4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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
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>
43 #include <linux/hugetlb.h>
44 #include <linux/mman.h>
45 #include <linux/swap.h>
46 #include <linux/highmem.h>
47 #include <linux/pagemap.h>
48 #include <linux/ksm.h>
49 #include <linux/rmap.h>
50 #include <linux/module.h>
51 #include <linux/delayacct.h>
52 #include <linux/init.h>
53 #include <linux/writeback.h>
54 #include <linux/memcontrol.h>
55 #include <linux/mmu_notifier.h>
56 #include <linux/kallsyms.h>
57 #include <linux/swapops.h>
58 #include <linux/elf.h>
59 #include <linux/gfp.h>
62 #include <asm/pgalloc.h>
63 #include <asm/uaccess.h>
65 #include <asm/tlbflush.h>
66 #include <asm/pgtable.h>
70 #ifndef CONFIG_NEED_MULTIPLE_NODES
71 /* use the per-pgdat data instead for discontigmem - mbligh */
72 unsigned long max_mapnr;
75 EXPORT_SYMBOL(max_mapnr);
76 EXPORT_SYMBOL(mem_map);
79 unsigned long num_physpages;
81 * A number of key systems in x86 including ioremap() rely on the assumption
82 * that high_memory defines the upper bound on direct map memory, then end
83 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
84 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
89 EXPORT_SYMBOL(num_physpages);
90 EXPORT_SYMBOL(high_memory);
93 * Randomize the address space (stacks, mmaps, brk, etc.).
95 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
96 * as ancient (libc5 based) binaries can segfault. )
98 int randomize_va_space __read_mostly =
99 #ifdef CONFIG_COMPAT_BRK
105 static int __init disable_randmaps(char *s)
107 randomize_va_space = 0;
110 __setup("norandmaps", disable_randmaps);
112 unsigned long zero_pfn __read_mostly;
113 unsigned long highest_memmap_pfn __read_mostly;
116 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
118 static int __init init_zero_pfn(void)
120 zero_pfn = page_to_pfn(ZERO_PAGE(0));
123 core_initcall(init_zero_pfn);
126 #if defined(SPLIT_RSS_COUNTING)
128 static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
132 for (i = 0; i < NR_MM_COUNTERS; i++) {
133 if (task->rss_stat.count[i]) {
134 add_mm_counter(mm, i, task->rss_stat.count[i]);
135 task->rss_stat.count[i] = 0;
138 task->rss_stat.events = 0;
141 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
143 struct task_struct *task = current;
145 if (likely(task->mm == mm))
146 task->rss_stat.count[member] += val;
148 add_mm_counter(mm, member, val);
150 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
151 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
153 /* sync counter once per 64 page faults */
154 #define TASK_RSS_EVENTS_THRESH (64)
155 static void check_sync_rss_stat(struct task_struct *task)
157 if (unlikely(task != current))
159 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
160 __sync_task_rss_stat(task, task->mm);
163 unsigned long get_mm_counter(struct mm_struct *mm, int member)
168 * Don't use task->mm here...for avoiding to use task_get_mm()..
169 * The caller must guarantee task->mm is not invalid.
171 val = atomic_long_read(&mm->rss_stat.count[member]);
173 * counter is updated in asynchronous manner and may go to minus.
174 * But it's never be expected number for users.
178 return (unsigned long)val;
181 void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
183 __sync_task_rss_stat(task, mm);
187 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
188 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
190 static void check_sync_rss_stat(struct task_struct *task)
197 * If a p?d_bad entry is found while walking page tables, report
198 * the error, before resetting entry to p?d_none. Usually (but
199 * very seldom) called out from the p?d_none_or_clear_bad macros.
202 void pgd_clear_bad(pgd_t *pgd)
208 void pud_clear_bad(pud_t *pud)
214 void pmd_clear_bad(pmd_t *pmd)
221 * Note: this doesn't free the actual pages themselves. That
222 * has been handled earlier when unmapping all the memory regions.
224 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
227 pgtable_t token = pmd_pgtable(*pmd);
229 pte_free_tlb(tlb, token, addr);
233 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
234 unsigned long addr, unsigned long end,
235 unsigned long floor, unsigned long ceiling)
242 pmd = pmd_offset(pud, addr);
244 next = pmd_addr_end(addr, end);
245 if (pmd_none_or_clear_bad(pmd))
247 free_pte_range(tlb, pmd, addr);
248 } while (pmd++, addr = next, addr != end);
258 if (end - 1 > ceiling - 1)
261 pmd = pmd_offset(pud, start);
263 pmd_free_tlb(tlb, pmd, start);
266 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
267 unsigned long addr, unsigned long end,
268 unsigned long floor, unsigned long ceiling)
275 pud = pud_offset(pgd, addr);
277 next = pud_addr_end(addr, end);
278 if (pud_none_or_clear_bad(pud))
280 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
281 } while (pud++, addr = next, addr != end);
287 ceiling &= PGDIR_MASK;
291 if (end - 1 > ceiling - 1)
294 pud = pud_offset(pgd, start);
296 pud_free_tlb(tlb, pud, start);
300 * This function frees user-level page tables of a process.
302 * Must be called with pagetable lock held.
304 void free_pgd_range(struct mmu_gather *tlb,
305 unsigned long addr, unsigned long end,
306 unsigned long floor, unsigned long ceiling)
312 * The next few lines have given us lots of grief...
314 * Why are we testing PMD* at this top level? Because often
315 * there will be no work to do at all, and we'd prefer not to
316 * go all the way down to the bottom just to discover that.
318 * Why all these "- 1"s? Because 0 represents both the bottom
319 * of the address space and the top of it (using -1 for the
320 * top wouldn't help much: the masks would do the wrong thing).
321 * The rule is that addr 0 and floor 0 refer to the bottom of
322 * the address space, but end 0 and ceiling 0 refer to the top
323 * Comparisons need to use "end - 1" and "ceiling - 1" (though
324 * that end 0 case should be mythical).
326 * Wherever addr is brought up or ceiling brought down, we must
327 * be careful to reject "the opposite 0" before it confuses the
328 * subsequent tests. But what about where end is brought down
329 * by PMD_SIZE below? no, end can't go down to 0 there.
331 * Whereas we round start (addr) and ceiling down, by different
332 * masks at different levels, in order to test whether a table
333 * now has no other vmas using it, so can be freed, we don't
334 * bother to round floor or end up - the tests don't need that.
348 if (end - 1 > ceiling - 1)
353 pgd = pgd_offset(tlb->mm, addr);
355 next = pgd_addr_end(addr, end);
356 if (pgd_none_or_clear_bad(pgd))
358 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
359 } while (pgd++, addr = next, addr != end);
362 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
363 unsigned long floor, unsigned long ceiling)
366 struct vm_area_struct *next = vma->vm_next;
367 unsigned long addr = vma->vm_start;
370 * Hide vma from rmap and truncate_pagecache before freeing
373 unlink_anon_vmas(vma);
374 unlink_file_vma(vma);
376 if (is_vm_hugetlb_page(vma)) {
377 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
378 floor, next? next->vm_start: ceiling);
381 * Optimization: gather nearby vmas into one call down
383 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
384 && !is_vm_hugetlb_page(next)) {
387 unlink_anon_vmas(vma);
388 unlink_file_vma(vma);
390 free_pgd_range(tlb, addr, vma->vm_end,
391 floor, next? next->vm_start: ceiling);
397 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
398 pmd_t *pmd, unsigned long address)
400 pgtable_t new = pte_alloc_one(mm, address);
401 int wait_split_huge_page;
406 * Ensure all pte setup (eg. pte page lock and page clearing) are
407 * visible before the pte is made visible to other CPUs by being
408 * put into page tables.
410 * The other side of the story is the pointer chasing in the page
411 * table walking code (when walking the page table without locking;
412 * ie. most of the time). Fortunately, these data accesses consist
413 * of a chain of data-dependent loads, meaning most CPUs (alpha
414 * being the notable exception) will already guarantee loads are
415 * seen in-order. See the alpha page table accessors for the
416 * smp_read_barrier_depends() barriers in page table walking code.
418 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
420 spin_lock(&mm->page_table_lock);
421 wait_split_huge_page = 0;
422 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
424 pmd_populate(mm, pmd, new);
426 } else if (unlikely(pmd_trans_splitting(*pmd)))
427 wait_split_huge_page = 1;
428 spin_unlock(&mm->page_table_lock);
431 if (wait_split_huge_page)
432 wait_split_huge_page(vma->anon_vma, pmd);
436 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
438 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
442 smp_wmb(); /* See comment in __pte_alloc */
444 spin_lock(&init_mm.page_table_lock);
445 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
446 pmd_populate_kernel(&init_mm, pmd, new);
449 VM_BUG_ON(pmd_trans_splitting(*pmd));
450 spin_unlock(&init_mm.page_table_lock);
452 pte_free_kernel(&init_mm, new);
456 static inline void init_rss_vec(int *rss)
458 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
461 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
465 if (current->mm == mm)
466 sync_mm_rss(current, mm);
467 for (i = 0; i < NR_MM_COUNTERS; i++)
469 add_mm_counter(mm, i, rss[i]);
473 * This function is called to print an error when a bad pte
474 * is found. For example, we might have a PFN-mapped pte in
475 * a region that doesn't allow it.
477 * The calling function must still handle the error.
479 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
480 pte_t pte, struct page *page)
482 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
483 pud_t *pud = pud_offset(pgd, addr);
484 pmd_t *pmd = pmd_offset(pud, addr);
485 struct address_space *mapping;
487 static unsigned long resume;
488 static unsigned long nr_shown;
489 static unsigned long nr_unshown;
492 * Allow a burst of 60 reports, then keep quiet for that minute;
493 * or allow a steady drip of one report per second.
495 if (nr_shown == 60) {
496 if (time_before(jiffies, resume)) {
502 "BUG: Bad page map: %lu messages suppressed\n",
509 resume = jiffies + 60 * HZ;
511 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
512 index = linear_page_index(vma, addr);
515 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
517 (long long)pte_val(pte), (long long)pmd_val(*pmd));
521 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
522 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
524 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
527 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
528 (unsigned long)vma->vm_ops->fault);
529 if (vma->vm_file && vma->vm_file->f_op)
530 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
531 (unsigned long)vma->vm_file->f_op->mmap);
533 add_taint(TAINT_BAD_PAGE);
536 static inline int is_cow_mapping(unsigned int flags)
538 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
542 static inline int is_zero_pfn(unsigned long pfn)
544 return pfn == zero_pfn;
549 static inline unsigned long my_zero_pfn(unsigned long addr)
556 * vm_normal_page -- This function gets the "struct page" associated with a pte.
558 * "Special" mappings do not wish to be associated with a "struct page" (either
559 * it doesn't exist, or it exists but they don't want to touch it). In this
560 * case, NULL is returned here. "Normal" mappings do have a struct page.
562 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
563 * pte bit, in which case this function is trivial. Secondly, an architecture
564 * may not have a spare pte bit, which requires a more complicated scheme,
567 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
568 * special mapping (even if there are underlying and valid "struct pages").
569 * COWed pages of a VM_PFNMAP are always normal.
571 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
572 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
573 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
574 * mapping will always honor the rule
576 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
578 * And for normal mappings this is false.
580 * This restricts such mappings to be a linear translation from virtual address
581 * to pfn. To get around this restriction, we allow arbitrary mappings so long
582 * as the vma is not a COW mapping; in that case, we know that all ptes are
583 * special (because none can have been COWed).
586 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
588 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
589 * page" backing, however the difference is that _all_ pages with a struct
590 * page (that is, those where pfn_valid is true) are refcounted and considered
591 * normal pages by the VM. The disadvantage is that pages are refcounted
592 * (which can be slower and simply not an option for some PFNMAP users). The
593 * advantage is that we don't have to follow the strict linearity rule of
594 * PFNMAP mappings in order to support COWable mappings.
597 #ifdef __HAVE_ARCH_PTE_SPECIAL
598 # define HAVE_PTE_SPECIAL 1
600 # define HAVE_PTE_SPECIAL 0
602 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
605 unsigned long pfn = pte_pfn(pte);
607 if (HAVE_PTE_SPECIAL) {
608 if (likely(!pte_special(pte)))
610 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
612 if (!is_zero_pfn(pfn))
613 print_bad_pte(vma, addr, pte, NULL);
617 /* !HAVE_PTE_SPECIAL case follows: */
619 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
620 if (vma->vm_flags & VM_MIXEDMAP) {
626 off = (addr - vma->vm_start) >> PAGE_SHIFT;
627 if (pfn == vma->vm_pgoff + off)
629 if (!is_cow_mapping(vma->vm_flags))
634 if (is_zero_pfn(pfn))
637 if (unlikely(pfn > highest_memmap_pfn)) {
638 print_bad_pte(vma, addr, pte, NULL);
643 * NOTE! We still have PageReserved() pages in the page tables.
644 * eg. VDSO mappings can cause them to exist.
647 return pfn_to_page(pfn);
651 * copy one vm_area from one task to the other. Assumes the page tables
652 * already present in the new task to be cleared in the whole range
653 * covered by this vma.
656 static inline unsigned long
657 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
658 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
659 unsigned long addr, int *rss)
661 unsigned long vm_flags = vma->vm_flags;
662 pte_t pte = *src_pte;
665 /* pte contains position in swap or file, so copy. */
666 if (unlikely(!pte_present(pte))) {
667 if (!pte_file(pte)) {
668 swp_entry_t entry = pte_to_swp_entry(pte);
670 if (swap_duplicate(entry) < 0)
673 /* make sure dst_mm is on swapoff's mmlist. */
674 if (unlikely(list_empty(&dst_mm->mmlist))) {
675 spin_lock(&mmlist_lock);
676 if (list_empty(&dst_mm->mmlist))
677 list_add(&dst_mm->mmlist,
679 spin_unlock(&mmlist_lock);
681 if (likely(!non_swap_entry(entry)))
683 else if (is_write_migration_entry(entry) &&
684 is_cow_mapping(vm_flags)) {
686 * COW mappings require pages in both parent
687 * and child to be set to read.
689 make_migration_entry_read(&entry);
690 pte = swp_entry_to_pte(entry);
691 set_pte_at(src_mm, addr, src_pte, pte);
698 * If it's a COW mapping, write protect it both
699 * in the parent and the child
701 if (is_cow_mapping(vm_flags)) {
702 ptep_set_wrprotect(src_mm, addr, src_pte);
703 pte = pte_wrprotect(pte);
707 * If it's a shared mapping, mark it clean in
710 if (vm_flags & VM_SHARED)
711 pte = pte_mkclean(pte);
712 pte = pte_mkold(pte);
714 page = vm_normal_page(vma, addr, pte);
725 set_pte_at(dst_mm, addr, dst_pte, pte);
729 int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
730 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
731 unsigned long addr, unsigned long end)
733 pte_t *orig_src_pte, *orig_dst_pte;
734 pte_t *src_pte, *dst_pte;
735 spinlock_t *src_ptl, *dst_ptl;
737 int rss[NR_MM_COUNTERS];
738 swp_entry_t entry = (swp_entry_t){0};
743 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
746 src_pte = pte_offset_map(src_pmd, addr);
747 src_ptl = pte_lockptr(src_mm, src_pmd);
748 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
749 orig_src_pte = src_pte;
750 orig_dst_pte = dst_pte;
751 arch_enter_lazy_mmu_mode();
755 * We are holding two locks at this point - either of them
756 * could generate latencies in another task on another CPU.
758 if (progress >= 32) {
760 if (need_resched() ||
761 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
764 if (pte_none(*src_pte)) {
768 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
773 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
775 arch_leave_lazy_mmu_mode();
776 spin_unlock(src_ptl);
777 pte_unmap(orig_src_pte);
778 add_mm_rss_vec(dst_mm, rss);
779 pte_unmap_unlock(orig_dst_pte, dst_ptl);
783 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
792 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
793 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
794 unsigned long addr, unsigned long end)
796 pmd_t *src_pmd, *dst_pmd;
799 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
802 src_pmd = pmd_offset(src_pud, addr);
804 next = pmd_addr_end(addr, end);
805 if (pmd_trans_huge(*src_pmd)) {
807 err = copy_huge_pmd(dst_mm, src_mm,
808 dst_pmd, src_pmd, addr, vma);
815 if (pmd_none_or_clear_bad(src_pmd))
817 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
820 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
824 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
825 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
826 unsigned long addr, unsigned long end)
828 pud_t *src_pud, *dst_pud;
831 dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
834 src_pud = pud_offset(src_pgd, addr);
836 next = pud_addr_end(addr, end);
837 if (pud_none_or_clear_bad(src_pud))
839 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
842 } while (dst_pud++, src_pud++, addr = next, addr != end);
846 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
847 struct vm_area_struct *vma)
849 pgd_t *src_pgd, *dst_pgd;
851 unsigned long addr = vma->vm_start;
852 unsigned long end = vma->vm_end;
856 * Don't copy ptes where a page fault will fill them correctly.
857 * Fork becomes much lighter when there are big shared or private
858 * readonly mappings. The tradeoff is that copy_page_range is more
859 * efficient than faulting.
861 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
866 if (is_vm_hugetlb_page(vma))
867 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
869 if (unlikely(is_pfn_mapping(vma))) {
871 * We do not free on error cases below as remove_vma
872 * gets called on error from higher level routine
874 ret = track_pfn_vma_copy(vma);
880 * We need to invalidate the secondary MMU mappings only when
881 * there could be a permission downgrade on the ptes of the
882 * parent mm. And a permission downgrade will only happen if
883 * is_cow_mapping() returns true.
885 if (is_cow_mapping(vma->vm_flags))
886 mmu_notifier_invalidate_range_start(src_mm, addr, end);
889 dst_pgd = pgd_offset(dst_mm, addr);
890 src_pgd = pgd_offset(src_mm, addr);
892 next = pgd_addr_end(addr, end);
893 if (pgd_none_or_clear_bad(src_pgd))
895 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
900 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
902 if (is_cow_mapping(vma->vm_flags))
903 mmu_notifier_invalidate_range_end(src_mm,
908 static unsigned long zap_pte_range(struct mmu_gather *tlb,
909 struct vm_area_struct *vma, pmd_t *pmd,
910 unsigned long addr, unsigned long end,
911 long *zap_work, struct zap_details *details)
913 struct mm_struct *mm = tlb->mm;
916 int rss[NR_MM_COUNTERS];
920 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
921 arch_enter_lazy_mmu_mode();
924 if (pte_none(ptent)) {
929 (*zap_work) -= PAGE_SIZE;
931 if (pte_present(ptent)) {
934 page = vm_normal_page(vma, addr, ptent);
935 if (unlikely(details) && page) {
937 * unmap_shared_mapping_pages() wants to
938 * invalidate cache without truncating:
939 * unmap shared but keep private pages.
941 if (details->check_mapping &&
942 details->check_mapping != page->mapping)
945 * Each page->index must be checked when
946 * invalidating or truncating nonlinear.
948 if (details->nonlinear_vma &&
949 (page->index < details->first_index ||
950 page->index > details->last_index))
953 ptent = ptep_get_and_clear_full(mm, addr, pte,
955 tlb_remove_tlb_entry(tlb, pte, addr);
958 if (unlikely(details) && details->nonlinear_vma
959 && linear_page_index(details->nonlinear_vma,
960 addr) != page->index)
961 set_pte_at(mm, addr, pte,
962 pgoff_to_pte(page->index));
966 if (pte_dirty(ptent))
967 set_page_dirty(page);
968 if (pte_young(ptent) &&
969 likely(!VM_SequentialReadHint(vma)))
970 mark_page_accessed(page);
973 page_remove_rmap(page);
974 if (unlikely(page_mapcount(page) < 0))
975 print_bad_pte(vma, addr, ptent, page);
976 tlb_remove_page(tlb, page);
980 * If details->check_mapping, we leave swap entries;
981 * if details->nonlinear_vma, we leave file entries.
983 if (unlikely(details))
985 if (pte_file(ptent)) {
986 if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
987 print_bad_pte(vma, addr, ptent, NULL);
989 swp_entry_t entry = pte_to_swp_entry(ptent);
991 if (!non_swap_entry(entry))
993 if (unlikely(!free_swap_and_cache(entry)))
994 print_bad_pte(vma, addr, ptent, NULL);
996 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
997 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
999 add_mm_rss_vec(mm, rss);
1000 arch_leave_lazy_mmu_mode();
1001 pte_unmap_unlock(pte - 1, ptl);
1006 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1007 struct vm_area_struct *vma, pud_t *pud,
1008 unsigned long addr, unsigned long end,
1009 long *zap_work, struct zap_details *details)
1014 pmd = pmd_offset(pud, addr);
1016 next = pmd_addr_end(addr, end);
1017 if (pmd_trans_huge(*pmd)) {
1018 if (next-addr != HPAGE_PMD_SIZE)
1019 split_huge_page_pmd(vma->vm_mm, pmd);
1020 else if (zap_huge_pmd(tlb, vma, pmd)) {
1026 if (pmd_none_or_clear_bad(pmd)) {
1030 next = zap_pte_range(tlb, vma, pmd, addr, next,
1032 } while (pmd++, addr = next, (addr != end && *zap_work > 0));
1037 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1038 struct vm_area_struct *vma, pgd_t *pgd,
1039 unsigned long addr, unsigned long end,
1040 long *zap_work, struct zap_details *details)
1045 pud = pud_offset(pgd, addr);
1047 next = pud_addr_end(addr, end);
1048 if (pud_none_or_clear_bad(pud)) {
1052 next = zap_pmd_range(tlb, vma, pud, addr, next,
1054 } while (pud++, addr = next, (addr != end && *zap_work > 0));
1059 static unsigned long unmap_page_range(struct mmu_gather *tlb,
1060 struct vm_area_struct *vma,
1061 unsigned long addr, unsigned long end,
1062 long *zap_work, struct zap_details *details)
1067 if (details && !details->check_mapping && !details->nonlinear_vma)
1070 BUG_ON(addr >= end);
1071 mem_cgroup_uncharge_start();
1072 tlb_start_vma(tlb, vma);
1073 pgd = pgd_offset(vma->vm_mm, addr);
1075 next = pgd_addr_end(addr, end);
1076 if (pgd_none_or_clear_bad(pgd)) {
1080 next = zap_pud_range(tlb, vma, pgd, addr, next,
1082 } while (pgd++, addr = next, (addr != end && *zap_work > 0));
1083 tlb_end_vma(tlb, vma);
1084 mem_cgroup_uncharge_end();
1089 #ifdef CONFIG_PREEMPT
1090 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
1092 /* No preempt: go for improved straight-line efficiency */
1093 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
1097 * unmap_vmas - unmap a range of memory covered by a list of vma's
1098 * @tlbp: address of the caller's struct mmu_gather
1099 * @vma: the starting vma
1100 * @start_addr: virtual address at which to start unmapping
1101 * @end_addr: virtual address at which to end unmapping
1102 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
1103 * @details: details of nonlinear truncation or shared cache invalidation
1105 * Returns the end address of the unmapping (restart addr if interrupted).
1107 * Unmap all pages in the vma list.
1109 * We aim to not hold locks for too long (for scheduling latency reasons).
1110 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to
1111 * return the ending mmu_gather to the caller.
1113 * Only addresses between `start' and `end' will be unmapped.
1115 * The VMA list must be sorted in ascending virtual address order.
1117 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1118 * range after unmap_vmas() returns. So the only responsibility here is to
1119 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1120 * drops the lock and schedules.
1122 unsigned long unmap_vmas(struct mmu_gather **tlbp,
1123 struct vm_area_struct *vma, unsigned long start_addr,
1124 unsigned long end_addr, unsigned long *nr_accounted,
1125 struct zap_details *details)
1127 long zap_work = ZAP_BLOCK_SIZE;
1128 unsigned long tlb_start = 0; /* For tlb_finish_mmu */
1129 int tlb_start_valid = 0;
1130 unsigned long start = start_addr;
1131 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
1132 int fullmm = (*tlbp)->fullmm;
1133 struct mm_struct *mm = vma->vm_mm;
1135 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1136 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
1139 start = max(vma->vm_start, start_addr);
1140 if (start >= vma->vm_end)
1142 end = min(vma->vm_end, end_addr);
1143 if (end <= vma->vm_start)
1146 if (vma->vm_flags & VM_ACCOUNT)
1147 *nr_accounted += (end - start) >> PAGE_SHIFT;
1149 if (unlikely(is_pfn_mapping(vma)))
1150 untrack_pfn_vma(vma, 0, 0);
1152 while (start != end) {
1153 if (!tlb_start_valid) {
1155 tlb_start_valid = 1;
1158 if (unlikely(is_vm_hugetlb_page(vma))) {
1160 * It is undesirable to test vma->vm_file as it
1161 * should be non-null for valid hugetlb area.
1162 * However, vm_file will be NULL in the error
1163 * cleanup path of do_mmap_pgoff. When
1164 * hugetlbfs ->mmap method fails,
1165 * do_mmap_pgoff() nullifies vma->vm_file
1166 * before calling this function to clean up.
1167 * Since no pte has actually been setup, it is
1168 * safe to do nothing in this case.
1171 unmap_hugepage_range(vma, start, end, NULL);
1172 zap_work -= (end - start) /
1173 pages_per_huge_page(hstate_vma(vma));
1178 start = unmap_page_range(*tlbp, vma,
1179 start, end, &zap_work, details);
1182 BUG_ON(start != end);
1186 tlb_finish_mmu(*tlbp, tlb_start, start);
1188 if (need_resched() ||
1189 (i_mmap_lock && spin_needbreak(i_mmap_lock))) {
1197 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
1198 tlb_start_valid = 0;
1199 zap_work = ZAP_BLOCK_SIZE;
1203 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1204 return start; /* which is now the end (or restart) address */
1208 * zap_page_range - remove user pages in a given range
1209 * @vma: vm_area_struct holding the applicable pages
1210 * @address: starting address of pages to zap
1211 * @size: number of bytes to zap
1212 * @details: details of nonlinear truncation or shared cache invalidation
1214 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1215 unsigned long size, struct zap_details *details)
1217 struct mm_struct *mm = vma->vm_mm;
1218 struct mmu_gather *tlb;
1219 unsigned long end = address + size;
1220 unsigned long nr_accounted = 0;
1223 tlb = tlb_gather_mmu(mm, 0);
1224 update_hiwater_rss(mm);
1225 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1227 tlb_finish_mmu(tlb, address, end);
1232 * zap_vma_ptes - remove ptes mapping the vma
1233 * @vma: vm_area_struct holding ptes to be zapped
1234 * @address: starting address of pages to zap
1235 * @size: number of bytes to zap
1237 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1239 * The entire address range must be fully contained within the vma.
1241 * Returns 0 if successful.
1243 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1246 if (address < vma->vm_start || address + size > vma->vm_end ||
1247 !(vma->vm_flags & VM_PFNMAP))
1249 zap_page_range(vma, address, size, NULL);
1252 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1255 * follow_page - look up a page descriptor from a user-virtual address
1256 * @vma: vm_area_struct mapping @address
1257 * @address: virtual address to look up
1258 * @flags: flags modifying lookup behaviour
1260 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1262 * Returns the mapped (struct page *), %NULL if no mapping exists, or
1263 * an error pointer if there is a mapping to something not represented
1264 * by a page descriptor (see also vm_normal_page()).
1266 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1275 struct mm_struct *mm = vma->vm_mm;
1277 page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1278 if (!IS_ERR(page)) {
1279 BUG_ON(flags & FOLL_GET);
1284 pgd = pgd_offset(mm, address);
1285 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1288 pud = pud_offset(pgd, address);
1291 if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1292 BUG_ON(flags & FOLL_GET);
1293 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1296 if (unlikely(pud_bad(*pud)))
1299 pmd = pmd_offset(pud, address);
1302 if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1303 BUG_ON(flags & FOLL_GET);
1304 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1307 if (pmd_trans_huge(*pmd)) {
1308 spin_lock(&mm->page_table_lock);
1309 if (likely(pmd_trans_huge(*pmd))) {
1310 if (unlikely(pmd_trans_splitting(*pmd))) {
1311 spin_unlock(&mm->page_table_lock);
1312 wait_split_huge_page(vma->anon_vma, pmd);
1314 page = follow_trans_huge_pmd(mm, address,
1316 spin_unlock(&mm->page_table_lock);
1320 spin_unlock(&mm->page_table_lock);
1323 if (unlikely(pmd_bad(*pmd)))
1326 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1329 if (!pte_present(pte))
1331 if ((flags & FOLL_WRITE) && !pte_write(pte))
1334 page = vm_normal_page(vma, address, pte);
1335 if (unlikely(!page)) {
1336 if ((flags & FOLL_DUMP) ||
1337 !is_zero_pfn(pte_pfn(pte)))
1339 page = pte_page(pte);
1342 if (flags & FOLL_GET)
1344 if (flags & FOLL_TOUCH) {
1345 if ((flags & FOLL_WRITE) &&
1346 !pte_dirty(pte) && !PageDirty(page))
1347 set_page_dirty(page);
1349 * pte_mkyoung() would be more correct here, but atomic care
1350 * is needed to avoid losing the dirty bit: it is easier to use
1351 * mark_page_accessed().
1353 mark_page_accessed(page);
1355 if (flags & FOLL_MLOCK) {
1357 * The preliminary mapping check is mainly to avoid the
1358 * pointless overhead of lock_page on the ZERO_PAGE
1359 * which might bounce very badly if there is contention.
1361 * If the page is already locked, we don't need to
1362 * handle it now - vmscan will handle it later if and
1363 * when it attempts to reclaim the page.
1365 if (page->mapping && trylock_page(page)) {
1366 lru_add_drain(); /* push cached pages to LRU */
1368 * Because we lock page here and migration is
1369 * blocked by the pte's page reference, we need
1370 * only check for file-cache page truncation.
1373 mlock_vma_page(page);
1378 pte_unmap_unlock(ptep, ptl);
1383 pte_unmap_unlock(ptep, ptl);
1384 return ERR_PTR(-EFAULT);
1387 pte_unmap_unlock(ptep, ptl);
1393 * When core dumping an enormous anonymous area that nobody
1394 * has touched so far, we don't want to allocate unnecessary pages or
1395 * page tables. Return error instead of NULL to skip handle_mm_fault,
1396 * then get_dump_page() will return NULL to leave a hole in the dump.
1397 * But we can only make this optimization where a hole would surely
1398 * be zero-filled if handle_mm_fault() actually did handle it.
1400 if ((flags & FOLL_DUMP) &&
1401 (!vma->vm_ops || !vma->vm_ops->fault))
1402 return ERR_PTR(-EFAULT);
1406 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1407 unsigned long start, int nr_pages, unsigned int gup_flags,
1408 struct page **pages, struct vm_area_struct **vmas,
1412 unsigned long vm_flags;
1417 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1420 * Require read or write permissions.
1421 * If FOLL_FORCE is set, we only require the "MAY" flags.
1423 vm_flags = (gup_flags & FOLL_WRITE) ?
1424 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1425 vm_flags &= (gup_flags & FOLL_FORCE) ?
1426 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1430 struct vm_area_struct *vma;
1432 vma = find_extend_vma(mm, start);
1433 if (!vma && in_gate_area(tsk, start)) {
1434 unsigned long pg = start & PAGE_MASK;
1435 struct vm_area_struct *gate_vma = get_gate_vma(tsk);
1441 /* user gate pages are read-only */
1442 if (gup_flags & FOLL_WRITE)
1443 return i ? : -EFAULT;
1445 pgd = pgd_offset_k(pg);
1447 pgd = pgd_offset_gate(mm, pg);
1448 BUG_ON(pgd_none(*pgd));
1449 pud = pud_offset(pgd, pg);
1450 BUG_ON(pud_none(*pud));
1451 pmd = pmd_offset(pud, pg);
1453 return i ? : -EFAULT;
1454 pte = pte_offset_map(pmd, pg);
1455 if (pte_none(*pte)) {
1457 return i ? : -EFAULT;
1462 page = vm_normal_page(gate_vma, start, *pte);
1464 if (!(gup_flags & FOLL_DUMP) &&
1465 is_zero_pfn(pte_pfn(*pte)))
1466 page = pte_page(*pte);
1469 return i ? : -EFAULT;
1485 (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1486 !(vm_flags & vma->vm_flags))
1487 return i ? : -EFAULT;
1489 if (is_vm_hugetlb_page(vma)) {
1490 i = follow_hugetlb_page(mm, vma, pages, vmas,
1491 &start, &nr_pages, i, gup_flags);
1497 unsigned int foll_flags = gup_flags;
1500 * If we have a pending SIGKILL, don't keep faulting
1501 * pages and potentially allocating memory.
1503 if (unlikely(fatal_signal_pending(current)))
1504 return i ? i : -ERESTARTSYS;
1507 while (!(page = follow_page(vma, start, foll_flags))) {
1509 unsigned int fault_flags = 0;
1511 if (foll_flags & FOLL_WRITE)
1512 fault_flags |= FAULT_FLAG_WRITE;
1514 fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1516 ret = handle_mm_fault(mm, vma, start,
1519 if (ret & VM_FAULT_ERROR) {
1520 if (ret & VM_FAULT_OOM)
1521 return i ? i : -ENOMEM;
1523 (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE|
1525 return i ? i : -EFAULT;
1528 if (ret & VM_FAULT_MAJOR)
1533 if (ret & VM_FAULT_RETRY) {
1539 * The VM_FAULT_WRITE bit tells us that
1540 * do_wp_page has broken COW when necessary,
1541 * even if maybe_mkwrite decided not to set
1542 * pte_write. We can thus safely do subsequent
1543 * page lookups as if they were reads. But only
1544 * do so when looping for pte_write is futile:
1545 * in some cases userspace may also be wanting
1546 * to write to the gotten user page, which a
1547 * read fault here might prevent (a readonly
1548 * page might get reCOWed by userspace write).
1550 if ((ret & VM_FAULT_WRITE) &&
1551 !(vma->vm_flags & VM_WRITE))
1552 foll_flags &= ~FOLL_WRITE;
1557 return i ? i : PTR_ERR(page);
1561 flush_anon_page(vma, page, start);
1562 flush_dcache_page(page);
1569 } while (nr_pages && start < vma->vm_end);
1575 * get_user_pages() - pin user pages in memory
1576 * @tsk: task_struct of target task
1577 * @mm: mm_struct of target mm
1578 * @start: starting user address
1579 * @nr_pages: number of pages from start to pin
1580 * @write: whether pages will be written to by the caller
1581 * @force: whether to force write access even if user mapping is
1582 * readonly. This will result in the page being COWed even
1583 * in MAP_SHARED mappings. You do not want this.
1584 * @pages: array that receives pointers to the pages pinned.
1585 * Should be at least nr_pages long. Or NULL, if caller
1586 * only intends to ensure the pages are faulted in.
1587 * @vmas: array of pointers to vmas corresponding to each page.
1588 * Or NULL if the caller does not require them.
1590 * Returns number of pages pinned. This may be fewer than the number
1591 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1592 * were pinned, returns -errno. Each page returned must be released
1593 * with a put_page() call when it is finished with. vmas will only
1594 * remain valid while mmap_sem is held.
1596 * Must be called with mmap_sem held for read or write.
1598 * get_user_pages walks a process's page tables and takes a reference to
1599 * each struct page that each user address corresponds to at a given
1600 * instant. That is, it takes the page that would be accessed if a user
1601 * thread accesses the given user virtual address at that instant.
1603 * This does not guarantee that the page exists in the user mappings when
1604 * get_user_pages returns, and there may even be a completely different
1605 * page there in some cases (eg. if mmapped pagecache has been invalidated
1606 * and subsequently re faulted). However it does guarantee that the page
1607 * won't be freed completely. And mostly callers simply care that the page
1608 * contains data that was valid *at some point in time*. Typically, an IO
1609 * or similar operation cannot guarantee anything stronger anyway because
1610 * locks can't be held over the syscall boundary.
1612 * If write=0, the page must not be written to. If the page is written to,
1613 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1614 * after the page is finished with, and before put_page is called.
1616 * get_user_pages is typically used for fewer-copy IO operations, to get a
1617 * handle on the memory by some means other than accesses via the user virtual
1618 * addresses. The pages may be submitted for DMA to devices or accessed via
1619 * their kernel linear mapping (via the kmap APIs). Care should be taken to
1620 * use the correct cache flushing APIs.
1622 * See also get_user_pages_fast, for performance critical applications.
1624 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1625 unsigned long start, int nr_pages, int write, int force,
1626 struct page **pages, struct vm_area_struct **vmas)
1628 int flags = FOLL_TOUCH;
1633 flags |= FOLL_WRITE;
1635 flags |= FOLL_FORCE;
1637 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
1640 EXPORT_SYMBOL(get_user_pages);
1643 * get_dump_page() - pin user page in memory while writing it to core dump
1644 * @addr: user address
1646 * Returns struct page pointer of user page pinned for dump,
1647 * to be freed afterwards by page_cache_release() or put_page().
1649 * Returns NULL on any kind of failure - a hole must then be inserted into
1650 * the corefile, to preserve alignment with its headers; and also returns
1651 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1652 * allowing a hole to be left in the corefile to save diskspace.
1654 * Called without mmap_sem, but after all other threads have been killed.
1656 #ifdef CONFIG_ELF_CORE
1657 struct page *get_dump_page(unsigned long addr)
1659 struct vm_area_struct *vma;
1662 if (__get_user_pages(current, current->mm, addr, 1,
1663 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
1666 flush_cache_page(vma, addr, page_to_pfn(page));
1669 #endif /* CONFIG_ELF_CORE */
1671 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1674 pgd_t * pgd = pgd_offset(mm, addr);
1675 pud_t * pud = pud_alloc(mm, pgd, addr);
1677 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1679 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1685 * This is the old fallback for page remapping.
1687 * For historical reasons, it only allows reserved pages. Only
1688 * old drivers should use this, and they needed to mark their
1689 * pages reserved for the old functions anyway.
1691 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1692 struct page *page, pgprot_t prot)
1694 struct mm_struct *mm = vma->vm_mm;
1703 flush_dcache_page(page);
1704 pte = get_locked_pte(mm, addr, &ptl);
1708 if (!pte_none(*pte))
1711 /* Ok, finally just insert the thing.. */
1713 inc_mm_counter_fast(mm, MM_FILEPAGES);
1714 page_add_file_rmap(page);
1715 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1718 pte_unmap_unlock(pte, ptl);
1721 pte_unmap_unlock(pte, ptl);
1727 * vm_insert_page - insert single page into user vma
1728 * @vma: user vma to map to
1729 * @addr: target user address of this page
1730 * @page: source kernel page
1732 * This allows drivers to insert individual pages they've allocated
1735 * The page has to be a nice clean _individual_ kernel allocation.
1736 * If you allocate a compound page, you need to have marked it as
1737 * such (__GFP_COMP), or manually just split the page up yourself
1738 * (see split_page()).
1740 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1741 * took an arbitrary page protection parameter. This doesn't allow
1742 * that. Your vma protection will have to be set up correctly, which
1743 * means that if you want a shared writable mapping, you'd better
1744 * ask for a shared writable mapping!
1746 * The page does not need to be reserved.
1748 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1751 if (addr < vma->vm_start || addr >= vma->vm_end)
1753 if (!page_count(page))
1755 vma->vm_flags |= VM_INSERTPAGE;
1756 return insert_page(vma, addr, page, vma->vm_page_prot);
1758 EXPORT_SYMBOL(vm_insert_page);
1760 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1761 unsigned long pfn, pgprot_t prot)
1763 struct mm_struct *mm = vma->vm_mm;
1769 pte = get_locked_pte(mm, addr, &ptl);
1773 if (!pte_none(*pte))
1776 /* Ok, finally just insert the thing.. */
1777 entry = pte_mkspecial(pfn_pte(pfn, prot));
1778 set_pte_at(mm, addr, pte, entry);
1779 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1783 pte_unmap_unlock(pte, ptl);
1789 * vm_insert_pfn - insert single pfn into user vma
1790 * @vma: user vma to map to
1791 * @addr: target user address of this page
1792 * @pfn: source kernel pfn
1794 * Similar to vm_inert_page, this allows drivers to insert individual pages
1795 * they've allocated into a user vma. Same comments apply.
1797 * This function should only be called from a vm_ops->fault handler, and
1798 * in that case the handler should return NULL.
1800 * vma cannot be a COW mapping.
1802 * As this is called only for pages that do not currently exist, we
1803 * do not need to flush old virtual caches or the TLB.
1805 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1809 pgprot_t pgprot = vma->vm_page_prot;
1811 * Technically, architectures with pte_special can avoid all these
1812 * restrictions (same for remap_pfn_range). However we would like
1813 * consistency in testing and feature parity among all, so we should
1814 * try to keep these invariants in place for everybody.
1816 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1817 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1818 (VM_PFNMAP|VM_MIXEDMAP));
1819 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1820 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1822 if (addr < vma->vm_start || addr >= vma->vm_end)
1824 if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1827 ret = insert_pfn(vma, addr, pfn, pgprot);
1830 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
1834 EXPORT_SYMBOL(vm_insert_pfn);
1836 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1839 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1841 if (addr < vma->vm_start || addr >= vma->vm_end)
1845 * If we don't have pte special, then we have to use the pfn_valid()
1846 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1847 * refcount the page if pfn_valid is true (hence insert_page rather
1848 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1849 * without pte special, it would there be refcounted as a normal page.
1851 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
1854 page = pfn_to_page(pfn);
1855 return insert_page(vma, addr, page, vma->vm_page_prot);
1857 return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
1859 EXPORT_SYMBOL(vm_insert_mixed);
1862 * maps a range of physical memory into the requested pages. the old
1863 * mappings are removed. any references to nonexistent pages results
1864 * in null mappings (currently treated as "copy-on-access")
1866 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1867 unsigned long addr, unsigned long end,
1868 unsigned long pfn, pgprot_t prot)
1873 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1876 arch_enter_lazy_mmu_mode();
1878 BUG_ON(!pte_none(*pte));
1879 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1881 } while (pte++, addr += PAGE_SIZE, addr != end);
1882 arch_leave_lazy_mmu_mode();
1883 pte_unmap_unlock(pte - 1, ptl);
1887 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1888 unsigned long addr, unsigned long end,
1889 unsigned long pfn, pgprot_t prot)
1894 pfn -= addr >> PAGE_SHIFT;
1895 pmd = pmd_alloc(mm, pud, addr);
1899 next = pmd_addr_end(addr, end);
1900 if (remap_pte_range(mm, pmd, addr, next,
1901 pfn + (addr >> PAGE_SHIFT), prot))
1903 } while (pmd++, addr = next, addr != end);
1907 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1908 unsigned long addr, unsigned long end,
1909 unsigned long pfn, pgprot_t prot)
1914 pfn -= addr >> PAGE_SHIFT;
1915 pud = pud_alloc(mm, pgd, addr);
1919 next = pud_addr_end(addr, end);
1920 if (remap_pmd_range(mm, pud, addr, next,
1921 pfn + (addr >> PAGE_SHIFT), prot))
1923 } while (pud++, addr = next, addr != end);
1928 * remap_pfn_range - remap kernel memory to userspace
1929 * @vma: user vma to map to
1930 * @addr: target user address to start at
1931 * @pfn: physical address of kernel memory
1932 * @size: size of map area
1933 * @prot: page protection flags for this mapping
1935 * Note: this is only safe if the mm semaphore is held when called.
1937 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1938 unsigned long pfn, unsigned long size, pgprot_t prot)
1942 unsigned long end = addr + PAGE_ALIGN(size);
1943 struct mm_struct *mm = vma->vm_mm;
1947 * Physically remapped pages are special. Tell the
1948 * rest of the world about it:
1949 * VM_IO tells people not to look at these pages
1950 * (accesses can have side effects).
1951 * VM_RESERVED is specified all over the place, because
1952 * in 2.4 it kept swapout's vma scan off this vma; but
1953 * in 2.6 the LRU scan won't even find its pages, so this
1954 * flag means no more than count its pages in reserved_vm,
1955 * and omit it from core dump, even when VM_IO turned off.
1956 * VM_PFNMAP tells the core MM that the base pages are just
1957 * raw PFN mappings, and do not have a "struct page" associated
1960 * There's a horrible special case to handle copy-on-write
1961 * behaviour that some programs depend on. We mark the "original"
1962 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1964 if (addr == vma->vm_start && end == vma->vm_end) {
1965 vma->vm_pgoff = pfn;
1966 vma->vm_flags |= VM_PFN_AT_MMAP;
1967 } else if (is_cow_mapping(vma->vm_flags))
1970 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1972 err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
1975 * To indicate that track_pfn related cleanup is not
1976 * needed from higher level routine calling unmap_vmas
1978 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
1979 vma->vm_flags &= ~VM_PFN_AT_MMAP;
1983 BUG_ON(addr >= end);
1984 pfn -= addr >> PAGE_SHIFT;
1985 pgd = pgd_offset(mm, addr);
1986 flush_cache_range(vma, addr, end);
1988 next = pgd_addr_end(addr, end);
1989 err = remap_pud_range(mm, pgd, addr, next,
1990 pfn + (addr >> PAGE_SHIFT), prot);
1993 } while (pgd++, addr = next, addr != end);
1996 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
2000 EXPORT_SYMBOL(remap_pfn_range);
2002 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2003 unsigned long addr, unsigned long end,
2004 pte_fn_t fn, void *data)
2009 spinlock_t *uninitialized_var(ptl);
2011 pte = (mm == &init_mm) ?
2012 pte_alloc_kernel(pmd, addr) :
2013 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2017 BUG_ON(pmd_huge(*pmd));
2019 arch_enter_lazy_mmu_mode();
2021 token = pmd_pgtable(*pmd);
2024 err = fn(pte++, token, addr, data);
2027 } while (addr += PAGE_SIZE, addr != end);
2029 arch_leave_lazy_mmu_mode();
2032 pte_unmap_unlock(pte-1, ptl);
2036 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2037 unsigned long addr, unsigned long end,
2038 pte_fn_t fn, void *data)
2044 BUG_ON(pud_huge(*pud));
2046 pmd = pmd_alloc(mm, pud, addr);
2050 next = pmd_addr_end(addr, end);
2051 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2054 } while (pmd++, addr = next, addr != end);
2058 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2059 unsigned long addr, unsigned long end,
2060 pte_fn_t fn, void *data)
2066 pud = pud_alloc(mm, pgd, addr);
2070 next = pud_addr_end(addr, end);
2071 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2074 } while (pud++, addr = next, addr != end);
2079 * Scan a region of virtual memory, filling in page tables as necessary
2080 * and calling a provided function on each leaf page table.
2082 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2083 unsigned long size, pte_fn_t fn, void *data)
2087 unsigned long end = addr + size;
2090 BUG_ON(addr >= end);
2091 pgd = pgd_offset(mm, addr);
2093 next = pgd_addr_end(addr, end);
2094 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2097 } while (pgd++, addr = next, addr != end);
2101 EXPORT_SYMBOL_GPL(apply_to_page_range);
2104 * handle_pte_fault chooses page fault handler according to an entry
2105 * which was read non-atomically. Before making any commitment, on
2106 * those architectures or configurations (e.g. i386 with PAE) which
2107 * might give a mix of unmatched parts, do_swap_page and do_file_page
2108 * must check under lock before unmapping the pte and proceeding
2109 * (but do_wp_page is only called after already making such a check;
2110 * and do_anonymous_page and do_no_page can safely check later on).
2112 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2113 pte_t *page_table, pte_t orig_pte)
2116 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2117 if (sizeof(pte_t) > sizeof(unsigned long)) {
2118 spinlock_t *ptl = pte_lockptr(mm, pmd);
2120 same = pte_same(*page_table, orig_pte);
2124 pte_unmap(page_table);
2128 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2131 * If the source page was a PFN mapping, we don't have
2132 * a "struct page" for it. We do a best-effort copy by
2133 * just copying from the original user address. If that
2134 * fails, we just zero-fill it. Live with it.
2136 if (unlikely(!src)) {
2137 void *kaddr = kmap_atomic(dst, KM_USER0);
2138 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2141 * This really shouldn't fail, because the page is there
2142 * in the page tables. But it might just be unreadable,
2143 * in which case we just give up and fill the result with
2146 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2148 kunmap_atomic(kaddr, KM_USER0);
2149 flush_dcache_page(dst);
2151 copy_user_highpage(dst, src, va, vma);
2155 * This routine handles present pages, when users try to write
2156 * to a shared page. It is done by copying the page to a new address
2157 * and decrementing the shared-page counter for the old page.
2159 * Note that this routine assumes that the protection checks have been
2160 * done by the caller (the low-level page fault routine in most cases).
2161 * Thus we can safely just mark it writable once we've done any necessary
2164 * We also mark the page dirty at this point even though the page will
2165 * change only once the write actually happens. This avoids a few races,
2166 * and potentially makes it more efficient.
2168 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2169 * but allow concurrent faults), with pte both mapped and locked.
2170 * We return with mmap_sem still held, but pte unmapped and unlocked.
2172 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2173 unsigned long address, pte_t *page_table, pmd_t *pmd,
2174 spinlock_t *ptl, pte_t orig_pte)
2177 struct page *old_page, *new_page;
2180 int page_mkwrite = 0;
2181 struct page *dirty_page = NULL;
2183 old_page = vm_normal_page(vma, address, orig_pte);
2186 * VM_MIXEDMAP !pfn_valid() case
2188 * We should not cow pages in a shared writeable mapping.
2189 * Just mark the pages writable as we can't do any dirty
2190 * accounting on raw pfn maps.
2192 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2193 (VM_WRITE|VM_SHARED))
2199 * Take out anonymous pages first, anonymous shared vmas are
2200 * not dirty accountable.
2202 if (PageAnon(old_page) && !PageKsm(old_page)) {
2203 if (!trylock_page(old_page)) {
2204 page_cache_get(old_page);
2205 pte_unmap_unlock(page_table, ptl);
2206 lock_page(old_page);
2207 page_table = pte_offset_map_lock(mm, pmd, address,
2209 if (!pte_same(*page_table, orig_pte)) {
2210 unlock_page(old_page);
2211 page_cache_release(old_page);
2214 page_cache_release(old_page);
2216 if (reuse_swap_page(old_page)) {
2218 * The page is all ours. Move it to our anon_vma so
2219 * the rmap code will not search our parent or siblings.
2220 * Protected against the rmap code by the page lock.
2222 page_move_anon_rmap(old_page, vma, address);
2223 unlock_page(old_page);
2226 unlock_page(old_page);
2227 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2228 (VM_WRITE|VM_SHARED))) {
2230 * Only catch write-faults on shared writable pages,
2231 * read-only shared pages can get COWed by
2232 * get_user_pages(.write=1, .force=1).
2234 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2235 struct vm_fault vmf;
2238 vmf.virtual_address = (void __user *)(address &
2240 vmf.pgoff = old_page->index;
2241 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2242 vmf.page = old_page;
2245 * Notify the address space that the page is about to
2246 * become writable so that it can prohibit this or wait
2247 * for the page to get into an appropriate state.
2249 * We do this without the lock held, so that it can
2250 * sleep if it needs to.
2252 page_cache_get(old_page);
2253 pte_unmap_unlock(page_table, ptl);
2255 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2257 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2259 goto unwritable_page;
2261 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2262 lock_page(old_page);
2263 if (!old_page->mapping) {
2264 ret = 0; /* retry the fault */
2265 unlock_page(old_page);
2266 goto unwritable_page;
2269 VM_BUG_ON(!PageLocked(old_page));
2272 * Since we dropped the lock we need to revalidate
2273 * the PTE as someone else may have changed it. If
2274 * they did, we just return, as we can count on the
2275 * MMU to tell us if they didn't also make it writable.
2277 page_table = pte_offset_map_lock(mm, pmd, address,
2279 if (!pte_same(*page_table, orig_pte)) {
2280 unlock_page(old_page);
2281 page_cache_release(old_page);
2287 dirty_page = old_page;
2288 get_page(dirty_page);
2291 flush_cache_page(vma, address, pte_pfn(orig_pte));
2292 entry = pte_mkyoung(orig_pte);
2293 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2294 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2295 update_mmu_cache(vma, address, page_table);
2296 pte_unmap_unlock(page_table, ptl);
2297 ret |= VM_FAULT_WRITE;
2303 * Yes, Virginia, this is actually required to prevent a race
2304 * with clear_page_dirty_for_io() from clearing the page dirty
2305 * bit after it clear all dirty ptes, but before a racing
2306 * do_wp_page installs a dirty pte.
2308 * do_no_page is protected similarly.
2310 if (!page_mkwrite) {
2311 wait_on_page_locked(dirty_page);
2312 set_page_dirty_balance(dirty_page, page_mkwrite);
2314 put_page(dirty_page);
2316 struct address_space *mapping = dirty_page->mapping;
2318 set_page_dirty(dirty_page);
2319 unlock_page(dirty_page);
2320 page_cache_release(dirty_page);
2323 * Some device drivers do not set page.mapping
2324 * but still dirty their pages
2326 balance_dirty_pages_ratelimited(mapping);
2330 /* file_update_time outside page_lock */
2332 file_update_time(vma->vm_file);
2338 * Ok, we need to copy. Oh, well..
2340 page_cache_get(old_page);
2342 pte_unmap_unlock(page_table, ptl);
2344 if (unlikely(anon_vma_prepare(vma)))
2347 if (is_zero_pfn(pte_pfn(orig_pte))) {
2348 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2352 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2355 cow_user_page(new_page, old_page, address, vma);
2357 __SetPageUptodate(new_page);
2360 * Don't let another task, with possibly unlocked vma,
2361 * keep the mlocked page.
2363 if ((vma->vm_flags & VM_LOCKED) && old_page) {
2364 lock_page(old_page); /* for LRU manipulation */
2365 clear_page_mlock(old_page);
2366 unlock_page(old_page);
2369 if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2373 * Re-check the pte - we dropped the lock
2375 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2376 if (likely(pte_same(*page_table, orig_pte))) {
2378 if (!PageAnon(old_page)) {
2379 dec_mm_counter_fast(mm, MM_FILEPAGES);
2380 inc_mm_counter_fast(mm, MM_ANONPAGES);
2383 inc_mm_counter_fast(mm, MM_ANONPAGES);
2384 flush_cache_page(vma, address, pte_pfn(orig_pte));
2385 entry = mk_pte(new_page, vma->vm_page_prot);
2386 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2388 * Clear the pte entry and flush it first, before updating the
2389 * pte with the new entry. This will avoid a race condition
2390 * seen in the presence of one thread doing SMC and another
2393 ptep_clear_flush(vma, address, page_table);
2394 page_add_new_anon_rmap(new_page, vma, address);
2396 * We call the notify macro here because, when using secondary
2397 * mmu page tables (such as kvm shadow page tables), we want the
2398 * new page to be mapped directly into the secondary page table.
2400 set_pte_at_notify(mm, address, page_table, entry);
2401 update_mmu_cache(vma, address, page_table);
2404 * Only after switching the pte to the new page may
2405 * we remove the mapcount here. Otherwise another
2406 * process may come and find the rmap count decremented
2407 * before the pte is switched to the new page, and
2408 * "reuse" the old page writing into it while our pte
2409 * here still points into it and can be read by other
2412 * The critical issue is to order this
2413 * page_remove_rmap with the ptp_clear_flush above.
2414 * Those stores are ordered by (if nothing else,)
2415 * the barrier present in the atomic_add_negative
2416 * in page_remove_rmap.
2418 * Then the TLB flush in ptep_clear_flush ensures that
2419 * no process can access the old page before the
2420 * decremented mapcount is visible. And the old page
2421 * cannot be reused until after the decremented
2422 * mapcount is visible. So transitively, TLBs to
2423 * old page will be flushed before it can be reused.
2425 page_remove_rmap(old_page);
2428 /* Free the old page.. */
2429 new_page = old_page;
2430 ret |= VM_FAULT_WRITE;
2432 mem_cgroup_uncharge_page(new_page);
2435 page_cache_release(new_page);
2437 page_cache_release(old_page);
2439 pte_unmap_unlock(page_table, ptl);
2442 page_cache_release(new_page);
2446 unlock_page(old_page);
2447 page_cache_release(old_page);
2449 page_cache_release(old_page);
2451 return VM_FAULT_OOM;
2454 page_cache_release(old_page);
2459 * Helper functions for unmap_mapping_range().
2461 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
2463 * We have to restart searching the prio_tree whenever we drop the lock,
2464 * since the iterator is only valid while the lock is held, and anyway
2465 * a later vma might be split and reinserted earlier while lock dropped.
2467 * The list of nonlinear vmas could be handled more efficiently, using
2468 * a placeholder, but handle it in the same way until a need is shown.
2469 * It is important to search the prio_tree before nonlinear list: a vma
2470 * may become nonlinear and be shifted from prio_tree to nonlinear list
2471 * while the lock is dropped; but never shifted from list to prio_tree.
2473 * In order to make forward progress despite restarting the search,
2474 * vm_truncate_count is used to mark a vma as now dealt with, so we can
2475 * quickly skip it next time around. Since the prio_tree search only
2476 * shows us those vmas affected by unmapping the range in question, we
2477 * can't efficiently keep all vmas in step with mapping->truncate_count:
2478 * so instead reset them all whenever it wraps back to 0 (then go to 1).
2479 * mapping->truncate_count and vma->vm_truncate_count are protected by
2482 * In order to make forward progress despite repeatedly restarting some
2483 * large vma, note the restart_addr from unmap_vmas when it breaks out:
2484 * and restart from that address when we reach that vma again. It might
2485 * have been split or merged, shrunk or extended, but never shifted: so
2486 * restart_addr remains valid so long as it remains in the vma's range.
2487 * unmap_mapping_range forces truncate_count to leap over page-aligned
2488 * values so we can save vma's restart_addr in its truncate_count field.
2490 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
2492 static void reset_vma_truncate_counts(struct address_space *mapping)
2494 struct vm_area_struct *vma;
2495 struct prio_tree_iter iter;
2497 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
2498 vma->vm_truncate_count = 0;
2499 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
2500 vma->vm_truncate_count = 0;
2503 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
2504 unsigned long start_addr, unsigned long end_addr,
2505 struct zap_details *details)
2507 unsigned long restart_addr;
2511 * files that support invalidating or truncating portions of the
2512 * file from under mmaped areas must have their ->fault function
2513 * return a locked page (and set VM_FAULT_LOCKED in the return).
2514 * This provides synchronisation against concurrent unmapping here.
2518 restart_addr = vma->vm_truncate_count;
2519 if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
2520 start_addr = restart_addr;
2521 if (start_addr >= end_addr) {
2522 /* Top of vma has been split off since last time */
2523 vma->vm_truncate_count = details->truncate_count;
2528 restart_addr = zap_page_range(vma, start_addr,
2529 end_addr - start_addr, details);
2530 need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
2532 if (restart_addr >= end_addr) {
2533 /* We have now completed this vma: mark it so */
2534 vma->vm_truncate_count = details->truncate_count;
2538 /* Note restart_addr in vma's truncate_count field */
2539 vma->vm_truncate_count = restart_addr;
2544 spin_unlock(details->i_mmap_lock);
2546 spin_lock(details->i_mmap_lock);
2550 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2551 struct zap_details *details)
2553 struct vm_area_struct *vma;
2554 struct prio_tree_iter iter;
2555 pgoff_t vba, vea, zba, zea;
2558 vma_prio_tree_foreach(vma, &iter, root,
2559 details->first_index, details->last_index) {
2560 /* Skip quickly over those we have already dealt with */
2561 if (vma->vm_truncate_count == details->truncate_count)
2564 vba = vma->vm_pgoff;
2565 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2566 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2567 zba = details->first_index;
2570 zea = details->last_index;
2574 if (unmap_mapping_range_vma(vma,
2575 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2576 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2582 static inline void unmap_mapping_range_list(struct list_head *head,
2583 struct zap_details *details)
2585 struct vm_area_struct *vma;
2588 * In nonlinear VMAs there is no correspondence between virtual address
2589 * offset and file offset. So we must perform an exhaustive search
2590 * across *all* the pages in each nonlinear VMA, not just the pages
2591 * whose virtual address lies outside the file truncation point.
2594 list_for_each_entry(vma, head, shared.vm_set.list) {
2595 /* Skip quickly over those we have already dealt with */
2596 if (vma->vm_truncate_count == details->truncate_count)
2598 details->nonlinear_vma = vma;
2599 if (unmap_mapping_range_vma(vma, vma->vm_start,
2600 vma->vm_end, details) < 0)
2606 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2607 * @mapping: the address space containing mmaps to be unmapped.
2608 * @holebegin: byte in first page to unmap, relative to the start of
2609 * the underlying file. This will be rounded down to a PAGE_SIZE
2610 * boundary. Note that this is different from truncate_pagecache(), which
2611 * must keep the partial page. In contrast, we must get rid of
2613 * @holelen: size of prospective hole in bytes. This will be rounded
2614 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2616 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2617 * but 0 when invalidating pagecache, don't throw away private data.
2619 void unmap_mapping_range(struct address_space *mapping,
2620 loff_t const holebegin, loff_t const holelen, int even_cows)
2622 struct zap_details details;
2623 pgoff_t hba = holebegin >> PAGE_SHIFT;
2624 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2626 /* Check for overflow. */
2627 if (sizeof(holelen) > sizeof(hlen)) {
2629 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2630 if (holeend & ~(long long)ULONG_MAX)
2631 hlen = ULONG_MAX - hba + 1;
2634 details.check_mapping = even_cows? NULL: mapping;
2635 details.nonlinear_vma = NULL;
2636 details.first_index = hba;
2637 details.last_index = hba + hlen - 1;
2638 if (details.last_index < details.first_index)
2639 details.last_index = ULONG_MAX;
2640 details.i_mmap_lock = &mapping->i_mmap_lock;
2642 spin_lock(&mapping->i_mmap_lock);
2644 /* Protect against endless unmapping loops */
2645 mapping->truncate_count++;
2646 if (unlikely(is_restart_addr(mapping->truncate_count))) {
2647 if (mapping->truncate_count == 0)
2648 reset_vma_truncate_counts(mapping);
2649 mapping->truncate_count++;
2651 details.truncate_count = mapping->truncate_count;
2653 if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2654 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2655 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2656 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2657 spin_unlock(&mapping->i_mmap_lock);
2659 EXPORT_SYMBOL(unmap_mapping_range);
2661 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
2663 struct address_space *mapping = inode->i_mapping;
2666 * If the underlying filesystem is not going to provide
2667 * a way to truncate a range of blocks (punch a hole) -
2668 * we should return failure right now.
2670 if (!inode->i_op->truncate_range)
2673 mutex_lock(&inode->i_mutex);
2674 down_write(&inode->i_alloc_sem);
2675 unmap_mapping_range(mapping, offset, (end - offset), 1);
2676 truncate_inode_pages_range(mapping, offset, end);
2677 unmap_mapping_range(mapping, offset, (end - offset), 1);
2678 inode->i_op->truncate_range(inode, offset, end);
2679 up_write(&inode->i_alloc_sem);
2680 mutex_unlock(&inode->i_mutex);
2686 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2687 * but allow concurrent faults), and pte mapped but not yet locked.
2688 * We return with mmap_sem still held, but pte unmapped and unlocked.
2690 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2691 unsigned long address, pte_t *page_table, pmd_t *pmd,
2692 unsigned int flags, pte_t orig_pte)
2695 struct page *page, *swapcache = NULL;
2699 struct mem_cgroup *ptr = NULL;
2703 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2706 entry = pte_to_swp_entry(orig_pte);
2707 if (unlikely(non_swap_entry(entry))) {
2708 if (is_migration_entry(entry)) {
2709 migration_entry_wait(mm, pmd, address);
2710 } else if (is_hwpoison_entry(entry)) {
2711 ret = VM_FAULT_HWPOISON;
2713 print_bad_pte(vma, address, orig_pte, NULL);
2714 ret = VM_FAULT_SIGBUS;
2718 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2719 page = lookup_swap_cache(entry);
2721 grab_swap_token(mm); /* Contend for token _before_ read-in */
2722 page = swapin_readahead(entry,
2723 GFP_HIGHUSER_MOVABLE, vma, address);
2726 * Back out if somebody else faulted in this pte
2727 * while we released the pte lock.
2729 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2730 if (likely(pte_same(*page_table, orig_pte)))
2732 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2736 /* Had to read the page from swap area: Major fault */
2737 ret = VM_FAULT_MAJOR;
2738 count_vm_event(PGMAJFAULT);
2739 } else if (PageHWPoison(page)) {
2741 * hwpoisoned dirty swapcache pages are kept for killing
2742 * owner processes (which may be unknown at hwpoison time)
2744 ret = VM_FAULT_HWPOISON;
2745 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2749 locked = lock_page_or_retry(page, mm, flags);
2750 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2752 ret |= VM_FAULT_RETRY;
2757 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2758 * release the swapcache from under us. The page pin, and pte_same
2759 * test below, are not enough to exclude that. Even if it is still
2760 * swapcache, we need to check that the page's swap has not changed.
2762 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2765 if (ksm_might_need_to_copy(page, vma, address)) {
2767 page = ksm_does_need_to_copy(page, vma, address);
2769 if (unlikely(!page)) {
2777 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2783 * Back out if somebody else already faulted in this pte.
2785 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2786 if (unlikely(!pte_same(*page_table, orig_pte)))
2789 if (unlikely(!PageUptodate(page))) {
2790 ret = VM_FAULT_SIGBUS;
2795 * The page isn't present yet, go ahead with the fault.
2797 * Be careful about the sequence of operations here.
2798 * To get its accounting right, reuse_swap_page() must be called
2799 * while the page is counted on swap but not yet in mapcount i.e.
2800 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2801 * must be called after the swap_free(), or it will never succeed.
2802 * Because delete_from_swap_page() may be called by reuse_swap_page(),
2803 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2804 * in page->private. In this case, a record in swap_cgroup is silently
2805 * discarded at swap_free().
2808 inc_mm_counter_fast(mm, MM_ANONPAGES);
2809 dec_mm_counter_fast(mm, MM_SWAPENTS);
2810 pte = mk_pte(page, vma->vm_page_prot);
2811 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2812 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2813 flags &= ~FAULT_FLAG_WRITE;
2814 ret |= VM_FAULT_WRITE;
2817 flush_icache_page(vma, page);
2818 set_pte_at(mm, address, page_table, pte);
2819 do_page_add_anon_rmap(page, vma, address, exclusive);
2820 /* It's better to call commit-charge after rmap is established */
2821 mem_cgroup_commit_charge_swapin(page, ptr);
2824 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2825 try_to_free_swap(page);
2829 * Hold the lock to avoid the swap entry to be reused
2830 * until we take the PT lock for the pte_same() check
2831 * (to avoid false positives from pte_same). For
2832 * further safety release the lock after the swap_free
2833 * so that the swap count won't change under a
2834 * parallel locked swapcache.
2836 unlock_page(swapcache);
2837 page_cache_release(swapcache);
2840 if (flags & FAULT_FLAG_WRITE) {
2841 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2842 if (ret & VM_FAULT_ERROR)
2843 ret &= VM_FAULT_ERROR;
2847 /* No need to invalidate - it was non-present before */
2848 update_mmu_cache(vma, address, page_table);
2850 pte_unmap_unlock(page_table, ptl);
2854 mem_cgroup_cancel_charge_swapin(ptr);
2855 pte_unmap_unlock(page_table, ptl);
2859 page_cache_release(page);
2861 unlock_page(swapcache);
2862 page_cache_release(swapcache);
2868 * This is like a special single-page "expand_{down|up}wards()",
2869 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2870 * doesn't hit another vma.
2872 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
2874 address &= PAGE_MASK;
2875 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
2876 struct vm_area_struct *prev = vma->vm_prev;
2879 * Is there a mapping abutting this one below?
2881 * That's only ok if it's the same stack mapping
2882 * that has gotten split..
2884 if (prev && prev->vm_end == address)
2885 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
2887 expand_stack(vma, address - PAGE_SIZE);
2889 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
2890 struct vm_area_struct *next = vma->vm_next;
2892 /* As VM_GROWSDOWN but s/below/above/ */
2893 if (next && next->vm_start == address + PAGE_SIZE)
2894 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
2896 expand_upwards(vma, address + PAGE_SIZE);
2902 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2903 * but allow concurrent faults), and pte mapped but not yet locked.
2904 * We return with mmap_sem still held, but pte unmapped and unlocked.
2906 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2907 unsigned long address, pte_t *page_table, pmd_t *pmd,
2914 pte_unmap(page_table);
2916 /* Check if we need to add a guard page to the stack */
2917 if (check_stack_guard_page(vma, address) < 0)
2918 return VM_FAULT_SIGBUS;
2920 /* Use the zero-page for reads */
2921 if (!(flags & FAULT_FLAG_WRITE)) {
2922 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
2923 vma->vm_page_prot));
2924 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2925 if (!pte_none(*page_table))
2930 /* Allocate our own private page. */
2931 if (unlikely(anon_vma_prepare(vma)))
2933 page = alloc_zeroed_user_highpage_movable(vma, address);
2936 __SetPageUptodate(page);
2938 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
2941 entry = mk_pte(page, vma->vm_page_prot);
2942 if (vma->vm_flags & VM_WRITE)
2943 entry = pte_mkwrite(pte_mkdirty(entry));
2945 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2946 if (!pte_none(*page_table))
2949 inc_mm_counter_fast(mm, MM_ANONPAGES);
2950 page_add_new_anon_rmap(page, vma, address);
2952 set_pte_at(mm, address, page_table, entry);
2954 /* No need to invalidate - it was non-present before */
2955 update_mmu_cache(vma, address, page_table);
2957 pte_unmap_unlock(page_table, ptl);
2960 mem_cgroup_uncharge_page(page);
2961 page_cache_release(page);
2964 page_cache_release(page);
2966 return VM_FAULT_OOM;
2970 * __do_fault() tries to create a new page mapping. It aggressively
2971 * tries to share with existing pages, but makes a separate copy if
2972 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
2973 * the next page fault.
2975 * As this is called only for pages that do not currently exist, we
2976 * do not need to flush old virtual caches or the TLB.
2978 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2979 * but allow concurrent faults), and pte neither mapped nor locked.
2980 * We return with mmap_sem still held, but pte unmapped and unlocked.
2982 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2983 unsigned long address, pmd_t *pmd,
2984 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
2992 struct page *dirty_page = NULL;
2993 struct vm_fault vmf;
2995 int page_mkwrite = 0;
2997 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3002 ret = vma->vm_ops->fault(vma, &vmf);
3003 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3007 if (unlikely(PageHWPoison(vmf.page))) {
3008 if (ret & VM_FAULT_LOCKED)
3009 unlock_page(vmf.page);
3010 return VM_FAULT_HWPOISON;
3014 * For consistency in subsequent calls, make the faulted page always
3017 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3018 lock_page(vmf.page);
3020 VM_BUG_ON(!PageLocked(vmf.page));
3023 * Should we do an early C-O-W break?
3026 if (flags & FAULT_FLAG_WRITE) {
3027 if (!(vma->vm_flags & VM_SHARED)) {
3029 if (unlikely(anon_vma_prepare(vma))) {
3033 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
3039 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
3041 page_cache_release(page);
3046 * Don't let another task, with possibly unlocked vma,
3047 * keep the mlocked page.
3049 if (vma->vm_flags & VM_LOCKED)
3050 clear_page_mlock(vmf.page);
3051 copy_user_highpage(page, vmf.page, address, vma);
3052 __SetPageUptodate(page);
3055 * If the page will be shareable, see if the backing
3056 * address space wants to know that the page is about
3057 * to become writable
3059 if (vma->vm_ops->page_mkwrite) {
3063 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3064 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3066 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3068 goto unwritable_page;
3070 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3072 if (!page->mapping) {
3073 ret = 0; /* retry the fault */
3075 goto unwritable_page;
3078 VM_BUG_ON(!PageLocked(page));
3085 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3088 * This silly early PAGE_DIRTY setting removes a race
3089 * due to the bad i386 page protection. But it's valid
3090 * for other architectures too.
3092 * Note that if FAULT_FLAG_WRITE is set, we either now have
3093 * an exclusive copy of the page, or this is a shared mapping,
3094 * so we can make it writable and dirty to avoid having to
3095 * handle that later.
3097 /* Only go through if we didn't race with anybody else... */
3098 if (likely(pte_same(*page_table, orig_pte))) {
3099 flush_icache_page(vma, page);
3100 entry = mk_pte(page, vma->vm_page_prot);
3101 if (flags & FAULT_FLAG_WRITE)
3102 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3104 inc_mm_counter_fast(mm, MM_ANONPAGES);
3105 page_add_new_anon_rmap(page, vma, address);
3107 inc_mm_counter_fast(mm, MM_FILEPAGES);
3108 page_add_file_rmap(page);
3109 if (flags & FAULT_FLAG_WRITE) {
3111 get_page(dirty_page);
3114 set_pte_at(mm, address, page_table, entry);
3116 /* no need to invalidate: a not-present page won't be cached */
3117 update_mmu_cache(vma, address, page_table);
3120 mem_cgroup_uncharge_page(page);
3122 page_cache_release(page);
3124 anon = 1; /* no anon but release faulted_page */
3127 pte_unmap_unlock(page_table, ptl);
3131 struct address_space *mapping = page->mapping;
3133 if (set_page_dirty(dirty_page))
3135 unlock_page(dirty_page);
3136 put_page(dirty_page);
3137 if (page_mkwrite && mapping) {
3139 * Some device drivers do not set page.mapping but still
3142 balance_dirty_pages_ratelimited(mapping);
3145 /* file_update_time outside page_lock */
3147 file_update_time(vma->vm_file);
3149 unlock_page(vmf.page);
3151 page_cache_release(vmf.page);
3157 page_cache_release(page);
3161 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3162 unsigned long address, pte_t *page_table, pmd_t *pmd,
3163 unsigned int flags, pte_t orig_pte)
3165 pgoff_t pgoff = (((address & PAGE_MASK)
3166 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3168 pte_unmap(page_table);
3169 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3173 * Fault of a previously existing named mapping. Repopulate the pte
3174 * from the encoded file_pte if possible. This enables swappable
3177 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3178 * but allow concurrent faults), and pte mapped but not yet locked.
3179 * We return with mmap_sem still held, but pte unmapped and unlocked.
3181 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3182 unsigned long address, pte_t *page_table, pmd_t *pmd,
3183 unsigned int flags, pte_t orig_pte)
3187 flags |= FAULT_FLAG_NONLINEAR;
3189 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3192 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3194 * Page table corrupted: show pte and kill process.
3196 print_bad_pte(vma, address, orig_pte, NULL);
3197 return VM_FAULT_SIGBUS;
3200 pgoff = pte_to_pgoff(orig_pte);
3201 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3205 * These routines also need to handle stuff like marking pages dirty
3206 * and/or accessed for architectures that don't do it in hardware (most
3207 * RISC architectures). The early dirtying is also good on the i386.
3209 * There is also a hook called "update_mmu_cache()" that architectures
3210 * with external mmu caches can use to update those (ie the Sparc or
3211 * PowerPC hashed page tables that act as extended TLBs).
3213 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3214 * but allow concurrent faults), and pte mapped but not yet locked.
3215 * We return with mmap_sem still held, but pte unmapped and unlocked.
3217 int handle_pte_fault(struct mm_struct *mm,
3218 struct vm_area_struct *vma, unsigned long address,
3219 pte_t *pte, pmd_t *pmd, unsigned int flags)
3225 if (!pte_present(entry)) {
3226 if (pte_none(entry)) {
3228 if (likely(vma->vm_ops->fault))
3229 return do_linear_fault(mm, vma, address,
3230 pte, pmd, flags, entry);
3232 return do_anonymous_page(mm, vma, address,
3235 if (pte_file(entry))
3236 return do_nonlinear_fault(mm, vma, address,
3237 pte, pmd, flags, entry);
3238 return do_swap_page(mm, vma, address,
3239 pte, pmd, flags, entry);
3242 ptl = pte_lockptr(mm, pmd);
3244 if (unlikely(!pte_same(*pte, entry)))
3246 if (flags & FAULT_FLAG_WRITE) {
3247 if (!pte_write(entry))
3248 return do_wp_page(mm, vma, address,
3249 pte, pmd, ptl, entry);
3250 entry = pte_mkdirty(entry);
3252 entry = pte_mkyoung(entry);
3253 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3254 update_mmu_cache(vma, address, pte);
3257 * This is needed only for protection faults but the arch code
3258 * is not yet telling us if this is a protection fault or not.
3259 * This still avoids useless tlb flushes for .text page faults
3262 if (flags & FAULT_FLAG_WRITE)
3263 flush_tlb_fix_spurious_fault(vma, address);
3266 pte_unmap_unlock(pte, ptl);
3271 * By the time we get here, we already hold the mm semaphore
3273 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3274 unsigned long address, unsigned int flags)
3281 __set_current_state(TASK_RUNNING);
3283 count_vm_event(PGFAULT);
3285 /* do counter updates before entering really critical section. */
3286 check_sync_rss_stat(current);
3288 if (unlikely(is_vm_hugetlb_page(vma)))
3289 return hugetlb_fault(mm, vma, address, flags);
3291 pgd = pgd_offset(mm, address);
3292 pud = pud_alloc(mm, pgd, address);
3294 return VM_FAULT_OOM;
3295 pmd = pmd_alloc(mm, pud, address);
3297 return VM_FAULT_OOM;
3298 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3300 return do_huge_pmd_anonymous_page(mm, vma, address,
3303 pmd_t orig_pmd = *pmd;
3305 if (pmd_trans_huge(orig_pmd)) {
3306 if (flags & FAULT_FLAG_WRITE &&
3307 !pmd_write(orig_pmd) &&
3308 !pmd_trans_splitting(orig_pmd))
3309 return do_huge_pmd_wp_page(mm, vma, address,
3316 * Use __pte_alloc instead of pte_alloc_map, because we can't
3317 * run pte_offset_map on the pmd, if an huge pmd could
3318 * materialize from under us from a different thread.
3320 if (unlikely(__pte_alloc(mm, vma, pmd, address)))
3321 return VM_FAULT_OOM;
3322 /* if an huge pmd materialized from under us just retry later */
3323 if (unlikely(pmd_trans_huge(*pmd)))
3326 * A regular pmd is established and it can't morph into a huge pmd
3327 * from under us anymore at this point because we hold the mmap_sem
3328 * read mode and khugepaged takes it in write mode. So now it's
3329 * safe to run pte_offset_map().
3331 pte = pte_offset_map(pmd, address);
3333 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3336 #ifndef __PAGETABLE_PUD_FOLDED
3338 * Allocate page upper directory.
3339 * We've already handled the fast-path in-line.
3341 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3343 pud_t *new = pud_alloc_one(mm, address);
3347 smp_wmb(); /* See comment in __pte_alloc */
3349 spin_lock(&mm->page_table_lock);
3350 if (pgd_present(*pgd)) /* Another has populated it */
3353 pgd_populate(mm, pgd, new);
3354 spin_unlock(&mm->page_table_lock);
3357 #endif /* __PAGETABLE_PUD_FOLDED */
3359 #ifndef __PAGETABLE_PMD_FOLDED
3361 * Allocate page middle directory.
3362 * We've already handled the fast-path in-line.
3364 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3366 pmd_t *new = pmd_alloc_one(mm, address);
3370 smp_wmb(); /* See comment in __pte_alloc */
3372 spin_lock(&mm->page_table_lock);
3373 #ifndef __ARCH_HAS_4LEVEL_HACK
3374 if (pud_present(*pud)) /* Another has populated it */
3377 pud_populate(mm, pud, new);
3379 if (pgd_present(*pud)) /* Another has populated it */
3382 pgd_populate(mm, pud, new);
3383 #endif /* __ARCH_HAS_4LEVEL_HACK */
3384 spin_unlock(&mm->page_table_lock);
3387 #endif /* __PAGETABLE_PMD_FOLDED */
3389 int make_pages_present(unsigned long addr, unsigned long end)
3391 int ret, len, write;
3392 struct vm_area_struct * vma;
3394 vma = find_vma(current->mm, addr);
3398 * We want to touch writable mappings with a write fault in order
3399 * to break COW, except for shared mappings because these don't COW
3400 * and we would not want to dirty them for nothing.
3402 write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;
3403 BUG_ON(addr >= end);
3404 BUG_ON(end > vma->vm_end);
3405 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3406 ret = get_user_pages(current, current->mm, addr,
3407 len, write, 0, NULL, NULL);
3410 return ret == len ? 0 : -EFAULT;
3413 #if !defined(__HAVE_ARCH_GATE_AREA)
3415 #if defined(AT_SYSINFO_EHDR)
3416 static struct vm_area_struct gate_vma;
3418 static int __init gate_vma_init(void)
3420 gate_vma.vm_mm = NULL;
3421 gate_vma.vm_start = FIXADDR_USER_START;
3422 gate_vma.vm_end = FIXADDR_USER_END;
3423 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3424 gate_vma.vm_page_prot = __P101;
3426 * Make sure the vDSO gets into every core dump.
3427 * Dumping its contents makes post-mortem fully interpretable later
3428 * without matching up the same kernel and hardware config to see
3429 * what PC values meant.
3431 gate_vma.vm_flags |= VM_ALWAYSDUMP;
3434 __initcall(gate_vma_init);
3437 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
3439 #ifdef AT_SYSINFO_EHDR
3446 int in_gate_area_no_task(unsigned long addr)
3448 #ifdef AT_SYSINFO_EHDR
3449 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3455 #endif /* __HAVE_ARCH_GATE_AREA */
3457 static int __follow_pte(struct mm_struct *mm, unsigned long address,
3458 pte_t **ptepp, spinlock_t **ptlp)
3465 pgd = pgd_offset(mm, address);
3466 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3469 pud = pud_offset(pgd, address);
3470 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3473 pmd = pmd_offset(pud, address);
3474 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3477 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3481 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3484 if (!pte_present(*ptep))
3489 pte_unmap_unlock(ptep, *ptlp);
3494 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3495 pte_t **ptepp, spinlock_t **ptlp)
3499 /* (void) is needed to make gcc happy */
3500 (void) __cond_lock(*ptlp,
3501 !(res = __follow_pte(mm, address, ptepp, ptlp)));
3506 * follow_pfn - look up PFN at a user virtual address
3507 * @vma: memory mapping
3508 * @address: user virtual address
3509 * @pfn: location to store found PFN
3511 * Only IO mappings and raw PFN mappings are allowed.
3513 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3515 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3522 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3525 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3528 *pfn = pte_pfn(*ptep);
3529 pte_unmap_unlock(ptep, ptl);
3532 EXPORT_SYMBOL(follow_pfn);
3534 #ifdef CONFIG_HAVE_IOREMAP_PROT
3535 int follow_phys(struct vm_area_struct *vma,
3536 unsigned long address, unsigned int flags,
3537 unsigned long *prot, resource_size_t *phys)
3543 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3546 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3550 if ((flags & FOLL_WRITE) && !pte_write(pte))
3553 *prot = pgprot_val(pte_pgprot(pte));
3554 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3558 pte_unmap_unlock(ptep, ptl);
3563 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3564 void *buf, int len, int write)
3566 resource_size_t phys_addr;
3567 unsigned long prot = 0;
3568 void __iomem *maddr;
3569 int offset = addr & (PAGE_SIZE-1);
3571 if (follow_phys(vma, addr, write, &prot, &phys_addr))
3574 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3576 memcpy_toio(maddr + offset, buf, len);
3578 memcpy_fromio(buf, maddr + offset, len);
3586 * Access another process' address space.
3587 * Source/target buffer must be kernel space,
3588 * Do not walk the page table directly, use get_user_pages
3590 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
3592 struct mm_struct *mm;
3593 struct vm_area_struct *vma;
3594 void *old_buf = buf;
3596 mm = get_task_mm(tsk);
3600 down_read(&mm->mmap_sem);
3601 /* ignore errors, just check how much was successfully transferred */
3603 int bytes, ret, offset;
3605 struct page *page = NULL;
3607 ret = get_user_pages(tsk, mm, addr, 1,
3608 write, 1, &page, &vma);
3611 * Check if this is a VM_IO | VM_PFNMAP VMA, which
3612 * we can access using slightly different code.
3614 #ifdef CONFIG_HAVE_IOREMAP_PROT
3615 vma = find_vma(mm, addr);
3618 if (vma->vm_ops && vma->vm_ops->access)
3619 ret = vma->vm_ops->access(vma, addr, buf,
3627 offset = addr & (PAGE_SIZE-1);
3628 if (bytes > PAGE_SIZE-offset)
3629 bytes = PAGE_SIZE-offset;
3633 copy_to_user_page(vma, page, addr,
3634 maddr + offset, buf, bytes);
3635 set_page_dirty_lock(page);
3637 copy_from_user_page(vma, page, addr,
3638 buf, maddr + offset, bytes);
3641 page_cache_release(page);
3647 up_read(&mm->mmap_sem);
3650 return buf - old_buf;
3654 * Print the name of a VMA.
3656 void print_vma_addr(char *prefix, unsigned long ip)
3658 struct mm_struct *mm = current->mm;
3659 struct vm_area_struct *vma;
3662 * Do not print if we are in atomic
3663 * contexts (in exception stacks, etc.):
3665 if (preempt_count())
3668 down_read(&mm->mmap_sem);
3669 vma = find_vma(mm, ip);
3670 if (vma && vma->vm_file) {
3671 struct file *f = vma->vm_file;
3672 char *buf = (char *)__get_free_page(GFP_KERNEL);
3676 p = d_path(&f->f_path, buf, PAGE_SIZE);
3679 s = strrchr(p, '/');
3682 printk("%s%s[%lx+%lx]", prefix, p,
3684 vma->vm_end - vma->vm_start);
3685 free_page((unsigned long)buf);
3688 up_read(¤t->mm->mmap_sem);
3691 #ifdef CONFIG_PROVE_LOCKING
3692 void might_fault(void)
3695 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3696 * holding the mmap_sem, this is safe because kernel memory doesn't
3697 * get paged out, therefore we'll never actually fault, and the
3698 * below annotations will generate false positives.
3700 if (segment_eq(get_fs(), KERNEL_DS))
3705 * it would be nicer only to annotate paths which are not under
3706 * pagefault_disable, however that requires a larger audit and
3707 * providing helpers like get_user_atomic.
3709 if (!in_atomic() && current->mm)
3710 might_lock_read(¤t->mm->mmap_sem);
3712 EXPORT_SYMBOL(might_fault);
3715 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3716 static void clear_gigantic_page(struct page *page,
3718 unsigned int pages_per_huge_page)
3721 struct page *p = page;
3724 for (i = 0; i < pages_per_huge_page;
3725 i++, p = mem_map_next(p, page, i)) {
3727 clear_user_highpage(p, addr + i * PAGE_SIZE);
3730 void clear_huge_page(struct page *page,
3731 unsigned long addr, unsigned int pages_per_huge_page)
3735 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3736 clear_gigantic_page(page, addr, pages_per_huge_page);
3741 for (i = 0; i < pages_per_huge_page; i++) {
3743 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3747 static void copy_user_gigantic_page(struct page *dst, struct page *src,
3749 struct vm_area_struct *vma,
3750 unsigned int pages_per_huge_page)
3753 struct page *dst_base = dst;
3754 struct page *src_base = src;
3756 for (i = 0; i < pages_per_huge_page; ) {
3758 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3761 dst = mem_map_next(dst, dst_base, i);
3762 src = mem_map_next(src, src_base, i);
3766 void copy_user_huge_page(struct page *dst, struct page *src,
3767 unsigned long addr, struct vm_area_struct *vma,
3768 unsigned int pages_per_huge_page)
3772 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3773 copy_user_gigantic_page(dst, src, addr, vma,
3774 pages_per_huge_page);
3779 for (i = 0; i < pages_per_huge_page; i++) {
3781 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3784 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */