tty: fix vt_compat_ioctl
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / mm / memory.c
blob7e91b5f9f690e4ae9d7c3e58bc1530c995311089
1 /*
2 * linux/mm/memory.c
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
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
13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14 * pages started 02.12.91, seems to work. - Linus.
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.
20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
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.
32 * 05.04.94 - Multi-page memory management added for v1.1.
33 * Idea by Alex Bligh (alex@cconcepts.co.uk)
35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36 * (Gerhard.Wichert@pdb.siemens.de)
38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
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>
60 #include <asm/io.h>
61 #include <asm/pgalloc.h>
62 #include <asm/uaccess.h>
63 #include <asm/tlb.h>
64 #include <asm/tlbflush.h>
65 #include <asm/pgtable.h>
67 #include "internal.h"
69 #ifndef CONFIG_NEED_MULTIPLE_NODES
70 /* use the per-pgdat data instead for discontigmem - mbligh */
71 unsigned long max_mapnr;
72 struct page *mem_map;
74 EXPORT_SYMBOL(max_mapnr);
75 EXPORT_SYMBOL(mem_map);
76 #endif
78 unsigned long num_physpages;
80 * A number of key systems in x86 including ioremap() rely on the assumption
81 * that high_memory defines the upper bound on direct map memory, then end
82 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
83 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
84 * and ZONE_HIGHMEM.
86 void * high_memory;
88 EXPORT_SYMBOL(num_physpages);
89 EXPORT_SYMBOL(high_memory);
92 * Randomize the address space (stacks, mmaps, brk, etc.).
94 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
95 * as ancient (libc5 based) binaries can segfault. )
97 int randomize_va_space __read_mostly =
98 #ifdef CONFIG_COMPAT_BRK
100 #else
102 #endif
104 static int __init disable_randmaps(char *s)
106 randomize_va_space = 0;
107 return 1;
109 __setup("norandmaps", disable_randmaps);
111 unsigned long zero_pfn __read_mostly;
112 unsigned long highest_memmap_pfn __read_mostly;
115 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
117 static int __init init_zero_pfn(void)
119 zero_pfn = page_to_pfn(ZERO_PAGE(0));
120 return 0;
122 core_initcall(init_zero_pfn);
125 * If a p?d_bad entry is found while walking page tables, report
126 * the error, before resetting entry to p?d_none. Usually (but
127 * very seldom) called out from the p?d_none_or_clear_bad macros.
130 void pgd_clear_bad(pgd_t *pgd)
132 pgd_ERROR(*pgd);
133 pgd_clear(pgd);
136 void pud_clear_bad(pud_t *pud)
138 pud_ERROR(*pud);
139 pud_clear(pud);
142 void pmd_clear_bad(pmd_t *pmd)
144 pmd_ERROR(*pmd);
145 pmd_clear(pmd);
149 * Note: this doesn't free the actual pages themselves. That
150 * has been handled earlier when unmapping all the memory regions.
152 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
153 unsigned long addr)
155 pgtable_t token = pmd_pgtable(*pmd);
156 pmd_clear(pmd);
157 pte_free_tlb(tlb, token, addr);
158 tlb->mm->nr_ptes--;
161 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
162 unsigned long addr, unsigned long end,
163 unsigned long floor, unsigned long ceiling)
165 pmd_t *pmd;
166 unsigned long next;
167 unsigned long start;
169 start = addr;
170 pmd = pmd_offset(pud, addr);
171 do {
172 next = pmd_addr_end(addr, end);
173 if (pmd_none_or_clear_bad(pmd))
174 continue;
175 free_pte_range(tlb, pmd, addr);
176 } while (pmd++, addr = next, addr != end);
178 start &= PUD_MASK;
179 if (start < floor)
180 return;
181 if (ceiling) {
182 ceiling &= PUD_MASK;
183 if (!ceiling)
184 return;
186 if (end - 1 > ceiling - 1)
187 return;
189 pmd = pmd_offset(pud, start);
190 pud_clear(pud);
191 pmd_free_tlb(tlb, pmd, start);
194 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
195 unsigned long addr, unsigned long end,
196 unsigned long floor, unsigned long ceiling)
198 pud_t *pud;
199 unsigned long next;
200 unsigned long start;
202 start = addr;
203 pud = pud_offset(pgd, addr);
204 do {
205 next = pud_addr_end(addr, end);
206 if (pud_none_or_clear_bad(pud))
207 continue;
208 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
209 } while (pud++, addr = next, addr != end);
211 start &= PGDIR_MASK;
212 if (start < floor)
213 return;
214 if (ceiling) {
215 ceiling &= PGDIR_MASK;
216 if (!ceiling)
217 return;
219 if (end - 1 > ceiling - 1)
220 return;
222 pud = pud_offset(pgd, start);
223 pgd_clear(pgd);
224 pud_free_tlb(tlb, pud, start);
228 * This function frees user-level page tables of a process.
230 * Must be called with pagetable lock held.
232 void free_pgd_range(struct mmu_gather *tlb,
233 unsigned long addr, unsigned long end,
234 unsigned long floor, unsigned long ceiling)
236 pgd_t *pgd;
237 unsigned long next;
238 unsigned long start;
241 * The next few lines have given us lots of grief...
243 * Why are we testing PMD* at this top level? Because often
244 * there will be no work to do at all, and we'd prefer not to
245 * go all the way down to the bottom just to discover that.
247 * Why all these "- 1"s? Because 0 represents both the bottom
248 * of the address space and the top of it (using -1 for the
249 * top wouldn't help much: the masks would do the wrong thing).
250 * The rule is that addr 0 and floor 0 refer to the bottom of
251 * the address space, but end 0 and ceiling 0 refer to the top
252 * Comparisons need to use "end - 1" and "ceiling - 1" (though
253 * that end 0 case should be mythical).
255 * Wherever addr is brought up or ceiling brought down, we must
256 * be careful to reject "the opposite 0" before it confuses the
257 * subsequent tests. But what about where end is brought down
258 * by PMD_SIZE below? no, end can't go down to 0 there.
260 * Whereas we round start (addr) and ceiling down, by different
261 * masks at different levels, in order to test whether a table
262 * now has no other vmas using it, so can be freed, we don't
263 * bother to round floor or end up - the tests don't need that.
266 addr &= PMD_MASK;
267 if (addr < floor) {
268 addr += PMD_SIZE;
269 if (!addr)
270 return;
272 if (ceiling) {
273 ceiling &= PMD_MASK;
274 if (!ceiling)
275 return;
277 if (end - 1 > ceiling - 1)
278 end -= PMD_SIZE;
279 if (addr > end - 1)
280 return;
282 start = addr;
283 pgd = pgd_offset(tlb->mm, addr);
284 do {
285 next = pgd_addr_end(addr, end);
286 if (pgd_none_or_clear_bad(pgd))
287 continue;
288 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
289 } while (pgd++, addr = next, addr != end);
292 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
293 unsigned long floor, unsigned long ceiling)
295 while (vma) {
296 struct vm_area_struct *next = vma->vm_next;
297 unsigned long addr = vma->vm_start;
300 * Hide vma from rmap and truncate_pagecache before freeing
301 * pgtables
303 anon_vma_unlink(vma);
304 unlink_file_vma(vma);
306 if (is_vm_hugetlb_page(vma)) {
307 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
308 floor, next? next->vm_start: ceiling);
309 } else {
311 * Optimization: gather nearby vmas into one call down
313 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
314 && !is_vm_hugetlb_page(next)) {
315 vma = next;
316 next = vma->vm_next;
317 anon_vma_unlink(vma);
318 unlink_file_vma(vma);
320 free_pgd_range(tlb, addr, vma->vm_end,
321 floor, next? next->vm_start: ceiling);
323 vma = next;
327 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
329 pgtable_t new = pte_alloc_one(mm, address);
330 if (!new)
331 return -ENOMEM;
334 * Ensure all pte setup (eg. pte page lock and page clearing) are
335 * visible before the pte is made visible to other CPUs by being
336 * put into page tables.
338 * The other side of the story is the pointer chasing in the page
339 * table walking code (when walking the page table without locking;
340 * ie. most of the time). Fortunately, these data accesses consist
341 * of a chain of data-dependent loads, meaning most CPUs (alpha
342 * being the notable exception) will already guarantee loads are
343 * seen in-order. See the alpha page table accessors for the
344 * smp_read_barrier_depends() barriers in page table walking code.
346 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
348 spin_lock(&mm->page_table_lock);
349 if (!pmd_present(*pmd)) { /* Has another populated it ? */
350 mm->nr_ptes++;
351 pmd_populate(mm, pmd, new);
352 new = NULL;
354 spin_unlock(&mm->page_table_lock);
355 if (new)
356 pte_free(mm, new);
357 return 0;
360 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
362 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
363 if (!new)
364 return -ENOMEM;
366 smp_wmb(); /* See comment in __pte_alloc */
368 spin_lock(&init_mm.page_table_lock);
369 if (!pmd_present(*pmd)) { /* Has another populated it ? */
370 pmd_populate_kernel(&init_mm, pmd, new);
371 new = NULL;
373 spin_unlock(&init_mm.page_table_lock);
374 if (new)
375 pte_free_kernel(&init_mm, new);
376 return 0;
379 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
381 if (file_rss)
382 add_mm_counter(mm, file_rss, file_rss);
383 if (anon_rss)
384 add_mm_counter(mm, anon_rss, anon_rss);
388 * This function is called to print an error when a bad pte
389 * is found. For example, we might have a PFN-mapped pte in
390 * a region that doesn't allow it.
392 * The calling function must still handle the error.
394 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
395 pte_t pte, struct page *page)
397 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
398 pud_t *pud = pud_offset(pgd, addr);
399 pmd_t *pmd = pmd_offset(pud, addr);
400 struct address_space *mapping;
401 pgoff_t index;
402 static unsigned long resume;
403 static unsigned long nr_shown;
404 static unsigned long nr_unshown;
407 * Allow a burst of 60 reports, then keep quiet for that minute;
408 * or allow a steady drip of one report per second.
410 if (nr_shown == 60) {
411 if (time_before(jiffies, resume)) {
412 nr_unshown++;
413 return;
415 if (nr_unshown) {
416 printk(KERN_ALERT
417 "BUG: Bad page map: %lu messages suppressed\n",
418 nr_unshown);
419 nr_unshown = 0;
421 nr_shown = 0;
423 if (nr_shown++ == 0)
424 resume = jiffies + 60 * HZ;
426 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
427 index = linear_page_index(vma, addr);
429 printk(KERN_ALERT
430 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
431 current->comm,
432 (long long)pte_val(pte), (long long)pmd_val(*pmd));
433 if (page) {
434 printk(KERN_ALERT
435 "page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n",
436 page, (void *)page->flags, page_count(page),
437 page_mapcount(page), page->mapping, page->index);
439 printk(KERN_ALERT
440 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
441 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
443 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
445 if (vma->vm_ops)
446 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
447 (unsigned long)vma->vm_ops->fault);
448 if (vma->vm_file && vma->vm_file->f_op)
449 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
450 (unsigned long)vma->vm_file->f_op->mmap);
451 dump_stack();
452 add_taint(TAINT_BAD_PAGE);
455 static inline int is_cow_mapping(unsigned int flags)
457 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
460 #ifndef is_zero_pfn
461 static inline int is_zero_pfn(unsigned long pfn)
463 return pfn == zero_pfn;
465 #endif
467 #ifndef my_zero_pfn
468 static inline unsigned long my_zero_pfn(unsigned long addr)
470 return zero_pfn;
472 #endif
475 * vm_normal_page -- This function gets the "struct page" associated with a pte.
477 * "Special" mappings do not wish to be associated with a "struct page" (either
478 * it doesn't exist, or it exists but they don't want to touch it). In this
479 * case, NULL is returned here. "Normal" mappings do have a struct page.
481 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
482 * pte bit, in which case this function is trivial. Secondly, an architecture
483 * may not have a spare pte bit, which requires a more complicated scheme,
484 * described below.
486 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
487 * special mapping (even if there are underlying and valid "struct pages").
488 * COWed pages of a VM_PFNMAP are always normal.
490 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
491 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
492 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
493 * mapping will always honor the rule
495 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
497 * And for normal mappings this is false.
499 * This restricts such mappings to be a linear translation from virtual address
500 * to pfn. To get around this restriction, we allow arbitrary mappings so long
501 * as the vma is not a COW mapping; in that case, we know that all ptes are
502 * special (because none can have been COWed).
505 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
507 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
508 * page" backing, however the difference is that _all_ pages with a struct
509 * page (that is, those where pfn_valid is true) are refcounted and considered
510 * normal pages by the VM. The disadvantage is that pages are refcounted
511 * (which can be slower and simply not an option for some PFNMAP users). The
512 * advantage is that we don't have to follow the strict linearity rule of
513 * PFNMAP mappings in order to support COWable mappings.
516 #ifdef __HAVE_ARCH_PTE_SPECIAL
517 # define HAVE_PTE_SPECIAL 1
518 #else
519 # define HAVE_PTE_SPECIAL 0
520 #endif
521 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
522 pte_t pte)
524 unsigned long pfn = pte_pfn(pte);
526 if (HAVE_PTE_SPECIAL) {
527 if (likely(!pte_special(pte)))
528 goto check_pfn;
529 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
530 return NULL;
531 if (!is_zero_pfn(pfn))
532 print_bad_pte(vma, addr, pte, NULL);
533 return NULL;
536 /* !HAVE_PTE_SPECIAL case follows: */
538 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
539 if (vma->vm_flags & VM_MIXEDMAP) {
540 if (!pfn_valid(pfn))
541 return NULL;
542 goto out;
543 } else {
544 unsigned long off;
545 off = (addr - vma->vm_start) >> PAGE_SHIFT;
546 if (pfn == vma->vm_pgoff + off)
547 return NULL;
548 if (!is_cow_mapping(vma->vm_flags))
549 return NULL;
553 if (is_zero_pfn(pfn))
554 return NULL;
555 check_pfn:
556 if (unlikely(pfn > highest_memmap_pfn)) {
557 print_bad_pte(vma, addr, pte, NULL);
558 return NULL;
562 * NOTE! We still have PageReserved() pages in the page tables.
563 * eg. VDSO mappings can cause them to exist.
565 out:
566 return pfn_to_page(pfn);
570 * copy one vm_area from one task to the other. Assumes the page tables
571 * already present in the new task to be cleared in the whole range
572 * covered by this vma.
575 static inline void
576 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
577 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
578 unsigned long addr, int *rss)
580 unsigned long vm_flags = vma->vm_flags;
581 pte_t pte = *src_pte;
582 struct page *page;
584 /* pte contains position in swap or file, so copy. */
585 if (unlikely(!pte_present(pte))) {
586 if (!pte_file(pte)) {
587 swp_entry_t entry = pte_to_swp_entry(pte);
589 swap_duplicate(entry);
590 /* make sure dst_mm is on swapoff's mmlist. */
591 if (unlikely(list_empty(&dst_mm->mmlist))) {
592 spin_lock(&mmlist_lock);
593 if (list_empty(&dst_mm->mmlist))
594 list_add(&dst_mm->mmlist,
595 &src_mm->mmlist);
596 spin_unlock(&mmlist_lock);
598 if (is_write_migration_entry(entry) &&
599 is_cow_mapping(vm_flags)) {
601 * COW mappings require pages in both parent
602 * and child to be set to read.
604 make_migration_entry_read(&entry);
605 pte = swp_entry_to_pte(entry);
606 set_pte_at(src_mm, addr, src_pte, pte);
609 goto out_set_pte;
613 * If it's a COW mapping, write protect it both
614 * in the parent and the child
616 if (is_cow_mapping(vm_flags)) {
617 ptep_set_wrprotect(src_mm, addr, src_pte);
618 pte = pte_wrprotect(pte);
622 * If it's a shared mapping, mark it clean in
623 * the child
625 if (vm_flags & VM_SHARED)
626 pte = pte_mkclean(pte);
627 pte = pte_mkold(pte);
629 page = vm_normal_page(vma, addr, pte);
630 if (page) {
631 get_page(page);
632 page_dup_rmap(page);
633 rss[PageAnon(page)]++;
636 out_set_pte:
637 set_pte_at(dst_mm, addr, dst_pte, pte);
640 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
641 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
642 unsigned long addr, unsigned long end)
644 pte_t *src_pte, *dst_pte;
645 spinlock_t *src_ptl, *dst_ptl;
646 int progress = 0;
647 int rss[2];
649 again:
650 rss[1] = rss[0] = 0;
651 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
652 if (!dst_pte)
653 return -ENOMEM;
654 src_pte = pte_offset_map_nested(src_pmd, addr);
655 src_ptl = pte_lockptr(src_mm, src_pmd);
656 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
657 arch_enter_lazy_mmu_mode();
659 do {
661 * We are holding two locks at this point - either of them
662 * could generate latencies in another task on another CPU.
664 if (progress >= 32) {
665 progress = 0;
666 if (need_resched() ||
667 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
668 break;
670 if (pte_none(*src_pte)) {
671 progress++;
672 continue;
674 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
675 progress += 8;
676 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
678 arch_leave_lazy_mmu_mode();
679 spin_unlock(src_ptl);
680 pte_unmap_nested(src_pte - 1);
681 add_mm_rss(dst_mm, rss[0], rss[1]);
682 pte_unmap_unlock(dst_pte - 1, dst_ptl);
683 cond_resched();
684 if (addr != end)
685 goto again;
686 return 0;
689 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
690 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
691 unsigned long addr, unsigned long end)
693 pmd_t *src_pmd, *dst_pmd;
694 unsigned long next;
696 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
697 if (!dst_pmd)
698 return -ENOMEM;
699 src_pmd = pmd_offset(src_pud, addr);
700 do {
701 next = pmd_addr_end(addr, end);
702 if (pmd_none_or_clear_bad(src_pmd))
703 continue;
704 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
705 vma, addr, next))
706 return -ENOMEM;
707 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
708 return 0;
711 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
712 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
713 unsigned long addr, unsigned long end)
715 pud_t *src_pud, *dst_pud;
716 unsigned long next;
718 dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
719 if (!dst_pud)
720 return -ENOMEM;
721 src_pud = pud_offset(src_pgd, addr);
722 do {
723 next = pud_addr_end(addr, end);
724 if (pud_none_or_clear_bad(src_pud))
725 continue;
726 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
727 vma, addr, next))
728 return -ENOMEM;
729 } while (dst_pud++, src_pud++, addr = next, addr != end);
730 return 0;
733 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
734 struct vm_area_struct *vma)
736 pgd_t *src_pgd, *dst_pgd;
737 unsigned long next;
738 unsigned long addr = vma->vm_start;
739 unsigned long end = vma->vm_end;
740 int ret;
743 * Don't copy ptes where a page fault will fill them correctly.
744 * Fork becomes much lighter when there are big shared or private
745 * readonly mappings. The tradeoff is that copy_page_range is more
746 * efficient than faulting.
748 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
749 if (!vma->anon_vma)
750 return 0;
753 if (is_vm_hugetlb_page(vma))
754 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
756 if (unlikely(is_pfn_mapping(vma))) {
758 * We do not free on error cases below as remove_vma
759 * gets called on error from higher level routine
761 ret = track_pfn_vma_copy(vma);
762 if (ret)
763 return ret;
767 * We need to invalidate the secondary MMU mappings only when
768 * there could be a permission downgrade on the ptes of the
769 * parent mm. And a permission downgrade will only happen if
770 * is_cow_mapping() returns true.
772 if (is_cow_mapping(vma->vm_flags))
773 mmu_notifier_invalidate_range_start(src_mm, addr, end);
775 ret = 0;
776 dst_pgd = pgd_offset(dst_mm, addr);
777 src_pgd = pgd_offset(src_mm, addr);
778 do {
779 next = pgd_addr_end(addr, end);
780 if (pgd_none_or_clear_bad(src_pgd))
781 continue;
782 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
783 vma, addr, next))) {
784 ret = -ENOMEM;
785 break;
787 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
789 if (is_cow_mapping(vma->vm_flags))
790 mmu_notifier_invalidate_range_end(src_mm,
791 vma->vm_start, end);
792 return ret;
795 static unsigned long zap_pte_range(struct mmu_gather *tlb,
796 struct vm_area_struct *vma, pmd_t *pmd,
797 unsigned long addr, unsigned long end,
798 long *zap_work, struct zap_details *details)
800 struct mm_struct *mm = tlb->mm;
801 pte_t *pte;
802 spinlock_t *ptl;
803 int file_rss = 0;
804 int anon_rss = 0;
806 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
807 arch_enter_lazy_mmu_mode();
808 do {
809 pte_t ptent = *pte;
810 if (pte_none(ptent)) {
811 (*zap_work)--;
812 continue;
815 (*zap_work) -= PAGE_SIZE;
817 if (pte_present(ptent)) {
818 struct page *page;
820 page = vm_normal_page(vma, addr, ptent);
821 if (unlikely(details) && page) {
823 * unmap_shared_mapping_pages() wants to
824 * invalidate cache without truncating:
825 * unmap shared but keep private pages.
827 if (details->check_mapping &&
828 details->check_mapping != page->mapping)
829 continue;
831 * Each page->index must be checked when
832 * invalidating or truncating nonlinear.
834 if (details->nonlinear_vma &&
835 (page->index < details->first_index ||
836 page->index > details->last_index))
837 continue;
839 ptent = ptep_get_and_clear_full(mm, addr, pte,
840 tlb->fullmm);
841 tlb_remove_tlb_entry(tlb, pte, addr);
842 if (unlikely(!page))
843 continue;
844 if (unlikely(details) && details->nonlinear_vma
845 && linear_page_index(details->nonlinear_vma,
846 addr) != page->index)
847 set_pte_at(mm, addr, pte,
848 pgoff_to_pte(page->index));
849 if (PageAnon(page))
850 anon_rss--;
851 else {
852 if (pte_dirty(ptent))
853 set_page_dirty(page);
854 if (pte_young(ptent) &&
855 likely(!VM_SequentialReadHint(vma)))
856 mark_page_accessed(page);
857 file_rss--;
859 page_remove_rmap(page);
860 if (unlikely(page_mapcount(page) < 0))
861 print_bad_pte(vma, addr, ptent, page);
862 tlb_remove_page(tlb, page);
863 continue;
866 * If details->check_mapping, we leave swap entries;
867 * if details->nonlinear_vma, we leave file entries.
869 if (unlikely(details))
870 continue;
871 if (pte_file(ptent)) {
872 if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
873 print_bad_pte(vma, addr, ptent, NULL);
874 } else if
875 (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent))))
876 print_bad_pte(vma, addr, ptent, NULL);
877 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
878 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
880 add_mm_rss(mm, file_rss, anon_rss);
881 arch_leave_lazy_mmu_mode();
882 pte_unmap_unlock(pte - 1, ptl);
884 return addr;
887 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
888 struct vm_area_struct *vma, pud_t *pud,
889 unsigned long addr, unsigned long end,
890 long *zap_work, struct zap_details *details)
892 pmd_t *pmd;
893 unsigned long next;
895 pmd = pmd_offset(pud, addr);
896 do {
897 next = pmd_addr_end(addr, end);
898 if (pmd_none_or_clear_bad(pmd)) {
899 (*zap_work)--;
900 continue;
902 next = zap_pte_range(tlb, vma, pmd, addr, next,
903 zap_work, details);
904 } while (pmd++, addr = next, (addr != end && *zap_work > 0));
906 return addr;
909 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
910 struct vm_area_struct *vma, pgd_t *pgd,
911 unsigned long addr, unsigned long end,
912 long *zap_work, struct zap_details *details)
914 pud_t *pud;
915 unsigned long next;
917 pud = pud_offset(pgd, addr);
918 do {
919 next = pud_addr_end(addr, end);
920 if (pud_none_or_clear_bad(pud)) {
921 (*zap_work)--;
922 continue;
924 next = zap_pmd_range(tlb, vma, pud, addr, next,
925 zap_work, details);
926 } while (pud++, addr = next, (addr != end && *zap_work > 0));
928 return addr;
931 static unsigned long unmap_page_range(struct mmu_gather *tlb,
932 struct vm_area_struct *vma,
933 unsigned long addr, unsigned long end,
934 long *zap_work, struct zap_details *details)
936 pgd_t *pgd;
937 unsigned long next;
939 if (details && !details->check_mapping && !details->nonlinear_vma)
940 details = NULL;
942 BUG_ON(addr >= end);
943 tlb_start_vma(tlb, vma);
944 pgd = pgd_offset(vma->vm_mm, addr);
945 do {
946 next = pgd_addr_end(addr, end);
947 if (pgd_none_or_clear_bad(pgd)) {
948 (*zap_work)--;
949 continue;
951 next = zap_pud_range(tlb, vma, pgd, addr, next,
952 zap_work, details);
953 } while (pgd++, addr = next, (addr != end && *zap_work > 0));
954 tlb_end_vma(tlb, vma);
956 return addr;
959 #ifdef CONFIG_PREEMPT
960 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
961 #else
962 /* No preempt: go for improved straight-line efficiency */
963 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
964 #endif
967 * unmap_vmas - unmap a range of memory covered by a list of vma's
968 * @tlbp: address of the caller's struct mmu_gather
969 * @vma: the starting vma
970 * @start_addr: virtual address at which to start unmapping
971 * @end_addr: virtual address at which to end unmapping
972 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
973 * @details: details of nonlinear truncation or shared cache invalidation
975 * Returns the end address of the unmapping (restart addr if interrupted).
977 * Unmap all pages in the vma list.
979 * We aim to not hold locks for too long (for scheduling latency reasons).
980 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to
981 * return the ending mmu_gather to the caller.
983 * Only addresses between `start' and `end' will be unmapped.
985 * The VMA list must be sorted in ascending virtual address order.
987 * unmap_vmas() assumes that the caller will flush the whole unmapped address
988 * range after unmap_vmas() returns. So the only responsibility here is to
989 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
990 * drops the lock and schedules.
992 unsigned long unmap_vmas(struct mmu_gather **tlbp,
993 struct vm_area_struct *vma, unsigned long start_addr,
994 unsigned long end_addr, unsigned long *nr_accounted,
995 struct zap_details *details)
997 long zap_work = ZAP_BLOCK_SIZE;
998 unsigned long tlb_start = 0; /* For tlb_finish_mmu */
999 int tlb_start_valid = 0;
1000 unsigned long start = start_addr;
1001 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
1002 int fullmm = (*tlbp)->fullmm;
1003 struct mm_struct *mm = vma->vm_mm;
1005 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1006 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
1007 unsigned long end;
1009 start = max(vma->vm_start, start_addr);
1010 if (start >= vma->vm_end)
1011 continue;
1012 end = min(vma->vm_end, end_addr);
1013 if (end <= vma->vm_start)
1014 continue;
1016 if (vma->vm_flags & VM_ACCOUNT)
1017 *nr_accounted += (end - start) >> PAGE_SHIFT;
1019 if (unlikely(is_pfn_mapping(vma)))
1020 untrack_pfn_vma(vma, 0, 0);
1022 while (start != end) {
1023 if (!tlb_start_valid) {
1024 tlb_start = start;
1025 tlb_start_valid = 1;
1028 if (unlikely(is_vm_hugetlb_page(vma))) {
1030 * It is undesirable to test vma->vm_file as it
1031 * should be non-null for valid hugetlb area.
1032 * However, vm_file will be NULL in the error
1033 * cleanup path of do_mmap_pgoff. When
1034 * hugetlbfs ->mmap method fails,
1035 * do_mmap_pgoff() nullifies vma->vm_file
1036 * before calling this function to clean up.
1037 * Since no pte has actually been setup, it is
1038 * safe to do nothing in this case.
1040 if (vma->vm_file) {
1041 unmap_hugepage_range(vma, start, end, NULL);
1042 zap_work -= (end - start) /
1043 pages_per_huge_page(hstate_vma(vma));
1046 start = end;
1047 } else
1048 start = unmap_page_range(*tlbp, vma,
1049 start, end, &zap_work, details);
1051 if (zap_work > 0) {
1052 BUG_ON(start != end);
1053 break;
1056 tlb_finish_mmu(*tlbp, tlb_start, start);
1058 if (need_resched() ||
1059 (i_mmap_lock && spin_needbreak(i_mmap_lock))) {
1060 if (i_mmap_lock) {
1061 *tlbp = NULL;
1062 goto out;
1064 cond_resched();
1067 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
1068 tlb_start_valid = 0;
1069 zap_work = ZAP_BLOCK_SIZE;
1072 out:
1073 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1074 return start; /* which is now the end (or restart) address */
1078 * zap_page_range - remove user pages in a given range
1079 * @vma: vm_area_struct holding the applicable pages
1080 * @address: starting address of pages to zap
1081 * @size: number of bytes to zap
1082 * @details: details of nonlinear truncation or shared cache invalidation
1084 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1085 unsigned long size, struct zap_details *details)
1087 struct mm_struct *mm = vma->vm_mm;
1088 struct mmu_gather *tlb;
1089 unsigned long end = address + size;
1090 unsigned long nr_accounted = 0;
1092 lru_add_drain();
1093 tlb = tlb_gather_mmu(mm, 0);
1094 update_hiwater_rss(mm);
1095 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1096 if (tlb)
1097 tlb_finish_mmu(tlb, address, end);
1098 return end;
1102 * zap_vma_ptes - remove ptes mapping the vma
1103 * @vma: vm_area_struct holding ptes to be zapped
1104 * @address: starting address of pages to zap
1105 * @size: number of bytes to zap
1107 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1109 * The entire address range must be fully contained within the vma.
1111 * Returns 0 if successful.
1113 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1114 unsigned long size)
1116 if (address < vma->vm_start || address + size > vma->vm_end ||
1117 !(vma->vm_flags & VM_PFNMAP))
1118 return -1;
1119 zap_page_range(vma, address, size, NULL);
1120 return 0;
1122 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1125 * Do a quick page-table lookup for a single page.
1127 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1128 unsigned int flags)
1130 pgd_t *pgd;
1131 pud_t *pud;
1132 pmd_t *pmd;
1133 pte_t *ptep, pte;
1134 spinlock_t *ptl;
1135 struct page *page;
1136 struct mm_struct *mm = vma->vm_mm;
1138 page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1139 if (!IS_ERR(page)) {
1140 BUG_ON(flags & FOLL_GET);
1141 goto out;
1144 page = NULL;
1145 pgd = pgd_offset(mm, address);
1146 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1147 goto no_page_table;
1149 pud = pud_offset(pgd, address);
1150 if (pud_none(*pud))
1151 goto no_page_table;
1152 if (pud_huge(*pud)) {
1153 BUG_ON(flags & FOLL_GET);
1154 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1155 goto out;
1157 if (unlikely(pud_bad(*pud)))
1158 goto no_page_table;
1160 pmd = pmd_offset(pud, address);
1161 if (pmd_none(*pmd))
1162 goto no_page_table;
1163 if (pmd_huge(*pmd)) {
1164 BUG_ON(flags & FOLL_GET);
1165 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1166 goto out;
1168 if (unlikely(pmd_bad(*pmd)))
1169 goto no_page_table;
1171 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1173 pte = *ptep;
1174 if (!pte_present(pte))
1175 goto no_page;
1176 if ((flags & FOLL_WRITE) && !pte_write(pte))
1177 goto unlock;
1179 page = vm_normal_page(vma, address, pte);
1180 if (unlikely(!page)) {
1181 if ((flags & FOLL_DUMP) ||
1182 !is_zero_pfn(pte_pfn(pte)))
1183 goto bad_page;
1184 page = pte_page(pte);
1187 if (flags & FOLL_GET)
1188 get_page(page);
1189 if (flags & FOLL_TOUCH) {
1190 if ((flags & FOLL_WRITE) &&
1191 !pte_dirty(pte) && !PageDirty(page))
1192 set_page_dirty(page);
1194 * pte_mkyoung() would be more correct here, but atomic care
1195 * is needed to avoid losing the dirty bit: it is easier to use
1196 * mark_page_accessed().
1198 mark_page_accessed(page);
1200 unlock:
1201 pte_unmap_unlock(ptep, ptl);
1202 out:
1203 return page;
1205 bad_page:
1206 pte_unmap_unlock(ptep, ptl);
1207 return ERR_PTR(-EFAULT);
1209 no_page:
1210 pte_unmap_unlock(ptep, ptl);
1211 if (!pte_none(pte))
1212 return page;
1214 no_page_table:
1216 * When core dumping an enormous anonymous area that nobody
1217 * has touched so far, we don't want to allocate unnecessary pages or
1218 * page tables. Return error instead of NULL to skip handle_mm_fault,
1219 * then get_dump_page() will return NULL to leave a hole in the dump.
1220 * But we can only make this optimization where a hole would surely
1221 * be zero-filled if handle_mm_fault() actually did handle it.
1223 if ((flags & FOLL_DUMP) &&
1224 (!vma->vm_ops || !vma->vm_ops->fault))
1225 return ERR_PTR(-EFAULT);
1226 return page;
1229 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1230 unsigned long start, int nr_pages, unsigned int gup_flags,
1231 struct page **pages, struct vm_area_struct **vmas)
1233 int i;
1234 unsigned long vm_flags;
1236 if (nr_pages <= 0)
1237 return 0;
1239 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1242 * Require read or write permissions.
1243 * If FOLL_FORCE is set, we only require the "MAY" flags.
1245 vm_flags = (gup_flags & FOLL_WRITE) ?
1246 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1247 vm_flags &= (gup_flags & FOLL_FORCE) ?
1248 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1249 i = 0;
1251 do {
1252 struct vm_area_struct *vma;
1254 vma = find_extend_vma(mm, start);
1255 if (!vma && in_gate_area(tsk, start)) {
1256 unsigned long pg = start & PAGE_MASK;
1257 struct vm_area_struct *gate_vma = get_gate_vma(tsk);
1258 pgd_t *pgd;
1259 pud_t *pud;
1260 pmd_t *pmd;
1261 pte_t *pte;
1263 /* user gate pages are read-only */
1264 if (gup_flags & FOLL_WRITE)
1265 return i ? : -EFAULT;
1266 if (pg > TASK_SIZE)
1267 pgd = pgd_offset_k(pg);
1268 else
1269 pgd = pgd_offset_gate(mm, pg);
1270 BUG_ON(pgd_none(*pgd));
1271 pud = pud_offset(pgd, pg);
1272 BUG_ON(pud_none(*pud));
1273 pmd = pmd_offset(pud, pg);
1274 if (pmd_none(*pmd))
1275 return i ? : -EFAULT;
1276 pte = pte_offset_map(pmd, pg);
1277 if (pte_none(*pte)) {
1278 pte_unmap(pte);
1279 return i ? : -EFAULT;
1281 if (pages) {
1282 struct page *page = vm_normal_page(gate_vma, start, *pte);
1283 pages[i] = page;
1284 if (page)
1285 get_page(page);
1287 pte_unmap(pte);
1288 if (vmas)
1289 vmas[i] = gate_vma;
1290 i++;
1291 start += PAGE_SIZE;
1292 nr_pages--;
1293 continue;
1296 if (!vma ||
1297 (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1298 !(vm_flags & vma->vm_flags))
1299 return i ? : -EFAULT;
1301 if (is_vm_hugetlb_page(vma)) {
1302 i = follow_hugetlb_page(mm, vma, pages, vmas,
1303 &start, &nr_pages, i, gup_flags);
1304 continue;
1307 do {
1308 struct page *page;
1309 unsigned int foll_flags = gup_flags;
1312 * If we have a pending SIGKILL, don't keep faulting
1313 * pages and potentially allocating memory.
1315 if (unlikely(fatal_signal_pending(current)))
1316 return i ? i : -ERESTARTSYS;
1318 cond_resched();
1319 while (!(page = follow_page(vma, start, foll_flags))) {
1320 int ret;
1322 ret = handle_mm_fault(mm, vma, start,
1323 (foll_flags & FOLL_WRITE) ?
1324 FAULT_FLAG_WRITE : 0);
1326 if (ret & VM_FAULT_ERROR) {
1327 if (ret & VM_FAULT_OOM)
1328 return i ? i : -ENOMEM;
1329 if (ret &
1330 (VM_FAULT_HWPOISON|VM_FAULT_SIGBUS))
1331 return i ? i : -EFAULT;
1332 BUG();
1334 if (ret & VM_FAULT_MAJOR)
1335 tsk->maj_flt++;
1336 else
1337 tsk->min_flt++;
1340 * The VM_FAULT_WRITE bit tells us that
1341 * do_wp_page has broken COW when necessary,
1342 * even if maybe_mkwrite decided not to set
1343 * pte_write. We can thus safely do subsequent
1344 * page lookups as if they were reads. But only
1345 * do so when looping for pte_write is futile:
1346 * in some cases userspace may also be wanting
1347 * to write to the gotten user page, which a
1348 * read fault here might prevent (a readonly
1349 * page might get reCOWed by userspace write).
1351 if ((ret & VM_FAULT_WRITE) &&
1352 !(vma->vm_flags & VM_WRITE))
1353 foll_flags &= ~FOLL_WRITE;
1355 cond_resched();
1357 if (IS_ERR(page))
1358 return i ? i : PTR_ERR(page);
1359 if (pages) {
1360 pages[i] = page;
1362 flush_anon_page(vma, page, start);
1363 flush_dcache_page(page);
1365 if (vmas)
1366 vmas[i] = vma;
1367 i++;
1368 start += PAGE_SIZE;
1369 nr_pages--;
1370 } while (nr_pages && start < vma->vm_end);
1371 } while (nr_pages);
1372 return i;
1376 * get_user_pages() - pin user pages in memory
1377 * @tsk: task_struct of target task
1378 * @mm: mm_struct of target mm
1379 * @start: starting user address
1380 * @nr_pages: number of pages from start to pin
1381 * @write: whether pages will be written to by the caller
1382 * @force: whether to force write access even if user mapping is
1383 * readonly. This will result in the page being COWed even
1384 * in MAP_SHARED mappings. You do not want this.
1385 * @pages: array that receives pointers to the pages pinned.
1386 * Should be at least nr_pages long. Or NULL, if caller
1387 * only intends to ensure the pages are faulted in.
1388 * @vmas: array of pointers to vmas corresponding to each page.
1389 * Or NULL if the caller does not require them.
1391 * Returns number of pages pinned. This may be fewer than the number
1392 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1393 * were pinned, returns -errno. Each page returned must be released
1394 * with a put_page() call when it is finished with. vmas will only
1395 * remain valid while mmap_sem is held.
1397 * Must be called with mmap_sem held for read or write.
1399 * get_user_pages walks a process's page tables and takes a reference to
1400 * each struct page that each user address corresponds to at a given
1401 * instant. That is, it takes the page that would be accessed if a user
1402 * thread accesses the given user virtual address at that instant.
1404 * This does not guarantee that the page exists in the user mappings when
1405 * get_user_pages returns, and there may even be a completely different
1406 * page there in some cases (eg. if mmapped pagecache has been invalidated
1407 * and subsequently re faulted). However it does guarantee that the page
1408 * won't be freed completely. And mostly callers simply care that the page
1409 * contains data that was valid *at some point in time*. Typically, an IO
1410 * or similar operation cannot guarantee anything stronger anyway because
1411 * locks can't be held over the syscall boundary.
1413 * If write=0, the page must not be written to. If the page is written to,
1414 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1415 * after the page is finished with, and before put_page is called.
1417 * get_user_pages is typically used for fewer-copy IO operations, to get a
1418 * handle on the memory by some means other than accesses via the user virtual
1419 * addresses. The pages may be submitted for DMA to devices or accessed via
1420 * their kernel linear mapping (via the kmap APIs). Care should be taken to
1421 * use the correct cache flushing APIs.
1423 * See also get_user_pages_fast, for performance critical applications.
1425 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1426 unsigned long start, int nr_pages, int write, int force,
1427 struct page **pages, struct vm_area_struct **vmas)
1429 int flags = FOLL_TOUCH;
1431 if (pages)
1432 flags |= FOLL_GET;
1433 if (write)
1434 flags |= FOLL_WRITE;
1435 if (force)
1436 flags |= FOLL_FORCE;
1438 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
1440 EXPORT_SYMBOL(get_user_pages);
1443 * get_dump_page() - pin user page in memory while writing it to core dump
1444 * @addr: user address
1446 * Returns struct page pointer of user page pinned for dump,
1447 * to be freed afterwards by page_cache_release() or put_page().
1449 * Returns NULL on any kind of failure - a hole must then be inserted into
1450 * the corefile, to preserve alignment with its headers; and also returns
1451 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1452 * allowing a hole to be left in the corefile to save diskspace.
1454 * Called without mmap_sem, but after all other threads have been killed.
1456 #ifdef CONFIG_ELF_CORE
1457 struct page *get_dump_page(unsigned long addr)
1459 struct vm_area_struct *vma;
1460 struct page *page;
1462 if (__get_user_pages(current, current->mm, addr, 1,
1463 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma) < 1)
1464 return NULL;
1465 flush_cache_page(vma, addr, page_to_pfn(page));
1466 return page;
1468 #endif /* CONFIG_ELF_CORE */
1470 pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
1471 spinlock_t **ptl)
1473 pgd_t * pgd = pgd_offset(mm, addr);
1474 pud_t * pud = pud_alloc(mm, pgd, addr);
1475 if (pud) {
1476 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1477 if (pmd)
1478 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1480 return NULL;
1484 * This is the old fallback for page remapping.
1486 * For historical reasons, it only allows reserved pages. Only
1487 * old drivers should use this, and they needed to mark their
1488 * pages reserved for the old functions anyway.
1490 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1491 struct page *page, pgprot_t prot)
1493 struct mm_struct *mm = vma->vm_mm;
1494 int retval;
1495 pte_t *pte;
1496 spinlock_t *ptl;
1498 retval = -EINVAL;
1499 if (PageAnon(page))
1500 goto out;
1501 retval = -ENOMEM;
1502 flush_dcache_page(page);
1503 pte = get_locked_pte(mm, addr, &ptl);
1504 if (!pte)
1505 goto out;
1506 retval = -EBUSY;
1507 if (!pte_none(*pte))
1508 goto out_unlock;
1510 /* Ok, finally just insert the thing.. */
1511 get_page(page);
1512 inc_mm_counter(mm, file_rss);
1513 page_add_file_rmap(page);
1514 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1516 retval = 0;
1517 pte_unmap_unlock(pte, ptl);
1518 return retval;
1519 out_unlock:
1520 pte_unmap_unlock(pte, ptl);
1521 out:
1522 return retval;
1526 * vm_insert_page - insert single page into user vma
1527 * @vma: user vma to map to
1528 * @addr: target user address of this page
1529 * @page: source kernel page
1531 * This allows drivers to insert individual pages they've allocated
1532 * into a user vma.
1534 * The page has to be a nice clean _individual_ kernel allocation.
1535 * If you allocate a compound page, you need to have marked it as
1536 * such (__GFP_COMP), or manually just split the page up yourself
1537 * (see split_page()).
1539 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1540 * took an arbitrary page protection parameter. This doesn't allow
1541 * that. Your vma protection will have to be set up correctly, which
1542 * means that if you want a shared writable mapping, you'd better
1543 * ask for a shared writable mapping!
1545 * The page does not need to be reserved.
1547 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1548 struct page *page)
1550 if (addr < vma->vm_start || addr >= vma->vm_end)
1551 return -EFAULT;
1552 if (!page_count(page))
1553 return -EINVAL;
1554 vma->vm_flags |= VM_INSERTPAGE;
1555 return insert_page(vma, addr, page, vma->vm_page_prot);
1557 EXPORT_SYMBOL(vm_insert_page);
1559 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1560 unsigned long pfn, pgprot_t prot)
1562 struct mm_struct *mm = vma->vm_mm;
1563 int retval;
1564 pte_t *pte, entry;
1565 spinlock_t *ptl;
1567 retval = -ENOMEM;
1568 pte = get_locked_pte(mm, addr, &ptl);
1569 if (!pte)
1570 goto out;
1571 retval = -EBUSY;
1572 if (!pte_none(*pte))
1573 goto out_unlock;
1575 /* Ok, finally just insert the thing.. */
1576 entry = pte_mkspecial(pfn_pte(pfn, prot));
1577 set_pte_at(mm, addr, pte, entry);
1578 update_mmu_cache(vma, addr, entry); /* XXX: why not for insert_page? */
1580 retval = 0;
1581 out_unlock:
1582 pte_unmap_unlock(pte, ptl);
1583 out:
1584 return retval;
1588 * vm_insert_pfn - insert single pfn into user vma
1589 * @vma: user vma to map to
1590 * @addr: target user address of this page
1591 * @pfn: source kernel pfn
1593 * Similar to vm_inert_page, this allows drivers to insert individual pages
1594 * they've allocated into a user vma. Same comments apply.
1596 * This function should only be called from a vm_ops->fault handler, and
1597 * in that case the handler should return NULL.
1599 * vma cannot be a COW mapping.
1601 * As this is called only for pages that do not currently exist, we
1602 * do not need to flush old virtual caches or the TLB.
1604 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1605 unsigned long pfn)
1607 int ret;
1608 pgprot_t pgprot = vma->vm_page_prot;
1610 * Technically, architectures with pte_special can avoid all these
1611 * restrictions (same for remap_pfn_range). However we would like
1612 * consistency in testing and feature parity among all, so we should
1613 * try to keep these invariants in place for everybody.
1615 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1616 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1617 (VM_PFNMAP|VM_MIXEDMAP));
1618 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1619 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1621 if (addr < vma->vm_start || addr >= vma->vm_end)
1622 return -EFAULT;
1623 if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1624 return -EINVAL;
1626 ret = insert_pfn(vma, addr, pfn, pgprot);
1628 if (ret)
1629 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
1631 return ret;
1633 EXPORT_SYMBOL(vm_insert_pfn);
1635 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1636 unsigned long pfn)
1638 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1640 if (addr < vma->vm_start || addr >= vma->vm_end)
1641 return -EFAULT;
1644 * If we don't have pte special, then we have to use the pfn_valid()
1645 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1646 * refcount the page if pfn_valid is true (hence insert_page rather
1647 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1648 * without pte special, it would there be refcounted as a normal page.
1650 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
1651 struct page *page;
1653 page = pfn_to_page(pfn);
1654 return insert_page(vma, addr, page, vma->vm_page_prot);
1656 return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
1658 EXPORT_SYMBOL(vm_insert_mixed);
1661 * maps a range of physical memory into the requested pages. the old
1662 * mappings are removed. any references to nonexistent pages results
1663 * in null mappings (currently treated as "copy-on-access")
1665 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1666 unsigned long addr, unsigned long end,
1667 unsigned long pfn, pgprot_t prot)
1669 pte_t *pte;
1670 spinlock_t *ptl;
1672 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1673 if (!pte)
1674 return -ENOMEM;
1675 arch_enter_lazy_mmu_mode();
1676 do {
1677 BUG_ON(!pte_none(*pte));
1678 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1679 pfn++;
1680 } while (pte++, addr += PAGE_SIZE, addr != end);
1681 arch_leave_lazy_mmu_mode();
1682 pte_unmap_unlock(pte - 1, ptl);
1683 return 0;
1686 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1687 unsigned long addr, unsigned long end,
1688 unsigned long pfn, pgprot_t prot)
1690 pmd_t *pmd;
1691 unsigned long next;
1693 pfn -= addr >> PAGE_SHIFT;
1694 pmd = pmd_alloc(mm, pud, addr);
1695 if (!pmd)
1696 return -ENOMEM;
1697 do {
1698 next = pmd_addr_end(addr, end);
1699 if (remap_pte_range(mm, pmd, addr, next,
1700 pfn + (addr >> PAGE_SHIFT), prot))
1701 return -ENOMEM;
1702 } while (pmd++, addr = next, addr != end);
1703 return 0;
1706 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1707 unsigned long addr, unsigned long end,
1708 unsigned long pfn, pgprot_t prot)
1710 pud_t *pud;
1711 unsigned long next;
1713 pfn -= addr >> PAGE_SHIFT;
1714 pud = pud_alloc(mm, pgd, addr);
1715 if (!pud)
1716 return -ENOMEM;
1717 do {
1718 next = pud_addr_end(addr, end);
1719 if (remap_pmd_range(mm, pud, addr, next,
1720 pfn + (addr >> PAGE_SHIFT), prot))
1721 return -ENOMEM;
1722 } while (pud++, addr = next, addr != end);
1723 return 0;
1727 * remap_pfn_range - remap kernel memory to userspace
1728 * @vma: user vma to map to
1729 * @addr: target user address to start at
1730 * @pfn: physical address of kernel memory
1731 * @size: size of map area
1732 * @prot: page protection flags for this mapping
1734 * Note: this is only safe if the mm semaphore is held when called.
1736 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1737 unsigned long pfn, unsigned long size, pgprot_t prot)
1739 pgd_t *pgd;
1740 unsigned long next;
1741 unsigned long end = addr + PAGE_ALIGN(size);
1742 struct mm_struct *mm = vma->vm_mm;
1743 int err;
1746 * Physically remapped pages are special. Tell the
1747 * rest of the world about it:
1748 * VM_IO tells people not to look at these pages
1749 * (accesses can have side effects).
1750 * VM_RESERVED is specified all over the place, because
1751 * in 2.4 it kept swapout's vma scan off this vma; but
1752 * in 2.6 the LRU scan won't even find its pages, so this
1753 * flag means no more than count its pages in reserved_vm,
1754 * and omit it from core dump, even when VM_IO turned off.
1755 * VM_PFNMAP tells the core MM that the base pages are just
1756 * raw PFN mappings, and do not have a "struct page" associated
1757 * with them.
1759 * There's a horrible special case to handle copy-on-write
1760 * behaviour that some programs depend on. We mark the "original"
1761 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1763 if (addr == vma->vm_start && end == vma->vm_end) {
1764 vma->vm_pgoff = pfn;
1765 vma->vm_flags |= VM_PFN_AT_MMAP;
1766 } else if (is_cow_mapping(vma->vm_flags))
1767 return -EINVAL;
1769 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1771 err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
1772 if (err) {
1774 * To indicate that track_pfn related cleanup is not
1775 * needed from higher level routine calling unmap_vmas
1777 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
1778 vma->vm_flags &= ~VM_PFN_AT_MMAP;
1779 return -EINVAL;
1782 BUG_ON(addr >= end);
1783 pfn -= addr >> PAGE_SHIFT;
1784 pgd = pgd_offset(mm, addr);
1785 flush_cache_range(vma, addr, end);
1786 do {
1787 next = pgd_addr_end(addr, end);
1788 err = remap_pud_range(mm, pgd, addr, next,
1789 pfn + (addr >> PAGE_SHIFT), prot);
1790 if (err)
1791 break;
1792 } while (pgd++, addr = next, addr != end);
1794 if (err)
1795 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
1797 return err;
1799 EXPORT_SYMBOL(remap_pfn_range);
1801 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1802 unsigned long addr, unsigned long end,
1803 pte_fn_t fn, void *data)
1805 pte_t *pte;
1806 int err;
1807 pgtable_t token;
1808 spinlock_t *uninitialized_var(ptl);
1810 pte = (mm == &init_mm) ?
1811 pte_alloc_kernel(pmd, addr) :
1812 pte_alloc_map_lock(mm, pmd, addr, &ptl);
1813 if (!pte)
1814 return -ENOMEM;
1816 BUG_ON(pmd_huge(*pmd));
1818 arch_enter_lazy_mmu_mode();
1820 token = pmd_pgtable(*pmd);
1822 do {
1823 err = fn(pte, token, addr, data);
1824 if (err)
1825 break;
1826 } while (pte++, addr += PAGE_SIZE, addr != end);
1828 arch_leave_lazy_mmu_mode();
1830 if (mm != &init_mm)
1831 pte_unmap_unlock(pte-1, ptl);
1832 return err;
1835 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
1836 unsigned long addr, unsigned long end,
1837 pte_fn_t fn, void *data)
1839 pmd_t *pmd;
1840 unsigned long next;
1841 int err;
1843 BUG_ON(pud_huge(*pud));
1845 pmd = pmd_alloc(mm, pud, addr);
1846 if (!pmd)
1847 return -ENOMEM;
1848 do {
1849 next = pmd_addr_end(addr, end);
1850 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
1851 if (err)
1852 break;
1853 } while (pmd++, addr = next, addr != end);
1854 return err;
1857 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
1858 unsigned long addr, unsigned long end,
1859 pte_fn_t fn, void *data)
1861 pud_t *pud;
1862 unsigned long next;
1863 int err;
1865 pud = pud_alloc(mm, pgd, addr);
1866 if (!pud)
1867 return -ENOMEM;
1868 do {
1869 next = pud_addr_end(addr, end);
1870 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
1871 if (err)
1872 break;
1873 } while (pud++, addr = next, addr != end);
1874 return err;
1878 * Scan a region of virtual memory, filling in page tables as necessary
1879 * and calling a provided function on each leaf page table.
1881 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
1882 unsigned long size, pte_fn_t fn, void *data)
1884 pgd_t *pgd;
1885 unsigned long next;
1886 unsigned long start = addr, end = addr + size;
1887 int err;
1889 BUG_ON(addr >= end);
1890 mmu_notifier_invalidate_range_start(mm, start, end);
1891 pgd = pgd_offset(mm, addr);
1892 do {
1893 next = pgd_addr_end(addr, end);
1894 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
1895 if (err)
1896 break;
1897 } while (pgd++, addr = next, addr != end);
1898 mmu_notifier_invalidate_range_end(mm, start, end);
1899 return err;
1901 EXPORT_SYMBOL_GPL(apply_to_page_range);
1904 * handle_pte_fault chooses page fault handler according to an entry
1905 * which was read non-atomically. Before making any commitment, on
1906 * those architectures or configurations (e.g. i386 with PAE) which
1907 * might give a mix of unmatched parts, do_swap_page and do_file_page
1908 * must check under lock before unmapping the pte and proceeding
1909 * (but do_wp_page is only called after already making such a check;
1910 * and do_anonymous_page and do_no_page can safely check later on).
1912 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1913 pte_t *page_table, pte_t orig_pte)
1915 int same = 1;
1916 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1917 if (sizeof(pte_t) > sizeof(unsigned long)) {
1918 spinlock_t *ptl = pte_lockptr(mm, pmd);
1919 spin_lock(ptl);
1920 same = pte_same(*page_table, orig_pte);
1921 spin_unlock(ptl);
1923 #endif
1924 pte_unmap(page_table);
1925 return same;
1929 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when
1930 * servicing faults for write access. In the normal case, do always want
1931 * pte_mkwrite. But get_user_pages can cause write faults for mappings
1932 * that do not have writing enabled, when used by access_process_vm.
1934 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1936 if (likely(vma->vm_flags & VM_WRITE))
1937 pte = pte_mkwrite(pte);
1938 return pte;
1941 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
1944 * If the source page was a PFN mapping, we don't have
1945 * a "struct page" for it. We do a best-effort copy by
1946 * just copying from the original user address. If that
1947 * fails, we just zero-fill it. Live with it.
1949 if (unlikely(!src)) {
1950 void *kaddr = kmap_atomic(dst, KM_USER0);
1951 void __user *uaddr = (void __user *)(va & PAGE_MASK);
1954 * This really shouldn't fail, because the page is there
1955 * in the page tables. But it might just be unreadable,
1956 * in which case we just give up and fill the result with
1957 * zeroes.
1959 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
1960 memset(kaddr, 0, PAGE_SIZE);
1961 kunmap_atomic(kaddr, KM_USER0);
1962 flush_dcache_page(dst);
1963 } else
1964 copy_user_highpage(dst, src, va, vma);
1968 * This routine handles present pages, when users try to write
1969 * to a shared page. It is done by copying the page to a new address
1970 * and decrementing the shared-page counter for the old page.
1972 * Note that this routine assumes that the protection checks have been
1973 * done by the caller (the low-level page fault routine in most cases).
1974 * Thus we can safely just mark it writable once we've done any necessary
1975 * COW.
1977 * We also mark the page dirty at this point even though the page will
1978 * change only once the write actually happens. This avoids a few races,
1979 * and potentially makes it more efficient.
1981 * We enter with non-exclusive mmap_sem (to exclude vma changes,
1982 * but allow concurrent faults), with pte both mapped and locked.
1983 * We return with mmap_sem still held, but pte unmapped and unlocked.
1985 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1986 unsigned long address, pte_t *page_table, pmd_t *pmd,
1987 spinlock_t *ptl, pte_t orig_pte)
1989 struct page *old_page, *new_page;
1990 pte_t entry;
1991 int reuse = 0, ret = 0;
1992 int page_mkwrite = 0;
1993 struct page *dirty_page = NULL;
1995 old_page = vm_normal_page(vma, address, orig_pte);
1996 if (!old_page) {
1998 * VM_MIXEDMAP !pfn_valid() case
2000 * We should not cow pages in a shared writeable mapping.
2001 * Just mark the pages writable as we can't do any dirty
2002 * accounting on raw pfn maps.
2004 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2005 (VM_WRITE|VM_SHARED))
2006 goto reuse;
2007 goto gotten;
2011 * Take out anonymous pages first, anonymous shared vmas are
2012 * not dirty accountable.
2014 if (PageAnon(old_page) && !PageKsm(old_page)) {
2015 if (!trylock_page(old_page)) {
2016 page_cache_get(old_page);
2017 pte_unmap_unlock(page_table, ptl);
2018 lock_page(old_page);
2019 page_table = pte_offset_map_lock(mm, pmd, address,
2020 &ptl);
2021 if (!pte_same(*page_table, orig_pte)) {
2022 unlock_page(old_page);
2023 page_cache_release(old_page);
2024 goto unlock;
2026 page_cache_release(old_page);
2028 reuse = reuse_swap_page(old_page);
2029 unlock_page(old_page);
2030 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2031 (VM_WRITE|VM_SHARED))) {
2033 * Only catch write-faults on shared writable pages,
2034 * read-only shared pages can get COWed by
2035 * get_user_pages(.write=1, .force=1).
2037 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2038 struct vm_fault vmf;
2039 int tmp;
2041 vmf.virtual_address = (void __user *)(address &
2042 PAGE_MASK);
2043 vmf.pgoff = old_page->index;
2044 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2045 vmf.page = old_page;
2048 * Notify the address space that the page is about to
2049 * become writable so that it can prohibit this or wait
2050 * for the page to get into an appropriate state.
2052 * We do this without the lock held, so that it can
2053 * sleep if it needs to.
2055 page_cache_get(old_page);
2056 pte_unmap_unlock(page_table, ptl);
2058 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2059 if (unlikely(tmp &
2060 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2061 ret = tmp;
2062 goto unwritable_page;
2064 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2065 lock_page(old_page);
2066 if (!old_page->mapping) {
2067 ret = 0; /* retry the fault */
2068 unlock_page(old_page);
2069 goto unwritable_page;
2071 } else
2072 VM_BUG_ON(!PageLocked(old_page));
2075 * Since we dropped the lock we need to revalidate
2076 * the PTE as someone else may have changed it. If
2077 * they did, we just return, as we can count on the
2078 * MMU to tell us if they didn't also make it writable.
2080 page_table = pte_offset_map_lock(mm, pmd, address,
2081 &ptl);
2082 if (!pte_same(*page_table, orig_pte)) {
2083 unlock_page(old_page);
2084 page_cache_release(old_page);
2085 goto unlock;
2088 page_mkwrite = 1;
2090 dirty_page = old_page;
2091 get_page(dirty_page);
2092 reuse = 1;
2095 if (reuse) {
2096 reuse:
2097 flush_cache_page(vma, address, pte_pfn(orig_pte));
2098 entry = pte_mkyoung(orig_pte);
2099 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2100 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2101 update_mmu_cache(vma, address, entry);
2102 ret |= VM_FAULT_WRITE;
2103 goto unlock;
2107 * Ok, we need to copy. Oh, well..
2109 page_cache_get(old_page);
2110 gotten:
2111 pte_unmap_unlock(page_table, ptl);
2113 if (unlikely(anon_vma_prepare(vma)))
2114 goto oom;
2116 if (is_zero_pfn(pte_pfn(orig_pte))) {
2117 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2118 if (!new_page)
2119 goto oom;
2120 } else {
2121 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2122 if (!new_page)
2123 goto oom;
2124 cow_user_page(new_page, old_page, address, vma);
2126 __SetPageUptodate(new_page);
2129 * Don't let another task, with possibly unlocked vma,
2130 * keep the mlocked page.
2132 if ((vma->vm_flags & VM_LOCKED) && old_page) {
2133 lock_page(old_page); /* for LRU manipulation */
2134 clear_page_mlock(old_page);
2135 unlock_page(old_page);
2138 if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2139 goto oom_free_new;
2142 * Re-check the pte - we dropped the lock
2144 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2145 if (likely(pte_same(*page_table, orig_pte))) {
2146 if (old_page) {
2147 if (!PageAnon(old_page)) {
2148 dec_mm_counter(mm, file_rss);
2149 inc_mm_counter(mm, anon_rss);
2151 } else
2152 inc_mm_counter(mm, anon_rss);
2153 flush_cache_page(vma, address, pte_pfn(orig_pte));
2154 entry = mk_pte(new_page, vma->vm_page_prot);
2155 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2157 * Clear the pte entry and flush it first, before updating the
2158 * pte with the new entry. This will avoid a race condition
2159 * seen in the presence of one thread doing SMC and another
2160 * thread doing COW.
2162 ptep_clear_flush(vma, address, page_table);
2163 page_add_new_anon_rmap(new_page, vma, address);
2165 * We call the notify macro here because, when using secondary
2166 * mmu page tables (such as kvm shadow page tables), we want the
2167 * new page to be mapped directly into the secondary page table.
2169 set_pte_at_notify(mm, address, page_table, entry);
2170 update_mmu_cache(vma, address, entry);
2171 if (old_page) {
2173 * Only after switching the pte to the new page may
2174 * we remove the mapcount here. Otherwise another
2175 * process may come and find the rmap count decremented
2176 * before the pte is switched to the new page, and
2177 * "reuse" the old page writing into it while our pte
2178 * here still points into it and can be read by other
2179 * threads.
2181 * The critical issue is to order this
2182 * page_remove_rmap with the ptp_clear_flush above.
2183 * Those stores are ordered by (if nothing else,)
2184 * the barrier present in the atomic_add_negative
2185 * in page_remove_rmap.
2187 * Then the TLB flush in ptep_clear_flush ensures that
2188 * no process can access the old page before the
2189 * decremented mapcount is visible. And the old page
2190 * cannot be reused until after the decremented
2191 * mapcount is visible. So transitively, TLBs to
2192 * old page will be flushed before it can be reused.
2194 page_remove_rmap(old_page);
2197 /* Free the old page.. */
2198 new_page = old_page;
2199 ret |= VM_FAULT_WRITE;
2200 } else
2201 mem_cgroup_uncharge_page(new_page);
2203 if (new_page)
2204 page_cache_release(new_page);
2205 if (old_page)
2206 page_cache_release(old_page);
2207 unlock:
2208 pte_unmap_unlock(page_table, ptl);
2209 if (dirty_page) {
2211 * Yes, Virginia, this is actually required to prevent a race
2212 * with clear_page_dirty_for_io() from clearing the page dirty
2213 * bit after it clear all dirty ptes, but before a racing
2214 * do_wp_page installs a dirty pte.
2216 * do_no_page is protected similarly.
2218 if (!page_mkwrite) {
2219 wait_on_page_locked(dirty_page);
2220 set_page_dirty_balance(dirty_page, page_mkwrite);
2222 put_page(dirty_page);
2223 if (page_mkwrite) {
2224 struct address_space *mapping = dirty_page->mapping;
2226 set_page_dirty(dirty_page);
2227 unlock_page(dirty_page);
2228 page_cache_release(dirty_page);
2229 if (mapping) {
2231 * Some device drivers do not set page.mapping
2232 * but still dirty their pages
2234 balance_dirty_pages_ratelimited(mapping);
2238 /* file_update_time outside page_lock */
2239 if (vma->vm_file)
2240 file_update_time(vma->vm_file);
2242 return ret;
2243 oom_free_new:
2244 page_cache_release(new_page);
2245 oom:
2246 if (old_page) {
2247 if (page_mkwrite) {
2248 unlock_page(old_page);
2249 page_cache_release(old_page);
2251 page_cache_release(old_page);
2253 return VM_FAULT_OOM;
2255 unwritable_page:
2256 page_cache_release(old_page);
2257 return ret;
2261 * Helper functions for unmap_mapping_range().
2263 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
2265 * We have to restart searching the prio_tree whenever we drop the lock,
2266 * since the iterator is only valid while the lock is held, and anyway
2267 * a later vma might be split and reinserted earlier while lock dropped.
2269 * The list of nonlinear vmas could be handled more efficiently, using
2270 * a placeholder, but handle it in the same way until a need is shown.
2271 * It is important to search the prio_tree before nonlinear list: a vma
2272 * may become nonlinear and be shifted from prio_tree to nonlinear list
2273 * while the lock is dropped; but never shifted from list to prio_tree.
2275 * In order to make forward progress despite restarting the search,
2276 * vm_truncate_count is used to mark a vma as now dealt with, so we can
2277 * quickly skip it next time around. Since the prio_tree search only
2278 * shows us those vmas affected by unmapping the range in question, we
2279 * can't efficiently keep all vmas in step with mapping->truncate_count:
2280 * so instead reset them all whenever it wraps back to 0 (then go to 1).
2281 * mapping->truncate_count and vma->vm_truncate_count are protected by
2282 * i_mmap_lock.
2284 * In order to make forward progress despite repeatedly restarting some
2285 * large vma, note the restart_addr from unmap_vmas when it breaks out:
2286 * and restart from that address when we reach that vma again. It might
2287 * have been split or merged, shrunk or extended, but never shifted: so
2288 * restart_addr remains valid so long as it remains in the vma's range.
2289 * unmap_mapping_range forces truncate_count to leap over page-aligned
2290 * values so we can save vma's restart_addr in its truncate_count field.
2292 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
2294 static void reset_vma_truncate_counts(struct address_space *mapping)
2296 struct vm_area_struct *vma;
2297 struct prio_tree_iter iter;
2299 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
2300 vma->vm_truncate_count = 0;
2301 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
2302 vma->vm_truncate_count = 0;
2305 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
2306 unsigned long start_addr, unsigned long end_addr,
2307 struct zap_details *details)
2309 unsigned long restart_addr;
2310 int need_break;
2313 * files that support invalidating or truncating portions of the
2314 * file from under mmaped areas must have their ->fault function
2315 * return a locked page (and set VM_FAULT_LOCKED in the return).
2316 * This provides synchronisation against concurrent unmapping here.
2319 again:
2320 restart_addr = vma->vm_truncate_count;
2321 if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
2322 start_addr = restart_addr;
2323 if (start_addr >= end_addr) {
2324 /* Top of vma has been split off since last time */
2325 vma->vm_truncate_count = details->truncate_count;
2326 return 0;
2330 restart_addr = zap_page_range(vma, start_addr,
2331 end_addr - start_addr, details);
2332 need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
2334 if (restart_addr >= end_addr) {
2335 /* We have now completed this vma: mark it so */
2336 vma->vm_truncate_count = details->truncate_count;
2337 if (!need_break)
2338 return 0;
2339 } else {
2340 /* Note restart_addr in vma's truncate_count field */
2341 vma->vm_truncate_count = restart_addr;
2342 if (!need_break)
2343 goto again;
2346 spin_unlock(details->i_mmap_lock);
2347 cond_resched();
2348 spin_lock(details->i_mmap_lock);
2349 return -EINTR;
2352 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2353 struct zap_details *details)
2355 struct vm_area_struct *vma;
2356 struct prio_tree_iter iter;
2357 pgoff_t vba, vea, zba, zea;
2359 restart:
2360 vma_prio_tree_foreach(vma, &iter, root,
2361 details->first_index, details->last_index) {
2362 /* Skip quickly over those we have already dealt with */
2363 if (vma->vm_truncate_count == details->truncate_count)
2364 continue;
2366 vba = vma->vm_pgoff;
2367 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2368 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2369 zba = details->first_index;
2370 if (zba < vba)
2371 zba = vba;
2372 zea = details->last_index;
2373 if (zea > vea)
2374 zea = vea;
2376 if (unmap_mapping_range_vma(vma,
2377 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2378 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2379 details) < 0)
2380 goto restart;
2384 static inline void unmap_mapping_range_list(struct list_head *head,
2385 struct zap_details *details)
2387 struct vm_area_struct *vma;
2390 * In nonlinear VMAs there is no correspondence between virtual address
2391 * offset and file offset. So we must perform an exhaustive search
2392 * across *all* the pages in each nonlinear VMA, not just the pages
2393 * whose virtual address lies outside the file truncation point.
2395 restart:
2396 list_for_each_entry(vma, head, shared.vm_set.list) {
2397 /* Skip quickly over those we have already dealt with */
2398 if (vma->vm_truncate_count == details->truncate_count)
2399 continue;
2400 details->nonlinear_vma = vma;
2401 if (unmap_mapping_range_vma(vma, vma->vm_start,
2402 vma->vm_end, details) < 0)
2403 goto restart;
2408 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2409 * @mapping: the address space containing mmaps to be unmapped.
2410 * @holebegin: byte in first page to unmap, relative to the start of
2411 * the underlying file. This will be rounded down to a PAGE_SIZE
2412 * boundary. Note that this is different from truncate_pagecache(), which
2413 * must keep the partial page. In contrast, we must get rid of
2414 * partial pages.
2415 * @holelen: size of prospective hole in bytes. This will be rounded
2416 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2417 * end of the file.
2418 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2419 * but 0 when invalidating pagecache, don't throw away private data.
2421 void unmap_mapping_range(struct address_space *mapping,
2422 loff_t const holebegin, loff_t const holelen, int even_cows)
2424 struct zap_details details;
2425 pgoff_t hba = holebegin >> PAGE_SHIFT;
2426 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2428 /* Check for overflow. */
2429 if (sizeof(holelen) > sizeof(hlen)) {
2430 long long holeend =
2431 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2432 if (holeend & ~(long long)ULONG_MAX)
2433 hlen = ULONG_MAX - hba + 1;
2436 details.check_mapping = even_cows? NULL: mapping;
2437 details.nonlinear_vma = NULL;
2438 details.first_index = hba;
2439 details.last_index = hba + hlen - 1;
2440 if (details.last_index < details.first_index)
2441 details.last_index = ULONG_MAX;
2442 details.i_mmap_lock = &mapping->i_mmap_lock;
2444 spin_lock(&mapping->i_mmap_lock);
2446 /* Protect against endless unmapping loops */
2447 mapping->truncate_count++;
2448 if (unlikely(is_restart_addr(mapping->truncate_count))) {
2449 if (mapping->truncate_count == 0)
2450 reset_vma_truncate_counts(mapping);
2451 mapping->truncate_count++;
2453 details.truncate_count = mapping->truncate_count;
2455 if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2456 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2457 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2458 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2459 spin_unlock(&mapping->i_mmap_lock);
2461 EXPORT_SYMBOL(unmap_mapping_range);
2463 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
2465 struct address_space *mapping = inode->i_mapping;
2468 * If the underlying filesystem is not going to provide
2469 * a way to truncate a range of blocks (punch a hole) -
2470 * we should return failure right now.
2472 if (!inode->i_op->truncate_range)
2473 return -ENOSYS;
2475 mutex_lock(&inode->i_mutex);
2476 down_write(&inode->i_alloc_sem);
2477 unmap_mapping_range(mapping, offset, (end - offset), 1);
2478 truncate_inode_pages_range(mapping, offset, end);
2479 unmap_mapping_range(mapping, offset, (end - offset), 1);
2480 inode->i_op->truncate_range(inode, offset, end);
2481 up_write(&inode->i_alloc_sem);
2482 mutex_unlock(&inode->i_mutex);
2484 return 0;
2488 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2489 * but allow concurrent faults), and pte mapped but not yet locked.
2490 * We return with mmap_sem still held, but pte unmapped and unlocked.
2492 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2493 unsigned long address, pte_t *page_table, pmd_t *pmd,
2494 unsigned int flags, pte_t orig_pte)
2496 spinlock_t *ptl;
2497 struct page *page;
2498 swp_entry_t entry;
2499 pte_t pte;
2500 struct mem_cgroup *ptr = NULL;
2501 int ret = 0;
2503 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2504 goto out;
2506 entry = pte_to_swp_entry(orig_pte);
2507 if (unlikely(non_swap_entry(entry))) {
2508 if (is_migration_entry(entry)) {
2509 migration_entry_wait(mm, pmd, address);
2510 } else if (is_hwpoison_entry(entry)) {
2511 ret = VM_FAULT_HWPOISON;
2512 } else {
2513 print_bad_pte(vma, address, orig_pte, NULL);
2514 ret = VM_FAULT_OOM;
2516 goto out;
2518 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2519 page = lookup_swap_cache(entry);
2520 if (!page) {
2521 grab_swap_token(mm); /* Contend for token _before_ read-in */
2522 page = swapin_readahead(entry,
2523 GFP_HIGHUSER_MOVABLE, vma, address);
2524 if (!page) {
2526 * Back out if somebody else faulted in this pte
2527 * while we released the pte lock.
2529 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2530 if (likely(pte_same(*page_table, orig_pte)))
2531 ret = VM_FAULT_OOM;
2532 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2533 goto unlock;
2536 /* Had to read the page from swap area: Major fault */
2537 ret = VM_FAULT_MAJOR;
2538 count_vm_event(PGMAJFAULT);
2539 } else if (PageHWPoison(page)) {
2540 ret = VM_FAULT_HWPOISON;
2541 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2542 goto out;
2545 lock_page(page);
2546 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2548 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2549 ret = VM_FAULT_OOM;
2550 goto out_page;
2554 * Back out if somebody else already faulted in this pte.
2556 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2557 if (unlikely(!pte_same(*page_table, orig_pte)))
2558 goto out_nomap;
2560 if (unlikely(!PageUptodate(page))) {
2561 ret = VM_FAULT_SIGBUS;
2562 goto out_nomap;
2566 * The page isn't present yet, go ahead with the fault.
2568 * Be careful about the sequence of operations here.
2569 * To get its accounting right, reuse_swap_page() must be called
2570 * while the page is counted on swap but not yet in mapcount i.e.
2571 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2572 * must be called after the swap_free(), or it will never succeed.
2573 * Because delete_from_swap_page() may be called by reuse_swap_page(),
2574 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2575 * in page->private. In this case, a record in swap_cgroup is silently
2576 * discarded at swap_free().
2579 inc_mm_counter(mm, anon_rss);
2580 pte = mk_pte(page, vma->vm_page_prot);
2581 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2582 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2583 flags &= ~FAULT_FLAG_WRITE;
2585 flush_icache_page(vma, page);
2586 set_pte_at(mm, address, page_table, pte);
2587 page_add_anon_rmap(page, vma, address);
2588 /* It's better to call commit-charge after rmap is established */
2589 mem_cgroup_commit_charge_swapin(page, ptr);
2591 swap_free(entry);
2592 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2593 try_to_free_swap(page);
2594 unlock_page(page);
2596 if (flags & FAULT_FLAG_WRITE) {
2597 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2598 if (ret & VM_FAULT_ERROR)
2599 ret &= VM_FAULT_ERROR;
2600 goto out;
2603 /* No need to invalidate - it was non-present before */
2604 update_mmu_cache(vma, address, pte);
2605 unlock:
2606 pte_unmap_unlock(page_table, ptl);
2607 out:
2608 return ret;
2609 out_nomap:
2610 mem_cgroup_cancel_charge_swapin(ptr);
2611 pte_unmap_unlock(page_table, ptl);
2612 out_page:
2613 unlock_page(page);
2614 page_cache_release(page);
2615 return ret;
2619 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2620 * but allow concurrent faults), and pte mapped but not yet locked.
2621 * We return with mmap_sem still held, but pte unmapped and unlocked.
2623 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2624 unsigned long address, pte_t *page_table, pmd_t *pmd,
2625 unsigned int flags)
2627 struct page *page;
2628 spinlock_t *ptl;
2629 pte_t entry;
2631 if (!(flags & FAULT_FLAG_WRITE)) {
2632 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
2633 vma->vm_page_prot));
2634 ptl = pte_lockptr(mm, pmd);
2635 spin_lock(ptl);
2636 if (!pte_none(*page_table))
2637 goto unlock;
2638 goto setpte;
2641 /* Allocate our own private page. */
2642 pte_unmap(page_table);
2644 if (unlikely(anon_vma_prepare(vma)))
2645 goto oom;
2646 page = alloc_zeroed_user_highpage_movable(vma, address);
2647 if (!page)
2648 goto oom;
2649 __SetPageUptodate(page);
2651 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
2652 goto oom_free_page;
2654 entry = mk_pte(page, vma->vm_page_prot);
2655 if (vma->vm_flags & VM_WRITE)
2656 entry = pte_mkwrite(pte_mkdirty(entry));
2658 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2659 if (!pte_none(*page_table))
2660 goto release;
2662 inc_mm_counter(mm, anon_rss);
2663 page_add_new_anon_rmap(page, vma, address);
2664 setpte:
2665 set_pte_at(mm, address, page_table, entry);
2667 /* No need to invalidate - it was non-present before */
2668 update_mmu_cache(vma, address, entry);
2669 unlock:
2670 pte_unmap_unlock(page_table, ptl);
2671 return 0;
2672 release:
2673 mem_cgroup_uncharge_page(page);
2674 page_cache_release(page);
2675 goto unlock;
2676 oom_free_page:
2677 page_cache_release(page);
2678 oom:
2679 return VM_FAULT_OOM;
2683 * __do_fault() tries to create a new page mapping. It aggressively
2684 * tries to share with existing pages, but makes a separate copy if
2685 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
2686 * the next page fault.
2688 * As this is called only for pages that do not currently exist, we
2689 * do not need to flush old virtual caches or the TLB.
2691 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2692 * but allow concurrent faults), and pte neither mapped nor locked.
2693 * We return with mmap_sem still held, but pte unmapped and unlocked.
2695 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2696 unsigned long address, pmd_t *pmd,
2697 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2699 pte_t *page_table;
2700 spinlock_t *ptl;
2701 struct page *page;
2702 pte_t entry;
2703 int anon = 0;
2704 int charged = 0;
2705 struct page *dirty_page = NULL;
2706 struct vm_fault vmf;
2707 int ret;
2708 int page_mkwrite = 0;
2710 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2711 vmf.pgoff = pgoff;
2712 vmf.flags = flags;
2713 vmf.page = NULL;
2715 ret = vma->vm_ops->fault(vma, &vmf);
2716 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2717 return ret;
2719 if (unlikely(PageHWPoison(vmf.page))) {
2720 if (ret & VM_FAULT_LOCKED)
2721 unlock_page(vmf.page);
2722 return VM_FAULT_HWPOISON;
2726 * For consistency in subsequent calls, make the faulted page always
2727 * locked.
2729 if (unlikely(!(ret & VM_FAULT_LOCKED)))
2730 lock_page(vmf.page);
2731 else
2732 VM_BUG_ON(!PageLocked(vmf.page));
2735 * Should we do an early C-O-W break?
2737 page = vmf.page;
2738 if (flags & FAULT_FLAG_WRITE) {
2739 if (!(vma->vm_flags & VM_SHARED)) {
2740 anon = 1;
2741 if (unlikely(anon_vma_prepare(vma))) {
2742 ret = VM_FAULT_OOM;
2743 goto out;
2745 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
2746 vma, address);
2747 if (!page) {
2748 ret = VM_FAULT_OOM;
2749 goto out;
2751 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
2752 ret = VM_FAULT_OOM;
2753 page_cache_release(page);
2754 goto out;
2756 charged = 1;
2758 * Don't let another task, with possibly unlocked vma,
2759 * keep the mlocked page.
2761 if (vma->vm_flags & VM_LOCKED)
2762 clear_page_mlock(vmf.page);
2763 copy_user_highpage(page, vmf.page, address, vma);
2764 __SetPageUptodate(page);
2765 } else {
2767 * If the page will be shareable, see if the backing
2768 * address space wants to know that the page is about
2769 * to become writable
2771 if (vma->vm_ops->page_mkwrite) {
2772 int tmp;
2774 unlock_page(page);
2775 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2776 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2777 if (unlikely(tmp &
2778 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2779 ret = tmp;
2780 goto unwritable_page;
2782 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2783 lock_page(page);
2784 if (!page->mapping) {
2785 ret = 0; /* retry the fault */
2786 unlock_page(page);
2787 goto unwritable_page;
2789 } else
2790 VM_BUG_ON(!PageLocked(page));
2791 page_mkwrite = 1;
2797 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2800 * This silly early PAGE_DIRTY setting removes a race
2801 * due to the bad i386 page protection. But it's valid
2802 * for other architectures too.
2804 * Note that if FAULT_FLAG_WRITE is set, we either now have
2805 * an exclusive copy of the page, or this is a shared mapping,
2806 * so we can make it writable and dirty to avoid having to
2807 * handle that later.
2809 /* Only go through if we didn't race with anybody else... */
2810 if (likely(pte_same(*page_table, orig_pte))) {
2811 flush_icache_page(vma, page);
2812 entry = mk_pte(page, vma->vm_page_prot);
2813 if (flags & FAULT_FLAG_WRITE)
2814 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2815 if (anon) {
2816 inc_mm_counter(mm, anon_rss);
2817 page_add_new_anon_rmap(page, vma, address);
2818 } else {
2819 inc_mm_counter(mm, file_rss);
2820 page_add_file_rmap(page);
2821 if (flags & FAULT_FLAG_WRITE) {
2822 dirty_page = page;
2823 get_page(dirty_page);
2826 set_pte_at(mm, address, page_table, entry);
2828 /* no need to invalidate: a not-present page won't be cached */
2829 update_mmu_cache(vma, address, entry);
2830 } else {
2831 if (charged)
2832 mem_cgroup_uncharge_page(page);
2833 if (anon)
2834 page_cache_release(page);
2835 else
2836 anon = 1; /* no anon but release faulted_page */
2839 pte_unmap_unlock(page_table, ptl);
2841 out:
2842 if (dirty_page) {
2843 struct address_space *mapping = page->mapping;
2845 if (set_page_dirty(dirty_page))
2846 page_mkwrite = 1;
2847 unlock_page(dirty_page);
2848 put_page(dirty_page);
2849 if (page_mkwrite && mapping) {
2851 * Some device drivers do not set page.mapping but still
2852 * dirty their pages
2854 balance_dirty_pages_ratelimited(mapping);
2857 /* file_update_time outside page_lock */
2858 if (vma->vm_file)
2859 file_update_time(vma->vm_file);
2860 } else {
2861 unlock_page(vmf.page);
2862 if (anon)
2863 page_cache_release(vmf.page);
2866 return ret;
2868 unwritable_page:
2869 page_cache_release(page);
2870 return ret;
2873 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2874 unsigned long address, pte_t *page_table, pmd_t *pmd,
2875 unsigned int flags, pte_t orig_pte)
2877 pgoff_t pgoff = (((address & PAGE_MASK)
2878 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2880 pte_unmap(page_table);
2881 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2885 * Fault of a previously existing named mapping. Repopulate the pte
2886 * from the encoded file_pte if possible. This enables swappable
2887 * nonlinear vmas.
2889 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2890 * but allow concurrent faults), and pte mapped but not yet locked.
2891 * We return with mmap_sem still held, but pte unmapped and unlocked.
2893 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2894 unsigned long address, pte_t *page_table, pmd_t *pmd,
2895 unsigned int flags, pte_t orig_pte)
2897 pgoff_t pgoff;
2899 flags |= FAULT_FLAG_NONLINEAR;
2901 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2902 return 0;
2904 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
2906 * Page table corrupted: show pte and kill process.
2908 print_bad_pte(vma, address, orig_pte, NULL);
2909 return VM_FAULT_OOM;
2912 pgoff = pte_to_pgoff(orig_pte);
2913 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
2917 * These routines also need to handle stuff like marking pages dirty
2918 * and/or accessed for architectures that don't do it in hardware (most
2919 * RISC architectures). The early dirtying is also good on the i386.
2921 * There is also a hook called "update_mmu_cache()" that architectures
2922 * with external mmu caches can use to update those (ie the Sparc or
2923 * PowerPC hashed page tables that act as extended TLBs).
2925 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2926 * but allow concurrent faults), and pte mapped but not yet locked.
2927 * We return with mmap_sem still held, but pte unmapped and unlocked.
2929 static inline int handle_pte_fault(struct mm_struct *mm,
2930 struct vm_area_struct *vma, unsigned long address,
2931 pte_t *pte, pmd_t *pmd, unsigned int flags)
2933 pte_t entry;
2934 spinlock_t *ptl;
2936 entry = *pte;
2937 if (!pte_present(entry)) {
2938 if (pte_none(entry)) {
2939 if (vma->vm_ops) {
2940 if (likely(vma->vm_ops->fault))
2941 return do_linear_fault(mm, vma, address,
2942 pte, pmd, flags, entry);
2944 return do_anonymous_page(mm, vma, address,
2945 pte, pmd, flags);
2947 if (pte_file(entry))
2948 return do_nonlinear_fault(mm, vma, address,
2949 pte, pmd, flags, entry);
2950 return do_swap_page(mm, vma, address,
2951 pte, pmd, flags, entry);
2954 ptl = pte_lockptr(mm, pmd);
2955 spin_lock(ptl);
2956 if (unlikely(!pte_same(*pte, entry)))
2957 goto unlock;
2958 if (flags & FAULT_FLAG_WRITE) {
2959 if (!pte_write(entry))
2960 return do_wp_page(mm, vma, address,
2961 pte, pmd, ptl, entry);
2962 entry = pte_mkdirty(entry);
2964 entry = pte_mkyoung(entry);
2965 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
2966 update_mmu_cache(vma, address, entry);
2967 } else {
2969 * This is needed only for protection faults but the arch code
2970 * is not yet telling us if this is a protection fault or not.
2971 * This still avoids useless tlb flushes for .text page faults
2972 * with threads.
2974 if (flags & FAULT_FLAG_WRITE)
2975 flush_tlb_page(vma, address);
2977 unlock:
2978 pte_unmap_unlock(pte, ptl);
2979 return 0;
2983 * By the time we get here, we already hold the mm semaphore
2985 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2986 unsigned long address, unsigned int flags)
2988 pgd_t *pgd;
2989 pud_t *pud;
2990 pmd_t *pmd;
2991 pte_t *pte;
2993 __set_current_state(TASK_RUNNING);
2995 count_vm_event(PGFAULT);
2997 if (unlikely(is_vm_hugetlb_page(vma)))
2998 return hugetlb_fault(mm, vma, address, flags);
3000 pgd = pgd_offset(mm, address);
3001 pud = pud_alloc(mm, pgd, address);
3002 if (!pud)
3003 return VM_FAULT_OOM;
3004 pmd = pmd_alloc(mm, pud, address);
3005 if (!pmd)
3006 return VM_FAULT_OOM;
3007 pte = pte_alloc_map(mm, pmd, address);
3008 if (!pte)
3009 return VM_FAULT_OOM;
3011 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3014 #ifndef __PAGETABLE_PUD_FOLDED
3016 * Allocate page upper directory.
3017 * We've already handled the fast-path in-line.
3019 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3021 pud_t *new = pud_alloc_one(mm, address);
3022 if (!new)
3023 return -ENOMEM;
3025 smp_wmb(); /* See comment in __pte_alloc */
3027 spin_lock(&mm->page_table_lock);
3028 if (pgd_present(*pgd)) /* Another has populated it */
3029 pud_free(mm, new);
3030 else
3031 pgd_populate(mm, pgd, new);
3032 spin_unlock(&mm->page_table_lock);
3033 return 0;
3035 #endif /* __PAGETABLE_PUD_FOLDED */
3037 #ifndef __PAGETABLE_PMD_FOLDED
3039 * Allocate page middle directory.
3040 * We've already handled the fast-path in-line.
3042 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3044 pmd_t *new = pmd_alloc_one(mm, address);
3045 if (!new)
3046 return -ENOMEM;
3048 smp_wmb(); /* See comment in __pte_alloc */
3050 spin_lock(&mm->page_table_lock);
3051 #ifndef __ARCH_HAS_4LEVEL_HACK
3052 if (pud_present(*pud)) /* Another has populated it */
3053 pmd_free(mm, new);
3054 else
3055 pud_populate(mm, pud, new);
3056 #else
3057 if (pgd_present(*pud)) /* Another has populated it */
3058 pmd_free(mm, new);
3059 else
3060 pgd_populate(mm, pud, new);
3061 #endif /* __ARCH_HAS_4LEVEL_HACK */
3062 spin_unlock(&mm->page_table_lock);
3063 return 0;
3065 #endif /* __PAGETABLE_PMD_FOLDED */
3067 int make_pages_present(unsigned long addr, unsigned long end)
3069 int ret, len, write;
3070 struct vm_area_struct * vma;
3072 vma = find_vma(current->mm, addr);
3073 if (!vma)
3074 return -ENOMEM;
3075 write = (vma->vm_flags & VM_WRITE) != 0;
3076 BUG_ON(addr >= end);
3077 BUG_ON(end > vma->vm_end);
3078 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3079 ret = get_user_pages(current, current->mm, addr,
3080 len, write, 0, NULL, NULL);
3081 if (ret < 0)
3082 return ret;
3083 return ret == len ? 0 : -EFAULT;
3086 #if !defined(__HAVE_ARCH_GATE_AREA)
3088 #if defined(AT_SYSINFO_EHDR)
3089 static struct vm_area_struct gate_vma;
3091 static int __init gate_vma_init(void)
3093 gate_vma.vm_mm = NULL;
3094 gate_vma.vm_start = FIXADDR_USER_START;
3095 gate_vma.vm_end = FIXADDR_USER_END;
3096 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3097 gate_vma.vm_page_prot = __P101;
3099 * Make sure the vDSO gets into every core dump.
3100 * Dumping its contents makes post-mortem fully interpretable later
3101 * without matching up the same kernel and hardware config to see
3102 * what PC values meant.
3104 gate_vma.vm_flags |= VM_ALWAYSDUMP;
3105 return 0;
3107 __initcall(gate_vma_init);
3108 #endif
3110 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
3112 #ifdef AT_SYSINFO_EHDR
3113 return &gate_vma;
3114 #else
3115 return NULL;
3116 #endif
3119 int in_gate_area_no_task(unsigned long addr)
3121 #ifdef AT_SYSINFO_EHDR
3122 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3123 return 1;
3124 #endif
3125 return 0;
3128 #endif /* __HAVE_ARCH_GATE_AREA */
3130 static int follow_pte(struct mm_struct *mm, unsigned long address,
3131 pte_t **ptepp, spinlock_t **ptlp)
3133 pgd_t *pgd;
3134 pud_t *pud;
3135 pmd_t *pmd;
3136 pte_t *ptep;
3138 pgd = pgd_offset(mm, address);
3139 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3140 goto out;
3142 pud = pud_offset(pgd, address);
3143 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3144 goto out;
3146 pmd = pmd_offset(pud, address);
3147 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3148 goto out;
3150 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3151 if (pmd_huge(*pmd))
3152 goto out;
3154 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3155 if (!ptep)
3156 goto out;
3157 if (!pte_present(*ptep))
3158 goto unlock;
3159 *ptepp = ptep;
3160 return 0;
3161 unlock:
3162 pte_unmap_unlock(ptep, *ptlp);
3163 out:
3164 return -EINVAL;
3168 * follow_pfn - look up PFN at a user virtual address
3169 * @vma: memory mapping
3170 * @address: user virtual address
3171 * @pfn: location to store found PFN
3173 * Only IO mappings and raw PFN mappings are allowed.
3175 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3177 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3178 unsigned long *pfn)
3180 int ret = -EINVAL;
3181 spinlock_t *ptl;
3182 pte_t *ptep;
3184 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3185 return ret;
3187 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3188 if (ret)
3189 return ret;
3190 *pfn = pte_pfn(*ptep);
3191 pte_unmap_unlock(ptep, ptl);
3192 return 0;
3194 EXPORT_SYMBOL(follow_pfn);
3196 #ifdef CONFIG_HAVE_IOREMAP_PROT
3197 int follow_phys(struct vm_area_struct *vma,
3198 unsigned long address, unsigned int flags,
3199 unsigned long *prot, resource_size_t *phys)
3201 int ret = -EINVAL;
3202 pte_t *ptep, pte;
3203 spinlock_t *ptl;
3205 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3206 goto out;
3208 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3209 goto out;
3210 pte = *ptep;
3212 if ((flags & FOLL_WRITE) && !pte_write(pte))
3213 goto unlock;
3215 *prot = pgprot_val(pte_pgprot(pte));
3216 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3218 ret = 0;
3219 unlock:
3220 pte_unmap_unlock(ptep, ptl);
3221 out:
3222 return ret;
3225 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3226 void *buf, int len, int write)
3228 resource_size_t phys_addr;
3229 unsigned long prot = 0;
3230 void __iomem *maddr;
3231 int offset = addr & (PAGE_SIZE-1);
3233 if (follow_phys(vma, addr, write, &prot, &phys_addr))
3234 return -EINVAL;
3236 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3237 if (write)
3238 memcpy_toio(maddr + offset, buf, len);
3239 else
3240 memcpy_fromio(buf, maddr + offset, len);
3241 iounmap(maddr);
3243 return len;
3245 #endif
3248 * Access another process' address space.
3249 * Source/target buffer must be kernel space,
3250 * Do not walk the page table directly, use get_user_pages
3252 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
3254 struct mm_struct *mm;
3255 struct vm_area_struct *vma;
3256 void *old_buf = buf;
3258 mm = get_task_mm(tsk);
3259 if (!mm)
3260 return 0;
3262 down_read(&mm->mmap_sem);
3263 /* ignore errors, just check how much was successfully transferred */
3264 while (len) {
3265 int bytes, ret, offset;
3266 void *maddr;
3267 struct page *page = NULL;
3269 ret = get_user_pages(tsk, mm, addr, 1,
3270 write, 1, &page, &vma);
3271 if (ret <= 0) {
3273 * Check if this is a VM_IO | VM_PFNMAP VMA, which
3274 * we can access using slightly different code.
3276 #ifdef CONFIG_HAVE_IOREMAP_PROT
3277 vma = find_vma(mm, addr);
3278 if (!vma)
3279 break;
3280 if (vma->vm_ops && vma->vm_ops->access)
3281 ret = vma->vm_ops->access(vma, addr, buf,
3282 len, write);
3283 if (ret <= 0)
3284 #endif
3285 break;
3286 bytes = ret;
3287 } else {
3288 bytes = len;
3289 offset = addr & (PAGE_SIZE-1);
3290 if (bytes > PAGE_SIZE-offset)
3291 bytes = PAGE_SIZE-offset;
3293 maddr = kmap(page);
3294 if (write) {
3295 copy_to_user_page(vma, page, addr,
3296 maddr + offset, buf, bytes);
3297 set_page_dirty_lock(page);
3298 } else {
3299 copy_from_user_page(vma, page, addr,
3300 buf, maddr + offset, bytes);
3302 kunmap(page);
3303 page_cache_release(page);
3305 len -= bytes;
3306 buf += bytes;
3307 addr += bytes;
3309 up_read(&mm->mmap_sem);
3310 mmput(mm);
3312 return buf - old_buf;
3316 * Print the name of a VMA.
3318 void print_vma_addr(char *prefix, unsigned long ip)
3320 struct mm_struct *mm = current->mm;
3321 struct vm_area_struct *vma;
3324 * Do not print if we are in atomic
3325 * contexts (in exception stacks, etc.):
3327 if (preempt_count())
3328 return;
3330 down_read(&mm->mmap_sem);
3331 vma = find_vma(mm, ip);
3332 if (vma && vma->vm_file) {
3333 struct file *f = vma->vm_file;
3334 char *buf = (char *)__get_free_page(GFP_KERNEL);
3335 if (buf) {
3336 char *p, *s;
3338 p = d_path(&f->f_path, buf, PAGE_SIZE);
3339 if (IS_ERR(p))
3340 p = "?";
3341 s = strrchr(p, '/');
3342 if (s)
3343 p = s+1;
3344 printk("%s%s[%lx+%lx]", prefix, p,
3345 vma->vm_start,
3346 vma->vm_end - vma->vm_start);
3347 free_page((unsigned long)buf);
3350 up_read(&current->mm->mmap_sem);
3353 #ifdef CONFIG_PROVE_LOCKING
3354 void might_fault(void)
3357 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3358 * holding the mmap_sem, this is safe because kernel memory doesn't
3359 * get paged out, therefore we'll never actually fault, and the
3360 * below annotations will generate false positives.
3362 if (segment_eq(get_fs(), KERNEL_DS))
3363 return;
3365 might_sleep();
3367 * it would be nicer only to annotate paths which are not under
3368 * pagefault_disable, however that requires a larger audit and
3369 * providing helpers like get_user_atomic.
3371 if (!in_atomic() && current->mm)
3372 might_lock_read(&current->mm->mmap_sem);
3374 EXPORT_SYMBOL(might_fault);
3375 #endif