2516 oom:
2517         if (old_page) {
2518                 if (page_mkwrite) {
2519                         unlock_page(old_page);
2520                         page_cache_release(old_page);
2521                 }
2522                 page_cache_release(old_page);
2523         }
2524         return VM_FAULT_OOM;
2525
2526 unwritable_page:
2527         page_cache_release(old_page);
2528         return ret;
2529 }
2530
2531 /*
2532  * Helper functions for unmap_mapping_range().
2533  *
2534  * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
2535  *
2536  * We have to restart searching the prio_tree whenever we drop the lock,
2537  * since the iterator is only valid while the lock is held, and anyway
2538  * a later vma might be split and reinserted earlier while lock dropped.
2539  *
2540  * The list of nonlinear vmas could be handled more efficiently, using
2541  * a placeholder, but handle it in the same way until a need is shown.
2542  * It is important to search the prio_tree before nonlinear list: a vma
2543  * may become nonlinear and be shifted from prio_tree to nonlinear list
2544  * while the lock is dropped; but never shifted from list to prio_tree.
2545  *
2546  * In order to make forward progress despite restarting the search,
2547  * vm_truncate_count is used to mark a vma as now dealt with, so we can
2548  * quickly skip it next time around.  Since the prio_tree search only
2549  * shows us those vmas affected by unmapping the range in question, we
2550  * can't efficiently keep all vmas in step with mapping->truncate_count:
2551  * so instead reset them all whenever it wraps back to 0 (then go to 1).
2552  * mapping->truncate_count and vma->vm_truncate_count are protected by
2553  * i_mmap_lock.
2554  *
2555  * In order to make forward progress despite repeatedly restarting some
2556  * large vma, note the restart_addr from unmap_vmas when it breaks out:
2557  * and restart from that address when we reach that vma again.  It might
2558  * have been split or merged, shrunk or extended, but never shifted: so
2559  * restart_addr remains valid so long as it remains in the vma's range.
2560  * unmap_mapping_range forces truncate_count to leap over page-aligned
2561  * values so we can save vma's restart_addr in its truncate_count field.
2562  */
2563 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
2564
2565 static void reset_vma_truncate_counts(struct address_space *mapping)
2566 {
2567         struct vm_area_struct *vma;
2568         struct prio_tree_iter iter;
2569
2570         vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
2571                 vma->vm_truncate_count = 0;
2572         list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
2573                 vma->vm_truncate_count = 0;
2574 }
2575
2576 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
2577                 unsigned long start_addr, unsigned long end_addr,
2578                 struct zap_details *details)
2579 {
2580         unsigned long restart_addr;
2581         int need_break;
2582
2583         /*
2584          * files that support invalidating or truncating portions of the
2585          * file from under mmaped areas must have their ->fault function
2586          * return a locked page (and set VM_FAULT_LOCKED in the return).
2587          * This provides synchronisation against concurrent unmapping here.
2588          */
2589
2590 again:
2591         restart_addr = vma->vm_truncate_count;
2592         if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
2593                 start_addr = restart_addr;
2594                 if (start_addr >= end_addr) {
2595                         /* Top of vma has been split off since last time */
2596                         vma->vm_truncate_count = details->truncate_count;
2597                         return 0;
2598                 }
2599         }
2600
2601         restart_addr = zap_page_range(vma, start_addr,
2602                                         end_addr - start_addr, details);
2603         need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
2604
2605         if (restart_addr >= end_addr) {
2606                 /* We have now completed this vma: mark it so */
2607                 vma->vm_truncate_count = details->truncate_count;
2608                 if (!need_break)
2609                         return 0;
2610         } else {
2611                 /* Note restart_addr in vma's truncate_count field */
2612                 vma->vm_truncate_count = restart_addr;
2613                 if (!need_break)
2614                         goto again;
2615         }
2616
2617         spin_unlock(details->i_mmap_lock);
2618         cond_resched();
2619         spin_lock(details->i_mmap_lock);
2620         return -EINTR;
2621 }
2622
2623 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2624                                             struct zap_details *details)
2625 {
2626         struct vm_area_struct *vma;
2627         struct prio_tree_iter iter;
2628         pgoff_t vba, vea, zba, zea;
2629
2630 restart:
2631         vma_prio_tree_foreach(vma, &iter, root,
2632                         details->first_index, details->last_index) {
2633                 /* Skip quickly over those we have already dealt with */
2634                 if (vma->vm_truncate_count == details->truncate_count)
2635                         continue;
2636
2637                 vba = vma->vm_pgoff;
2638                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2639                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2640                 zba = details->first_index;
2641                 if (zba < vba)
2642                         zba = vba;
2643                 zea = details->last_index;
2644                 if (zea > vea)
2645                         zea = vea;
2646
2647                 if (unmap_mapping_range_vma(vma,
2648                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2649                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2650                                 details) < 0)
2651                         goto restart;
2652         }
2653 }
2654
2655 static inline void unmap_mapping_range_list(struct list_head *head,
2656                                             struct zap_details *details)
2657 {
2658         struct vm_area_struct *vma;
2659
2660         /*
2661          * In nonlinear VMAs there is no correspondence between virtual address
2662          * offset and file offset.  So we must perform an exhaustive search
2663          * across *all* the pages in each nonlinear VMA, not just the pages
2664          * whose virtual address lies outside the file truncation point.
2665          */
2666 restart:
2667         list_for_each_entry(vma, head, shared.vm_set.list) {
2668                 /* Skip quickly over those we have already dealt with */
2669                 if (vma->vm_truncate_count == details->truncate_count)
2670                         continue;
2671                 details->nonlinear_vma = vma;
2672                 if (unmap_mapping_range_vma(vma, vma->vm_start,
2673                                         vma->vm_end, details) < 0)
2674                         goto restart;
2675         }
2676 }
2677
2678 /**
2679  * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2680  * @mapping: the address space containing mmaps to be unmapped.
2681  * @holebegin: byte in first page to unmap, relative to the start of
2682  * the underlying file.  This will be rounded down to a PAGE_SIZE
2683  * boundary.  Note that this is different from truncate_pagecache(), which
2684  * must keep the partial page.  In contrast, we must get rid of
2685  * partial pages.
2686  * @holelen: size of prospective hole in bytes.  This will be rounded
2687  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2688  * end of the file.
2689  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2690  * but 0 when invalidating pagecache, don't throw away private data.
2691  */
2692 void unmap_mapping_range(struct address_space *mapping,
2693                 loff_t const holebegin, loff_t const holelen, int even_cows)
2694 {
2695         struct zap_details details;
2696         pgoff_t hba = holebegin >> PAGE_SHIFT;
2697         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2698
2699         /* Check for overflow. */
2700         if (sizeof(holelen) > sizeof(hlen)) {
2701                 long long holeend =
2702                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2703                 if (holeend & ~(long long)ULONG_MAX)
2704                         hlen = ULONG_MAX - hba + 1;
2705         }
2706
2707         details.check_mapping = even_cows? NULL: mapping;
2708         details.nonlinear_vma = NULL;
2709         details.first_index = hba;
2710         details.last_index = hba + hlen - 1;
2711         if (details.last_index < details.first_index)
2712                 details.last_index = ULONG_MAX;
2713         details.i_mmap_lock = &mapping->i_mmap_lock;
2714
2715         mutex_lock(&mapping->unmap_mutex);
2716         spin_lock(&mapping->i_mmap_lock);
2717
2718         /* Protect against endless unmapping loops */
2719         mapping->truncate_count++;
2720         if (unlikely(is_restart_addr(mapping->truncate_count))) {
2721                 if (mapping->truncate_count == 0)
2722                         reset_vma_truncate_counts(mapping);
2723                 mapping->truncate_count++;
2724         }
2725         details.truncate_count = mapping->truncate_count;
2726
2727         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2728                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2729         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2730                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2731         spin_unlock(&mapping->i_mmap_lock);
2732         mutex_unlock(&mapping->unmap_mutex);
2733 }
2734 EXPORT_SYMBOL(unmap_mapping_range);
2735
2736 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
2737 {
2738         struct address_space *mapping = inode->i_mapping;
2739
2740         /*
2741          * If the underlying filesystem is not going to provide
2742          * a way to truncate a range of blocks (punch a hole) -
2743          * we should return failure right now.
2744          */
2745         if (!inode->i_op->truncate_range)
2746                 return -ENOSYS;
2747
2748         mutex_lock(&inode->i_mutex);
2749         down_write(&inode->i_alloc_sem);
2750         unmap_mapping_range(mapping, offset, (end - offset), 1);
2751         truncate_inode_pages_range(mapping, offset, end);
2752         unmap_mapping_range(mapping, offset, (end - offset), 1);
2753         inode->i_op->truncate_range(inode, offset, end);
2754         up_write(&inode->i_alloc_sem);
2755         mutex_unlock(&inode->i_mutex);
2756
2757         return 0;
2758 }
2759
2760 /*
2761  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2762  * but allow concurrent faults), and pte mapped but not yet locked.
2763  * We return with mmap_sem still held, but pte unmapped and unlocked.
2764  */
2765 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2766                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2767                 unsigned int flags, pte_t orig_pte)
2768 {
2769         spinlock_t *ptl;
2770         struct page *page, *swapcache = NULL;
2771         swp_entry_t entry;
2772         pte_t pte;
2773         int locked;
2774         struct mem_cgroup *ptr;
2775         int exclusive = 0;
2776         int ret = 0;
2777
2778         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2779                 goto out;
2780
2781         entry = pte_to_swp_entry(orig_pte);
2782         if (unlikely(non_swap_entry(entry))) {
2783                 if (is_migration_entry(entry)) {
2784                         migration_entry_wait(mm, pmd, address);
2785                 } else if (is_hwpoison_entry(entry)) {
2786                         ret = VM_FAULT_HWPOISON;
2787                 } else {
2788                         print_bad_pte(vma, address, orig_pte, NULL);
2789                         ret = VM_FAULT_SIGBUS;
2790                 }
2791                 goto out;
2792         }
2793         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2794         page = lookup_swap_cache(entry);
2795         if (!page) {
2796                 grab_swap_token(mm); /* Contend for token _before_ read-in */
2797                 page = swapin_readahead(entry,
2798                                         GFP_HIGHUSER_MOVABLE, vma, address);
2799                 if (!page) {
2800                         /*
2801                          * Back out if somebody else faulted in this pte
2802                          * while we released the pte lock.
2803                          */
2804                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2805                         if (likely(pte_same(*page_table, orig_pte)))
2806                                 ret = VM_FAULT_OOM;
2807                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2808                         goto unlock;
2809                 }
2810
2811                 /* Had to read the page from swap area: Major fault */
2812                 ret = VM_FAULT_MAJOR;
2813                 count_vm_event(PGMAJFAULT);
2814         } else if (PageHWPoison(page)) {
2815                 /*
2816                  * hwpoisoned dirty swapcache pages are kept for killing
2817                  * owner processes (which may be unknown at hwpoison time)
2818                  */
2819                 ret = VM_FAULT_HWPOISON;
2820                 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2821                 goto out_release;
2822         }
2823
2824         locked = lock_page_or_retry(page, mm, flags);
2825         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2826         if (!locked) {
2827                 ret |= VM_FAULT_RETRY;
2828                 goto out_release;
2829         }
2830
2831         /*
2832          * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2833          * release the swapcache from under us.  The page pin, and pte_same
2834          * test below, are not enough to exclude that.  Even if it is still
2835          * swapcache, we need to check that the page's swap has not changed.
2836          */
2837         if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2838                 goto out_page;
2839
2840         if (ksm_might_need_to_copy(page, vma, address)) {
2841                 swapcache = page;
2842                 page = ksm_does_need_to_copy(page, vma, address);
2843
2844                 if (unlikely(!page)) {
2845                         ret = VM_FAULT_OOM;
2846                         page = swapcache;
2847                         swapcache = NULL;
2848                         goto out_page;
2849                 }
2850         }
2851
2852         if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2853                 ret = VM_FAULT_OOM;
2854                 goto out_page;
2855         }
2856
2857         /*
2858          * Back out if somebody else already faulted in this pte.
2859          */
2860         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2861         if (unlikely(!pte_same(*page_table, orig_pte)))
2862                 goto out_nomap;
2863
2864         if (unlikely(!PageUptodate(page))) {
2865                 ret = VM_FAULT_SIGBUS;
2866                 goto out_nomap;
2867         }
2868
2869         /*
2870          * The page isn't present yet, go ahead with the fault.
2871          *
2872          * Be careful about the sequence of operations here.
2873          * To get its accounting right, reuse_swap_page() must be called
2874          * while the page is counted on swap but not yet in mapcount i.e.
2875          * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2876          * must be called after the swap_free(), or it will never succeed.
2877          * Because delete_from_swap_page() may be called by reuse_swap_page(),
2878          * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2879          * in page->private. In this case, a record in swap_cgroup  is silently
2880          * discarded at swap_free().
2881          */
2882
2883         inc_mm_counter_fast(mm, MM_ANONPAGES);
2884         dec_mm_counter_fast(mm, MM_SWAPENTS);
2885         pte = mk_pte(page, vma->vm_page_prot);
2886         if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2887                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2888                 flags &= ~FAULT_FLAG_WRITE;
2889                 ret |= VM_FAULT_WRITE;
2890                 exclusive = 1;
2891         }
2892         flush_icache_page(vma, page);
2893         set_pte_at(mm, address, page_table, pte);
2894         do_page_add_anon_rmap(page, vma, address, exclusive);
2895         /* It's better to call commit-charge after rmap is established */
2896         mem_cgroup_commit_charge_swapin(page, ptr);
2897
2898         swap_free(entry);
2899         if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2900                 try_to_free_swap(page);
2901         unlock_page(page);
2902         if (swapcache) {
2903                 /*
2904                  * Hold the lock to avoid the swap entry to be reused
2905                  * until we take the PT lock for the pte_same() check
2906                  * (to avoid false positives from pte_same). For
2907                  * further safety release the lock after the swap_free
2908                  * so that the swap count won't change under a
2909                  * parallel locked swapcache.
2910                  */
2911                 unlock_page(swapcache);
2912                 page_cache_release(swapcache);
2913         }
2914
2915         if (flags & FAULT_FLAG_WRITE) {
2916                 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2917                 if (ret & VM_FAULT_ERROR)
2918                         ret &= VM_FAULT_ERROR;
2919                 goto out;
2920         }
2921
2922         /* No need to invalidate - it was non-present before */
2923         update_mmu_cache(vma, address, page_table);
2924 unlock:
2925         pte_unmap_unlock(page_table, ptl);
2926 out:
2927         return ret;
2928 out_nomap:
2929         mem_cgroup_cancel_charge_swapin(ptr);
2930         pte_unmap_unlock(page_table, ptl);
2931 out_page:
2932         unlock_page(page);
2933 out_release:
2934         page_cache_release(page);
2935         if (swapcache) {
2936                 unlock_page(swapcache);
2937                 page_cache_release(swapcache);
2938         }
2939         return ret;
2940 }
2941
2942 /*
2943  * This is like a special single-page "expand_{down|up}wards()",
2944  * except we must first make sure that 'address{-|+}PAGE_SIZE'
2945  * doesn't hit another vma.
2946  */
2947 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
2948 {
2949         address &= PAGE_MASK;
2950         if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
2951                 struct vm_area_struct *prev = vma->vm_prev;
2952
2953                 /*
2954                  * Is there a mapping abutting this one below?
2955                  *
2956                  * That's only ok if it's the same stack mapping
2957                  * that has gotten split..
2958                  */
2959                 if (prev && prev->vm_end == address)
2960                         return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
2961
2962                 expand_stack(vma, address - PAGE_SIZE);
2963         }
2964         if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
2965                 struct vm_area_struct *next = vma->vm_next;
2966
2967                 /* As VM_GROWSDOWN but s/below/above/ */
2968                 if (next && next->vm_start == address + PAGE_SIZE)
2969                         return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
2970
2971                 expand_upwards(vma, address + PAGE_SIZE);
2972         }
2973         return 0;
2974 }
2975
2976 /*
2977  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2978  * but allow concurrent faults), and pte mapped but not yet locked.
2979  * We return with mmap_sem still held, but pte unmapped and unlocked.
2980  */
2981 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2982                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2983                 unsigned int flags)
2984 {
2985         struct page *page;
2986         spinlock_t *ptl;
2987         pte_t entry;
2988
2989         pte_unmap(page_table);
2990
2991         /* Check if we need to add a guard page to the stack */
2992         if (check_stack_guard_page(vma, address) < 0)
2993                 return VM_FAULT_SIGBUS;
2994
2995         /* Use the zero-page for reads */
2996         if (!(flags & FAULT_FLAG_WRITE)) {
2997                 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
2998                                                 vma->vm_page_prot));
2999                 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3000                 if (!pte_none(*page_table))
3001                         goto unlock;
3002                 goto setpte;
3003         }
3004
3005         /* Allocate our own private page. */
3006         if (unlikely(anon_vma_prepare(vma)))
3007                 goto oom;
3008         page = alloc_zeroed_user_highpage_movable(vma, address);
3009         if (!page)
3010                 goto oom;
3011         __SetPageUptodate(page);
3012
3013         if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3014                 goto oom_free_page;
3015
3016         entry = mk_pte(page, vma->vm_page_prot);
3017         if (vma->vm_flags & VM_WRITE)
3018                 entry = pte_mkwrite(pte_mkdirty(entry));
3019
3020         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3021         if (!pte_none(*page_table))
3022                 goto release;
3023
3024         inc_mm_counter_fast(mm, MM_ANONPAGES);
3025         page_add_new_anon_rmap(page, vma, address);
3026 setpte:
3027         set_pte_at(mm, address, page_table, entry);
3028
3029         /* No need to invalidate - it was non-present before */
3030         update_mmu_cache(vma, address, page_table);
3031 unlock:
3032         pte_unmap_unlock(page_table, ptl);
3033         return 0;
3034 release:
3035         mem_cgroup_uncharge_page(page);
3036         page_cache_release(page);
3037         goto unlock;
3038 oom_free_page:
3039         page_cache_release(page);
3040 oom:
3041         return VM_FAULT_OOM;
3042 }
3043
3044 /*
3045  * __do_fault() tries to create a new page mapping. It aggressively
3046  * tries to share with existing pages, but makes a separate copy if
3047  * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3048  * the next page fault.
3049  *
3050  * As this is called only for pages that do not currently exist, we
3051  * do not need to flush old virtual caches or the TLB.
3052  *
3053  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3054  * but allow concurrent faults), and pte neither mapped nor locked.
3055  * We return with mmap_sem still held, but pte unmapped and unlocked.
3056  */
3057 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3058                 unsigned long address, pmd_t *pmd,
3059                 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3060 {
3061         pte_t *page_table;
3062         spinlock_t *ptl;
3063         struct page *page;
3064         pte_t entry;
3065         int anon = 0;
3066         int charged = 0;
3067         struct page *dirty_page = NULL;
3068         struct vm_fault vmf;
3069         int ret;
3070         int page_mkwrite = 0;
3071
3072         vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3073         vmf.pgoff = pgoff;
3074         vmf.flags = flags;
3075         vmf.page = NULL;
3076
3077         ret = vma->vm_ops->fault(vma, &vmf);
3078         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3079                             VM_FAULT_RETRY)))
3080                 return ret;
3081
3082         if (unlikely(PageHWPoison(vmf.page))) {
3083                 if (ret & VM_FAULT_LOCKED)
3084                         unlock_page(vmf.page);
3085                 return VM_FAULT_HWPOISON;
3086         }
3087
3088         /*
3089          * For consistency in subsequent calls, make the faulted page always
3090          * locked.
3091          */
3092         if (unlikely(!(ret & VM_FAULT_LOCKED)))
3093                 lock_page(vmf.page);
3094         else
3095                 VM_BUG_ON(!PageLocked(vmf.page));
3096
3097         /*
3098          * Should we do an early C-O-W break?
3099          */
3100         page = vmf.page;
3101         if (flags & FAULT_FLAG_WRITE) {
3102                 if (!(vma->vm_flags & VM_SHARED)) {
3103                         anon = 1;
3104                         if (unlikely(anon_vma_prepare(vma))) {
3105                                 ret = VM_FAULT_OOM;
3106                                 goto out;
3107                         }
3108                         page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
3109                                                 vma, address);
3110                         if (!page) {
3111                                 ret = VM_FAULT_OOM;
3112                                 goto out;
3113                         }
3114                         if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
3115                                 ret = VM_FAULT_OOM;
3116                                 page_cache_release(page);
3117                                 goto out;
3118                         }
3119                         charged = 1;
3120                         copy_user_highpage(page, vmf.page, address, vma);
3121                         __SetPageUptodate(page);
3122                 } else {
3123                         /*
3124                          * If the page will be shareable, see if the backing
3125                          * address space wants to know that the page is about
3126                          * to become writable
3127                          */
3128                         if (vma->vm_ops->page_mkwrite) {
3129                                 int tmp;
3130
3131                                 unlock_page(page);
3132                                 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3133                                 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3134                                 if (unlikely(tmp &
3135                                           (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3136                                         ret = tmp;
3137                                         goto unwritable_page;
3138                                 }
3139                                 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3140                                         lock_page(page);
3141                                         if (!page->mapping) {
3142                                                 ret = 0; /* retry the fault */
3143                                                 unlock_page(page);
3144                                                 goto unwritable_page;
3145                                         }
3146                                 } else
3147                                         VM_BUG_ON(!PageLocked(page));
3148                                 page_mkwrite = 1;
3149                         }
3150                 }
3151
3152         }
3153
3154         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3155
3156         /*
3157          * This silly early PAGE_DIRTY setting removes a race
3158          * due to the bad i386 page protection. But it's valid
3159          * for other architectures too.
3160          *
3161          * Note that if FAULT_FLAG_WRITE is set, we either now have
3162          * an exclusive copy of the page, or this is a shared mapping,
3163          * so we can make it writable and dirty to avoid having to
3164          * handle that later.
3165          */
3166         /* Only go through if we didn't race with anybody else... */
3167         if (likely(pte_same(*page_table, orig_pte))) {
3168                 flush_icache_page(vma, page);
3169                 entry = mk_pte(page, vma->vm_page_prot);
3170                 if (flags & FAULT_FLAG_WRITE)
3171                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3172                 if (anon) {
3173                         inc_mm_counter_fast(mm, MM_ANONPAGES);
3174                         page_add_new_anon_rmap(page, vma, address);
3175                 } else {
3176                         inc_mm_counter_fast(mm, MM_FILEPAGES);
3177                         page_add_file_rmap(page);
3178                         if (flags & FAULT_FLAG_WRITE) {
3179                                 dirty_page = page;
3180                                 get_page(dirty_page);
3181                         }
3182                 }
3183                 set_pte_at(mm, address, page_table, entry);
3184
3185                 /* no need to invalidate: a not-present page won't be cached */
3186                 update_mmu_cache(vma, address, page_table);
3187         } else {
3188                 if (charged)
3189                         mem_cgroup_uncharge_page(page);
3190                 if (anon)
3191                         page_cache_release(page);
3192                 else
3193                         anon = 1; /* no anon but release faulted_page */
3194         }
3195
3196         pte_unmap_unlock(page_table, ptl);
3197
3198 out:
3199         if (dirty_page) {
3200                 struct address_space *mapping = page->mapping;
3201
3202                 if (set_page_dirty(dirty_page))
3203                         page_mkwrite = 1;
3204                 unlock_page(dirty_page);
3205                 put_page(dirty_page);
3206                 if (page_mkwrite && mapping) {
3207                         /*
3208                          * Some device drivers do not set page.mapping but still
3209                          * dirty their pages
3210                          */
3211                         balance_dirty_pages_ratelimited(mapping);
3212                 }
3213
3214                 /* file_update_time outside page_lock */
3215                 if (vma->vm_file)
3216                         file_update_time(vma->vm_file);
3217         } else {
3218                 unlock_page(vmf.page);
3219                 if (anon)
3220                         page_cache_release(vmf.page);
3221         }
3222
3223         return ret;
3224
3225 unwritable_page:
3226         page_cache_release(page);
3227         return ret;
3228 }
3229
3230 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3231                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3232                 unsigned int flags, pte_t orig_pte)
3233 {
3234         pgoff_t pgoff = (((address & PAGE_MASK)
3235                         - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3236
3237         pte_unmap(page_table);
3238         return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3239 }
3240
3241 /*
3242  * Fault of a previously existing named mapping. Repopulate the pte
3243  * from the encoded file_pte if possible. This enables swappable
3244  * nonlinear vmas.
3245  *
3246  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3247  * but allow concurrent faults), and pte mapped but not yet locked.
3248  * We return with mmap_sem still held, but pte unmapped and unlocked.
3249  */
3250 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3251                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3252                 unsigned int flags, pte_t orig_pte)
3253 {
3254         pgoff_t pgoff;
3255
3256         flags |= FAULT_FLAG_NONLINEAR;
3257
3258         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3259                 return 0;
3260
3261         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3262                 /*
3263                  * Page table corrupted: show pte and kill process.
3264                  */
3265                 print_bad_pte(vma, address, orig_pte, NULL);
3266                 return VM_FAULT_SIGBUS;
3267         }
3268
3269         pgoff = pte_to_pgoff(orig_pte);
3270         return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3271 }
3272
3273 /*
3274  * These routines also need to handle stuff like marking pages dirty
3275  * and/or accessed for architectures that don't do it in hardware (most
3276  * RISC architectures).  The early dirtying is also good on the i386.
3277  *
3278  * There is also a hook called "update_mmu_cache()" that architectures
3279  * with external mmu caches can use to update those (ie the Sparc or
3280  * PowerPC hashed page tables that act as extended TLBs).
3281  *
3282  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3283  * but allow concurrent faults), and pte mapped but not yet locked.
3284  * We return with mmap_sem still held, but pte unmapped and unlocked.
3285  */
3286 int handle_pte_fault(struct mm_struct *mm,
3287                      struct vm_area_struct *vma, unsigned long address,
3288                      pte_t *pte, pmd_t *pmd, unsigned int flags)
3289 {
3290         pte_t entry;
3291         spinlock_t *ptl;
3292
3293         entry = *pte;
3294         if (!pte_present(entry)) {
3295                 if (pte_none(entry)) {
3296                         if (vma->vm_ops) {
3297                                 if (likely(vma->vm_ops->fault))
3298                                         return do_linear_fault(mm, vma, address,
3299                                                 pte, pmd, flags, entry);
3300                         }
3301                         return do_anonymous_page(mm, vma, address,
3302                                                  pte, pmd, flags);
3303                 }
3304                 if (pte_file(entry))
3305                         return do_nonlinear_fault(mm, vma, address,
3306                                         pte, pmd, flags, entry);
3307                 return do_swap_page(mm, vma, address,
3308                                         pte, pmd, flags, entry);
3309         }
3310
3311         ptl = pte_lockptr(mm, pmd);
3312         spin_lock(ptl);
3313         if (unlikely(!pte_same(*pte, entry)))
3314                 goto unlock;
3315         if (flags & FAULT_FLAG_WRITE) {
3316                 if (!pte_write(entry))
3317                         return do_wp_page(mm, vma, address,
3318                                         pte, pmd, ptl, entry);
3319                 entry = pte_mkdirty(entry);
3320         }
3321         entry = pte_mkyoung(entry);
3322         if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3323                 update_mmu_cache(vma, address, pte);
3324         } else {
3325                 /*
3326                  * This is needed only for protection faults but the arch code
3327                  * is not yet telling us if this is a protection fault or not.
3328                  * This still avoids useless tlb flushes for .text page faults
3329                  * with threads.
3330                  */
3331                 if (flags & FAULT_FLAG_WRITE)
3332                         flush_tlb_fix_spurious_fault(vma, address);
3333         }
3334 unlock:
3335         pte_unmap_unlock(pte, ptl);
3336         return 0;
3337 }
3338
3339 /*
3340  * By the time we get here, we already hold the mm semaphore
3341  */
3342 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3343                 unsigned long address, unsigned int flags)
3344 {
3345         pgd_t *pgd;
3346         pud_t *pud;
3347         pmd_t *pmd;
3348         pte_t *pte;
3349
3350         __set_current_state(TASK_RUNNING);
3351
3352         count_vm_event(PGFAULT);
3353
3354         /* do counter updates before entering really critical section. */
3355         check_sync_rss_stat(current);
3356
3357         if (unlikely(is_vm_hugetlb_page(vma)))
3358                 return hugetlb_fault(mm, vma, address, flags);
3359
3360         pgd = pgd_offset(mm, address);
3361         pud = pud_alloc(mm, pgd, address);
3362         if (!pud)
3363                 return VM_FAULT_OOM;
3364         pmd = pmd_alloc(mm, pud, address);
3365         if (!pmd)
3366                 return VM_FAULT_OOM;
3367         if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3368                 if (!vma->vm_ops)
3369                         return do_huge_pmd_anonymous_page(mm, vma, address,
3370                                                           pmd, flags);
3371         } else {
3372                 pmd_t orig_pmd = *pmd;
3373                 barrier();
3374                 if (pmd_trans_huge(orig_pmd)) {
3375                         if (flags & FAULT_FLAG_WRITE &&
3376                             !pmd_write(orig_pmd) &&
3377                             !pmd_trans_splitting(orig_pmd))
3378                                 return do_huge_pmd_wp_page(mm, vma, address,
3379                                                            pmd, orig_pmd);
3380                         return 0;
3381                 }
3382         }
3383
3384         /*
3385          * Use __pte_alloc instead of pte_alloc_map, because we can't
3386          * run pte_offset_map on the pmd, if an huge pmd could
3387          * materialize from under us from a different thread.
3388          */
3389         if (unlikely(__pte_alloc(mm, vma, pmd, address)))
3390                 return VM_FAULT_OOM;
3391         /* if an huge pmd materialized from under us just retry later */
3392         if (unlikely(pmd_trans_huge(*pmd)))
3393                 return 0;
3394         /*
3395          * A regular pmd is established and it can't morph into a huge pmd
3396          * from under us anymore at this point because we hold the mmap_sem
3397          * read mode and khugepaged takes it in write mode. So now it's
3398          * safe to run pte_offset_map().
3399          */
3400         pte = pte_offset_map(pmd, address);
3401
3402         return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3403 }
3404
3405 #ifndef __PAGETABLE_PUD_FOLDED
3406 /*
3407  * Allocate page upper directory.
3408  * We've already handled the fast-path in-line.
3409  */
3410 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3411 {
3412         pud_t *new = pud_alloc_one(mm, address);
3413         if (!new)
3414                 return -ENOMEM;
3415
3416         smp_wmb(); /* See comment in __pte_alloc */
3417
3418         spin_lock(&mm->page_table_lock);
3419         if (pgd_present(*pgd))          /* Another has populated it */
3420                 pud_free(mm, new);
3421         else
3422                 pgd_populate(mm, pgd, new);
3423         spin_unlock(&mm->page_table_lock);
3424         return 0;
3425 }
3426 #endif /* __PAGETABLE_PUD_FOLDED */
3427
3428 #ifndef __PAGETABLE_PMD_FOLDED
3429 /*
3430  * Allocate page middle directory.
3431  * We've already handled the fast-path in-line.
3432  */
3433 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3434 {
3435         pmd_t *new = pmd_alloc_one(mm, address);
3436         if (!new)
3437                 return -ENOMEM;
3438
3439         smp_wmb(); /* See comment in __pte_alloc */
3440
3441         spin_lock(&mm->page_table_lock);
3442 #ifndef __ARCH_HAS_4LEVEL_HACK
3443         if (pud_present(*pud))          /* Another has populated it */
3444                 pmd_free(mm, new);
3445         else
3446                 pud_populate(mm, pud, new);
3447 #else
3448         if (pgd_present(*pud))          /* Another has populated it */
3449                 pmd_free(mm, new);
3450         else
3451                 pgd_populate(mm, pud, new);
3452 #endif /* __ARCH_HAS_4LEVEL_HACK */
3453         spin_unlock(&mm->page_table_lock);
3454         return 0;
3455 }
3456 #endif /* __PAGETABLE_PMD_FOLDED */
3457
3458 int make_pages_present(unsigned long addr, unsigned long end)
3459 {
3460         int ret, len, write;
3461         struct vm_area_struct * vma;
3462
3463         vma = find_vma(current->mm, addr);
3464         if (!vma)
3465                 return -ENOMEM;
3466         /*
3467          * We want to touch writable mappings with a write fault in order
3468          * to break COW, except for shared mappings because these don't COW
3469          * and we would not want to dirty them for nothing.
3470          */
3471         write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;
3472         BUG_ON(addr >= end);
3473         BUG_ON(end > vma->vm_end);
3474         len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3475         ret = get_user_pages(current, current->mm, addr,
3476                         len, write, 0, NULL, NULL);
3477         if (ret < 0)
3478                 return ret;
3479         return ret == len ? 0 : -EFAULT;
3480 }
3481
3482 #if !defined(__HAVE_ARCH_GATE_AREA)
3483
3484 #if defined(AT_SYSINFO_EHDR)
3485 static struct vm_area_struct gate_vma;
3486
3487 static int __init gate_vma_init(void)
3488 {
3489         gate_vma.vm_mm = NULL;
3490         gate_vma.vm_start = FIXADDR_USER_START;
3491         gate_vma.vm_end = FIXADDR_USER_END;
3492         gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3493         gate_vma.vm_page_prot = __P101;
3494         /*
3495          * Make sure the vDSO gets into every core dump.
3496          * Dumping its contents makes post-mortem fully interpretable later
3497          * without matching up the same kernel and hardware config to see
3498          * what PC values meant.
3499          */
3500         gate_vma.vm_flags |= VM_ALWAYSDUMP;
3501         return 0;
3502 }
3503 __initcall(gate_vma_init);
3504 #endif
3505
3506 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
3507 {
3508 #ifdef AT_SYSINFO_EHDR
3509         return &gate_vma;
3510 #else
3511         return NULL;
3512 #endif
3513 }
3514
3515 int in_gate_area_no_mm(unsigned long addr)
3516 {
3517 #ifdef AT_SYSINFO_EHDR
3518         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3519                 return 1;
3520 #endif
3521         return 0;
3522 }
3523
3524 #endif  /* __HAVE_ARCH_GATE_AREA */
3525
3526 static int __follow_pte(struct mm_struct *mm, unsigned long address,
3527                 pte_t **ptepp, spinlock_t **ptlp)
3528 {
3529         pgd_t *pgd;
3530         pud_t *pud;
3531         pmd_t *pmd;
3532         pte_t *ptep;
3533
3534         pgd = pgd_offset(mm, address);
3535         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3536                 goto out;
3537
3538         pud = pud_offset(pgd, address);
3539         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3540                 goto out;
3541
3542         pmd = pmd_offset(pud, address);
3543         VM_BUG_ON(pmd_trans_huge(*pmd));
3544         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3545                 goto out;
3546
3547         /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3548         if (pmd_huge(*pmd))
3549                 goto out;
3550
3551         ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3552         if (!ptep)
3553                 goto out;
3554         if (!pte_present(*ptep))
3555                 goto unlock;
3556         *ptepp = ptep;
3557         return 0;
3558 unlock:
3559         pte_unmap_unlock(ptep, *ptlp);
3560 out:
3561         return -EINVAL;
3562 }
3563
3564 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3565                              pte_t **ptepp, spinlock_t **ptlp)
3566 {
3567         int res;
3568
3569         /* (void) is needed to make gcc happy */
3570         (void) __cond_lock(*ptlp,
3571                            !(res = __follow_pte(mm, address, ptepp, ptlp)));
3572         return res;
3573 }
3574
3575 /**
3576  * follow_pfn - look up PFN at a user virtual address
3577  * @vma: memory mapping
3578  * @address: user virtual address
3579  * @pfn: location to store found PFN
3580  *
3581  * Only IO mappings and raw PFN mappings are allowed.
3582  *
3583  * Returns zero and the pfn at @pfn on success, -ve otherwise.
3584  */
3585 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3586         unsigned long *pfn)
3587 {
3588         int ret = -EINVAL;
3589         spinlock_t *ptl;
3590         pte_t *ptep;
3591
3592         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3593                 return ret;
3594
3595         ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3596         if (ret)
3597                 return ret;
3598         *pfn = pte_pfn(*ptep);
3599         pte_unmap_unlock(ptep, ptl);
3600         return 0;
3601 }
3602 EXPORT_SYMBOL(follow_pfn);
3603
3604 #ifdef CONFIG_HAVE_IOREMAP_PROT
3605 int follow_phys(struct vm_area_struct *vma,
3606                 unsigned long address, unsigned int flags,
3607                 unsigned long *prot, resource_size_t *phys)
3608 {
3609         int ret = -EINVAL;
3610         pte_t *ptep, pte;
3611         spinlock_t *ptl;
3612
3613         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3614                 goto out;
3615
3616         if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3617                 goto out;
3618         pte = *ptep;
3619
3620         if ((flags & FOLL_WRITE) && !pte_write(pte))
3621                 goto unlock;
3622
3623         *prot = pgprot_val(pte_pgprot(pte));
3624         *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3625
3626         ret = 0;
3627 unlock:
3628         pte_unmap_unlock(ptep, ptl);
3629 out:
3630         return ret;
3631 }
3632
3633 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3634                         void *buf, int len, int write)
3635 {
3636         resource_size_t phys_addr;
3637         unsigned long prot = 0;
3638         void __iomem *maddr;
3639         int offset = addr & (PAGE_SIZE-1);
3640
3641         if (follow_phys(vma, addr, write, &prot, &phys_addr))
3642                 return -EINVAL;
3643
3644         maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3645         if (write)
3646                 memcpy_toio(maddr + offset, buf, len);
3647         else
3648                 memcpy_fromio(buf, maddr + offset, len);
3649         iounmap(maddr);
3650
3651         return len;
3652 }
3653 #endif
3654
3655 /*
3656  * Access another process' address space as given in mm.  If non-NULL, use the
3657  * given task for page fault accounting.
3658  */
3659 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3660                 unsigned long addr, void *buf, int len, int write)
3661 {
3662         struct vm_area_struct *vma;
3663         void *old_buf = buf;
3664
3665         down_read(&mm->mmap_sem);
3666         /* ignore errors, just check how much was successfully transferred */
3667         while (len) {
3668                 int bytes, ret, offset;
3669                 void *maddr;
3670                 struct page *page = NULL;
3671
3672                 ret = get_user_pages(tsk, mm, addr, 1,
3673                                 write, 1, &page, &vma);
3674                 if (ret <= 0) {
3675                         /*
3676                          * Check if this is a VM_IO | VM_PFNMAP VMA, which
3677                          * we can access using slightly different code.
3678                          */
3679 #ifdef CONFIG_HAVE_IOREMAP_PROT
3680                         vma = find_vma(mm, addr);
3681                         if (!vma)
3682                                 break;
3683                         if (vma->vm_ops && vma->vm_ops->access)
3684                                 ret = vma->vm_ops->access(vma, addr, buf,
3685                                                           len, write);
3686                         if (ret <= 0)
3687 #endif
3688                                 break;
3689                         bytes = ret;
3690                 } else {
3691                         bytes = len;
3692                         offset = addr & (PAGE_SIZE-1);
3693                         if (bytes > PAGE_SIZE-offset)
3694                                 bytes = PAGE_SIZE-offset;
3695
3696                         maddr = kmap(page);
3697                         if (write) {
3698                                 copy_to_user_page(vma, page, addr,
3699                                                   maddr + offset, buf, bytes);
3700                                 set_page_dirty_lock(page);
3701                         } else {
3702                                 copy_from_user_page(vma, page, addr,
3703                                                     buf, maddr + offset, bytes);
3704                         }
3705                         kunmap(page);
3706                         page_cache_release(page);
3707                 }
3708                 len -= bytes;
3709                 buf += bytes;
3710                 addr += bytes;
3711         }
3712         up_read(&mm->mmap_sem);
3713
3714         return buf - old_buf;
3715 }
3716
3717 /**
3718  * access_remote_vm - access another process' address space
3719  * @mm:         the mm_struct of the target address space
3720  * @addr:       start address to access
3721  * @buf:        source or destination buffer
3722  * @len:        number of bytes to transfer
3723  * @write:      whether the access is a write
3724  *
3725  * The caller must hold a reference on @mm.
3726  */
3727 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3728                 void *buf, int len, int write)
3729 {
3730         return __access_remote_vm(NULL, mm, addr, buf, len, write);
3731 }
3732
3733 /*
3734  * Access another process' address space.
3735  * Source/target buffer must be kernel space,
3736  * Do not walk the page table directly, use get_user_pages
3737  */
3738 int access_process_vm(struct task_struct *tsk, unsigned long addr,
3739                 void *buf, int len, int write)
3740 {
3741         struct mm_struct *mm;
3742         int ret;
3743
3744         mm = get_task_mm(tsk);
3745         if (!mm)
3746                 return 0;
3747
3748         ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3749         mmput(mm);
3750
3751         return ret;
3752 }
3753
3754 /*
3755  * Print the name of a VMA.
3756  */
3757 void print_vma_addr(char *prefix, unsigned long ip)
3758 {
3759         struct mm_struct *mm = current->mm;
3760         struct vm_area_struct *vma;
3761
3762         /*
3763          * Do not print if we are in atomic
3764          * contexts (in exception stacks, etc.):
3765          */
3766         if (preempt_count())
3767                 return;
3768
3769         down_read(&mm->mmap_sem);
3770         vma = find_vma(mm, ip);
3771         if (vma && vma->vm_file) {
3772                 struct file *f = vma->vm_file;
3773                 char *buf = (char *)__get_free_page(GFP_KERNEL);
3774                 if (buf) {
3775                         char *p, *s;
3776
3777                         p = d_path(&f->f_path, buf, PAGE_SIZE);
3778                         if (IS_ERR(p))
3779                                 p = "?";
3780                         s = strrchr(p, '/');
3781                         if (s)
3782                                 p = s+1;
3783                         printk("%s%s[%lx+%lx]", prefix, p,
3784                                         vma->vm_start,
3785                                         vma->vm_end - vma->vm_start);
3786                         free_page((unsigned long)buf);
3787                 }
3788         }
3789         up_read(&current->mm->mmap_sem);
3790 }
3791
3792 #ifdef CONFIG_PROVE_LOCKING
3793 void might_fault(void)
3794 {
3795         /*
3796          * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3797          * holding the mmap_sem, this is safe because kernel memory doesn't
3798          * get paged out, therefore we'll never actually fault, and the
3799          * below annotations will generate false positives.
3800          */
3801         if (segment_eq(get_fs(), KERNEL_DS))
3802                 return;
3803
3804         might_sleep();
3805         /*
3806          * it would be nicer only to annotate paths which are not under
3807          * pagefault_disable, however that requires a larger audit and
3808          * providing helpers like get_user_atomic.
3809          */
3810         if (!in_atomic() && current->mm)
3811                 might_lock_read(&current->mm->mmap_sem);
3812 }
3813 EXPORT_SYMBOL(might_fault);
3814 #endif
3815
3816 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3817 static void clear_gigantic_page(struct page *page,
3818                                 unsigned long addr,
3819                                 unsigned int pages_per_huge_page)
3820 {
3821         int i;
3822         struct page *p = page;
3823
3824         might_sleep();
3825         for (i = 0; i < pages_per_huge_page;
3826              i++, p = mem_map_next(p, page, i)) {
3827                 cond_resched();
3828                 clear_user_highpage(p, addr + i * PAGE_SIZE);
3829         }
3830 }
3831 void clear_huge_page(struct page *page,
3832                      unsigned long addr, unsigned int pages_per_huge_page)
3833 {
3834         int i;
3835
3836         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3837                 clear_gigantic_page(page, addr, pages_per_huge_page);
3838                 return;
3839         }
3840
3841         might_sleep();
3842         for (i = 0; i < pages_per_huge_page; i++) {
3843                 cond_resched();
3844                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3845         }
3846 }
3847
3848 static void copy_user_gigantic_page(struct page *dst, struct page *src,
3849                                     unsigned long addr,
3850                                     struct vm_area_struct *vma,
3851                                     unsigned int pages_per_huge_page)
3852 {
3853         int i;
3854         struct page *dst_base = dst;
3855         struct page *src_base = src;
3856
3857         for (i = 0; i < pages_per_huge_page; ) {
3858                 cond_resched();
3859                 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3860
3861                 i++;
3862                 dst = mem_map_next(dst, dst_base, i);
3863                 src = mem_map_next(src, src_base, i);
3864         }
3865 }
3866
3867 void copy_user_huge_page(struct page *dst, struct page *src,
3868                          unsigned long addr, struct vm_area_struct *vma,
3869                          unsigned int pages_per_huge_page)
3870 {
3871         int i;
3872
3873         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3874                 copy_user_gigantic_page(dst, src, addr, vma,
3875                                         pages_per_huge_page);
3876                 return;
3877         }
3878
3879         might_sleep();
3880         for (i = 0; i < pages_per_huge_page; i++) {
3881                 cond_resched();
3882                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3883         }
3884 }
3885 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */