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 if (flags
& FOLL_SPLIT
) {
1309 split_huge_page_pmd(mm
, pmd
);
1310 goto split_fallthrough
;
1312 spin_lock(&mm
->page_table_lock
);
1313 if (likely(pmd_trans_huge(*pmd
))) {
1314 if (unlikely(pmd_trans_splitting(*pmd
))) {
1315 spin_unlock(&mm
->page_table_lock
);
1316 wait_split_huge_page(vma
->anon_vma
, pmd
);
1318 page
= follow_trans_huge_pmd(mm
, address
,
1320 spin_unlock(&mm
->page_table_lock
);
1324 spin_unlock(&mm
->page_table_lock
);
1328 if (unlikely(pmd_bad(*pmd
)))
1331 ptep
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
1334 if (!pte_present(pte
))
1336 if ((flags
& FOLL_WRITE
) && !pte_write(pte
))
1339 page
= vm_normal_page(vma
, address
, pte
);
1340 if (unlikely(!page
)) {
1341 if ((flags
& FOLL_DUMP
) ||
1342 !is_zero_pfn(pte_pfn(pte
)))
1344 page
= pte_page(pte
);
1347 if (flags
& FOLL_GET
)
1349 if (flags
& FOLL_TOUCH
) {
1350 if ((flags
& FOLL_WRITE
) &&
1351 !pte_dirty(pte
) && !PageDirty(page
))
1352 set_page_dirty(page
);
1354 * pte_mkyoung() would be more correct here, but atomic care
1355 * is needed to avoid losing the dirty bit: it is easier to use
1356 * mark_page_accessed().
1358 mark_page_accessed(page
);
1360 if (flags
& FOLL_MLOCK
) {
1362 * The preliminary mapping check is mainly to avoid the
1363 * pointless overhead of lock_page on the ZERO_PAGE
1364 * which might bounce very badly if there is contention.
1366 * If the page is already locked, we don't need to
1367 * handle it now - vmscan will handle it later if and
1368 * when it attempts to reclaim the page.
1370 if (page
->mapping
&& trylock_page(page
)) {
1371 lru_add_drain(); /* push cached pages to LRU */
1373 * Because we lock page here and migration is
1374 * blocked by the pte's page reference, we need
1375 * only check for file-cache page truncation.
1378 mlock_vma_page(page
);
1383 pte_unmap_unlock(ptep
, ptl
);
1388 pte_unmap_unlock(ptep
, ptl
);
1389 return ERR_PTR(-EFAULT
);
1392 pte_unmap_unlock(ptep
, ptl
);
1398 * When core dumping an enormous anonymous area that nobody
1399 * has touched so far, we don't want to allocate unnecessary pages or
1400 * page tables. Return error instead of NULL to skip handle_mm_fault,
1401 * then get_dump_page() will return NULL to leave a hole in the dump.
1402 * But we can only make this optimization where a hole would surely
1403 * be zero-filled if handle_mm_fault() actually did handle it.
1405 if ((flags
& FOLL_DUMP
) &&
1406 (!vma
->vm_ops
|| !vma
->vm_ops
->fault
))
1407 return ERR_PTR(-EFAULT
);
1411 int __get_user_pages(struct task_struct
*tsk
, struct mm_struct
*mm
,
1412 unsigned long start
, int nr_pages
, unsigned int gup_flags
,
1413 struct page
**pages
, struct vm_area_struct
**vmas
,
1417 unsigned long vm_flags
;
1422 VM_BUG_ON(!!pages
!= !!(gup_flags
& FOLL_GET
));
1425 * Require read or write permissions.
1426 * If FOLL_FORCE is set, we only require the "MAY" flags.
1428 vm_flags
= (gup_flags
& FOLL_WRITE
) ?
1429 (VM_WRITE
| VM_MAYWRITE
) : (VM_READ
| VM_MAYREAD
);
1430 vm_flags
&= (gup_flags
& FOLL_FORCE
) ?
1431 (VM_MAYREAD
| VM_MAYWRITE
) : (VM_READ
| VM_WRITE
);
1435 struct vm_area_struct
*vma
;
1437 vma
= find_extend_vma(mm
, start
);
1438 if (!vma
&& in_gate_area(tsk
, start
)) {
1439 unsigned long pg
= start
& PAGE_MASK
;
1440 struct vm_area_struct
*gate_vma
= get_gate_vma(tsk
);
1446 /* user gate pages are read-only */
1447 if (gup_flags
& FOLL_WRITE
)
1448 return i
? : -EFAULT
;
1450 pgd
= pgd_offset_k(pg
);
1452 pgd
= pgd_offset_gate(mm
, pg
);
1453 BUG_ON(pgd_none(*pgd
));
1454 pud
= pud_offset(pgd
, pg
);
1455 BUG_ON(pud_none(*pud
));
1456 pmd
= pmd_offset(pud
, pg
);
1458 return i
? : -EFAULT
;
1459 VM_BUG_ON(pmd_trans_huge(*pmd
));
1460 pte
= pte_offset_map(pmd
, pg
);
1461 if (pte_none(*pte
)) {
1463 return i
? : -EFAULT
;
1468 page
= vm_normal_page(gate_vma
, start
, *pte
);
1470 if (!(gup_flags
& FOLL_DUMP
) &&
1471 is_zero_pfn(pte_pfn(*pte
)))
1472 page
= pte_page(*pte
);
1475 return i
? : -EFAULT
;
1491 (vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)) ||
1492 !(vm_flags
& vma
->vm_flags
))
1493 return i
? : -EFAULT
;
1495 if (is_vm_hugetlb_page(vma
)) {
1496 i
= follow_hugetlb_page(mm
, vma
, pages
, vmas
,
1497 &start
, &nr_pages
, i
, gup_flags
);
1503 unsigned int foll_flags
= gup_flags
;
1506 * If we have a pending SIGKILL, don't keep faulting
1507 * pages and potentially allocating memory.
1509 if (unlikely(fatal_signal_pending(current
)))
1510 return i
? i
: -ERESTARTSYS
;
1513 while (!(page
= follow_page(vma
, start
, foll_flags
))) {
1515 unsigned int fault_flags
= 0;
1517 if (foll_flags
& FOLL_WRITE
)
1518 fault_flags
|= FAULT_FLAG_WRITE
;
1520 fault_flags
|= FAULT_FLAG_ALLOW_RETRY
;
1522 ret
= handle_mm_fault(mm
, vma
, start
,
1525 if (ret
& VM_FAULT_ERROR
) {
1526 if (ret
& VM_FAULT_OOM
)
1527 return i
? i
: -ENOMEM
;
1529 (VM_FAULT_HWPOISON
|VM_FAULT_HWPOISON_LARGE
|
1531 return i
? i
: -EFAULT
;
1534 if (ret
& VM_FAULT_MAJOR
)
1539 if (ret
& VM_FAULT_RETRY
) {
1545 * The VM_FAULT_WRITE bit tells us that
1546 * do_wp_page has broken COW when necessary,
1547 * even if maybe_mkwrite decided not to set
1548 * pte_write. We can thus safely do subsequent
1549 * page lookups as if they were reads. But only
1550 * do so when looping for pte_write is futile:
1551 * in some cases userspace may also be wanting
1552 * to write to the gotten user page, which a
1553 * read fault here might prevent (a readonly
1554 * page might get reCOWed by userspace write).
1556 if ((ret
& VM_FAULT_WRITE
) &&
1557 !(vma
->vm_flags
& VM_WRITE
))
1558 foll_flags
&= ~FOLL_WRITE
;
1563 return i
? i
: PTR_ERR(page
);
1567 flush_anon_page(vma
, page
, start
);
1568 flush_dcache_page(page
);
1575 } while (nr_pages
&& start
< vma
->vm_end
);
1581 * get_user_pages() - pin user pages in memory
1582 * @tsk: task_struct of target task
1583 * @mm: mm_struct of target mm
1584 * @start: starting user address
1585 * @nr_pages: number of pages from start to pin
1586 * @write: whether pages will be written to by the caller
1587 * @force: whether to force write access even if user mapping is
1588 * readonly. This will result in the page being COWed even
1589 * in MAP_SHARED mappings. You do not want this.
1590 * @pages: array that receives pointers to the pages pinned.
1591 * Should be at least nr_pages long. Or NULL, if caller
1592 * only intends to ensure the pages are faulted in.
1593 * @vmas: array of pointers to vmas corresponding to each page.
1594 * Or NULL if the caller does not require them.
1596 * Returns number of pages pinned. This may be fewer than the number
1597 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1598 * were pinned, returns -errno. Each page returned must be released
1599 * with a put_page() call when it is finished with. vmas will only
1600 * remain valid while mmap_sem is held.
1602 * Must be called with mmap_sem held for read or write.
1604 * get_user_pages walks a process's page tables and takes a reference to
1605 * each struct page that each user address corresponds to at a given
1606 * instant. That is, it takes the page that would be accessed if a user
1607 * thread accesses the given user virtual address at that instant.
1609 * This does not guarantee that the page exists in the user mappings when
1610 * get_user_pages returns, and there may even be a completely different
1611 * page there in some cases (eg. if mmapped pagecache has been invalidated
1612 * and subsequently re faulted). However it does guarantee that the page
1613 * won't be freed completely. And mostly callers simply care that the page
1614 * contains data that was valid *at some point in time*. Typically, an IO
1615 * or similar operation cannot guarantee anything stronger anyway because
1616 * locks can't be held over the syscall boundary.
1618 * If write=0, the page must not be written to. If the page is written to,
1619 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1620 * after the page is finished with, and before put_page is called.
1622 * get_user_pages is typically used for fewer-copy IO operations, to get a
1623 * handle on the memory by some means other than accesses via the user virtual
1624 * addresses. The pages may be submitted for DMA to devices or accessed via
1625 * their kernel linear mapping (via the kmap APIs). Care should be taken to
1626 * use the correct cache flushing APIs.
1628 * See also get_user_pages_fast, for performance critical applications.
1630 int get_user_pages(struct task_struct
*tsk
, struct mm_struct
*mm
,
1631 unsigned long start
, int nr_pages
, int write
, int force
,
1632 struct page
**pages
, struct vm_area_struct
**vmas
)
1634 int flags
= FOLL_TOUCH
;
1639 flags
|= FOLL_WRITE
;
1641 flags
|= FOLL_FORCE
;
1643 return __get_user_pages(tsk
, mm
, start
, nr_pages
, flags
, pages
, vmas
,
1646 EXPORT_SYMBOL(get_user_pages
);
1649 * get_dump_page() - pin user page in memory while writing it to core dump
1650 * @addr: user address
1652 * Returns struct page pointer of user page pinned for dump,
1653 * to be freed afterwards by page_cache_release() or put_page().
1655 * Returns NULL on any kind of failure - a hole must then be inserted into
1656 * the corefile, to preserve alignment with its headers; and also returns
1657 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1658 * allowing a hole to be left in the corefile to save diskspace.
1660 * Called without mmap_sem, but after all other threads have been killed.
1662 #ifdef CONFIG_ELF_CORE
1663 struct page
*get_dump_page(unsigned long addr
)
1665 struct vm_area_struct
*vma
;
1668 if (__get_user_pages(current
, current
->mm
, addr
, 1,
1669 FOLL_FORCE
| FOLL_DUMP
| FOLL_GET
, &page
, &vma
,
1672 flush_cache_page(vma
, addr
, page_to_pfn(page
));
1675 #endif /* CONFIG_ELF_CORE */
1677 pte_t
*__get_locked_pte(struct mm_struct
*mm
, unsigned long addr
,
1680 pgd_t
* pgd
= pgd_offset(mm
, addr
);
1681 pud_t
* pud
= pud_alloc(mm
, pgd
, addr
);
1683 pmd_t
* pmd
= pmd_alloc(mm
, pud
, addr
);
1685 VM_BUG_ON(pmd_trans_huge(*pmd
));
1686 return pte_alloc_map_lock(mm
, pmd
, addr
, ptl
);
1693 * This is the old fallback for page remapping.
1695 * For historical reasons, it only allows reserved pages. Only
1696 * old drivers should use this, and they needed to mark their
1697 * pages reserved for the old functions anyway.
1699 static int insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
1700 struct page
*page
, pgprot_t prot
)
1702 struct mm_struct
*mm
= vma
->vm_mm
;
1711 flush_dcache_page(page
);
1712 pte
= get_locked_pte(mm
, addr
, &ptl
);
1716 if (!pte_none(*pte
))
1719 /* Ok, finally just insert the thing.. */
1721 inc_mm_counter_fast(mm
, MM_FILEPAGES
);
1722 page_add_file_rmap(page
);
1723 set_pte_at(mm
, addr
, pte
, mk_pte(page
, prot
));
1726 pte_unmap_unlock(pte
, ptl
);
1729 pte_unmap_unlock(pte
, ptl
);
1735 * vm_insert_page - insert single page into user vma
1736 * @vma: user vma to map to
1737 * @addr: target user address of this page
1738 * @page: source kernel page
1740 * This allows drivers to insert individual pages they've allocated
1743 * The page has to be a nice clean _individual_ kernel allocation.
1744 * If you allocate a compound page, you need to have marked it as
1745 * such (__GFP_COMP), or manually just split the page up yourself
1746 * (see split_page()).
1748 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1749 * took an arbitrary page protection parameter. This doesn't allow
1750 * that. Your vma protection will have to be set up correctly, which
1751 * means that if you want a shared writable mapping, you'd better
1752 * ask for a shared writable mapping!
1754 * The page does not need to be reserved.
1756 int vm_insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
1759 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
1761 if (!page_count(page
))
1763 vma
->vm_flags
|= VM_INSERTPAGE
;
1764 return insert_page(vma
, addr
, page
, vma
->vm_page_prot
);
1766 EXPORT_SYMBOL(vm_insert_page
);
1768 static int insert_pfn(struct vm_area_struct
*vma
, unsigned long addr
,
1769 unsigned long pfn
, pgprot_t prot
)
1771 struct mm_struct
*mm
= vma
->vm_mm
;
1777 pte
= get_locked_pte(mm
, addr
, &ptl
);
1781 if (!pte_none(*pte
))
1784 /* Ok, finally just insert the thing.. */
1785 entry
= pte_mkspecial(pfn_pte(pfn
, prot
));
1786 set_pte_at(mm
, addr
, pte
, entry
);
1787 update_mmu_cache(vma
, addr
, pte
); /* XXX: why not for insert_page? */
1791 pte_unmap_unlock(pte
, ptl
);
1797 * vm_insert_pfn - insert single pfn into user vma
1798 * @vma: user vma to map to
1799 * @addr: target user address of this page
1800 * @pfn: source kernel pfn
1802 * Similar to vm_inert_page, this allows drivers to insert individual pages
1803 * they've allocated into a user vma. Same comments apply.
1805 * This function should only be called from a vm_ops->fault handler, and
1806 * in that case the handler should return NULL.
1808 * vma cannot be a COW mapping.
1810 * As this is called only for pages that do not currently exist, we
1811 * do not need to flush old virtual caches or the TLB.
1813 int vm_insert_pfn(struct vm_area_struct
*vma
, unsigned long addr
,
1817 pgprot_t pgprot
= vma
->vm_page_prot
;
1819 * Technically, architectures with pte_special can avoid all these
1820 * restrictions (same for remap_pfn_range). However we would like
1821 * consistency in testing and feature parity among all, so we should
1822 * try to keep these invariants in place for everybody.
1824 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
1825 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
1826 (VM_PFNMAP
|VM_MIXEDMAP
));
1827 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
1828 BUG_ON((vma
->vm_flags
& VM_MIXEDMAP
) && pfn_valid(pfn
));
1830 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
1832 if (track_pfn_vma_new(vma
, &pgprot
, pfn
, PAGE_SIZE
))
1835 ret
= insert_pfn(vma
, addr
, pfn
, pgprot
);
1838 untrack_pfn_vma(vma
, pfn
, PAGE_SIZE
);
1842 EXPORT_SYMBOL(vm_insert_pfn
);
1844 int vm_insert_mixed(struct vm_area_struct
*vma
, unsigned long addr
,
1847 BUG_ON(!(vma
->vm_flags
& VM_MIXEDMAP
));
1849 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
1853 * If we don't have pte special, then we have to use the pfn_valid()
1854 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1855 * refcount the page if pfn_valid is true (hence insert_page rather
1856 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1857 * without pte special, it would there be refcounted as a normal page.
1859 if (!HAVE_PTE_SPECIAL
&& pfn_valid(pfn
)) {
1862 page
= pfn_to_page(pfn
);
1863 return insert_page(vma
, addr
, page
, vma
->vm_page_prot
);
1865 return insert_pfn(vma
, addr
, pfn
, vma
->vm_page_prot
);
1867 EXPORT_SYMBOL(vm_insert_mixed
);
1870 * maps a range of physical memory into the requested pages. the old
1871 * mappings are removed. any references to nonexistent pages results
1872 * in null mappings (currently treated as "copy-on-access")
1874 static int remap_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
1875 unsigned long addr
, unsigned long end
,
1876 unsigned long pfn
, pgprot_t prot
)
1881 pte
= pte_alloc_map_lock(mm
, pmd
, addr
, &ptl
);
1884 arch_enter_lazy_mmu_mode();
1886 BUG_ON(!pte_none(*pte
));
1887 set_pte_at(mm
, addr
, pte
, pte_mkspecial(pfn_pte(pfn
, prot
)));
1889 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
1890 arch_leave_lazy_mmu_mode();
1891 pte_unmap_unlock(pte
- 1, ptl
);
1895 static inline int remap_pmd_range(struct mm_struct
*mm
, pud_t
*pud
,
1896 unsigned long addr
, unsigned long end
,
1897 unsigned long pfn
, pgprot_t prot
)
1902 pfn
-= addr
>> PAGE_SHIFT
;
1903 pmd
= pmd_alloc(mm
, pud
, addr
);
1906 VM_BUG_ON(pmd_trans_huge(*pmd
));
1908 next
= pmd_addr_end(addr
, end
);
1909 if (remap_pte_range(mm
, pmd
, addr
, next
,
1910 pfn
+ (addr
>> PAGE_SHIFT
), prot
))
1912 } while (pmd
++, addr
= next
, addr
!= end
);
1916 static inline int remap_pud_range(struct mm_struct
*mm
, pgd_t
*pgd
,
1917 unsigned long addr
, unsigned long end
,
1918 unsigned long pfn
, pgprot_t prot
)
1923 pfn
-= addr
>> PAGE_SHIFT
;
1924 pud
= pud_alloc(mm
, pgd
, addr
);
1928 next
= pud_addr_end(addr
, end
);
1929 if (remap_pmd_range(mm
, pud
, addr
, next
,
1930 pfn
+ (addr
>> PAGE_SHIFT
), prot
))
1932 } while (pud
++, addr
= next
, addr
!= end
);
1937 * remap_pfn_range - remap kernel memory to userspace
1938 * @vma: user vma to map to
1939 * @addr: target user address to start at
1940 * @pfn: physical address of kernel memory
1941 * @size: size of map area
1942 * @prot: page protection flags for this mapping
1944 * Note: this is only safe if the mm semaphore is held when called.
1946 int remap_pfn_range(struct vm_area_struct
*vma
, unsigned long addr
,
1947 unsigned long pfn
, unsigned long size
, pgprot_t prot
)
1951 unsigned long end
= addr
+ PAGE_ALIGN(size
);
1952 struct mm_struct
*mm
= vma
->vm_mm
;
1956 * Physically remapped pages are special. Tell the
1957 * rest of the world about it:
1958 * VM_IO tells people not to look at these pages
1959 * (accesses can have side effects).
1960 * VM_RESERVED is specified all over the place, because
1961 * in 2.4 it kept swapout's vma scan off this vma; but
1962 * in 2.6 the LRU scan won't even find its pages, so this
1963 * flag means no more than count its pages in reserved_vm,
1964 * and omit it from core dump, even when VM_IO turned off.
1965 * VM_PFNMAP tells the core MM that the base pages are just
1966 * raw PFN mappings, and do not have a "struct page" associated
1969 * There's a horrible special case to handle copy-on-write
1970 * behaviour that some programs depend on. We mark the "original"
1971 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1973 if (addr
== vma
->vm_start
&& end
== vma
->vm_end
) {
1974 vma
->vm_pgoff
= pfn
;
1975 vma
->vm_flags
|= VM_PFN_AT_MMAP
;
1976 } else if (is_cow_mapping(vma
->vm_flags
))
1979 vma
->vm_flags
|= VM_IO
| VM_RESERVED
| VM_PFNMAP
;
1981 err
= track_pfn_vma_new(vma
, &prot
, pfn
, PAGE_ALIGN(size
));
1984 * To indicate that track_pfn related cleanup is not
1985 * needed from higher level routine calling unmap_vmas
1987 vma
->vm_flags
&= ~(VM_IO
| VM_RESERVED
| VM_PFNMAP
);
1988 vma
->vm_flags
&= ~VM_PFN_AT_MMAP
;
1992 BUG_ON(addr
>= end
);
1993 pfn
-= addr
>> PAGE_SHIFT
;
1994 pgd
= pgd_offset(mm
, addr
);
1995 flush_cache_range(vma
, addr
, end
);
1997 next
= pgd_addr_end(addr
, end
);
1998 err
= remap_pud_range(mm
, pgd
, addr
, next
,
1999 pfn
+ (addr
>> PAGE_SHIFT
), prot
);
2002 } while (pgd
++, addr
= next
, addr
!= end
);
2005 untrack_pfn_vma(vma
, pfn
, PAGE_ALIGN(size
));
2009 EXPORT_SYMBOL(remap_pfn_range
);
2011 static int apply_to_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
2012 unsigned long addr
, unsigned long end
,
2013 pte_fn_t fn
, void *data
)
2018 spinlock_t
*uninitialized_var(ptl
);
2020 pte
= (mm
== &init_mm
) ?
2021 pte_alloc_kernel(pmd
, addr
) :
2022 pte_alloc_map_lock(mm
, pmd
, addr
, &ptl
);
2026 BUG_ON(pmd_huge(*pmd
));
2028 arch_enter_lazy_mmu_mode();
2030 token
= pmd_pgtable(*pmd
);
2033 err
= fn(pte
++, token
, addr
, data
);
2036 } while (addr
+= PAGE_SIZE
, addr
!= end
);
2038 arch_leave_lazy_mmu_mode();
2041 pte_unmap_unlock(pte
-1, ptl
);
2045 static int apply_to_pmd_range(struct mm_struct
*mm
, pud_t
*pud
,
2046 unsigned long addr
, unsigned long end
,
2047 pte_fn_t fn
, void *data
)
2053 BUG_ON(pud_huge(*pud
));
2055 pmd
= pmd_alloc(mm
, pud
, addr
);
2059 next
= pmd_addr_end(addr
, end
);
2060 err
= apply_to_pte_range(mm
, pmd
, addr
, next
, fn
, data
);
2063 } while (pmd
++, addr
= next
, addr
!= end
);
2067 static int apply_to_pud_range(struct mm_struct
*mm
, pgd_t
*pgd
,
2068 unsigned long addr
, unsigned long end
,
2069 pte_fn_t fn
, void *data
)
2075 pud
= pud_alloc(mm
, pgd
, addr
);
2079 next
= pud_addr_end(addr
, end
);
2080 err
= apply_to_pmd_range(mm
, pud
, addr
, next
, fn
, data
);
2083 } while (pud
++, addr
= next
, addr
!= end
);
2088 * Scan a region of virtual memory, filling in page tables as necessary
2089 * and calling a provided function on each leaf page table.
2091 int apply_to_page_range(struct mm_struct
*mm
, unsigned long addr
,
2092 unsigned long size
, pte_fn_t fn
, void *data
)
2096 unsigned long end
= addr
+ size
;
2099 BUG_ON(addr
>= end
);
2100 pgd
= pgd_offset(mm
, addr
);
2102 next
= pgd_addr_end(addr
, end
);
2103 err
= apply_to_pud_range(mm
, pgd
, addr
, next
, fn
, data
);
2106 } while (pgd
++, addr
= next
, addr
!= end
);
2110 EXPORT_SYMBOL_GPL(apply_to_page_range
);
2113 * handle_pte_fault chooses page fault handler according to an entry
2114 * which was read non-atomically. Before making any commitment, on
2115 * those architectures or configurations (e.g. i386 with PAE) which
2116 * might give a mix of unmatched parts, do_swap_page and do_file_page
2117 * must check under lock before unmapping the pte and proceeding
2118 * (but do_wp_page is only called after already making such a check;
2119 * and do_anonymous_page and do_no_page can safely check later on).
2121 static inline int pte_unmap_same(struct mm_struct
*mm
, pmd_t
*pmd
,
2122 pte_t
*page_table
, pte_t orig_pte
)
2125 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2126 if (sizeof(pte_t
) > sizeof(unsigned long)) {
2127 spinlock_t
*ptl
= pte_lockptr(mm
, pmd
);
2129 same
= pte_same(*page_table
, orig_pte
);
2133 pte_unmap(page_table
);
2137 static inline void cow_user_page(struct page
*dst
, struct page
*src
, unsigned long va
, struct vm_area_struct
*vma
)
2140 * If the source page was a PFN mapping, we don't have
2141 * a "struct page" for it. We do a best-effort copy by
2142 * just copying from the original user address. If that
2143 * fails, we just zero-fill it. Live with it.
2145 if (unlikely(!src
)) {
2146 void *kaddr
= kmap_atomic(dst
, KM_USER0
);
2147 void __user
*uaddr
= (void __user
*)(va
& PAGE_MASK
);
2150 * This really shouldn't fail, because the page is there
2151 * in the page tables. But it might just be unreadable,
2152 * in which case we just give up and fill the result with
2155 if (__copy_from_user_inatomic(kaddr
, uaddr
, PAGE_SIZE
))
2157 kunmap_atomic(kaddr
, KM_USER0
);
2158 flush_dcache_page(dst
);
2160 copy_user_highpage(dst
, src
, va
, vma
);
2164 * This routine handles present pages, when users try to write
2165 * to a shared page. It is done by copying the page to a new address
2166 * and decrementing the shared-page counter for the old page.
2168 * Note that this routine assumes that the protection checks have been
2169 * done by the caller (the low-level page fault routine in most cases).
2170 * Thus we can safely just mark it writable once we've done any necessary
2173 * We also mark the page dirty at this point even though the page will
2174 * change only once the write actually happens. This avoids a few races,
2175 * and potentially makes it more efficient.
2177 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2178 * but allow concurrent faults), with pte both mapped and locked.
2179 * We return with mmap_sem still held, but pte unmapped and unlocked.
2181 static int do_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2182 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
2183 spinlock_t
*ptl
, pte_t orig_pte
)
2186 struct page
*old_page
, *new_page
;
2189 int page_mkwrite
= 0;
2190 struct page
*dirty_page
= NULL
;
2192 old_page
= vm_normal_page(vma
, address
, orig_pte
);
2195 * VM_MIXEDMAP !pfn_valid() case
2197 * We should not cow pages in a shared writeable mapping.
2198 * Just mark the pages writable as we can't do any dirty
2199 * accounting on raw pfn maps.
2201 if ((vma
->vm_flags
& (VM_WRITE
|VM_SHARED
)) ==
2202 (VM_WRITE
|VM_SHARED
))
2208 * Take out anonymous pages first, anonymous shared vmas are
2209 * not dirty accountable.
2211 if (PageAnon(old_page
) && !PageKsm(old_page
)) {
2212 if (!trylock_page(old_page
)) {
2213 page_cache_get(old_page
);
2214 pte_unmap_unlock(page_table
, ptl
);
2215 lock_page(old_page
);
2216 page_table
= pte_offset_map_lock(mm
, pmd
, address
,
2218 if (!pte_same(*page_table
, orig_pte
)) {
2219 unlock_page(old_page
);
2220 page_cache_release(old_page
);
2223 page_cache_release(old_page
);
2225 if (reuse_swap_page(old_page
)) {
2227 * The page is all ours. Move it to our anon_vma so
2228 * the rmap code will not search our parent or siblings.
2229 * Protected against the rmap code by the page lock.
2231 page_move_anon_rmap(old_page
, vma
, address
);
2232 unlock_page(old_page
);
2235 unlock_page(old_page
);
2236 } else if (unlikely((vma
->vm_flags
& (VM_WRITE
|VM_SHARED
)) ==
2237 (VM_WRITE
|VM_SHARED
))) {
2239 * Only catch write-faults on shared writable pages,
2240 * read-only shared pages can get COWed by
2241 * get_user_pages(.write=1, .force=1).
2243 if (vma
->vm_ops
&& vma
->vm_ops
->page_mkwrite
) {
2244 struct vm_fault vmf
;
2247 vmf
.virtual_address
= (void __user
*)(address
&
2249 vmf
.pgoff
= old_page
->index
;
2250 vmf
.flags
= FAULT_FLAG_WRITE
|FAULT_FLAG_MKWRITE
;
2251 vmf
.page
= old_page
;
2254 * Notify the address space that the page is about to
2255 * become writable so that it can prohibit this or wait
2256 * for the page to get into an appropriate state.
2258 * We do this without the lock held, so that it can
2259 * sleep if it needs to.
2261 page_cache_get(old_page
);
2262 pte_unmap_unlock(page_table
, ptl
);
2264 tmp
= vma
->vm_ops
->page_mkwrite(vma
, &vmf
);
2266 (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
))) {
2268 goto unwritable_page
;
2270 if (unlikely(!(tmp
& VM_FAULT_LOCKED
))) {
2271 lock_page(old_page
);
2272 if (!old_page
->mapping
) {
2273 ret
= 0; /* retry the fault */
2274 unlock_page(old_page
);
2275 goto unwritable_page
;
2278 VM_BUG_ON(!PageLocked(old_page
));
2281 * Since we dropped the lock we need to revalidate
2282 * the PTE as someone else may have changed it. If
2283 * they did, we just return, as we can count on the
2284 * MMU to tell us if they didn't also make it writable.
2286 page_table
= pte_offset_map_lock(mm
, pmd
, address
,
2288 if (!pte_same(*page_table
, orig_pte
)) {
2289 unlock_page(old_page
);
2290 page_cache_release(old_page
);
2296 dirty_page
= old_page
;
2297 get_page(dirty_page
);
2300 flush_cache_page(vma
, address
, pte_pfn(orig_pte
));
2301 entry
= pte_mkyoung(orig_pte
);
2302 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
2303 if (ptep_set_access_flags(vma
, address
, page_table
, entry
,1))
2304 update_mmu_cache(vma
, address
, page_table
);
2305 pte_unmap_unlock(page_table
, ptl
);
2306 ret
|= VM_FAULT_WRITE
;
2312 * Yes, Virginia, this is actually required to prevent a race
2313 * with clear_page_dirty_for_io() from clearing the page dirty
2314 * bit after it clear all dirty ptes, but before a racing
2315 * do_wp_page installs a dirty pte.
2317 * do_no_page is protected similarly.
2319 if (!page_mkwrite
) {
2320 wait_on_page_locked(dirty_page
);
2321 set_page_dirty_balance(dirty_page
, page_mkwrite
);
2323 put_page(dirty_page
);
2325 struct address_space
*mapping
= dirty_page
->mapping
;
2327 set_page_dirty(dirty_page
);
2328 unlock_page(dirty_page
);
2329 page_cache_release(dirty_page
);
2332 * Some device drivers do not set page.mapping
2333 * but still dirty their pages
2335 balance_dirty_pages_ratelimited(mapping
);
2339 /* file_update_time outside page_lock */
2341 file_update_time(vma
->vm_file
);
2347 * Ok, we need to copy. Oh, well..
2349 page_cache_get(old_page
);
2351 pte_unmap_unlock(page_table
, ptl
);
2353 if (unlikely(anon_vma_prepare(vma
)))
2356 if (is_zero_pfn(pte_pfn(orig_pte
))) {
2357 new_page
= alloc_zeroed_user_highpage_movable(vma
, address
);
2361 new_page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
, address
);
2364 cow_user_page(new_page
, old_page
, address
, vma
);
2366 __SetPageUptodate(new_page
);
2369 * Don't let another task, with possibly unlocked vma,
2370 * keep the mlocked page.
2372 if ((vma
->vm_flags
& VM_LOCKED
) && old_page
) {
2373 lock_page(old_page
); /* for LRU manipulation */
2374 clear_page_mlock(old_page
);
2375 unlock_page(old_page
);
2378 if (mem_cgroup_newpage_charge(new_page
, mm
, GFP_KERNEL
))
2382 * Re-check the pte - we dropped the lock
2384 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2385 if (likely(pte_same(*page_table
, orig_pte
))) {
2387 if (!PageAnon(old_page
)) {
2388 dec_mm_counter_fast(mm
, MM_FILEPAGES
);
2389 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
2392 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
2393 flush_cache_page(vma
, address
, pte_pfn(orig_pte
));
2394 entry
= mk_pte(new_page
, vma
->vm_page_prot
);
2395 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
2397 * Clear the pte entry and flush it first, before updating the
2398 * pte with the new entry. This will avoid a race condition
2399 * seen in the presence of one thread doing SMC and another
2402 ptep_clear_flush(vma
, address
, page_table
);
2403 page_add_new_anon_rmap(new_page
, vma
, address
);
2405 * We call the notify macro here because, when using secondary
2406 * mmu page tables (such as kvm shadow page tables), we want the
2407 * new page to be mapped directly into the secondary page table.
2409 set_pte_at_notify(mm
, address
, page_table
, entry
);
2410 update_mmu_cache(vma
, address
, page_table
);
2413 * Only after switching the pte to the new page may
2414 * we remove the mapcount here. Otherwise another
2415 * process may come and find the rmap count decremented
2416 * before the pte is switched to the new page, and
2417 * "reuse" the old page writing into it while our pte
2418 * here still points into it and can be read by other
2421 * The critical issue is to order this
2422 * page_remove_rmap with the ptp_clear_flush above.
2423 * Those stores are ordered by (if nothing else,)
2424 * the barrier present in the atomic_add_negative
2425 * in page_remove_rmap.
2427 * Then the TLB flush in ptep_clear_flush ensures that
2428 * no process can access the old page before the
2429 * decremented mapcount is visible. And the old page
2430 * cannot be reused until after the decremented
2431 * mapcount is visible. So transitively, TLBs to
2432 * old page will be flushed before it can be reused.
2434 page_remove_rmap(old_page
);
2437 /* Free the old page.. */
2438 new_page
= old_page
;
2439 ret
|= VM_FAULT_WRITE
;
2441 mem_cgroup_uncharge_page(new_page
);
2444 page_cache_release(new_page
);
2446 page_cache_release(old_page
);
2448 pte_unmap_unlock(page_table
, ptl
);
2451 page_cache_release(new_page
);
2455 unlock_page(old_page
);
2456 page_cache_release(old_page
);
2458 page_cache_release(old_page
);
2460 return VM_FAULT_OOM
;
2463 page_cache_release(old_page
);
2468 * Helper functions for unmap_mapping_range().
2470 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
2472 * We have to restart searching the prio_tree whenever we drop the lock,
2473 * since the iterator is only valid while the lock is held, and anyway
2474 * a later vma might be split and reinserted earlier while lock dropped.
2476 * The list of nonlinear vmas could be handled more efficiently, using
2477 * a placeholder, but handle it in the same way until a need is shown.
2478 * It is important to search the prio_tree before nonlinear list: a vma
2479 * may become nonlinear and be shifted from prio_tree to nonlinear list
2480 * while the lock is dropped; but never shifted from list to prio_tree.
2482 * In order to make forward progress despite restarting the search,
2483 * vm_truncate_count is used to mark a vma as now dealt with, so we can
2484 * quickly skip it next time around. Since the prio_tree search only
2485 * shows us those vmas affected by unmapping the range in question, we
2486 * can't efficiently keep all vmas in step with mapping->truncate_count:
2487 * so instead reset them all whenever it wraps back to 0 (then go to 1).
2488 * mapping->truncate_count and vma->vm_truncate_count are protected by
2491 * In order to make forward progress despite repeatedly restarting some
2492 * large vma, note the restart_addr from unmap_vmas when it breaks out:
2493 * and restart from that address when we reach that vma again. It might
2494 * have been split or merged, shrunk or extended, but never shifted: so
2495 * restart_addr remains valid so long as it remains in the vma's range.
2496 * unmap_mapping_range forces truncate_count to leap over page-aligned
2497 * values so we can save vma's restart_addr in its truncate_count field.
2499 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
2501 static void reset_vma_truncate_counts(struct address_space
*mapping
)
2503 struct vm_area_struct
*vma
;
2504 struct prio_tree_iter iter
;
2506 vma_prio_tree_foreach(vma
, &iter
, &mapping
->i_mmap
, 0, ULONG_MAX
)
2507 vma
->vm_truncate_count
= 0;
2508 list_for_each_entry(vma
, &mapping
->i_mmap_nonlinear
, shared
.vm_set
.list
)
2509 vma
->vm_truncate_count
= 0;
2512 static int unmap_mapping_range_vma(struct vm_area_struct
*vma
,
2513 unsigned long start_addr
, unsigned long end_addr
,
2514 struct zap_details
*details
)
2516 unsigned long restart_addr
;
2520 * files that support invalidating or truncating portions of the
2521 * file from under mmaped areas must have their ->fault function
2522 * return a locked page (and set VM_FAULT_LOCKED in the return).
2523 * This provides synchronisation against concurrent unmapping here.
2527 restart_addr
= vma
->vm_truncate_count
;
2528 if (is_restart_addr(restart_addr
) && start_addr
< restart_addr
) {
2529 start_addr
= restart_addr
;
2530 if (start_addr
>= end_addr
) {
2531 /* Top of vma has been split off since last time */
2532 vma
->vm_truncate_count
= details
->truncate_count
;
2537 restart_addr
= zap_page_range(vma
, start_addr
,
2538 end_addr
- start_addr
, details
);
2539 need_break
= need_resched() || spin_needbreak(details
->i_mmap_lock
);
2541 if (restart_addr
>= end_addr
) {
2542 /* We have now completed this vma: mark it so */
2543 vma
->vm_truncate_count
= details
->truncate_count
;
2547 /* Note restart_addr in vma's truncate_count field */
2548 vma
->vm_truncate_count
= restart_addr
;
2553 spin_unlock(details
->i_mmap_lock
);
2555 spin_lock(details
->i_mmap_lock
);
2559 static inline void unmap_mapping_range_tree(struct prio_tree_root
*root
,
2560 struct zap_details
*details
)
2562 struct vm_area_struct
*vma
;
2563 struct prio_tree_iter iter
;
2564 pgoff_t vba
, vea
, zba
, zea
;
2567 vma_prio_tree_foreach(vma
, &iter
, root
,
2568 details
->first_index
, details
->last_index
) {
2569 /* Skip quickly over those we have already dealt with */
2570 if (vma
->vm_truncate_count
== details
->truncate_count
)
2573 vba
= vma
->vm_pgoff
;
2574 vea
= vba
+ ((vma
->vm_end
- vma
->vm_start
) >> PAGE_SHIFT
) - 1;
2575 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2576 zba
= details
->first_index
;
2579 zea
= details
->last_index
;
2583 if (unmap_mapping_range_vma(vma
,
2584 ((zba
- vba
) << PAGE_SHIFT
) + vma
->vm_start
,
2585 ((zea
- vba
+ 1) << PAGE_SHIFT
) + vma
->vm_start
,
2591 static inline void unmap_mapping_range_list(struct list_head
*head
,
2592 struct zap_details
*details
)
2594 struct vm_area_struct
*vma
;
2597 * In nonlinear VMAs there is no correspondence between virtual address
2598 * offset and file offset. So we must perform an exhaustive search
2599 * across *all* the pages in each nonlinear VMA, not just the pages
2600 * whose virtual address lies outside the file truncation point.
2603 list_for_each_entry(vma
, head
, shared
.vm_set
.list
) {
2604 /* Skip quickly over those we have already dealt with */
2605 if (vma
->vm_truncate_count
== details
->truncate_count
)
2607 details
->nonlinear_vma
= vma
;
2608 if (unmap_mapping_range_vma(vma
, vma
->vm_start
,
2609 vma
->vm_end
, details
) < 0)
2615 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2616 * @mapping: the address space containing mmaps to be unmapped.
2617 * @holebegin: byte in first page to unmap, relative to the start of
2618 * the underlying file. This will be rounded down to a PAGE_SIZE
2619 * boundary. Note that this is different from truncate_pagecache(), which
2620 * must keep the partial page. In contrast, we must get rid of
2622 * @holelen: size of prospective hole in bytes. This will be rounded
2623 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2625 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2626 * but 0 when invalidating pagecache, don't throw away private data.
2628 void unmap_mapping_range(struct address_space
*mapping
,
2629 loff_t
const holebegin
, loff_t
const holelen
, int even_cows
)
2631 struct zap_details details
;
2632 pgoff_t hba
= holebegin
>> PAGE_SHIFT
;
2633 pgoff_t hlen
= (holelen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
2635 /* Check for overflow. */
2636 if (sizeof(holelen
) > sizeof(hlen
)) {
2638 (holebegin
+ holelen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
2639 if (holeend
& ~(long long)ULONG_MAX
)
2640 hlen
= ULONG_MAX
- hba
+ 1;
2643 details
.check_mapping
= even_cows
? NULL
: mapping
;
2644 details
.nonlinear_vma
= NULL
;
2645 details
.first_index
= hba
;
2646 details
.last_index
= hba
+ hlen
- 1;
2647 if (details
.last_index
< details
.first_index
)
2648 details
.last_index
= ULONG_MAX
;
2649 details
.i_mmap_lock
= &mapping
->i_mmap_lock
;
2651 spin_lock(&mapping
->i_mmap_lock
);
2653 /* Protect against endless unmapping loops */
2654 mapping
->truncate_count
++;
2655 if (unlikely(is_restart_addr(mapping
->truncate_count
))) {
2656 if (mapping
->truncate_count
== 0)
2657 reset_vma_truncate_counts(mapping
);
2658 mapping
->truncate_count
++;
2660 details
.truncate_count
= mapping
->truncate_count
;
2662 if (unlikely(!prio_tree_empty(&mapping
->i_mmap
)))
2663 unmap_mapping_range_tree(&mapping
->i_mmap
, &details
);
2664 if (unlikely(!list_empty(&mapping
->i_mmap_nonlinear
)))
2665 unmap_mapping_range_list(&mapping
->i_mmap_nonlinear
, &details
);
2666 spin_unlock(&mapping
->i_mmap_lock
);
2668 EXPORT_SYMBOL(unmap_mapping_range
);
2670 int vmtruncate_range(struct inode
*inode
, loff_t offset
, loff_t end
)
2672 struct address_space
*mapping
= inode
->i_mapping
;
2675 * If the underlying filesystem is not going to provide
2676 * a way to truncate a range of blocks (punch a hole) -
2677 * we should return failure right now.
2679 if (!inode
->i_op
->truncate_range
)
2682 mutex_lock(&inode
->i_mutex
);
2683 down_write(&inode
->i_alloc_sem
);
2684 unmap_mapping_range(mapping
, offset
, (end
- offset
), 1);
2685 truncate_inode_pages_range(mapping
, offset
, end
);
2686 unmap_mapping_range(mapping
, offset
, (end
- offset
), 1);
2687 inode
->i_op
->truncate_range(inode
, offset
, end
);
2688 up_write(&inode
->i_alloc_sem
);
2689 mutex_unlock(&inode
->i_mutex
);
2695 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2696 * but allow concurrent faults), and pte mapped but not yet locked.
2697 * We return with mmap_sem still held, but pte unmapped and unlocked.
2699 static int do_swap_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2700 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
2701 unsigned int flags
, pte_t orig_pte
)
2704 struct page
*page
, *swapcache
= NULL
;
2708 struct mem_cgroup
*ptr
= NULL
;
2712 if (!pte_unmap_same(mm
, pmd
, page_table
, orig_pte
))
2715 entry
= pte_to_swp_entry(orig_pte
);
2716 if (unlikely(non_swap_entry(entry
))) {
2717 if (is_migration_entry(entry
)) {
2718 migration_entry_wait(mm
, pmd
, address
);
2719 } else if (is_hwpoison_entry(entry
)) {
2720 ret
= VM_FAULT_HWPOISON
;
2722 print_bad_pte(vma
, address
, orig_pte
, NULL
);
2723 ret
= VM_FAULT_SIGBUS
;
2727 delayacct_set_flag(DELAYACCT_PF_SWAPIN
);
2728 page
= lookup_swap_cache(entry
);
2730 grab_swap_token(mm
); /* Contend for token _before_ read-in */
2731 page
= swapin_readahead(entry
,
2732 GFP_HIGHUSER_MOVABLE
, vma
, address
);
2735 * Back out if somebody else faulted in this pte
2736 * while we released the pte lock.
2738 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2739 if (likely(pte_same(*page_table
, orig_pte
)))
2741 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
2745 /* Had to read the page from swap area: Major fault */
2746 ret
= VM_FAULT_MAJOR
;
2747 count_vm_event(PGMAJFAULT
);
2748 } else if (PageHWPoison(page
)) {
2750 * hwpoisoned dirty swapcache pages are kept for killing
2751 * owner processes (which may be unknown at hwpoison time)
2753 ret
= VM_FAULT_HWPOISON
;
2754 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
2758 locked
= lock_page_or_retry(page
, mm
, flags
);
2759 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
2761 ret
|= VM_FAULT_RETRY
;
2766 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2767 * release the swapcache from under us. The page pin, and pte_same
2768 * test below, are not enough to exclude that. Even if it is still
2769 * swapcache, we need to check that the page's swap has not changed.
2771 if (unlikely(!PageSwapCache(page
) || page_private(page
) != entry
.val
))
2774 if (ksm_might_need_to_copy(page
, vma
, address
)) {
2776 page
= ksm_does_need_to_copy(page
, vma
, address
);
2778 if (unlikely(!page
)) {
2786 if (mem_cgroup_try_charge_swapin(mm
, page
, GFP_KERNEL
, &ptr
)) {
2792 * Back out if somebody else already faulted in this pte.
2794 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2795 if (unlikely(!pte_same(*page_table
, orig_pte
)))
2798 if (unlikely(!PageUptodate(page
))) {
2799 ret
= VM_FAULT_SIGBUS
;
2804 * The page isn't present yet, go ahead with the fault.
2806 * Be careful about the sequence of operations here.
2807 * To get its accounting right, reuse_swap_page() must be called
2808 * while the page is counted on swap but not yet in mapcount i.e.
2809 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2810 * must be called after the swap_free(), or it will never succeed.
2811 * Because delete_from_swap_page() may be called by reuse_swap_page(),
2812 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2813 * in page->private. In this case, a record in swap_cgroup is silently
2814 * discarded at swap_free().
2817 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
2818 dec_mm_counter_fast(mm
, MM_SWAPENTS
);
2819 pte
= mk_pte(page
, vma
->vm_page_prot
);
2820 if ((flags
& FAULT_FLAG_WRITE
) && reuse_swap_page(page
)) {
2821 pte
= maybe_mkwrite(pte_mkdirty(pte
), vma
);
2822 flags
&= ~FAULT_FLAG_WRITE
;
2823 ret
|= VM_FAULT_WRITE
;
2826 flush_icache_page(vma
, page
);
2827 set_pte_at(mm
, address
, page_table
, pte
);
2828 do_page_add_anon_rmap(page
, vma
, address
, exclusive
);
2829 /* It's better to call commit-charge after rmap is established */
2830 mem_cgroup_commit_charge_swapin(page
, ptr
);
2833 if (vm_swap_full() || (vma
->vm_flags
& VM_LOCKED
) || PageMlocked(page
))
2834 try_to_free_swap(page
);
2838 * Hold the lock to avoid the swap entry to be reused
2839 * until we take the PT lock for the pte_same() check
2840 * (to avoid false positives from pte_same). For
2841 * further safety release the lock after the swap_free
2842 * so that the swap count won't change under a
2843 * parallel locked swapcache.
2845 unlock_page(swapcache
);
2846 page_cache_release(swapcache
);
2849 if (flags
& FAULT_FLAG_WRITE
) {
2850 ret
|= do_wp_page(mm
, vma
, address
, page_table
, pmd
, ptl
, pte
);
2851 if (ret
& VM_FAULT_ERROR
)
2852 ret
&= VM_FAULT_ERROR
;
2856 /* No need to invalidate - it was non-present before */
2857 update_mmu_cache(vma
, address
, page_table
);
2859 pte_unmap_unlock(page_table
, ptl
);
2863 mem_cgroup_cancel_charge_swapin(ptr
);
2864 pte_unmap_unlock(page_table
, ptl
);
2868 page_cache_release(page
);
2870 unlock_page(swapcache
);
2871 page_cache_release(swapcache
);
2877 * This is like a special single-page "expand_{down|up}wards()",
2878 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2879 * doesn't hit another vma.
2881 static inline int check_stack_guard_page(struct vm_area_struct
*vma
, unsigned long address
)
2883 address
&= PAGE_MASK
;
2884 if ((vma
->vm_flags
& VM_GROWSDOWN
) && address
== vma
->vm_start
) {
2885 struct vm_area_struct
*prev
= vma
->vm_prev
;
2888 * Is there a mapping abutting this one below?
2890 * That's only ok if it's the same stack mapping
2891 * that has gotten split..
2893 if (prev
&& prev
->vm_end
== address
)
2894 return prev
->vm_flags
& VM_GROWSDOWN
? 0 : -ENOMEM
;
2896 expand_stack(vma
, address
- PAGE_SIZE
);
2898 if ((vma
->vm_flags
& VM_GROWSUP
) && address
+ PAGE_SIZE
== vma
->vm_end
) {
2899 struct vm_area_struct
*next
= vma
->vm_next
;
2901 /* As VM_GROWSDOWN but s/below/above/ */
2902 if (next
&& next
->vm_start
== address
+ PAGE_SIZE
)
2903 return next
->vm_flags
& VM_GROWSUP
? 0 : -ENOMEM
;
2905 expand_upwards(vma
, address
+ PAGE_SIZE
);
2911 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2912 * but allow concurrent faults), and pte mapped but not yet locked.
2913 * We return with mmap_sem still held, but pte unmapped and unlocked.
2915 static int do_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2916 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
2923 pte_unmap(page_table
);
2925 /* Check if we need to add a guard page to the stack */
2926 if (check_stack_guard_page(vma
, address
) < 0)
2927 return VM_FAULT_SIGBUS
;
2929 /* Use the zero-page for reads */
2930 if (!(flags
& FAULT_FLAG_WRITE
)) {
2931 entry
= pte_mkspecial(pfn_pte(my_zero_pfn(address
),
2932 vma
->vm_page_prot
));
2933 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2934 if (!pte_none(*page_table
))
2939 /* Allocate our own private page. */
2940 if (unlikely(anon_vma_prepare(vma
)))
2942 page
= alloc_zeroed_user_highpage_movable(vma
, address
);
2945 __SetPageUptodate(page
);
2947 if (mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
))
2950 entry
= mk_pte(page
, vma
->vm_page_prot
);
2951 if (vma
->vm_flags
& VM_WRITE
)
2952 entry
= pte_mkwrite(pte_mkdirty(entry
));
2954 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
2955 if (!pte_none(*page_table
))
2958 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
2959 page_add_new_anon_rmap(page
, vma
, address
);
2961 set_pte_at(mm
, address
, page_table
, entry
);
2963 /* No need to invalidate - it was non-present before */
2964 update_mmu_cache(vma
, address
, page_table
);
2966 pte_unmap_unlock(page_table
, ptl
);
2969 mem_cgroup_uncharge_page(page
);
2970 page_cache_release(page
);
2973 page_cache_release(page
);
2975 return VM_FAULT_OOM
;
2979 * __do_fault() tries to create a new page mapping. It aggressively
2980 * tries to share with existing pages, but makes a separate copy if
2981 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
2982 * the next page fault.
2984 * As this is called only for pages that do not currently exist, we
2985 * do not need to flush old virtual caches or the TLB.
2987 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2988 * but allow concurrent faults), and pte neither mapped nor locked.
2989 * We return with mmap_sem still held, but pte unmapped and unlocked.
2991 static int __do_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2992 unsigned long address
, pmd_t
*pmd
,
2993 pgoff_t pgoff
, unsigned int flags
, pte_t orig_pte
)
3001 struct page
*dirty_page
= NULL
;
3002 struct vm_fault vmf
;
3004 int page_mkwrite
= 0;
3006 vmf
.virtual_address
= (void __user
*)(address
& PAGE_MASK
);
3011 ret
= vma
->vm_ops
->fault(vma
, &vmf
);
3012 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
|
3016 if (unlikely(PageHWPoison(vmf
.page
))) {
3017 if (ret
& VM_FAULT_LOCKED
)
3018 unlock_page(vmf
.page
);
3019 return VM_FAULT_HWPOISON
;
3023 * For consistency in subsequent calls, make the faulted page always
3026 if (unlikely(!(ret
& VM_FAULT_LOCKED
)))
3027 lock_page(vmf
.page
);
3029 VM_BUG_ON(!PageLocked(vmf
.page
));
3032 * Should we do an early C-O-W break?
3035 if (flags
& FAULT_FLAG_WRITE
) {
3036 if (!(vma
->vm_flags
& VM_SHARED
)) {
3038 if (unlikely(anon_vma_prepare(vma
))) {
3042 page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
,
3048 if (mem_cgroup_newpage_charge(page
, mm
, GFP_KERNEL
)) {
3050 page_cache_release(page
);
3055 * Don't let another task, with possibly unlocked vma,
3056 * keep the mlocked page.
3058 if (vma
->vm_flags
& VM_LOCKED
)
3059 clear_page_mlock(vmf
.page
);
3060 copy_user_highpage(page
, vmf
.page
, address
, vma
);
3061 __SetPageUptodate(page
);
3064 * If the page will be shareable, see if the backing
3065 * address space wants to know that the page is about
3066 * to become writable
3068 if (vma
->vm_ops
->page_mkwrite
) {
3072 vmf
.flags
= FAULT_FLAG_WRITE
|FAULT_FLAG_MKWRITE
;
3073 tmp
= vma
->vm_ops
->page_mkwrite(vma
, &vmf
);
3075 (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
))) {
3077 goto unwritable_page
;
3079 if (unlikely(!(tmp
& VM_FAULT_LOCKED
))) {
3081 if (!page
->mapping
) {
3082 ret
= 0; /* retry the fault */
3084 goto unwritable_page
;
3087 VM_BUG_ON(!PageLocked(page
));
3094 page_table
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
3097 * This silly early PAGE_DIRTY setting removes a race
3098 * due to the bad i386 page protection. But it's valid
3099 * for other architectures too.
3101 * Note that if FAULT_FLAG_WRITE is set, we either now have
3102 * an exclusive copy of the page, or this is a shared mapping,
3103 * so we can make it writable and dirty to avoid having to
3104 * handle that later.
3106 /* Only go through if we didn't race with anybody else... */
3107 if (likely(pte_same(*page_table
, orig_pte
))) {
3108 flush_icache_page(vma
, page
);
3109 entry
= mk_pte(page
, vma
->vm_page_prot
);
3110 if (flags
& FAULT_FLAG_WRITE
)
3111 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
3113 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
3114 page_add_new_anon_rmap(page
, vma
, address
);
3116 inc_mm_counter_fast(mm
, MM_FILEPAGES
);
3117 page_add_file_rmap(page
);
3118 if (flags
& FAULT_FLAG_WRITE
) {
3120 get_page(dirty_page
);
3123 set_pte_at(mm
, address
, page_table
, entry
);
3125 /* no need to invalidate: a not-present page won't be cached */
3126 update_mmu_cache(vma
, address
, page_table
);
3129 mem_cgroup_uncharge_page(page
);
3131 page_cache_release(page
);
3133 anon
= 1; /* no anon but release faulted_page */
3136 pte_unmap_unlock(page_table
, ptl
);
3140 struct address_space
*mapping
= page
->mapping
;
3142 if (set_page_dirty(dirty_page
))
3144 unlock_page(dirty_page
);
3145 put_page(dirty_page
);
3146 if (page_mkwrite
&& mapping
) {
3148 * Some device drivers do not set page.mapping but still
3151 balance_dirty_pages_ratelimited(mapping
);
3154 /* file_update_time outside page_lock */
3156 file_update_time(vma
->vm_file
);
3158 unlock_page(vmf
.page
);
3160 page_cache_release(vmf
.page
);
3166 page_cache_release(page
);
3170 static int do_linear_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
3171 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
3172 unsigned int flags
, pte_t orig_pte
)
3174 pgoff_t pgoff
= (((address
& PAGE_MASK
)
3175 - vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
3177 pte_unmap(page_table
);
3178 return __do_fault(mm
, vma
, address
, pmd
, pgoff
, flags
, orig_pte
);
3182 * Fault of a previously existing named mapping. Repopulate the pte
3183 * from the encoded file_pte if possible. This enables swappable
3186 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3187 * but allow concurrent faults), and pte mapped but not yet locked.
3188 * We return with mmap_sem still held, but pte unmapped and unlocked.
3190 static int do_nonlinear_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
3191 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
3192 unsigned int flags
, pte_t orig_pte
)
3196 flags
|= FAULT_FLAG_NONLINEAR
;
3198 if (!pte_unmap_same(mm
, pmd
, page_table
, orig_pte
))
3201 if (unlikely(!(vma
->vm_flags
& VM_NONLINEAR
))) {
3203 * Page table corrupted: show pte and kill process.
3205 print_bad_pte(vma
, address
, orig_pte
, NULL
);
3206 return VM_FAULT_SIGBUS
;
3209 pgoff
= pte_to_pgoff(orig_pte
);
3210 return __do_fault(mm
, vma
, address
, pmd
, pgoff
, flags
, orig_pte
);
3214 * These routines also need to handle stuff like marking pages dirty
3215 * and/or accessed for architectures that don't do it in hardware (most
3216 * RISC architectures). The early dirtying is also good on the i386.
3218 * There is also a hook called "update_mmu_cache()" that architectures
3219 * with external mmu caches can use to update those (ie the Sparc or
3220 * PowerPC hashed page tables that act as extended TLBs).
3222 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3223 * but allow concurrent faults), and pte mapped but not yet locked.
3224 * We return with mmap_sem still held, but pte unmapped and unlocked.
3226 int handle_pte_fault(struct mm_struct
*mm
,
3227 struct vm_area_struct
*vma
, unsigned long address
,
3228 pte_t
*pte
, pmd_t
*pmd
, unsigned int flags
)
3234 if (!pte_present(entry
)) {
3235 if (pte_none(entry
)) {
3237 if (likely(vma
->vm_ops
->fault
))
3238 return do_linear_fault(mm
, vma
, address
,
3239 pte
, pmd
, flags
, entry
);
3241 return do_anonymous_page(mm
, vma
, address
,
3244 if (pte_file(entry
))
3245 return do_nonlinear_fault(mm
, vma
, address
,
3246 pte
, pmd
, flags
, entry
);
3247 return do_swap_page(mm
, vma
, address
,
3248 pte
, pmd
, flags
, entry
);
3251 ptl
= pte_lockptr(mm
, pmd
);
3253 if (unlikely(!pte_same(*pte
, entry
)))
3255 if (flags
& FAULT_FLAG_WRITE
) {
3256 if (!pte_write(entry
))
3257 return do_wp_page(mm
, vma
, address
,
3258 pte
, pmd
, ptl
, entry
);
3259 entry
= pte_mkdirty(entry
);
3261 entry
= pte_mkyoung(entry
);
3262 if (ptep_set_access_flags(vma
, address
, pte
, entry
, flags
& FAULT_FLAG_WRITE
)) {
3263 update_mmu_cache(vma
, address
, pte
);
3266 * This is needed only for protection faults but the arch code
3267 * is not yet telling us if this is a protection fault or not.
3268 * This still avoids useless tlb flushes for .text page faults
3271 if (flags
& FAULT_FLAG_WRITE
)
3272 flush_tlb_fix_spurious_fault(vma
, address
);
3275 pte_unmap_unlock(pte
, ptl
);
3280 * By the time we get here, we already hold the mm semaphore
3282 int handle_mm_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
3283 unsigned long address
, unsigned int flags
)
3290 __set_current_state(TASK_RUNNING
);
3292 count_vm_event(PGFAULT
);
3294 /* do counter updates before entering really critical section. */
3295 check_sync_rss_stat(current
);
3297 if (unlikely(is_vm_hugetlb_page(vma
)))
3298 return hugetlb_fault(mm
, vma
, address
, flags
);
3300 pgd
= pgd_offset(mm
, address
);
3301 pud
= pud_alloc(mm
, pgd
, address
);
3303 return VM_FAULT_OOM
;
3304 pmd
= pmd_alloc(mm
, pud
, address
);
3306 return VM_FAULT_OOM
;
3307 if (pmd_none(*pmd
) && transparent_hugepage_enabled(vma
)) {
3309 return do_huge_pmd_anonymous_page(mm
, vma
, address
,
3312 pmd_t orig_pmd
= *pmd
;
3314 if (pmd_trans_huge(orig_pmd
)) {
3315 if (flags
& FAULT_FLAG_WRITE
&&
3316 !pmd_write(orig_pmd
) &&
3317 !pmd_trans_splitting(orig_pmd
))
3318 return do_huge_pmd_wp_page(mm
, vma
, address
,
3325 * Use __pte_alloc instead of pte_alloc_map, because we can't
3326 * run pte_offset_map on the pmd, if an huge pmd could
3327 * materialize from under us from a different thread.
3329 if (unlikely(__pte_alloc(mm
, vma
, pmd
, address
)))
3330 return VM_FAULT_OOM
;
3331 /* if an huge pmd materialized from under us just retry later */
3332 if (unlikely(pmd_trans_huge(*pmd
)))
3335 * A regular pmd is established and it can't morph into a huge pmd
3336 * from under us anymore at this point because we hold the mmap_sem
3337 * read mode and khugepaged takes it in write mode. So now it's
3338 * safe to run pte_offset_map().
3340 pte
= pte_offset_map(pmd
, address
);
3342 return handle_pte_fault(mm
, vma
, address
, pte
, pmd
, flags
);
3345 #ifndef __PAGETABLE_PUD_FOLDED
3347 * Allocate page upper directory.
3348 * We've already handled the fast-path in-line.
3350 int __pud_alloc(struct mm_struct
*mm
, pgd_t
*pgd
, unsigned long address
)
3352 pud_t
*new = pud_alloc_one(mm
, address
);
3356 smp_wmb(); /* See comment in __pte_alloc */
3358 spin_lock(&mm
->page_table_lock
);
3359 if (pgd_present(*pgd
)) /* Another has populated it */
3362 pgd_populate(mm
, pgd
, new);
3363 spin_unlock(&mm
->page_table_lock
);
3366 #endif /* __PAGETABLE_PUD_FOLDED */
3368 #ifndef __PAGETABLE_PMD_FOLDED
3370 * Allocate page middle directory.
3371 * We've already handled the fast-path in-line.
3373 int __pmd_alloc(struct mm_struct
*mm
, pud_t
*pud
, unsigned long address
)
3375 pmd_t
*new = pmd_alloc_one(mm
, address
);
3379 smp_wmb(); /* See comment in __pte_alloc */
3381 spin_lock(&mm
->page_table_lock
);
3382 #ifndef __ARCH_HAS_4LEVEL_HACK
3383 if (pud_present(*pud
)) /* Another has populated it */
3386 pud_populate(mm
, pud
, new);
3388 if (pgd_present(*pud
)) /* Another has populated it */
3391 pgd_populate(mm
, pud
, new);
3392 #endif /* __ARCH_HAS_4LEVEL_HACK */
3393 spin_unlock(&mm
->page_table_lock
);
3396 #endif /* __PAGETABLE_PMD_FOLDED */
3398 int make_pages_present(unsigned long addr
, unsigned long end
)
3400 int ret
, len
, write
;
3401 struct vm_area_struct
* vma
;
3403 vma
= find_vma(current
->mm
, addr
);
3407 * We want to touch writable mappings with a write fault in order
3408 * to break COW, except for shared mappings because these don't COW
3409 * and we would not want to dirty them for nothing.
3411 write
= (vma
->vm_flags
& (VM_WRITE
| VM_SHARED
)) == VM_WRITE
;
3412 BUG_ON(addr
>= end
);
3413 BUG_ON(end
> vma
->vm_end
);
3414 len
= DIV_ROUND_UP(end
, PAGE_SIZE
) - addr
/PAGE_SIZE
;
3415 ret
= get_user_pages(current
, current
->mm
, addr
,
3416 len
, write
, 0, NULL
, NULL
);
3419 return ret
== len
? 0 : -EFAULT
;
3422 #if !defined(__HAVE_ARCH_GATE_AREA)
3424 #if defined(AT_SYSINFO_EHDR)
3425 static struct vm_area_struct gate_vma
;
3427 static int __init
gate_vma_init(void)
3429 gate_vma
.vm_mm
= NULL
;
3430 gate_vma
.vm_start
= FIXADDR_USER_START
;
3431 gate_vma
.vm_end
= FIXADDR_USER_END
;
3432 gate_vma
.vm_flags
= VM_READ
| VM_MAYREAD
| VM_EXEC
| VM_MAYEXEC
;
3433 gate_vma
.vm_page_prot
= __P101
;
3435 * Make sure the vDSO gets into every core dump.
3436 * Dumping its contents makes post-mortem fully interpretable later
3437 * without matching up the same kernel and hardware config to see
3438 * what PC values meant.
3440 gate_vma
.vm_flags
|= VM_ALWAYSDUMP
;
3443 __initcall(gate_vma_init
);
3446 struct vm_area_struct
*get_gate_vma(struct task_struct
*tsk
)
3448 #ifdef AT_SYSINFO_EHDR
3455 int in_gate_area_no_task(unsigned long addr
)
3457 #ifdef AT_SYSINFO_EHDR
3458 if ((addr
>= FIXADDR_USER_START
) && (addr
< FIXADDR_USER_END
))
3464 #endif /* __HAVE_ARCH_GATE_AREA */
3466 static int __follow_pte(struct mm_struct
*mm
, unsigned long address
,
3467 pte_t
**ptepp
, spinlock_t
**ptlp
)
3474 pgd
= pgd_offset(mm
, address
);
3475 if (pgd_none(*pgd
) || unlikely(pgd_bad(*pgd
)))
3478 pud
= pud_offset(pgd
, address
);
3479 if (pud_none(*pud
) || unlikely(pud_bad(*pud
)))
3482 pmd
= pmd_offset(pud
, address
);
3483 VM_BUG_ON(pmd_trans_huge(*pmd
));
3484 if (pmd_none(*pmd
) || unlikely(pmd_bad(*pmd
)))
3487 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3491 ptep
= pte_offset_map_lock(mm
, pmd
, address
, ptlp
);
3494 if (!pte_present(*ptep
))
3499 pte_unmap_unlock(ptep
, *ptlp
);
3504 static inline int follow_pte(struct mm_struct
*mm
, unsigned long address
,
3505 pte_t
**ptepp
, spinlock_t
**ptlp
)
3509 /* (void) is needed to make gcc happy */
3510 (void) __cond_lock(*ptlp
,
3511 !(res
= __follow_pte(mm
, address
, ptepp
, ptlp
)));
3516 * follow_pfn - look up PFN at a user virtual address
3517 * @vma: memory mapping
3518 * @address: user virtual address
3519 * @pfn: location to store found PFN
3521 * Only IO mappings and raw PFN mappings are allowed.
3523 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3525 int follow_pfn(struct vm_area_struct
*vma
, unsigned long address
,
3532 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
3535 ret
= follow_pte(vma
->vm_mm
, address
, &ptep
, &ptl
);
3538 *pfn
= pte_pfn(*ptep
);
3539 pte_unmap_unlock(ptep
, ptl
);
3542 EXPORT_SYMBOL(follow_pfn
);
3544 #ifdef CONFIG_HAVE_IOREMAP_PROT
3545 int follow_phys(struct vm_area_struct
*vma
,
3546 unsigned long address
, unsigned int flags
,
3547 unsigned long *prot
, resource_size_t
*phys
)
3553 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
3556 if (follow_pte(vma
->vm_mm
, address
, &ptep
, &ptl
))
3560 if ((flags
& FOLL_WRITE
) && !pte_write(pte
))
3563 *prot
= pgprot_val(pte_pgprot(pte
));
3564 *phys
= (resource_size_t
)pte_pfn(pte
) << PAGE_SHIFT
;
3568 pte_unmap_unlock(ptep
, ptl
);
3573 int generic_access_phys(struct vm_area_struct
*vma
, unsigned long addr
,
3574 void *buf
, int len
, int write
)
3576 resource_size_t phys_addr
;
3577 unsigned long prot
= 0;
3578 void __iomem
*maddr
;
3579 int offset
= addr
& (PAGE_SIZE
-1);
3581 if (follow_phys(vma
, addr
, write
, &prot
, &phys_addr
))
3584 maddr
= ioremap_prot(phys_addr
, PAGE_SIZE
, prot
);
3586 memcpy_toio(maddr
+ offset
, buf
, len
);
3588 memcpy_fromio(buf
, maddr
+ offset
, len
);
3596 * Access another process' address space.
3597 * Source/target buffer must be kernel space,
3598 * Do not walk the page table directly, use get_user_pages
3600 int access_process_vm(struct task_struct
*tsk
, unsigned long addr
, void *buf
, int len
, int write
)
3602 struct mm_struct
*mm
;
3603 struct vm_area_struct
*vma
;
3604 void *old_buf
= buf
;
3606 mm
= get_task_mm(tsk
);
3610 down_read(&mm
->mmap_sem
);
3611 /* ignore errors, just check how much was successfully transferred */
3613 int bytes
, ret
, offset
;
3615 struct page
*page
= NULL
;
3617 ret
= get_user_pages(tsk
, mm
, addr
, 1,
3618 write
, 1, &page
, &vma
);
3621 * Check if this is a VM_IO | VM_PFNMAP VMA, which
3622 * we can access using slightly different code.
3624 #ifdef CONFIG_HAVE_IOREMAP_PROT
3625 vma
= find_vma(mm
, addr
);
3628 if (vma
->vm_ops
&& vma
->vm_ops
->access
)
3629 ret
= vma
->vm_ops
->access(vma
, addr
, buf
,
3637 offset
= addr
& (PAGE_SIZE
-1);
3638 if (bytes
> PAGE_SIZE
-offset
)
3639 bytes
= PAGE_SIZE
-offset
;
3643 copy_to_user_page(vma
, page
, addr
,
3644 maddr
+ offset
, buf
, bytes
);
3645 set_page_dirty_lock(page
);
3647 copy_from_user_page(vma
, page
, addr
,
3648 buf
, maddr
+ offset
, bytes
);
3651 page_cache_release(page
);
3657 up_read(&mm
->mmap_sem
);
3660 return buf
- old_buf
;
3664 * Print the name of a VMA.
3666 void print_vma_addr(char *prefix
, unsigned long ip
)
3668 struct mm_struct
*mm
= current
->mm
;
3669 struct vm_area_struct
*vma
;
3672 * Do not print if we are in atomic
3673 * contexts (in exception stacks, etc.):
3675 if (preempt_count())
3678 down_read(&mm
->mmap_sem
);
3679 vma
= find_vma(mm
, ip
);
3680 if (vma
&& vma
->vm_file
) {
3681 struct file
*f
= vma
->vm_file
;
3682 char *buf
= (char *)__get_free_page(GFP_KERNEL
);
3686 p
= d_path(&f
->f_path
, buf
, PAGE_SIZE
);
3689 s
= strrchr(p
, '/');
3692 printk("%s%s[%lx+%lx]", prefix
, p
,
3694 vma
->vm_end
- vma
->vm_start
);
3695 free_page((unsigned long)buf
);
3698 up_read(¤t
->mm
->mmap_sem
);
3701 #ifdef CONFIG_PROVE_LOCKING
3702 void might_fault(void)
3705 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3706 * holding the mmap_sem, this is safe because kernel memory doesn't
3707 * get paged out, therefore we'll never actually fault, and the
3708 * below annotations will generate false positives.
3710 if (segment_eq(get_fs(), KERNEL_DS
))
3715 * it would be nicer only to annotate paths which are not under
3716 * pagefault_disable, however that requires a larger audit and
3717 * providing helpers like get_user_atomic.
3719 if (!in_atomic() && current
->mm
)
3720 might_lock_read(¤t
->mm
->mmap_sem
);
3722 EXPORT_SYMBOL(might_fault
);
3725 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3726 static void clear_gigantic_page(struct page
*page
,
3728 unsigned int pages_per_huge_page
)
3731 struct page
*p
= page
;
3734 for (i
= 0; i
< pages_per_huge_page
;
3735 i
++, p
= mem_map_next(p
, page
, i
)) {
3737 clear_user_highpage(p
, addr
+ i
* PAGE_SIZE
);
3740 void clear_huge_page(struct page
*page
,
3741 unsigned long addr
, unsigned int pages_per_huge_page
)
3745 if (unlikely(pages_per_huge_page
> MAX_ORDER_NR_PAGES
)) {
3746 clear_gigantic_page(page
, addr
, pages_per_huge_page
);
3751 for (i
= 0; i
< pages_per_huge_page
; i
++) {
3753 clear_user_highpage(page
+ i
, addr
+ i
* PAGE_SIZE
);
3757 static void copy_user_gigantic_page(struct page
*dst
, struct page
*src
,
3759 struct vm_area_struct
*vma
,
3760 unsigned int pages_per_huge_page
)
3763 struct page
*dst_base
= dst
;
3764 struct page
*src_base
= src
;
3766 for (i
= 0; i
< pages_per_huge_page
; ) {
3768 copy_user_highpage(dst
, src
, addr
+ i
*PAGE_SIZE
, vma
);
3771 dst
= mem_map_next(dst
, dst_base
, i
);
3772 src
= mem_map_next(src
, src_base
, i
);
3776 void copy_user_huge_page(struct page
*dst
, struct page
*src
,
3777 unsigned long addr
, struct vm_area_struct
*vma
,
3778 unsigned int pages_per_huge_page
)
3782 if (unlikely(pages_per_huge_page
> MAX_ORDER_NR_PAGES
)) {
3783 copy_user_gigantic_page(dst
, src
, addr
, vma
,
3784 pages_per_huge_page
);
3789 for (i
= 0; i
< pages_per_huge_page
; i
++) {
3791 copy_user_highpage(dst
+ i
, src
+ i
, addr
+ i
*PAGE_SIZE
, vma
);
3794 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */