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/export.h>
51 #include <linux/delayacct.h>
52 #include <linux/init.h>
53 #include <linux/pfn_t.h>
54 #include <linux/writeback.h>
55 #include <linux/memcontrol.h>
56 #include <linux/mmu_notifier.h>
57 #include <linux/kallsyms.h>
58 #include <linux/swapops.h>
59 #include <linux/elf.h>
60 #include <linux/gfp.h>
61 #include <linux/migrate.h>
62 #include <linux/string.h>
63 #include <linux/dma-debug.h>
64 #include <linux/debugfs.h>
65 #include <linux/userfaultfd_k.h>
66 #include <linux/dax.h>
69 #include <asm/mmu_context.h>
70 #include <asm/pgalloc.h>
71 #include <asm/uaccess.h>
73 #include <asm/tlbflush.h>
74 #include <asm/pgtable.h>
78 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
79 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
82 #ifndef CONFIG_NEED_MULTIPLE_NODES
83 /* use the per-pgdat data instead for discontigmem - mbligh */
84 unsigned long max_mapnr
;
87 EXPORT_SYMBOL(max_mapnr
);
88 EXPORT_SYMBOL(mem_map
);
92 * A number of key systems in x86 including ioremap() rely on the assumption
93 * that high_memory defines the upper bound on direct map memory, then end
94 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
95 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
100 EXPORT_SYMBOL(high_memory
);
103 * Randomize the address space (stacks, mmaps, brk, etc.).
105 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
106 * as ancient (libc5 based) binaries can segfault. )
108 int randomize_va_space __read_mostly
=
109 #ifdef CONFIG_COMPAT_BRK
115 static int __init
disable_randmaps(char *s
)
117 randomize_va_space
= 0;
120 __setup("norandmaps", disable_randmaps
);
122 unsigned long zero_pfn __read_mostly
;
123 unsigned long highest_memmap_pfn __read_mostly
;
125 EXPORT_SYMBOL(zero_pfn
);
128 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
130 static int __init
init_zero_pfn(void)
132 zero_pfn
= page_to_pfn(ZERO_PAGE(0));
135 core_initcall(init_zero_pfn
);
138 #if defined(SPLIT_RSS_COUNTING)
140 void sync_mm_rss(struct mm_struct
*mm
)
144 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
145 if (current
->rss_stat
.count
[i
]) {
146 add_mm_counter(mm
, i
, current
->rss_stat
.count
[i
]);
147 current
->rss_stat
.count
[i
] = 0;
150 current
->rss_stat
.events
= 0;
153 static void add_mm_counter_fast(struct mm_struct
*mm
, int member
, int val
)
155 struct task_struct
*task
= current
;
157 if (likely(task
->mm
== mm
))
158 task
->rss_stat
.count
[member
] += val
;
160 add_mm_counter(mm
, member
, val
);
162 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
163 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
165 /* sync counter once per 64 page faults */
166 #define TASK_RSS_EVENTS_THRESH (64)
167 static void check_sync_rss_stat(struct task_struct
*task
)
169 if (unlikely(task
!= current
))
171 if (unlikely(task
->rss_stat
.events
++ > TASK_RSS_EVENTS_THRESH
))
172 sync_mm_rss(task
->mm
);
174 #else /* SPLIT_RSS_COUNTING */
176 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
177 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
179 static void check_sync_rss_stat(struct task_struct
*task
)
183 #endif /* SPLIT_RSS_COUNTING */
185 #ifdef HAVE_GENERIC_MMU_GATHER
187 static bool tlb_next_batch(struct mmu_gather
*tlb
)
189 struct mmu_gather_batch
*batch
;
193 tlb
->active
= batch
->next
;
197 if (tlb
->batch_count
== MAX_GATHER_BATCH_COUNT
)
200 batch
= (void *)__get_free_pages(GFP_NOWAIT
| __GFP_NOWARN
, 0);
207 batch
->max
= MAX_GATHER_BATCH
;
209 tlb
->active
->next
= batch
;
216 * Called to initialize an (on-stack) mmu_gather structure for page-table
217 * tear-down from @mm. The @fullmm argument is used when @mm is without
218 * users and we're going to destroy the full address space (exit/execve).
220 void tlb_gather_mmu(struct mmu_gather
*tlb
, struct mm_struct
*mm
, unsigned long start
, unsigned long end
)
224 /* Is it from 0 to ~0? */
225 tlb
->fullmm
= !(start
| (end
+1));
226 tlb
->need_flush_all
= 0;
227 tlb
->local
.next
= NULL
;
229 tlb
->local
.max
= ARRAY_SIZE(tlb
->__pages
);
230 tlb
->active
= &tlb
->local
;
231 tlb
->batch_count
= 0;
233 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
238 __tlb_reset_range(tlb
);
241 static void tlb_flush_mmu_tlbonly(struct mmu_gather
*tlb
)
247 mmu_notifier_invalidate_range(tlb
->mm
, tlb
->start
, tlb
->end
);
248 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
249 tlb_table_flush(tlb
);
251 __tlb_reset_range(tlb
);
254 static void tlb_flush_mmu_free(struct mmu_gather
*tlb
)
256 struct mmu_gather_batch
*batch
;
258 for (batch
= &tlb
->local
; batch
&& batch
->nr
; batch
= batch
->next
) {
259 free_pages_and_swap_cache(batch
->pages
, batch
->nr
);
262 tlb
->active
= &tlb
->local
;
265 void tlb_flush_mmu(struct mmu_gather
*tlb
)
267 tlb_flush_mmu_tlbonly(tlb
);
268 tlb_flush_mmu_free(tlb
);
272 * Called at the end of the shootdown operation to free up any resources
273 * that were required.
275 void tlb_finish_mmu(struct mmu_gather
*tlb
, unsigned long start
, unsigned long end
)
277 struct mmu_gather_batch
*batch
, *next
;
281 /* keep the page table cache within bounds */
284 for (batch
= tlb
->local
.next
; batch
; batch
= next
) {
286 free_pages((unsigned long)batch
, 0);
288 tlb
->local
.next
= NULL
;
292 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
293 * handling the additional races in SMP caused by other CPUs caching valid
294 * mappings in their TLBs. Returns the number of free page slots left.
295 * When out of page slots we must call tlb_flush_mmu().
296 *returns true if the caller should flush.
298 bool __tlb_remove_page_size(struct mmu_gather
*tlb
, struct page
*page
, int page_size
)
300 struct mmu_gather_batch
*batch
;
302 VM_BUG_ON(!tlb
->end
);
305 tlb
->page_size
= page_size
;
307 if (page_size
!= tlb
->page_size
)
312 if (batch
->nr
== batch
->max
) {
313 if (!tlb_next_batch(tlb
))
317 VM_BUG_ON_PAGE(batch
->nr
> batch
->max
, page
);
319 batch
->pages
[batch
->nr
++] = page
;
323 #endif /* HAVE_GENERIC_MMU_GATHER */
325 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
328 * See the comment near struct mmu_table_batch.
331 static void tlb_remove_table_smp_sync(void *arg
)
333 /* Simply deliver the interrupt */
336 static void tlb_remove_table_one(void *table
)
339 * This isn't an RCU grace period and hence the page-tables cannot be
340 * assumed to be actually RCU-freed.
342 * It is however sufficient for software page-table walkers that rely on
343 * IRQ disabling. See the comment near struct mmu_table_batch.
345 smp_call_function(tlb_remove_table_smp_sync
, NULL
, 1);
346 __tlb_remove_table(table
);
349 static void tlb_remove_table_rcu(struct rcu_head
*head
)
351 struct mmu_table_batch
*batch
;
354 batch
= container_of(head
, struct mmu_table_batch
, rcu
);
356 for (i
= 0; i
< batch
->nr
; i
++)
357 __tlb_remove_table(batch
->tables
[i
]);
359 free_page((unsigned long)batch
);
362 void tlb_table_flush(struct mmu_gather
*tlb
)
364 struct mmu_table_batch
**batch
= &tlb
->batch
;
367 call_rcu_sched(&(*batch
)->rcu
, tlb_remove_table_rcu
);
372 void tlb_remove_table(struct mmu_gather
*tlb
, void *table
)
374 struct mmu_table_batch
**batch
= &tlb
->batch
;
377 * When there's less then two users of this mm there cannot be a
378 * concurrent page-table walk.
380 if (atomic_read(&tlb
->mm
->mm_users
) < 2) {
381 __tlb_remove_table(table
);
385 if (*batch
== NULL
) {
386 *batch
= (struct mmu_table_batch
*)__get_free_page(GFP_NOWAIT
| __GFP_NOWARN
);
387 if (*batch
== NULL
) {
388 tlb_remove_table_one(table
);
393 (*batch
)->tables
[(*batch
)->nr
++] = table
;
394 if ((*batch
)->nr
== MAX_TABLE_BATCH
)
395 tlb_table_flush(tlb
);
398 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
401 * Note: this doesn't free the actual pages themselves. That
402 * has been handled earlier when unmapping all the memory regions.
404 static void free_pte_range(struct mmu_gather
*tlb
, pmd_t
*pmd
,
407 pgtable_t token
= pmd_pgtable(*pmd
);
409 pte_free_tlb(tlb
, token
, addr
);
410 atomic_long_dec(&tlb
->mm
->nr_ptes
);
413 static inline void free_pmd_range(struct mmu_gather
*tlb
, pud_t
*pud
,
414 unsigned long addr
, unsigned long end
,
415 unsigned long floor
, unsigned long ceiling
)
422 pmd
= pmd_offset(pud
, addr
);
424 next
= pmd_addr_end(addr
, end
);
425 if (pmd_none_or_clear_bad(pmd
))
427 free_pte_range(tlb
, pmd
, addr
);
428 } while (pmd
++, addr
= next
, addr
!= end
);
438 if (end
- 1 > ceiling
- 1)
441 pmd
= pmd_offset(pud
, start
);
443 pmd_free_tlb(tlb
, pmd
, start
);
444 mm_dec_nr_pmds(tlb
->mm
);
447 static inline void free_pud_range(struct mmu_gather
*tlb
, pgd_t
*pgd
,
448 unsigned long addr
, unsigned long end
,
449 unsigned long floor
, unsigned long ceiling
)
456 pud
= pud_offset(pgd
, addr
);
458 next
= pud_addr_end(addr
, end
);
459 if (pud_none_or_clear_bad(pud
))
461 free_pmd_range(tlb
, pud
, addr
, next
, floor
, ceiling
);
462 } while (pud
++, addr
= next
, addr
!= end
);
468 ceiling
&= PGDIR_MASK
;
472 if (end
- 1 > ceiling
- 1)
475 pud
= pud_offset(pgd
, start
);
477 pud_free_tlb(tlb
, pud
, start
);
481 * This function frees user-level page tables of a process.
483 void free_pgd_range(struct mmu_gather
*tlb
,
484 unsigned long addr
, unsigned long end
,
485 unsigned long floor
, unsigned long ceiling
)
491 * The next few lines have given us lots of grief...
493 * Why are we testing PMD* at this top level? Because often
494 * there will be no work to do at all, and we'd prefer not to
495 * go all the way down to the bottom just to discover that.
497 * Why all these "- 1"s? Because 0 represents both the bottom
498 * of the address space and the top of it (using -1 for the
499 * top wouldn't help much: the masks would do the wrong thing).
500 * The rule is that addr 0 and floor 0 refer to the bottom of
501 * the address space, but end 0 and ceiling 0 refer to the top
502 * Comparisons need to use "end - 1" and "ceiling - 1" (though
503 * that end 0 case should be mythical).
505 * Wherever addr is brought up or ceiling brought down, we must
506 * be careful to reject "the opposite 0" before it confuses the
507 * subsequent tests. But what about where end is brought down
508 * by PMD_SIZE below? no, end can't go down to 0 there.
510 * Whereas we round start (addr) and ceiling down, by different
511 * masks at different levels, in order to test whether a table
512 * now has no other vmas using it, so can be freed, we don't
513 * bother to round floor or end up - the tests don't need that.
527 if (end
- 1 > ceiling
- 1)
532 pgd
= pgd_offset(tlb
->mm
, addr
);
534 next
= pgd_addr_end(addr
, end
);
535 if (pgd_none_or_clear_bad(pgd
))
537 free_pud_range(tlb
, pgd
, addr
, next
, floor
, ceiling
);
538 } while (pgd
++, addr
= next
, addr
!= end
);
541 void free_pgtables(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
542 unsigned long floor
, unsigned long ceiling
)
545 struct vm_area_struct
*next
= vma
->vm_next
;
546 unsigned long addr
= vma
->vm_start
;
549 * Hide vma from rmap and truncate_pagecache before freeing
552 unlink_anon_vmas(vma
);
553 unlink_file_vma(vma
);
555 if (is_vm_hugetlb_page(vma
)) {
556 hugetlb_free_pgd_range(tlb
, addr
, vma
->vm_end
,
557 floor
, next
? next
->vm_start
: ceiling
);
560 * Optimization: gather nearby vmas into one call down
562 while (next
&& next
->vm_start
<= vma
->vm_end
+ PMD_SIZE
563 && !is_vm_hugetlb_page(next
)) {
566 unlink_anon_vmas(vma
);
567 unlink_file_vma(vma
);
569 free_pgd_range(tlb
, addr
, vma
->vm_end
,
570 floor
, next
? next
->vm_start
: ceiling
);
576 int __pte_alloc(struct mm_struct
*mm
, pmd_t
*pmd
, unsigned long address
)
579 pgtable_t
new = pte_alloc_one(mm
, address
);
584 * Ensure all pte setup (eg. pte page lock and page clearing) are
585 * visible before the pte is made visible to other CPUs by being
586 * put into page tables.
588 * The other side of the story is the pointer chasing in the page
589 * table walking code (when walking the page table without locking;
590 * ie. most of the time). Fortunately, these data accesses consist
591 * of a chain of data-dependent loads, meaning most CPUs (alpha
592 * being the notable exception) will already guarantee loads are
593 * seen in-order. See the alpha page table accessors for the
594 * smp_read_barrier_depends() barriers in page table walking code.
596 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
598 ptl
= pmd_lock(mm
, pmd
);
599 if (likely(pmd_none(*pmd
))) { /* Has another populated it ? */
600 atomic_long_inc(&mm
->nr_ptes
);
601 pmd_populate(mm
, pmd
, new);
610 int __pte_alloc_kernel(pmd_t
*pmd
, unsigned long address
)
612 pte_t
*new = pte_alloc_one_kernel(&init_mm
, address
);
616 smp_wmb(); /* See comment in __pte_alloc */
618 spin_lock(&init_mm
.page_table_lock
);
619 if (likely(pmd_none(*pmd
))) { /* Has another populated it ? */
620 pmd_populate_kernel(&init_mm
, pmd
, new);
623 spin_unlock(&init_mm
.page_table_lock
);
625 pte_free_kernel(&init_mm
, new);
629 static inline void init_rss_vec(int *rss
)
631 memset(rss
, 0, sizeof(int) * NR_MM_COUNTERS
);
634 static inline void add_mm_rss_vec(struct mm_struct
*mm
, int *rss
)
638 if (current
->mm
== mm
)
640 for (i
= 0; i
< NR_MM_COUNTERS
; i
++)
642 add_mm_counter(mm
, i
, rss
[i
]);
646 * This function is called to print an error when a bad pte
647 * is found. For example, we might have a PFN-mapped pte in
648 * a region that doesn't allow it.
650 * The calling function must still handle the error.
652 static void print_bad_pte(struct vm_area_struct
*vma
, unsigned long addr
,
653 pte_t pte
, struct page
*page
)
655 pgd_t
*pgd
= pgd_offset(vma
->vm_mm
, addr
);
656 pud_t
*pud
= pud_offset(pgd
, addr
);
657 pmd_t
*pmd
= pmd_offset(pud
, addr
);
658 struct address_space
*mapping
;
660 static unsigned long resume
;
661 static unsigned long nr_shown
;
662 static unsigned long nr_unshown
;
665 * Allow a burst of 60 reports, then keep quiet for that minute;
666 * or allow a steady drip of one report per second.
668 if (nr_shown
== 60) {
669 if (time_before(jiffies
, resume
)) {
674 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
681 resume
= jiffies
+ 60 * HZ
;
683 mapping
= vma
->vm_file
? vma
->vm_file
->f_mapping
: NULL
;
684 index
= linear_page_index(vma
, addr
);
686 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
688 (long long)pte_val(pte
), (long long)pmd_val(*pmd
));
690 dump_page(page
, "bad pte");
691 pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
692 (void *)addr
, vma
->vm_flags
, vma
->anon_vma
, mapping
, index
);
694 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
696 pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
698 vma
->vm_ops
? vma
->vm_ops
->fault
: NULL
,
699 vma
->vm_file
? vma
->vm_file
->f_op
->mmap
: NULL
,
700 mapping
? mapping
->a_ops
->readpage
: NULL
);
702 add_taint(TAINT_BAD_PAGE
, LOCKDEP_NOW_UNRELIABLE
);
706 * vm_normal_page -- This function gets the "struct page" associated with a pte.
708 * "Special" mappings do not wish to be associated with a "struct page" (either
709 * it doesn't exist, or it exists but they don't want to touch it). In this
710 * case, NULL is returned here. "Normal" mappings do have a struct page.
712 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
713 * pte bit, in which case this function is trivial. Secondly, an architecture
714 * may not have a spare pte bit, which requires a more complicated scheme,
717 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
718 * special mapping (even if there are underlying and valid "struct pages").
719 * COWed pages of a VM_PFNMAP are always normal.
721 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
722 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
723 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
724 * mapping will always honor the rule
726 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
728 * And for normal mappings this is false.
730 * This restricts such mappings to be a linear translation from virtual address
731 * to pfn. To get around this restriction, we allow arbitrary mappings so long
732 * as the vma is not a COW mapping; in that case, we know that all ptes are
733 * special (because none can have been COWed).
736 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
738 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
739 * page" backing, however the difference is that _all_ pages with a struct
740 * page (that is, those where pfn_valid is true) are refcounted and considered
741 * normal pages by the VM. The disadvantage is that pages are refcounted
742 * (which can be slower and simply not an option for some PFNMAP users). The
743 * advantage is that we don't have to follow the strict linearity rule of
744 * PFNMAP mappings in order to support COWable mappings.
747 #ifdef __HAVE_ARCH_PTE_SPECIAL
748 # define HAVE_PTE_SPECIAL 1
750 # define HAVE_PTE_SPECIAL 0
752 struct page
*vm_normal_page(struct vm_area_struct
*vma
, unsigned long addr
,
755 unsigned long pfn
= pte_pfn(pte
);
757 if (HAVE_PTE_SPECIAL
) {
758 if (likely(!pte_special(pte
)))
760 if (vma
->vm_ops
&& vma
->vm_ops
->find_special_page
)
761 return vma
->vm_ops
->find_special_page(vma
, addr
);
762 if (vma
->vm_flags
& (VM_PFNMAP
| VM_MIXEDMAP
))
764 if (!is_zero_pfn(pfn
))
765 print_bad_pte(vma
, addr
, pte
, NULL
);
769 /* !HAVE_PTE_SPECIAL case follows: */
771 if (unlikely(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
))) {
772 if (vma
->vm_flags
& VM_MIXEDMAP
) {
778 off
= (addr
- vma
->vm_start
) >> PAGE_SHIFT
;
779 if (pfn
== vma
->vm_pgoff
+ off
)
781 if (!is_cow_mapping(vma
->vm_flags
))
786 if (is_zero_pfn(pfn
))
789 if (unlikely(pfn
> highest_memmap_pfn
)) {
790 print_bad_pte(vma
, addr
, pte
, NULL
);
795 * NOTE! We still have PageReserved() pages in the page tables.
796 * eg. VDSO mappings can cause them to exist.
799 return pfn_to_page(pfn
);
802 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
803 struct page
*vm_normal_page_pmd(struct vm_area_struct
*vma
, unsigned long addr
,
806 unsigned long pfn
= pmd_pfn(pmd
);
809 * There is no pmd_special() but there may be special pmds, e.g.
810 * in a direct-access (dax) mapping, so let's just replicate the
811 * !HAVE_PTE_SPECIAL case from vm_normal_page() here.
813 if (unlikely(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
))) {
814 if (vma
->vm_flags
& VM_MIXEDMAP
) {
820 off
= (addr
- vma
->vm_start
) >> PAGE_SHIFT
;
821 if (pfn
== vma
->vm_pgoff
+ off
)
823 if (!is_cow_mapping(vma
->vm_flags
))
828 if (is_zero_pfn(pfn
))
830 if (unlikely(pfn
> highest_memmap_pfn
))
834 * NOTE! We still have PageReserved() pages in the page tables.
835 * eg. VDSO mappings can cause them to exist.
838 return pfn_to_page(pfn
);
843 * copy one vm_area from one task to the other. Assumes the page tables
844 * already present in the new task to be cleared in the whole range
845 * covered by this vma.
848 static inline unsigned long
849 copy_one_pte(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
850 pte_t
*dst_pte
, pte_t
*src_pte
, struct vm_area_struct
*vma
,
851 unsigned long addr
, int *rss
)
853 unsigned long vm_flags
= vma
->vm_flags
;
854 pte_t pte
= *src_pte
;
857 /* pte contains position in swap or file, so copy. */
858 if (unlikely(!pte_present(pte
))) {
859 swp_entry_t entry
= pte_to_swp_entry(pte
);
861 if (likely(!non_swap_entry(entry
))) {
862 if (swap_duplicate(entry
) < 0)
865 /* make sure dst_mm is on swapoff's mmlist. */
866 if (unlikely(list_empty(&dst_mm
->mmlist
))) {
867 spin_lock(&mmlist_lock
);
868 if (list_empty(&dst_mm
->mmlist
))
869 list_add(&dst_mm
->mmlist
,
871 spin_unlock(&mmlist_lock
);
874 } else if (is_migration_entry(entry
)) {
875 page
= migration_entry_to_page(entry
);
877 rss
[mm_counter(page
)]++;
879 if (is_write_migration_entry(entry
) &&
880 is_cow_mapping(vm_flags
)) {
882 * COW mappings require pages in both
883 * parent and child to be set to read.
885 make_migration_entry_read(&entry
);
886 pte
= swp_entry_to_pte(entry
);
887 if (pte_swp_soft_dirty(*src_pte
))
888 pte
= pte_swp_mksoft_dirty(pte
);
889 set_pte_at(src_mm
, addr
, src_pte
, pte
);
896 * If it's a COW mapping, write protect it both
897 * in the parent and the child
899 if (is_cow_mapping(vm_flags
)) {
900 ptep_set_wrprotect(src_mm
, addr
, src_pte
);
901 pte
= pte_wrprotect(pte
);
905 * If it's a shared mapping, mark it clean in
908 if (vm_flags
& VM_SHARED
)
909 pte
= pte_mkclean(pte
);
910 pte
= pte_mkold(pte
);
912 page
= vm_normal_page(vma
, addr
, pte
);
915 page_dup_rmap(page
, false);
916 rss
[mm_counter(page
)]++;
920 set_pte_at(dst_mm
, addr
, dst_pte
, pte
);
924 static int copy_pte_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
925 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, struct vm_area_struct
*vma
,
926 unsigned long addr
, unsigned long end
)
928 pte_t
*orig_src_pte
, *orig_dst_pte
;
929 pte_t
*src_pte
, *dst_pte
;
930 spinlock_t
*src_ptl
, *dst_ptl
;
932 int rss
[NR_MM_COUNTERS
];
933 swp_entry_t entry
= (swp_entry_t
){0};
938 dst_pte
= pte_alloc_map_lock(dst_mm
, dst_pmd
, addr
, &dst_ptl
);
941 src_pte
= pte_offset_map(src_pmd
, addr
);
942 src_ptl
= pte_lockptr(src_mm
, src_pmd
);
943 spin_lock_nested(src_ptl
, SINGLE_DEPTH_NESTING
);
944 orig_src_pte
= src_pte
;
945 orig_dst_pte
= dst_pte
;
946 arch_enter_lazy_mmu_mode();
950 * We are holding two locks at this point - either of them
951 * could generate latencies in another task on another CPU.
953 if (progress
>= 32) {
955 if (need_resched() ||
956 spin_needbreak(src_ptl
) || spin_needbreak(dst_ptl
))
959 if (pte_none(*src_pte
)) {
963 entry
.val
= copy_one_pte(dst_mm
, src_mm
, dst_pte
, src_pte
,
968 } while (dst_pte
++, src_pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
970 arch_leave_lazy_mmu_mode();
971 spin_unlock(src_ptl
);
972 pte_unmap(orig_src_pte
);
973 add_mm_rss_vec(dst_mm
, rss
);
974 pte_unmap_unlock(orig_dst_pte
, dst_ptl
);
978 if (add_swap_count_continuation(entry
, GFP_KERNEL
) < 0)
987 static inline int copy_pmd_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
988 pud_t
*dst_pud
, pud_t
*src_pud
, struct vm_area_struct
*vma
,
989 unsigned long addr
, unsigned long end
)
991 pmd_t
*src_pmd
, *dst_pmd
;
994 dst_pmd
= pmd_alloc(dst_mm
, dst_pud
, addr
);
997 src_pmd
= pmd_offset(src_pud
, addr
);
999 next
= pmd_addr_end(addr
, end
);
1000 if (pmd_trans_huge(*src_pmd
) || pmd_devmap(*src_pmd
)) {
1002 VM_BUG_ON(next
-addr
!= HPAGE_PMD_SIZE
);
1003 err
= copy_huge_pmd(dst_mm
, src_mm
,
1004 dst_pmd
, src_pmd
, addr
, vma
);
1011 if (pmd_none_or_clear_bad(src_pmd
))
1013 if (copy_pte_range(dst_mm
, src_mm
, dst_pmd
, src_pmd
,
1016 } while (dst_pmd
++, src_pmd
++, addr
= next
, addr
!= end
);
1020 static inline int copy_pud_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1021 pgd_t
*dst_pgd
, pgd_t
*src_pgd
, struct vm_area_struct
*vma
,
1022 unsigned long addr
, unsigned long end
)
1024 pud_t
*src_pud
, *dst_pud
;
1027 dst_pud
= pud_alloc(dst_mm
, dst_pgd
, addr
);
1030 src_pud
= pud_offset(src_pgd
, addr
);
1032 next
= pud_addr_end(addr
, end
);
1033 if (pud_none_or_clear_bad(src_pud
))
1035 if (copy_pmd_range(dst_mm
, src_mm
, dst_pud
, src_pud
,
1038 } while (dst_pud
++, src_pud
++, addr
= next
, addr
!= end
);
1042 int copy_page_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
1043 struct vm_area_struct
*vma
)
1045 pgd_t
*src_pgd
, *dst_pgd
;
1047 unsigned long addr
= vma
->vm_start
;
1048 unsigned long end
= vma
->vm_end
;
1049 unsigned long mmun_start
; /* For mmu_notifiers */
1050 unsigned long mmun_end
; /* For mmu_notifiers */
1055 * Don't copy ptes where a page fault will fill them correctly.
1056 * Fork becomes much lighter when there are big shared or private
1057 * readonly mappings. The tradeoff is that copy_page_range is more
1058 * efficient than faulting.
1060 if (!(vma
->vm_flags
& (VM_HUGETLB
| VM_PFNMAP
| VM_MIXEDMAP
)) &&
1064 if (is_vm_hugetlb_page(vma
))
1065 return copy_hugetlb_page_range(dst_mm
, src_mm
, vma
);
1067 if (unlikely(vma
->vm_flags
& VM_PFNMAP
)) {
1069 * We do not free on error cases below as remove_vma
1070 * gets called on error from higher level routine
1072 ret
= track_pfn_copy(vma
);
1078 * We need to invalidate the secondary MMU mappings only when
1079 * there could be a permission downgrade on the ptes of the
1080 * parent mm. And a permission downgrade will only happen if
1081 * is_cow_mapping() returns true.
1083 is_cow
= is_cow_mapping(vma
->vm_flags
);
1087 mmu_notifier_invalidate_range_start(src_mm
, mmun_start
,
1091 dst_pgd
= pgd_offset(dst_mm
, addr
);
1092 src_pgd
= pgd_offset(src_mm
, addr
);
1094 next
= pgd_addr_end(addr
, end
);
1095 if (pgd_none_or_clear_bad(src_pgd
))
1097 if (unlikely(copy_pud_range(dst_mm
, src_mm
, dst_pgd
, src_pgd
,
1098 vma
, addr
, next
))) {
1102 } while (dst_pgd
++, src_pgd
++, addr
= next
, addr
!= end
);
1105 mmu_notifier_invalidate_range_end(src_mm
, mmun_start
, mmun_end
);
1109 static unsigned long zap_pte_range(struct mmu_gather
*tlb
,
1110 struct vm_area_struct
*vma
, pmd_t
*pmd
,
1111 unsigned long addr
, unsigned long end
,
1112 struct zap_details
*details
)
1114 struct mm_struct
*mm
= tlb
->mm
;
1115 int force_flush
= 0;
1116 int rss
[NR_MM_COUNTERS
];
1121 struct page
*pending_page
= NULL
;
1125 start_pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
1127 arch_enter_lazy_mmu_mode();
1130 if (pte_none(ptent
)) {
1134 if (pte_present(ptent
)) {
1137 page
= vm_normal_page(vma
, addr
, ptent
);
1138 if (unlikely(details
) && page
) {
1140 * unmap_shared_mapping_pages() wants to
1141 * invalidate cache without truncating:
1142 * unmap shared but keep private pages.
1144 if (details
->check_mapping
&&
1145 details
->check_mapping
!= page_rmapping(page
))
1148 ptent
= ptep_get_and_clear_full(mm
, addr
, pte
,
1150 tlb_remove_tlb_entry(tlb
, pte
, addr
);
1151 if (unlikely(!page
))
1154 if (!PageAnon(page
)) {
1155 if (pte_dirty(ptent
)) {
1157 * oom_reaper cannot tear down dirty
1160 if (unlikely(details
&& details
->ignore_dirty
))
1163 set_page_dirty(page
);
1165 if (pte_young(ptent
) &&
1166 likely(!(vma
->vm_flags
& VM_SEQ_READ
)))
1167 mark_page_accessed(page
);
1169 rss
[mm_counter(page
)]--;
1170 page_remove_rmap(page
, false);
1171 if (unlikely(page_mapcount(page
) < 0))
1172 print_bad_pte(vma
, addr
, ptent
, page
);
1173 if (unlikely(__tlb_remove_page(tlb
, page
))) {
1175 pending_page
= page
;
1181 /* only check swap_entries if explicitly asked for in details */
1182 if (unlikely(details
&& !details
->check_swap_entries
))
1185 entry
= pte_to_swp_entry(ptent
);
1186 if (!non_swap_entry(entry
))
1188 else if (is_migration_entry(entry
)) {
1191 page
= migration_entry_to_page(entry
);
1192 rss
[mm_counter(page
)]--;
1194 if (unlikely(!free_swap_and_cache(entry
)))
1195 print_bad_pte(vma
, addr
, ptent
, NULL
);
1196 pte_clear_not_present_full(mm
, addr
, pte
, tlb
->fullmm
);
1197 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
1199 add_mm_rss_vec(mm
, rss
);
1200 arch_leave_lazy_mmu_mode();
1202 /* Do the actual TLB flush before dropping ptl */
1204 tlb_flush_mmu_tlbonly(tlb
);
1205 pte_unmap_unlock(start_pte
, ptl
);
1208 * If we forced a TLB flush (either due to running out of
1209 * batch buffers or because we needed to flush dirty TLB
1210 * entries before releasing the ptl), free the batched
1211 * memory too. Restart if we didn't do everything.
1215 tlb_flush_mmu_free(tlb
);
1217 /* remove the page with new size */
1218 __tlb_remove_pte_page(tlb
, pending_page
);
1219 pending_page
= NULL
;
1228 static inline unsigned long zap_pmd_range(struct mmu_gather
*tlb
,
1229 struct vm_area_struct
*vma
, pud_t
*pud
,
1230 unsigned long addr
, unsigned long end
,
1231 struct zap_details
*details
)
1236 pmd
= pmd_offset(pud
, addr
);
1238 next
= pmd_addr_end(addr
, end
);
1239 if (pmd_trans_huge(*pmd
) || pmd_devmap(*pmd
)) {
1240 if (next
- addr
!= HPAGE_PMD_SIZE
) {
1241 VM_BUG_ON_VMA(vma_is_anonymous(vma
) &&
1242 !rwsem_is_locked(&tlb
->mm
->mmap_sem
), vma
);
1243 split_huge_pmd(vma
, pmd
, addr
);
1244 } else if (zap_huge_pmd(tlb
, vma
, pmd
, addr
))
1249 * Here there can be other concurrent MADV_DONTNEED or
1250 * trans huge page faults running, and if the pmd is
1251 * none or trans huge it can change under us. This is
1252 * because MADV_DONTNEED holds the mmap_sem in read
1255 if (pmd_none_or_trans_huge_or_clear_bad(pmd
))
1257 next
= zap_pte_range(tlb
, vma
, pmd
, addr
, next
, details
);
1260 } while (pmd
++, addr
= next
, addr
!= end
);
1265 static inline unsigned long zap_pud_range(struct mmu_gather
*tlb
,
1266 struct vm_area_struct
*vma
, pgd_t
*pgd
,
1267 unsigned long addr
, unsigned long end
,
1268 struct zap_details
*details
)
1273 pud
= pud_offset(pgd
, addr
);
1275 next
= pud_addr_end(addr
, end
);
1276 if (pud_none_or_clear_bad(pud
))
1278 next
= zap_pmd_range(tlb
, vma
, pud
, addr
, next
, details
);
1279 } while (pud
++, addr
= next
, addr
!= end
);
1284 void unmap_page_range(struct mmu_gather
*tlb
,
1285 struct vm_area_struct
*vma
,
1286 unsigned long addr
, unsigned long end
,
1287 struct zap_details
*details
)
1292 BUG_ON(addr
>= end
);
1293 tlb_start_vma(tlb
, vma
);
1294 pgd
= pgd_offset(vma
->vm_mm
, addr
);
1296 next
= pgd_addr_end(addr
, end
);
1297 if (pgd_none_or_clear_bad(pgd
))
1299 next
= zap_pud_range(tlb
, vma
, pgd
, addr
, next
, details
);
1300 } while (pgd
++, addr
= next
, addr
!= end
);
1301 tlb_end_vma(tlb
, vma
);
1305 static void unmap_single_vma(struct mmu_gather
*tlb
,
1306 struct vm_area_struct
*vma
, unsigned long start_addr
,
1307 unsigned long end_addr
,
1308 struct zap_details
*details
)
1310 unsigned long start
= max(vma
->vm_start
, start_addr
);
1313 if (start
>= vma
->vm_end
)
1315 end
= min(vma
->vm_end
, end_addr
);
1316 if (end
<= vma
->vm_start
)
1320 uprobe_munmap(vma
, start
, end
);
1322 if (unlikely(vma
->vm_flags
& VM_PFNMAP
))
1323 untrack_pfn(vma
, 0, 0);
1326 if (unlikely(is_vm_hugetlb_page(vma
))) {
1328 * It is undesirable to test vma->vm_file as it
1329 * should be non-null for valid hugetlb area.
1330 * However, vm_file will be NULL in the error
1331 * cleanup path of mmap_region. When
1332 * hugetlbfs ->mmap method fails,
1333 * mmap_region() nullifies vma->vm_file
1334 * before calling this function to clean up.
1335 * Since no pte has actually been setup, it is
1336 * safe to do nothing in this case.
1339 i_mmap_lock_write(vma
->vm_file
->f_mapping
);
1340 __unmap_hugepage_range_final(tlb
, vma
, start
, end
, NULL
);
1341 i_mmap_unlock_write(vma
->vm_file
->f_mapping
);
1344 unmap_page_range(tlb
, vma
, start
, end
, details
);
1349 * unmap_vmas - unmap a range of memory covered by a list of vma's
1350 * @tlb: address of the caller's struct mmu_gather
1351 * @vma: the starting vma
1352 * @start_addr: virtual address at which to start unmapping
1353 * @end_addr: virtual address at which to end unmapping
1355 * Unmap all pages in the vma list.
1357 * Only addresses between `start' and `end' will be unmapped.
1359 * The VMA list must be sorted in ascending virtual address order.
1361 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1362 * range after unmap_vmas() returns. So the only responsibility here is to
1363 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1364 * drops the lock and schedules.
1366 void unmap_vmas(struct mmu_gather
*tlb
,
1367 struct vm_area_struct
*vma
, unsigned long start_addr
,
1368 unsigned long end_addr
)
1370 struct mm_struct
*mm
= vma
->vm_mm
;
1372 mmu_notifier_invalidate_range_start(mm
, start_addr
, end_addr
);
1373 for ( ; vma
&& vma
->vm_start
< end_addr
; vma
= vma
->vm_next
)
1374 unmap_single_vma(tlb
, vma
, start_addr
, end_addr
, NULL
);
1375 mmu_notifier_invalidate_range_end(mm
, start_addr
, end_addr
);
1379 * zap_page_range - remove user pages in a given range
1380 * @vma: vm_area_struct holding the applicable pages
1381 * @start: starting address of pages to zap
1382 * @size: number of bytes to zap
1383 * @details: details of shared cache invalidation
1385 * Caller must protect the VMA list
1387 void zap_page_range(struct vm_area_struct
*vma
, unsigned long start
,
1388 unsigned long size
, struct zap_details
*details
)
1390 struct mm_struct
*mm
= vma
->vm_mm
;
1391 struct mmu_gather tlb
;
1392 unsigned long end
= start
+ size
;
1395 tlb_gather_mmu(&tlb
, mm
, start
, end
);
1396 update_hiwater_rss(mm
);
1397 mmu_notifier_invalidate_range_start(mm
, start
, end
);
1398 for ( ; vma
&& vma
->vm_start
< end
; vma
= vma
->vm_next
)
1399 unmap_single_vma(&tlb
, vma
, start
, end
, details
);
1400 mmu_notifier_invalidate_range_end(mm
, start
, end
);
1401 tlb_finish_mmu(&tlb
, start
, end
);
1405 * zap_page_range_single - remove user pages in a given range
1406 * @vma: vm_area_struct holding the applicable pages
1407 * @address: starting address of pages to zap
1408 * @size: number of bytes to zap
1409 * @details: details of shared cache invalidation
1411 * The range must fit into one VMA.
1413 static void zap_page_range_single(struct vm_area_struct
*vma
, unsigned long address
,
1414 unsigned long size
, struct zap_details
*details
)
1416 struct mm_struct
*mm
= vma
->vm_mm
;
1417 struct mmu_gather tlb
;
1418 unsigned long end
= address
+ size
;
1421 tlb_gather_mmu(&tlb
, mm
, address
, end
);
1422 update_hiwater_rss(mm
);
1423 mmu_notifier_invalidate_range_start(mm
, address
, end
);
1424 unmap_single_vma(&tlb
, vma
, address
, end
, details
);
1425 mmu_notifier_invalidate_range_end(mm
, address
, end
);
1426 tlb_finish_mmu(&tlb
, address
, end
);
1430 * zap_vma_ptes - remove ptes mapping the vma
1431 * @vma: vm_area_struct holding ptes to be zapped
1432 * @address: starting address of pages to zap
1433 * @size: number of bytes to zap
1435 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1437 * The entire address range must be fully contained within the vma.
1439 * Returns 0 if successful.
1441 int zap_vma_ptes(struct vm_area_struct
*vma
, unsigned long address
,
1444 if (address
< vma
->vm_start
|| address
+ size
> vma
->vm_end
||
1445 !(vma
->vm_flags
& VM_PFNMAP
))
1447 zap_page_range_single(vma
, address
, size
, NULL
);
1450 EXPORT_SYMBOL_GPL(zap_vma_ptes
);
1452 pte_t
*__get_locked_pte(struct mm_struct
*mm
, unsigned long addr
,
1455 pgd_t
* pgd
= pgd_offset(mm
, addr
);
1456 pud_t
* pud
= pud_alloc(mm
, pgd
, addr
);
1458 pmd_t
* pmd
= pmd_alloc(mm
, pud
, addr
);
1460 VM_BUG_ON(pmd_trans_huge(*pmd
));
1461 return pte_alloc_map_lock(mm
, pmd
, addr
, ptl
);
1468 * This is the old fallback for page remapping.
1470 * For historical reasons, it only allows reserved pages. Only
1471 * old drivers should use this, and they needed to mark their
1472 * pages reserved for the old functions anyway.
1474 static int insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
1475 struct page
*page
, pgprot_t prot
)
1477 struct mm_struct
*mm
= vma
->vm_mm
;
1486 flush_dcache_page(page
);
1487 pte
= get_locked_pte(mm
, addr
, &ptl
);
1491 if (!pte_none(*pte
))
1494 /* Ok, finally just insert the thing.. */
1496 inc_mm_counter_fast(mm
, mm_counter_file(page
));
1497 page_add_file_rmap(page
, false);
1498 set_pte_at(mm
, addr
, pte
, mk_pte(page
, prot
));
1501 pte_unmap_unlock(pte
, ptl
);
1504 pte_unmap_unlock(pte
, ptl
);
1510 * vm_insert_page - insert single page into user vma
1511 * @vma: user vma to map to
1512 * @addr: target user address of this page
1513 * @page: source kernel page
1515 * This allows drivers to insert individual pages they've allocated
1518 * The page has to be a nice clean _individual_ kernel allocation.
1519 * If you allocate a compound page, you need to have marked it as
1520 * such (__GFP_COMP), or manually just split the page up yourself
1521 * (see split_page()).
1523 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1524 * took an arbitrary page protection parameter. This doesn't allow
1525 * that. Your vma protection will have to be set up correctly, which
1526 * means that if you want a shared writable mapping, you'd better
1527 * ask for a shared writable mapping!
1529 * The page does not need to be reserved.
1531 * Usually this function is called from f_op->mmap() handler
1532 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1533 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1534 * function from other places, for example from page-fault handler.
1536 int vm_insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
1539 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
1541 if (!page_count(page
))
1543 if (!(vma
->vm_flags
& VM_MIXEDMAP
)) {
1544 BUG_ON(down_read_trylock(&vma
->vm_mm
->mmap_sem
));
1545 BUG_ON(vma
->vm_flags
& VM_PFNMAP
);
1546 vma
->vm_flags
|= VM_MIXEDMAP
;
1548 return insert_page(vma
, addr
, page
, vma
->vm_page_prot
);
1550 EXPORT_SYMBOL(vm_insert_page
);
1552 static int insert_pfn(struct vm_area_struct
*vma
, unsigned long addr
,
1553 pfn_t pfn
, pgprot_t prot
)
1555 struct mm_struct
*mm
= vma
->vm_mm
;
1561 pte
= get_locked_pte(mm
, addr
, &ptl
);
1565 if (!pte_none(*pte
))
1568 /* Ok, finally just insert the thing.. */
1569 if (pfn_t_devmap(pfn
))
1570 entry
= pte_mkdevmap(pfn_t_pte(pfn
, prot
));
1572 entry
= pte_mkspecial(pfn_t_pte(pfn
, prot
));
1573 set_pte_at(mm
, addr
, pte
, entry
);
1574 update_mmu_cache(vma
, addr
, pte
); /* XXX: why not for insert_page? */
1578 pte_unmap_unlock(pte
, ptl
);
1584 * vm_insert_pfn - insert single pfn into user vma
1585 * @vma: user vma to map to
1586 * @addr: target user address of this page
1587 * @pfn: source kernel pfn
1589 * Similar to vm_insert_page, this allows drivers to insert individual pages
1590 * they've allocated into a user vma. Same comments apply.
1592 * This function should only be called from a vm_ops->fault handler, and
1593 * in that case the handler should return NULL.
1595 * vma cannot be a COW mapping.
1597 * As this is called only for pages that do not currently exist, we
1598 * do not need to flush old virtual caches or the TLB.
1600 int vm_insert_pfn(struct vm_area_struct
*vma
, unsigned long addr
,
1603 return vm_insert_pfn_prot(vma
, addr
, pfn
, vma
->vm_page_prot
);
1605 EXPORT_SYMBOL(vm_insert_pfn
);
1608 * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1609 * @vma: user vma to map to
1610 * @addr: target user address of this page
1611 * @pfn: source kernel pfn
1612 * @pgprot: pgprot flags for the inserted page
1614 * This is exactly like vm_insert_pfn, except that it allows drivers to
1615 * to override pgprot on a per-page basis.
1617 * This only makes sense for IO mappings, and it makes no sense for
1618 * cow mappings. In general, using multiple vmas is preferable;
1619 * vm_insert_pfn_prot should only be used if using multiple VMAs is
1622 int vm_insert_pfn_prot(struct vm_area_struct
*vma
, unsigned long addr
,
1623 unsigned long pfn
, pgprot_t pgprot
)
1627 * Technically, architectures with pte_special can avoid all these
1628 * restrictions (same for remap_pfn_range). However we would like
1629 * consistency in testing and feature parity among all, so we should
1630 * try to keep these invariants in place for everybody.
1632 BUG_ON(!(vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)));
1633 BUG_ON((vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) ==
1634 (VM_PFNMAP
|VM_MIXEDMAP
));
1635 BUG_ON((vma
->vm_flags
& VM_PFNMAP
) && is_cow_mapping(vma
->vm_flags
));
1636 BUG_ON((vma
->vm_flags
& VM_MIXEDMAP
) && pfn_valid(pfn
));
1638 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
1640 if (track_pfn_insert(vma
, &pgprot
, __pfn_to_pfn_t(pfn
, PFN_DEV
)))
1643 ret
= insert_pfn(vma
, addr
, __pfn_to_pfn_t(pfn
, PFN_DEV
), pgprot
);
1647 EXPORT_SYMBOL(vm_insert_pfn_prot
);
1649 int vm_insert_mixed(struct vm_area_struct
*vma
, unsigned long addr
,
1652 pgprot_t pgprot
= vma
->vm_page_prot
;
1654 BUG_ON(!(vma
->vm_flags
& VM_MIXEDMAP
));
1656 if (addr
< vma
->vm_start
|| addr
>= vma
->vm_end
)
1658 if (track_pfn_insert(vma
, &pgprot
, pfn
))
1662 * If we don't have pte special, then we have to use the pfn_valid()
1663 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1664 * refcount the page if pfn_valid is true (hence insert_page rather
1665 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1666 * without pte special, it would there be refcounted as a normal page.
1668 if (!HAVE_PTE_SPECIAL
&& !pfn_t_devmap(pfn
) && pfn_t_valid(pfn
)) {
1672 * At this point we are committed to insert_page()
1673 * regardless of whether the caller specified flags that
1674 * result in pfn_t_has_page() == false.
1676 page
= pfn_to_page(pfn_t_to_pfn(pfn
));
1677 return insert_page(vma
, addr
, page
, pgprot
);
1679 return insert_pfn(vma
, addr
, pfn
, pgprot
);
1681 EXPORT_SYMBOL(vm_insert_mixed
);
1684 * maps a range of physical memory into the requested pages. the old
1685 * mappings are removed. any references to nonexistent pages results
1686 * in null mappings (currently treated as "copy-on-access")
1688 static int remap_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
1689 unsigned long addr
, unsigned long end
,
1690 unsigned long pfn
, pgprot_t prot
)
1695 pte
= pte_alloc_map_lock(mm
, pmd
, addr
, &ptl
);
1698 arch_enter_lazy_mmu_mode();
1700 BUG_ON(!pte_none(*pte
));
1701 set_pte_at(mm
, addr
, pte
, pte_mkspecial(pfn_pte(pfn
, prot
)));
1703 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
1704 arch_leave_lazy_mmu_mode();
1705 pte_unmap_unlock(pte
- 1, ptl
);
1709 static inline int remap_pmd_range(struct mm_struct
*mm
, pud_t
*pud
,
1710 unsigned long addr
, unsigned long end
,
1711 unsigned long pfn
, pgprot_t prot
)
1716 pfn
-= addr
>> PAGE_SHIFT
;
1717 pmd
= pmd_alloc(mm
, pud
, addr
);
1720 VM_BUG_ON(pmd_trans_huge(*pmd
));
1722 next
= pmd_addr_end(addr
, end
);
1723 if (remap_pte_range(mm
, pmd
, addr
, next
,
1724 pfn
+ (addr
>> PAGE_SHIFT
), prot
))
1726 } while (pmd
++, addr
= next
, addr
!= end
);
1730 static inline int remap_pud_range(struct mm_struct
*mm
, pgd_t
*pgd
,
1731 unsigned long addr
, unsigned long end
,
1732 unsigned long pfn
, pgprot_t prot
)
1737 pfn
-= addr
>> PAGE_SHIFT
;
1738 pud
= pud_alloc(mm
, pgd
, addr
);
1742 next
= pud_addr_end(addr
, end
);
1743 if (remap_pmd_range(mm
, pud
, addr
, next
,
1744 pfn
+ (addr
>> PAGE_SHIFT
), prot
))
1746 } while (pud
++, addr
= next
, addr
!= end
);
1751 * remap_pfn_range - remap kernel memory to userspace
1752 * @vma: user vma to map to
1753 * @addr: target user address to start at
1754 * @pfn: physical address of kernel memory
1755 * @size: size of map area
1756 * @prot: page protection flags for this mapping
1758 * Note: this is only safe if the mm semaphore is held when called.
1760 int remap_pfn_range(struct vm_area_struct
*vma
, unsigned long addr
,
1761 unsigned long pfn
, unsigned long size
, pgprot_t prot
)
1765 unsigned long end
= addr
+ PAGE_ALIGN(size
);
1766 struct mm_struct
*mm
= vma
->vm_mm
;
1767 unsigned long remap_pfn
= pfn
;
1771 * Physically remapped pages are special. Tell the
1772 * rest of the world about it:
1773 * VM_IO tells people not to look at these pages
1774 * (accesses can have side effects).
1775 * VM_PFNMAP tells the core MM that the base pages are just
1776 * raw PFN mappings, and do not have a "struct page" associated
1779 * Disable vma merging and expanding with mremap().
1781 * Omit vma from core dump, even when VM_IO turned off.
1783 * There's a horrible special case to handle copy-on-write
1784 * behaviour that some programs depend on. We mark the "original"
1785 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1786 * See vm_normal_page() for details.
1788 if (is_cow_mapping(vma
->vm_flags
)) {
1789 if (addr
!= vma
->vm_start
|| end
!= vma
->vm_end
)
1791 vma
->vm_pgoff
= pfn
;
1794 err
= track_pfn_remap(vma
, &prot
, remap_pfn
, addr
, PAGE_ALIGN(size
));
1798 vma
->vm_flags
|= VM_IO
| VM_PFNMAP
| VM_DONTEXPAND
| VM_DONTDUMP
;
1800 BUG_ON(addr
>= end
);
1801 pfn
-= addr
>> PAGE_SHIFT
;
1802 pgd
= pgd_offset(mm
, addr
);
1803 flush_cache_range(vma
, addr
, end
);
1805 next
= pgd_addr_end(addr
, end
);
1806 err
= remap_pud_range(mm
, pgd
, addr
, next
,
1807 pfn
+ (addr
>> PAGE_SHIFT
), prot
);
1810 } while (pgd
++, addr
= next
, addr
!= end
);
1813 untrack_pfn(vma
, remap_pfn
, PAGE_ALIGN(size
));
1817 EXPORT_SYMBOL(remap_pfn_range
);
1820 * vm_iomap_memory - remap memory to userspace
1821 * @vma: user vma to map to
1822 * @start: start of area
1823 * @len: size of area
1825 * This is a simplified io_remap_pfn_range() for common driver use. The
1826 * driver just needs to give us the physical memory range to be mapped,
1827 * we'll figure out the rest from the vma information.
1829 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
1830 * whatever write-combining details or similar.
1832 int vm_iomap_memory(struct vm_area_struct
*vma
, phys_addr_t start
, unsigned long len
)
1834 unsigned long vm_len
, pfn
, pages
;
1836 /* Check that the physical memory area passed in looks valid */
1837 if (start
+ len
< start
)
1840 * You *really* shouldn't map things that aren't page-aligned,
1841 * but we've historically allowed it because IO memory might
1842 * just have smaller alignment.
1844 len
+= start
& ~PAGE_MASK
;
1845 pfn
= start
>> PAGE_SHIFT
;
1846 pages
= (len
+ ~PAGE_MASK
) >> PAGE_SHIFT
;
1847 if (pfn
+ pages
< pfn
)
1850 /* We start the mapping 'vm_pgoff' pages into the area */
1851 if (vma
->vm_pgoff
> pages
)
1853 pfn
+= vma
->vm_pgoff
;
1854 pages
-= vma
->vm_pgoff
;
1856 /* Can we fit all of the mapping? */
1857 vm_len
= vma
->vm_end
- vma
->vm_start
;
1858 if (vm_len
>> PAGE_SHIFT
> pages
)
1861 /* Ok, let it rip */
1862 return io_remap_pfn_range(vma
, vma
->vm_start
, pfn
, vm_len
, vma
->vm_page_prot
);
1864 EXPORT_SYMBOL(vm_iomap_memory
);
1866 static int apply_to_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
1867 unsigned long addr
, unsigned long end
,
1868 pte_fn_t fn
, void *data
)
1873 spinlock_t
*uninitialized_var(ptl
);
1875 pte
= (mm
== &init_mm
) ?
1876 pte_alloc_kernel(pmd
, addr
) :
1877 pte_alloc_map_lock(mm
, pmd
, addr
, &ptl
);
1881 BUG_ON(pmd_huge(*pmd
));
1883 arch_enter_lazy_mmu_mode();
1885 token
= pmd_pgtable(*pmd
);
1888 err
= fn(pte
++, token
, addr
, data
);
1891 } while (addr
+= PAGE_SIZE
, addr
!= end
);
1893 arch_leave_lazy_mmu_mode();
1896 pte_unmap_unlock(pte
-1, ptl
);
1900 static int apply_to_pmd_range(struct mm_struct
*mm
, pud_t
*pud
,
1901 unsigned long addr
, unsigned long end
,
1902 pte_fn_t fn
, void *data
)
1908 BUG_ON(pud_huge(*pud
));
1910 pmd
= pmd_alloc(mm
, pud
, addr
);
1914 next
= pmd_addr_end(addr
, end
);
1915 err
= apply_to_pte_range(mm
, pmd
, addr
, next
, fn
, data
);
1918 } while (pmd
++, addr
= next
, addr
!= end
);
1922 static int apply_to_pud_range(struct mm_struct
*mm
, pgd_t
*pgd
,
1923 unsigned long addr
, unsigned long end
,
1924 pte_fn_t fn
, void *data
)
1930 pud
= pud_alloc(mm
, pgd
, addr
);
1934 next
= pud_addr_end(addr
, end
);
1935 err
= apply_to_pmd_range(mm
, pud
, addr
, next
, fn
, data
);
1938 } while (pud
++, addr
= next
, addr
!= end
);
1943 * Scan a region of virtual memory, filling in page tables as necessary
1944 * and calling a provided function on each leaf page table.
1946 int apply_to_page_range(struct mm_struct
*mm
, unsigned long addr
,
1947 unsigned long size
, pte_fn_t fn
, void *data
)
1951 unsigned long end
= addr
+ size
;
1954 if (WARN_ON(addr
>= end
))
1957 pgd
= pgd_offset(mm
, addr
);
1959 next
= pgd_addr_end(addr
, end
);
1960 err
= apply_to_pud_range(mm
, pgd
, addr
, next
, fn
, data
);
1963 } while (pgd
++, addr
= next
, addr
!= end
);
1967 EXPORT_SYMBOL_GPL(apply_to_page_range
);
1970 * handle_pte_fault chooses page fault handler according to an entry which was
1971 * read non-atomically. Before making any commitment, on those architectures
1972 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
1973 * parts, do_swap_page must check under lock before unmapping the pte and
1974 * proceeding (but do_wp_page is only called after already making such a check;
1975 * and do_anonymous_page can safely check later on).
1977 static inline int pte_unmap_same(struct mm_struct
*mm
, pmd_t
*pmd
,
1978 pte_t
*page_table
, pte_t orig_pte
)
1981 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1982 if (sizeof(pte_t
) > sizeof(unsigned long)) {
1983 spinlock_t
*ptl
= pte_lockptr(mm
, pmd
);
1985 same
= pte_same(*page_table
, orig_pte
);
1989 pte_unmap(page_table
);
1993 static inline void cow_user_page(struct page
*dst
, struct page
*src
, unsigned long va
, struct vm_area_struct
*vma
)
1995 debug_dma_assert_idle(src
);
1998 * If the source page was a PFN mapping, we don't have
1999 * a "struct page" for it. We do a best-effort copy by
2000 * just copying from the original user address. If that
2001 * fails, we just zero-fill it. Live with it.
2003 if (unlikely(!src
)) {
2004 void *kaddr
= kmap_atomic(dst
);
2005 void __user
*uaddr
= (void __user
*)(va
& PAGE_MASK
);
2008 * This really shouldn't fail, because the page is there
2009 * in the page tables. But it might just be unreadable,
2010 * in which case we just give up and fill the result with
2013 if (__copy_from_user_inatomic(kaddr
, uaddr
, PAGE_SIZE
))
2015 kunmap_atomic(kaddr
);
2016 flush_dcache_page(dst
);
2018 copy_user_highpage(dst
, src
, va
, vma
);
2021 static gfp_t
__get_fault_gfp_mask(struct vm_area_struct
*vma
)
2023 struct file
*vm_file
= vma
->vm_file
;
2026 return mapping_gfp_mask(vm_file
->f_mapping
) | __GFP_FS
| __GFP_IO
;
2029 * Special mappings (e.g. VDSO) do not have any file so fake
2030 * a default GFP_KERNEL for them.
2036 * Notify the address space that the page is about to become writable so that
2037 * it can prohibit this or wait for the page to get into an appropriate state.
2039 * We do this without the lock held, so that it can sleep if it needs to.
2041 static int do_page_mkwrite(struct vm_area_struct
*vma
, struct page
*page
,
2042 unsigned long address
)
2044 struct vm_fault vmf
;
2047 vmf
.virtual_address
= (void __user
*)(address
& PAGE_MASK
);
2048 vmf
.pgoff
= page
->index
;
2049 vmf
.flags
= FAULT_FLAG_WRITE
|FAULT_FLAG_MKWRITE
;
2050 vmf
.gfp_mask
= __get_fault_gfp_mask(vma
);
2052 vmf
.cow_page
= NULL
;
2054 ret
= vma
->vm_ops
->page_mkwrite(vma
, &vmf
);
2055 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
)))
2057 if (unlikely(!(ret
& VM_FAULT_LOCKED
))) {
2059 if (!page
->mapping
) {
2061 return 0; /* retry */
2063 ret
|= VM_FAULT_LOCKED
;
2065 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
2070 * Handle write page faults for pages that can be reused in the current vma
2072 * This can happen either due to the mapping being with the VM_SHARED flag,
2073 * or due to us being the last reference standing to the page. In either
2074 * case, all we need to do here is to mark the page as writable and update
2075 * any related book-keeping.
2077 static inline int wp_page_reuse(struct fault_env
*fe
, pte_t orig_pte
,
2078 struct page
*page
, int page_mkwrite
, int dirty_shared
)
2081 struct vm_area_struct
*vma
= fe
->vma
;
2084 * Clear the pages cpupid information as the existing
2085 * information potentially belongs to a now completely
2086 * unrelated process.
2089 page_cpupid_xchg_last(page
, (1 << LAST_CPUPID_SHIFT
) - 1);
2091 flush_cache_page(vma
, fe
->address
, pte_pfn(orig_pte
));
2092 entry
= pte_mkyoung(orig_pte
);
2093 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
2094 if (ptep_set_access_flags(vma
, fe
->address
, fe
->pte
, entry
, 1))
2095 update_mmu_cache(vma
, fe
->address
, fe
->pte
);
2096 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2099 struct address_space
*mapping
;
2105 dirtied
= set_page_dirty(page
);
2106 VM_BUG_ON_PAGE(PageAnon(page
), page
);
2107 mapping
= page
->mapping
;
2111 if ((dirtied
|| page_mkwrite
) && mapping
) {
2113 * Some device drivers do not set page.mapping
2114 * but still dirty their pages
2116 balance_dirty_pages_ratelimited(mapping
);
2120 file_update_time(vma
->vm_file
);
2123 return VM_FAULT_WRITE
;
2127 * Handle the case of a page which we actually need to copy to a new page.
2129 * Called with mmap_sem locked and the old page referenced, but
2130 * without the ptl held.
2132 * High level logic flow:
2134 * - Allocate a page, copy the content of the old page to the new one.
2135 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2136 * - Take the PTL. If the pte changed, bail out and release the allocated page
2137 * - If the pte is still the way we remember it, update the page table and all
2138 * relevant references. This includes dropping the reference the page-table
2139 * held to the old page, as well as updating the rmap.
2140 * - In any case, unlock the PTL and drop the reference we took to the old page.
2142 static int wp_page_copy(struct fault_env
*fe
, pte_t orig_pte
,
2143 struct page
*old_page
)
2145 struct vm_area_struct
*vma
= fe
->vma
;
2146 struct mm_struct
*mm
= vma
->vm_mm
;
2147 struct page
*new_page
= NULL
;
2149 int page_copied
= 0;
2150 const unsigned long mmun_start
= fe
->address
& PAGE_MASK
;
2151 const unsigned long mmun_end
= mmun_start
+ PAGE_SIZE
;
2152 struct mem_cgroup
*memcg
;
2154 if (unlikely(anon_vma_prepare(vma
)))
2157 if (is_zero_pfn(pte_pfn(orig_pte
))) {
2158 new_page
= alloc_zeroed_user_highpage_movable(vma
, fe
->address
);
2162 new_page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
,
2166 cow_user_page(new_page
, old_page
, fe
->address
, vma
);
2169 if (mem_cgroup_try_charge(new_page
, mm
, GFP_KERNEL
, &memcg
, false))
2172 __SetPageUptodate(new_page
);
2174 mmu_notifier_invalidate_range_start(mm
, mmun_start
, mmun_end
);
2177 * Re-check the pte - we dropped the lock
2179 fe
->pte
= pte_offset_map_lock(mm
, fe
->pmd
, fe
->address
, &fe
->ptl
);
2180 if (likely(pte_same(*fe
->pte
, orig_pte
))) {
2182 if (!PageAnon(old_page
)) {
2183 dec_mm_counter_fast(mm
,
2184 mm_counter_file(old_page
));
2185 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
2188 inc_mm_counter_fast(mm
, MM_ANONPAGES
);
2190 flush_cache_page(vma
, fe
->address
, pte_pfn(orig_pte
));
2191 entry
= mk_pte(new_page
, vma
->vm_page_prot
);
2192 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
2194 * Clear the pte entry and flush it first, before updating the
2195 * pte with the new entry. This will avoid a race condition
2196 * seen in the presence of one thread doing SMC and another
2199 ptep_clear_flush_notify(vma
, fe
->address
, fe
->pte
);
2200 page_add_new_anon_rmap(new_page
, vma
, fe
->address
, false);
2201 mem_cgroup_commit_charge(new_page
, memcg
, false, false);
2202 lru_cache_add_active_or_unevictable(new_page
, vma
);
2204 * We call the notify macro here because, when using secondary
2205 * mmu page tables (such as kvm shadow page tables), we want the
2206 * new page to be mapped directly into the secondary page table.
2208 set_pte_at_notify(mm
, fe
->address
, fe
->pte
, entry
);
2209 update_mmu_cache(vma
, fe
->address
, fe
->pte
);
2212 * Only after switching the pte to the new page may
2213 * we remove the mapcount here. Otherwise another
2214 * process may come and find the rmap count decremented
2215 * before the pte is switched to the new page, and
2216 * "reuse" the old page writing into it while our pte
2217 * here still points into it and can be read by other
2220 * The critical issue is to order this
2221 * page_remove_rmap with the ptp_clear_flush above.
2222 * Those stores are ordered by (if nothing else,)
2223 * the barrier present in the atomic_add_negative
2224 * in page_remove_rmap.
2226 * Then the TLB flush in ptep_clear_flush ensures that
2227 * no process can access the old page before the
2228 * decremented mapcount is visible. And the old page
2229 * cannot be reused until after the decremented
2230 * mapcount is visible. So transitively, TLBs to
2231 * old page will be flushed before it can be reused.
2233 page_remove_rmap(old_page
, false);
2236 /* Free the old page.. */
2237 new_page
= old_page
;
2240 mem_cgroup_cancel_charge(new_page
, memcg
, false);
2246 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2247 mmu_notifier_invalidate_range_end(mm
, mmun_start
, mmun_end
);
2250 * Don't let another task, with possibly unlocked vma,
2251 * keep the mlocked page.
2253 if (page_copied
&& (vma
->vm_flags
& VM_LOCKED
)) {
2254 lock_page(old_page
); /* LRU manipulation */
2255 if (PageMlocked(old_page
))
2256 munlock_vma_page(old_page
);
2257 unlock_page(old_page
);
2261 return page_copied
? VM_FAULT_WRITE
: 0;
2267 return VM_FAULT_OOM
;
2271 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2274 static int wp_pfn_shared(struct fault_env
*fe
, pte_t orig_pte
)
2276 struct vm_area_struct
*vma
= fe
->vma
;
2278 if (vma
->vm_ops
&& vma
->vm_ops
->pfn_mkwrite
) {
2279 struct vm_fault vmf
= {
2281 .pgoff
= linear_page_index(vma
, fe
->address
),
2283 (void __user
*)(fe
->address
& PAGE_MASK
),
2284 .flags
= FAULT_FLAG_WRITE
| FAULT_FLAG_MKWRITE
,
2288 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2289 ret
= vma
->vm_ops
->pfn_mkwrite(vma
, &vmf
);
2290 if (ret
& VM_FAULT_ERROR
)
2292 fe
->pte
= pte_offset_map_lock(vma
->vm_mm
, fe
->pmd
, fe
->address
,
2295 * We might have raced with another page fault while we
2296 * released the pte_offset_map_lock.
2298 if (!pte_same(*fe
->pte
, orig_pte
)) {
2299 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2303 return wp_page_reuse(fe
, orig_pte
, NULL
, 0, 0);
2306 static int wp_page_shared(struct fault_env
*fe
, pte_t orig_pte
,
2307 struct page
*old_page
)
2310 struct vm_area_struct
*vma
= fe
->vma
;
2311 int page_mkwrite
= 0;
2315 if (vma
->vm_ops
&& vma
->vm_ops
->page_mkwrite
) {
2318 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2319 tmp
= do_page_mkwrite(vma
, old_page
, fe
->address
);
2320 if (unlikely(!tmp
|| (tmp
&
2321 (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
)))) {
2326 * Since we dropped the lock we need to revalidate
2327 * the PTE as someone else may have changed it. If
2328 * they did, we just return, as we can count on the
2329 * MMU to tell us if they didn't also make it writable.
2331 fe
->pte
= pte_offset_map_lock(vma
->vm_mm
, fe
->pmd
, fe
->address
,
2333 if (!pte_same(*fe
->pte
, orig_pte
)) {
2334 unlock_page(old_page
);
2335 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2342 return wp_page_reuse(fe
, orig_pte
, old_page
, page_mkwrite
, 1);
2346 * This routine handles present pages, when users try to write
2347 * to a shared page. It is done by copying the page to a new address
2348 * and decrementing the shared-page counter for the old page.
2350 * Note that this routine assumes that the protection checks have been
2351 * done by the caller (the low-level page fault routine in most cases).
2352 * Thus we can safely just mark it writable once we've done any necessary
2355 * We also mark the page dirty at this point even though the page will
2356 * change only once the write actually happens. This avoids a few races,
2357 * and potentially makes it more efficient.
2359 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2360 * but allow concurrent faults), with pte both mapped and locked.
2361 * We return with mmap_sem still held, but pte unmapped and unlocked.
2363 static int do_wp_page(struct fault_env
*fe
, pte_t orig_pte
)
2366 struct vm_area_struct
*vma
= fe
->vma
;
2367 struct page
*old_page
;
2369 old_page
= vm_normal_page(vma
, fe
->address
, orig_pte
);
2372 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2375 * We should not cow pages in a shared writeable mapping.
2376 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2378 if ((vma
->vm_flags
& (VM_WRITE
|VM_SHARED
)) ==
2379 (VM_WRITE
|VM_SHARED
))
2380 return wp_pfn_shared(fe
, orig_pte
);
2382 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2383 return wp_page_copy(fe
, orig_pte
, old_page
);
2387 * Take out anonymous pages first, anonymous shared vmas are
2388 * not dirty accountable.
2390 if (PageAnon(old_page
) && !PageKsm(old_page
)) {
2392 if (!trylock_page(old_page
)) {
2394 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2395 lock_page(old_page
);
2396 fe
->pte
= pte_offset_map_lock(vma
->vm_mm
, fe
->pmd
,
2397 fe
->address
, &fe
->ptl
);
2398 if (!pte_same(*fe
->pte
, orig_pte
)) {
2399 unlock_page(old_page
);
2400 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2406 if (reuse_swap_page(old_page
, &total_mapcount
)) {
2407 if (total_mapcount
== 1) {
2409 * The page is all ours. Move it to
2410 * our anon_vma so the rmap code will
2411 * not search our parent or siblings.
2412 * Protected against the rmap code by
2415 page_move_anon_rmap(old_page
, vma
);
2417 unlock_page(old_page
);
2418 return wp_page_reuse(fe
, orig_pte
, old_page
, 0, 0);
2420 unlock_page(old_page
);
2421 } else if (unlikely((vma
->vm_flags
& (VM_WRITE
|VM_SHARED
)) ==
2422 (VM_WRITE
|VM_SHARED
))) {
2423 return wp_page_shared(fe
, orig_pte
, old_page
);
2427 * Ok, we need to copy. Oh, well..
2431 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2432 return wp_page_copy(fe
, orig_pte
, old_page
);
2435 static void unmap_mapping_range_vma(struct vm_area_struct
*vma
,
2436 unsigned long start_addr
, unsigned long end_addr
,
2437 struct zap_details
*details
)
2439 zap_page_range_single(vma
, start_addr
, end_addr
- start_addr
, details
);
2442 static inline void unmap_mapping_range_tree(struct rb_root
*root
,
2443 struct zap_details
*details
)
2445 struct vm_area_struct
*vma
;
2446 pgoff_t vba
, vea
, zba
, zea
;
2448 vma_interval_tree_foreach(vma
, root
,
2449 details
->first_index
, details
->last_index
) {
2451 vba
= vma
->vm_pgoff
;
2452 vea
= vba
+ vma_pages(vma
) - 1;
2453 zba
= details
->first_index
;
2456 zea
= details
->last_index
;
2460 unmap_mapping_range_vma(vma
,
2461 ((zba
- vba
) << PAGE_SHIFT
) + vma
->vm_start
,
2462 ((zea
- vba
+ 1) << PAGE_SHIFT
) + vma
->vm_start
,
2468 * unmap_mapping_range - unmap the portion of all mmaps in the specified
2469 * address_space corresponding to the specified page range in the underlying
2472 * @mapping: the address space containing mmaps to be unmapped.
2473 * @holebegin: byte in first page to unmap, relative to the start of
2474 * the underlying file. This will be rounded down to a PAGE_SIZE
2475 * boundary. Note that this is different from truncate_pagecache(), which
2476 * must keep the partial page. In contrast, we must get rid of
2478 * @holelen: size of prospective hole in bytes. This will be rounded
2479 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2481 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2482 * but 0 when invalidating pagecache, don't throw away private data.
2484 void unmap_mapping_range(struct address_space
*mapping
,
2485 loff_t
const holebegin
, loff_t
const holelen
, int even_cows
)
2487 struct zap_details details
= { };
2488 pgoff_t hba
= holebegin
>> PAGE_SHIFT
;
2489 pgoff_t hlen
= (holelen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
2491 /* Check for overflow. */
2492 if (sizeof(holelen
) > sizeof(hlen
)) {
2494 (holebegin
+ holelen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
2495 if (holeend
& ~(long long)ULONG_MAX
)
2496 hlen
= ULONG_MAX
- hba
+ 1;
2499 details
.check_mapping
= even_cows
? NULL
: mapping
;
2500 details
.first_index
= hba
;
2501 details
.last_index
= hba
+ hlen
- 1;
2502 if (details
.last_index
< details
.first_index
)
2503 details
.last_index
= ULONG_MAX
;
2505 i_mmap_lock_write(mapping
);
2506 if (unlikely(!RB_EMPTY_ROOT(&mapping
->i_mmap
)))
2507 unmap_mapping_range_tree(&mapping
->i_mmap
, &details
);
2508 i_mmap_unlock_write(mapping
);
2510 EXPORT_SYMBOL(unmap_mapping_range
);
2513 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2514 * but allow concurrent faults), and pte mapped but not yet locked.
2515 * We return with pte unmapped and unlocked.
2517 * We return with the mmap_sem locked or unlocked in the same cases
2518 * as does filemap_fault().
2520 int do_swap_page(struct fault_env
*fe
, pte_t orig_pte
)
2522 struct vm_area_struct
*vma
= fe
->vma
;
2523 struct page
*page
, *swapcache
;
2524 struct mem_cgroup
*memcg
;
2531 if (!pte_unmap_same(vma
->vm_mm
, fe
->pmd
, fe
->pte
, orig_pte
))
2534 entry
= pte_to_swp_entry(orig_pte
);
2535 if (unlikely(non_swap_entry(entry
))) {
2536 if (is_migration_entry(entry
)) {
2537 migration_entry_wait(vma
->vm_mm
, fe
->pmd
, fe
->address
);
2538 } else if (is_hwpoison_entry(entry
)) {
2539 ret
= VM_FAULT_HWPOISON
;
2541 print_bad_pte(vma
, fe
->address
, orig_pte
, NULL
);
2542 ret
= VM_FAULT_SIGBUS
;
2546 delayacct_set_flag(DELAYACCT_PF_SWAPIN
);
2547 page
= lookup_swap_cache(entry
);
2549 page
= swapin_readahead(entry
,
2550 GFP_HIGHUSER_MOVABLE
, vma
, fe
->address
);
2553 * Back out if somebody else faulted in this pte
2554 * while we released the pte lock.
2556 fe
->pte
= pte_offset_map_lock(vma
->vm_mm
, fe
->pmd
,
2557 fe
->address
, &fe
->ptl
);
2558 if (likely(pte_same(*fe
->pte
, orig_pte
)))
2560 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
2564 /* Had to read the page from swap area: Major fault */
2565 ret
= VM_FAULT_MAJOR
;
2566 count_vm_event(PGMAJFAULT
);
2567 mem_cgroup_count_vm_event(vma
->vm_mm
, PGMAJFAULT
);
2568 } else if (PageHWPoison(page
)) {
2570 * hwpoisoned dirty swapcache pages are kept for killing
2571 * owner processes (which may be unknown at hwpoison time)
2573 ret
= VM_FAULT_HWPOISON
;
2574 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
2580 locked
= lock_page_or_retry(page
, vma
->vm_mm
, fe
->flags
);
2582 delayacct_clear_flag(DELAYACCT_PF_SWAPIN
);
2584 ret
|= VM_FAULT_RETRY
;
2589 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2590 * release the swapcache from under us. The page pin, and pte_same
2591 * test below, are not enough to exclude that. Even if it is still
2592 * swapcache, we need to check that the page's swap has not changed.
2594 if (unlikely(!PageSwapCache(page
) || page_private(page
) != entry
.val
))
2597 page
= ksm_might_need_to_copy(page
, vma
, fe
->address
);
2598 if (unlikely(!page
)) {
2604 if (mem_cgroup_try_charge(page
, vma
->vm_mm
, GFP_KERNEL
,
2611 * Back out if somebody else already faulted in this pte.
2613 fe
->pte
= pte_offset_map_lock(vma
->vm_mm
, fe
->pmd
, fe
->address
,
2615 if (unlikely(!pte_same(*fe
->pte
, orig_pte
)))
2618 if (unlikely(!PageUptodate(page
))) {
2619 ret
= VM_FAULT_SIGBUS
;
2624 * The page isn't present yet, go ahead with the fault.
2626 * Be careful about the sequence of operations here.
2627 * To get its accounting right, reuse_swap_page() must be called
2628 * while the page is counted on swap but not yet in mapcount i.e.
2629 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2630 * must be called after the swap_free(), or it will never succeed.
2633 inc_mm_counter_fast(vma
->vm_mm
, MM_ANONPAGES
);
2634 dec_mm_counter_fast(vma
->vm_mm
, MM_SWAPENTS
);
2635 pte
= mk_pte(page
, vma
->vm_page_prot
);
2636 if ((fe
->flags
& FAULT_FLAG_WRITE
) && reuse_swap_page(page
, NULL
)) {
2637 pte
= maybe_mkwrite(pte_mkdirty(pte
), vma
);
2638 fe
->flags
&= ~FAULT_FLAG_WRITE
;
2639 ret
|= VM_FAULT_WRITE
;
2640 exclusive
= RMAP_EXCLUSIVE
;
2642 flush_icache_page(vma
, page
);
2643 if (pte_swp_soft_dirty(orig_pte
))
2644 pte
= pte_mksoft_dirty(pte
);
2645 set_pte_at(vma
->vm_mm
, fe
->address
, fe
->pte
, pte
);
2646 if (page
== swapcache
) {
2647 do_page_add_anon_rmap(page
, vma
, fe
->address
, exclusive
);
2648 mem_cgroup_commit_charge(page
, memcg
, true, false);
2649 activate_page(page
);
2650 } else { /* ksm created a completely new copy */
2651 page_add_new_anon_rmap(page
, vma
, fe
->address
, false);
2652 mem_cgroup_commit_charge(page
, memcg
, false, false);
2653 lru_cache_add_active_or_unevictable(page
, vma
);
2657 if (mem_cgroup_swap_full(page
) ||
2658 (vma
->vm_flags
& VM_LOCKED
) || PageMlocked(page
))
2659 try_to_free_swap(page
);
2661 if (page
!= swapcache
) {
2663 * Hold the lock to avoid the swap entry to be reused
2664 * until we take the PT lock for the pte_same() check
2665 * (to avoid false positives from pte_same). For
2666 * further safety release the lock after the swap_free
2667 * so that the swap count won't change under a
2668 * parallel locked swapcache.
2670 unlock_page(swapcache
);
2671 put_page(swapcache
);
2674 if (fe
->flags
& FAULT_FLAG_WRITE
) {
2675 ret
|= do_wp_page(fe
, pte
);
2676 if (ret
& VM_FAULT_ERROR
)
2677 ret
&= VM_FAULT_ERROR
;
2681 /* No need to invalidate - it was non-present before */
2682 update_mmu_cache(vma
, fe
->address
, fe
->pte
);
2684 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2688 mem_cgroup_cancel_charge(page
, memcg
, false);
2689 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2694 if (page
!= swapcache
) {
2695 unlock_page(swapcache
);
2696 put_page(swapcache
);
2702 * This is like a special single-page "expand_{down|up}wards()",
2703 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2704 * doesn't hit another vma.
2706 static inline int check_stack_guard_page(struct vm_area_struct
*vma
, unsigned long address
)
2708 address
&= PAGE_MASK
;
2709 if ((vma
->vm_flags
& VM_GROWSDOWN
) && address
== vma
->vm_start
) {
2710 struct vm_area_struct
*prev
= vma
->vm_prev
;
2713 * Is there a mapping abutting this one below?
2715 * That's only ok if it's the same stack mapping
2716 * that has gotten split..
2718 if (prev
&& prev
->vm_end
== address
)
2719 return prev
->vm_flags
& VM_GROWSDOWN
? 0 : -ENOMEM
;
2721 return expand_downwards(vma
, address
- PAGE_SIZE
);
2723 if ((vma
->vm_flags
& VM_GROWSUP
) && address
+ PAGE_SIZE
== vma
->vm_end
) {
2724 struct vm_area_struct
*next
= vma
->vm_next
;
2726 /* As VM_GROWSDOWN but s/below/above/ */
2727 if (next
&& next
->vm_start
== address
+ PAGE_SIZE
)
2728 return next
->vm_flags
& VM_GROWSUP
? 0 : -ENOMEM
;
2730 return expand_upwards(vma
, address
+ PAGE_SIZE
);
2736 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2737 * but allow concurrent faults), and pte mapped but not yet locked.
2738 * We return with mmap_sem still held, but pte unmapped and unlocked.
2740 static int do_anonymous_page(struct fault_env
*fe
)
2742 struct vm_area_struct
*vma
= fe
->vma
;
2743 struct mem_cgroup
*memcg
;
2747 /* File mapping without ->vm_ops ? */
2748 if (vma
->vm_flags
& VM_SHARED
)
2749 return VM_FAULT_SIGBUS
;
2751 /* Check if we need to add a guard page to the stack */
2752 if (check_stack_guard_page(vma
, fe
->address
) < 0)
2753 return VM_FAULT_SIGSEGV
;
2756 * Use pte_alloc() instead of pte_alloc_map(). We can't run
2757 * pte_offset_map() on pmds where a huge pmd might be created
2758 * from a different thread.
2760 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
2761 * parallel threads are excluded by other means.
2763 * Here we only have down_read(mmap_sem).
2765 if (pte_alloc(vma
->vm_mm
, fe
->pmd
, fe
->address
))
2766 return VM_FAULT_OOM
;
2768 /* See the comment in pte_alloc_one_map() */
2769 if (unlikely(pmd_trans_unstable(fe
->pmd
)))
2772 /* Use the zero-page for reads */
2773 if (!(fe
->flags
& FAULT_FLAG_WRITE
) &&
2774 !mm_forbids_zeropage(vma
->vm_mm
)) {
2775 entry
= pte_mkspecial(pfn_pte(my_zero_pfn(fe
->address
),
2776 vma
->vm_page_prot
));
2777 fe
->pte
= pte_offset_map_lock(vma
->vm_mm
, fe
->pmd
, fe
->address
,
2779 if (!pte_none(*fe
->pte
))
2781 /* Deliver the page fault to userland, check inside PT lock */
2782 if (userfaultfd_missing(vma
)) {
2783 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2784 return handle_userfault(fe
, VM_UFFD_MISSING
);
2789 /* Allocate our own private page. */
2790 if (unlikely(anon_vma_prepare(vma
)))
2792 page
= alloc_zeroed_user_highpage_movable(vma
, fe
->address
);
2796 if (mem_cgroup_try_charge(page
, vma
->vm_mm
, GFP_KERNEL
, &memcg
, false))
2800 * The memory barrier inside __SetPageUptodate makes sure that
2801 * preceeding stores to the page contents become visible before
2802 * the set_pte_at() write.
2804 __SetPageUptodate(page
);
2806 entry
= mk_pte(page
, vma
->vm_page_prot
);
2807 if (vma
->vm_flags
& VM_WRITE
)
2808 entry
= pte_mkwrite(pte_mkdirty(entry
));
2810 fe
->pte
= pte_offset_map_lock(vma
->vm_mm
, fe
->pmd
, fe
->address
,
2812 if (!pte_none(*fe
->pte
))
2815 /* Deliver the page fault to userland, check inside PT lock */
2816 if (userfaultfd_missing(vma
)) {
2817 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2818 mem_cgroup_cancel_charge(page
, memcg
, false);
2820 return handle_userfault(fe
, VM_UFFD_MISSING
);
2823 inc_mm_counter_fast(vma
->vm_mm
, MM_ANONPAGES
);
2824 page_add_new_anon_rmap(page
, vma
, fe
->address
, false);
2825 mem_cgroup_commit_charge(page
, memcg
, false, false);
2826 lru_cache_add_active_or_unevictable(page
, vma
);
2828 set_pte_at(vma
->vm_mm
, fe
->address
, fe
->pte
, entry
);
2830 /* No need to invalidate - it was non-present before */
2831 update_mmu_cache(vma
, fe
->address
, fe
->pte
);
2833 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
2836 mem_cgroup_cancel_charge(page
, memcg
, false);
2842 return VM_FAULT_OOM
;
2846 * The mmap_sem must have been held on entry, and may have been
2847 * released depending on flags and vma->vm_ops->fault() return value.
2848 * See filemap_fault() and __lock_page_retry().
2850 static int __do_fault(struct fault_env
*fe
, pgoff_t pgoff
,
2851 struct page
*cow_page
, struct page
**page
, void **entry
)
2853 struct vm_area_struct
*vma
= fe
->vma
;
2854 struct vm_fault vmf
;
2857 vmf
.virtual_address
= (void __user
*)(fe
->address
& PAGE_MASK
);
2859 vmf
.flags
= fe
->flags
;
2861 vmf
.gfp_mask
= __get_fault_gfp_mask(vma
);
2862 vmf
.cow_page
= cow_page
;
2864 ret
= vma
->vm_ops
->fault(vma
, &vmf
);
2865 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
)))
2867 if (ret
& VM_FAULT_DAX_LOCKED
) {
2872 if (unlikely(PageHWPoison(vmf
.page
))) {
2873 if (ret
& VM_FAULT_LOCKED
)
2874 unlock_page(vmf
.page
);
2876 return VM_FAULT_HWPOISON
;
2879 if (unlikely(!(ret
& VM_FAULT_LOCKED
)))
2880 lock_page(vmf
.page
);
2882 VM_BUG_ON_PAGE(!PageLocked(vmf
.page
), vmf
.page
);
2888 static int pte_alloc_one_map(struct fault_env
*fe
)
2890 struct vm_area_struct
*vma
= fe
->vma
;
2892 if (!pmd_none(*fe
->pmd
))
2894 if (fe
->prealloc_pte
) {
2895 fe
->ptl
= pmd_lock(vma
->vm_mm
, fe
->pmd
);
2896 if (unlikely(!pmd_none(*fe
->pmd
))) {
2897 spin_unlock(fe
->ptl
);
2901 atomic_long_inc(&vma
->vm_mm
->nr_ptes
);
2902 pmd_populate(vma
->vm_mm
, fe
->pmd
, fe
->prealloc_pte
);
2903 spin_unlock(fe
->ptl
);
2904 fe
->prealloc_pte
= 0;
2905 } else if (unlikely(pte_alloc(vma
->vm_mm
, fe
->pmd
, fe
->address
))) {
2906 return VM_FAULT_OOM
;
2910 * If a huge pmd materialized under us just retry later. Use
2911 * pmd_trans_unstable() instead of pmd_trans_huge() to ensure the pmd
2912 * didn't become pmd_trans_huge under us and then back to pmd_none, as
2913 * a result of MADV_DONTNEED running immediately after a huge pmd fault
2914 * in a different thread of this mm, in turn leading to a misleading
2915 * pmd_trans_huge() retval. All we have to ensure is that it is a
2916 * regular pmd that we can walk with pte_offset_map() and we can do that
2917 * through an atomic read in C, which is what pmd_trans_unstable()
2920 if (pmd_trans_unstable(fe
->pmd
) || pmd_devmap(*fe
->pmd
))
2921 return VM_FAULT_NOPAGE
;
2923 fe
->pte
= pte_offset_map_lock(vma
->vm_mm
, fe
->pmd
, fe
->address
,
2928 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
2930 #define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
2931 static inline bool transhuge_vma_suitable(struct vm_area_struct
*vma
,
2932 unsigned long haddr
)
2934 if (((vma
->vm_start
>> PAGE_SHIFT
) & HPAGE_CACHE_INDEX_MASK
) !=
2935 (vma
->vm_pgoff
& HPAGE_CACHE_INDEX_MASK
))
2937 if (haddr
< vma
->vm_start
|| haddr
+ HPAGE_PMD_SIZE
> vma
->vm_end
)
2942 static int do_set_pmd(struct fault_env
*fe
, struct page
*page
)
2944 struct vm_area_struct
*vma
= fe
->vma
;
2945 bool write
= fe
->flags
& FAULT_FLAG_WRITE
;
2946 unsigned long haddr
= fe
->address
& HPAGE_PMD_MASK
;
2950 if (!transhuge_vma_suitable(vma
, haddr
))
2951 return VM_FAULT_FALLBACK
;
2953 ret
= VM_FAULT_FALLBACK
;
2954 page
= compound_head(page
);
2956 fe
->ptl
= pmd_lock(vma
->vm_mm
, fe
->pmd
);
2957 if (unlikely(!pmd_none(*fe
->pmd
)))
2960 for (i
= 0; i
< HPAGE_PMD_NR
; i
++)
2961 flush_icache_page(vma
, page
+ i
);
2963 entry
= mk_huge_pmd(page
, vma
->vm_page_prot
);
2965 entry
= maybe_pmd_mkwrite(pmd_mkdirty(entry
), vma
);
2967 add_mm_counter(vma
->vm_mm
, MM_FILEPAGES
, HPAGE_PMD_NR
);
2968 page_add_file_rmap(page
, true);
2970 set_pmd_at(vma
->vm_mm
, haddr
, fe
->pmd
, entry
);
2972 update_mmu_cache_pmd(vma
, haddr
, fe
->pmd
);
2974 /* fault is handled */
2976 count_vm_event(THP_FILE_MAPPED
);
2978 spin_unlock(fe
->ptl
);
2982 static int do_set_pmd(struct fault_env
*fe
, struct page
*page
)
2990 * alloc_set_pte - setup new PTE entry for given page and add reverse page
2991 * mapping. If needed, the fucntion allocates page table or use pre-allocated.
2993 * @fe: fault environment
2994 * @memcg: memcg to charge page (only for private mappings)
2995 * @page: page to map
2997 * Caller must take care of unlocking fe->ptl, if fe->pte is non-NULL on return.
2999 * Target users are page handler itself and implementations of
3000 * vm_ops->map_pages.
3002 int alloc_set_pte(struct fault_env
*fe
, struct mem_cgroup
*memcg
,
3005 struct vm_area_struct
*vma
= fe
->vma
;
3006 bool write
= fe
->flags
& FAULT_FLAG_WRITE
;
3010 if (pmd_none(*fe
->pmd
) && PageTransCompound(page
) &&
3011 IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE
)) {
3013 VM_BUG_ON_PAGE(memcg
, page
);
3015 ret
= do_set_pmd(fe
, page
);
3016 if (ret
!= VM_FAULT_FALLBACK
)
3021 ret
= pte_alloc_one_map(fe
);
3026 /* Re-check under ptl */
3027 if (unlikely(!pte_none(*fe
->pte
)))
3028 return VM_FAULT_NOPAGE
;
3030 flush_icache_page(vma
, page
);
3031 entry
= mk_pte(page
, vma
->vm_page_prot
);
3033 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
3034 /* copy-on-write page */
3035 if (write
&& !(vma
->vm_flags
& VM_SHARED
)) {
3036 inc_mm_counter_fast(vma
->vm_mm
, MM_ANONPAGES
);
3037 page_add_new_anon_rmap(page
, vma
, fe
->address
, false);
3038 mem_cgroup_commit_charge(page
, memcg
, false, false);
3039 lru_cache_add_active_or_unevictable(page
, vma
);
3041 inc_mm_counter_fast(vma
->vm_mm
, mm_counter_file(page
));
3042 page_add_file_rmap(page
, false);
3044 set_pte_at(vma
->vm_mm
, fe
->address
, fe
->pte
, entry
);
3046 /* no need to invalidate: a not-present page won't be cached */
3047 update_mmu_cache(vma
, fe
->address
, fe
->pte
);
3052 static unsigned long fault_around_bytes __read_mostly
=
3053 rounddown_pow_of_two(65536);
3055 #ifdef CONFIG_DEBUG_FS
3056 static int fault_around_bytes_get(void *data
, u64
*val
)
3058 *val
= fault_around_bytes
;
3063 * fault_around_pages() and fault_around_mask() expects fault_around_bytes
3064 * rounded down to nearest page order. It's what do_fault_around() expects to
3067 static int fault_around_bytes_set(void *data
, u64 val
)
3069 if (val
/ PAGE_SIZE
> PTRS_PER_PTE
)
3071 if (val
> PAGE_SIZE
)
3072 fault_around_bytes
= rounddown_pow_of_two(val
);
3074 fault_around_bytes
= PAGE_SIZE
; /* rounddown_pow_of_two(0) is undefined */
3077 DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops
,
3078 fault_around_bytes_get
, fault_around_bytes_set
, "%llu\n");
3080 static int __init
fault_around_debugfs(void)
3084 ret
= debugfs_create_file("fault_around_bytes", 0644, NULL
, NULL
,
3085 &fault_around_bytes_fops
);
3087 pr_warn("Failed to create fault_around_bytes in debugfs");
3090 late_initcall(fault_around_debugfs
);
3094 * do_fault_around() tries to map few pages around the fault address. The hope
3095 * is that the pages will be needed soon and this will lower the number of
3098 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3099 * not ready to be mapped: not up-to-date, locked, etc.
3101 * This function is called with the page table lock taken. In the split ptlock
3102 * case the page table lock only protects only those entries which belong to
3103 * the page table corresponding to the fault address.
3105 * This function doesn't cross the VMA boundaries, in order to call map_pages()
3108 * fault_around_pages() defines how many pages we'll try to map.
3109 * do_fault_around() expects it to return a power of two less than or equal to
3112 * The virtual address of the area that we map is naturally aligned to the
3113 * fault_around_pages() value (and therefore to page order). This way it's
3114 * easier to guarantee that we don't cross page table boundaries.
3116 static int do_fault_around(struct fault_env
*fe
, pgoff_t start_pgoff
)
3118 unsigned long address
= fe
->address
, nr_pages
, mask
;
3122 nr_pages
= READ_ONCE(fault_around_bytes
) >> PAGE_SHIFT
;
3123 mask
= ~(nr_pages
* PAGE_SIZE
- 1) & PAGE_MASK
;
3125 fe
->address
= max(address
& mask
, fe
->vma
->vm_start
);
3126 off
= ((address
- fe
->address
) >> PAGE_SHIFT
) & (PTRS_PER_PTE
- 1);
3130 * end_pgoff is either end of page table or end of vma
3131 * or fault_around_pages() from start_pgoff, depending what is nearest.
3133 end_pgoff
= start_pgoff
-
3134 ((fe
->address
>> PAGE_SHIFT
) & (PTRS_PER_PTE
- 1)) +
3136 end_pgoff
= min3(end_pgoff
, vma_pages(fe
->vma
) + fe
->vma
->vm_pgoff
- 1,
3137 start_pgoff
+ nr_pages
- 1);
3139 if (pmd_none(*fe
->pmd
)) {
3140 fe
->prealloc_pte
= pte_alloc_one(fe
->vma
->vm_mm
, fe
->address
);
3141 if (!fe
->prealloc_pte
)
3143 smp_wmb(); /* See comment in __pte_alloc() */
3146 fe
->vma
->vm_ops
->map_pages(fe
, start_pgoff
, end_pgoff
);
3148 /* preallocated pagetable is unused: free it */
3149 if (fe
->prealloc_pte
) {
3150 pte_free(fe
->vma
->vm_mm
, fe
->prealloc_pte
);
3151 fe
->prealloc_pte
= 0;
3153 /* Huge page is mapped? Page fault is solved */
3154 if (pmd_trans_huge(*fe
->pmd
)) {
3155 ret
= VM_FAULT_NOPAGE
;
3159 /* ->map_pages() haven't done anything useful. Cold page cache? */
3163 /* check if the page fault is solved */
3164 fe
->pte
-= (fe
->address
>> PAGE_SHIFT
) - (address
>> PAGE_SHIFT
);
3165 if (!pte_none(*fe
->pte
))
3166 ret
= VM_FAULT_NOPAGE
;
3167 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
3169 fe
->address
= address
;
3174 static int do_read_fault(struct fault_env
*fe
, pgoff_t pgoff
)
3176 struct vm_area_struct
*vma
= fe
->vma
;
3177 struct page
*fault_page
;
3181 * Let's call ->map_pages() first and use ->fault() as fallback
3182 * if page by the offset is not ready to be mapped (cold cache or
3185 if (vma
->vm_ops
->map_pages
&& fault_around_bytes
>> PAGE_SHIFT
> 1) {
3186 ret
= do_fault_around(fe
, pgoff
);
3191 ret
= __do_fault(fe
, pgoff
, NULL
, &fault_page
, NULL
);
3192 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
)))
3195 ret
|= alloc_set_pte(fe
, NULL
, fault_page
);
3197 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
3198 unlock_page(fault_page
);
3199 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
)))
3200 put_page(fault_page
);
3204 static int do_cow_fault(struct fault_env
*fe
, pgoff_t pgoff
)
3206 struct vm_area_struct
*vma
= fe
->vma
;
3207 struct page
*fault_page
, *new_page
;
3209 struct mem_cgroup
*memcg
;
3212 if (unlikely(anon_vma_prepare(vma
)))
3213 return VM_FAULT_OOM
;
3215 new_page
= alloc_page_vma(GFP_HIGHUSER_MOVABLE
, vma
, fe
->address
);
3217 return VM_FAULT_OOM
;
3219 if (mem_cgroup_try_charge(new_page
, vma
->vm_mm
, GFP_KERNEL
,
3222 return VM_FAULT_OOM
;
3225 ret
= __do_fault(fe
, pgoff
, new_page
, &fault_page
, &fault_entry
);
3226 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
)))
3229 if (!(ret
& VM_FAULT_DAX_LOCKED
))
3230 copy_user_highpage(new_page
, fault_page
, fe
->address
, vma
);
3231 __SetPageUptodate(new_page
);
3233 ret
|= alloc_set_pte(fe
, memcg
, new_page
);
3235 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
3236 if (!(ret
& VM_FAULT_DAX_LOCKED
)) {
3237 unlock_page(fault_page
);
3238 put_page(fault_page
);
3240 dax_unlock_mapping_entry(vma
->vm_file
->f_mapping
, pgoff
);
3242 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
)))
3246 mem_cgroup_cancel_charge(new_page
, memcg
, false);
3251 static int do_shared_fault(struct fault_env
*fe
, pgoff_t pgoff
)
3253 struct vm_area_struct
*vma
= fe
->vma
;
3254 struct page
*fault_page
;
3255 struct address_space
*mapping
;
3259 ret
= __do_fault(fe
, pgoff
, NULL
, &fault_page
, NULL
);
3260 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
| VM_FAULT_RETRY
)))
3264 * Check if the backing address space wants to know that the page is
3265 * about to become writable
3267 if (vma
->vm_ops
->page_mkwrite
) {
3268 unlock_page(fault_page
);
3269 tmp
= do_page_mkwrite(vma
, fault_page
, fe
->address
);
3270 if (unlikely(!tmp
||
3271 (tmp
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
)))) {
3272 put_page(fault_page
);
3277 ret
|= alloc_set_pte(fe
, NULL
, fault_page
);
3279 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
3280 if (unlikely(ret
& (VM_FAULT_ERROR
| VM_FAULT_NOPAGE
|
3282 unlock_page(fault_page
);
3283 put_page(fault_page
);
3287 if (set_page_dirty(fault_page
))
3290 * Take a local copy of the address_space - page.mapping may be zeroed
3291 * by truncate after unlock_page(). The address_space itself remains
3292 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
3293 * release semantics to prevent the compiler from undoing this copying.
3295 mapping
= page_rmapping(fault_page
);
3296 unlock_page(fault_page
);
3297 if ((dirtied
|| vma
->vm_ops
->page_mkwrite
) && mapping
) {
3299 * Some device drivers do not set page.mapping but still
3302 balance_dirty_pages_ratelimited(mapping
);
3305 if (!vma
->vm_ops
->page_mkwrite
)
3306 file_update_time(vma
->vm_file
);
3312 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3313 * but allow concurrent faults).
3314 * The mmap_sem may have been released depending on flags and our
3315 * return value. See filemap_fault() and __lock_page_or_retry().
3317 static int do_fault(struct fault_env
*fe
)
3319 struct vm_area_struct
*vma
= fe
->vma
;
3320 pgoff_t pgoff
= linear_page_index(vma
, fe
->address
);
3322 /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
3323 if (!vma
->vm_ops
->fault
)
3324 return VM_FAULT_SIGBUS
;
3325 if (!(fe
->flags
& FAULT_FLAG_WRITE
))
3326 return do_read_fault(fe
, pgoff
);
3327 if (!(vma
->vm_flags
& VM_SHARED
))
3328 return do_cow_fault(fe
, pgoff
);
3329 return do_shared_fault(fe
, pgoff
);
3332 static int numa_migrate_prep(struct page
*page
, struct vm_area_struct
*vma
,
3333 unsigned long addr
, int page_nid
,
3338 count_vm_numa_event(NUMA_HINT_FAULTS
);
3339 if (page_nid
== numa_node_id()) {
3340 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL
);
3341 *flags
|= TNF_FAULT_LOCAL
;
3344 return mpol_misplaced(page
, vma
, addr
);
3347 static int do_numa_page(struct fault_env
*fe
, pte_t pte
)
3349 struct vm_area_struct
*vma
= fe
->vma
;
3350 struct page
*page
= NULL
;
3354 bool migrated
= false;
3355 bool was_writable
= pte_write(pte
);
3359 * The "pte" at this point cannot be used safely without
3360 * validation through pte_unmap_same(). It's of NUMA type but
3361 * the pfn may be screwed if the read is non atomic.
3363 * We can safely just do a "set_pte_at()", because the old
3364 * page table entry is not accessible, so there would be no
3365 * concurrent hardware modifications to the PTE.
3367 fe
->ptl
= pte_lockptr(vma
->vm_mm
, fe
->pmd
);
3369 if (unlikely(!pte_same(*fe
->pte
, pte
))) {
3370 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
3374 /* Make it present again */
3375 pte
= pte_modify(pte
, vma
->vm_page_prot
);
3376 pte
= pte_mkyoung(pte
);
3378 pte
= pte_mkwrite(pte
);
3379 set_pte_at(vma
->vm_mm
, fe
->address
, fe
->pte
, pte
);
3380 update_mmu_cache(vma
, fe
->address
, fe
->pte
);
3382 page
= vm_normal_page(vma
, fe
->address
, pte
);
3384 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
3388 /* TODO: handle PTE-mapped THP */
3389 if (PageCompound(page
)) {
3390 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
3395 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3396 * much anyway since they can be in shared cache state. This misses
3397 * the case where a mapping is writable but the process never writes
3398 * to it but pte_write gets cleared during protection updates and
3399 * pte_dirty has unpredictable behaviour between PTE scan updates,
3400 * background writeback, dirty balancing and application behaviour.
3402 if (!pte_write(pte
))
3403 flags
|= TNF_NO_GROUP
;
3406 * Flag if the page is shared between multiple address spaces. This
3407 * is later used when determining whether to group tasks together
3409 if (page_mapcount(page
) > 1 && (vma
->vm_flags
& VM_SHARED
))
3410 flags
|= TNF_SHARED
;
3412 last_cpupid
= page_cpupid_last(page
);
3413 page_nid
= page_to_nid(page
);
3414 target_nid
= numa_migrate_prep(page
, vma
, fe
->address
, page_nid
,
3416 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
3417 if (target_nid
== -1) {
3422 /* Migrate to the requested node */
3423 migrated
= migrate_misplaced_page(page
, vma
, target_nid
);
3425 page_nid
= target_nid
;
3426 flags
|= TNF_MIGRATED
;
3428 flags
|= TNF_MIGRATE_FAIL
;
3432 task_numa_fault(last_cpupid
, page_nid
, 1, flags
);
3436 static int create_huge_pmd(struct fault_env
*fe
)
3438 struct vm_area_struct
*vma
= fe
->vma
;
3439 if (vma_is_anonymous(vma
))
3440 return do_huge_pmd_anonymous_page(fe
);
3441 if (vma
->vm_ops
->pmd_fault
)
3442 return vma
->vm_ops
->pmd_fault(vma
, fe
->address
, fe
->pmd
,
3444 return VM_FAULT_FALLBACK
;
3447 static int wp_huge_pmd(struct fault_env
*fe
, pmd_t orig_pmd
)
3449 if (vma_is_anonymous(fe
->vma
))
3450 return do_huge_pmd_wp_page(fe
, orig_pmd
);
3451 if (fe
->vma
->vm_ops
->pmd_fault
)
3452 return fe
->vma
->vm_ops
->pmd_fault(fe
->vma
, fe
->address
, fe
->pmd
,
3455 /* COW handled on pte level: split pmd */
3456 VM_BUG_ON_VMA(fe
->vma
->vm_flags
& VM_SHARED
, fe
->vma
);
3457 split_huge_pmd(fe
->vma
, fe
->pmd
, fe
->address
);
3459 return VM_FAULT_FALLBACK
;
3462 static inline bool vma_is_accessible(struct vm_area_struct
*vma
)
3464 return vma
->vm_flags
& (VM_READ
| VM_EXEC
| VM_WRITE
);
3468 * These routines also need to handle stuff like marking pages dirty
3469 * and/or accessed for architectures that don't do it in hardware (most
3470 * RISC architectures). The early dirtying is also good on the i386.
3472 * There is also a hook called "update_mmu_cache()" that architectures
3473 * with external mmu caches can use to update those (ie the Sparc or
3474 * PowerPC hashed page tables that act as extended TLBs).
3476 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
3477 * concurrent faults).
3479 * The mmap_sem may have been released depending on flags and our return value.
3480 * See filemap_fault() and __lock_page_or_retry().
3482 static int handle_pte_fault(struct fault_env
*fe
)
3486 if (unlikely(pmd_none(*fe
->pmd
))) {
3488 * Leave __pte_alloc() until later: because vm_ops->fault may
3489 * want to allocate huge page, and if we expose page table
3490 * for an instant, it will be difficult to retract from
3491 * concurrent faults and from rmap lookups.
3495 /* See comment in pte_alloc_one_map() */
3496 if (pmd_trans_unstable(fe
->pmd
) || pmd_devmap(*fe
->pmd
))
3499 * A regular pmd is established and it can't morph into a huge
3500 * pmd from under us anymore at this point because we hold the
3501 * mmap_sem read mode and khugepaged takes it in write mode.
3502 * So now it's safe to run pte_offset_map().
3504 fe
->pte
= pte_offset_map(fe
->pmd
, fe
->address
);
3509 * some architectures can have larger ptes than wordsize,
3510 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
3511 * CONFIG_32BIT=y, so READ_ONCE or ACCESS_ONCE cannot guarantee
3512 * atomic accesses. The code below just needs a consistent
3513 * view for the ifs and we later double check anyway with the
3514 * ptl lock held. So here a barrier will do.
3517 if (pte_none(entry
)) {
3524 if (vma_is_anonymous(fe
->vma
))
3525 return do_anonymous_page(fe
);
3527 return do_fault(fe
);
3530 if (!pte_present(entry
))
3531 return do_swap_page(fe
, entry
);
3533 if (pte_protnone(entry
) && vma_is_accessible(fe
->vma
))
3534 return do_numa_page(fe
, entry
);
3536 fe
->ptl
= pte_lockptr(fe
->vma
->vm_mm
, fe
->pmd
);
3538 if (unlikely(!pte_same(*fe
->pte
, entry
)))
3540 if (fe
->flags
& FAULT_FLAG_WRITE
) {
3541 if (!pte_write(entry
))
3542 return do_wp_page(fe
, entry
);
3543 entry
= pte_mkdirty(entry
);
3545 entry
= pte_mkyoung(entry
);
3546 if (ptep_set_access_flags(fe
->vma
, fe
->address
, fe
->pte
, entry
,
3547 fe
->flags
& FAULT_FLAG_WRITE
)) {
3548 update_mmu_cache(fe
->vma
, fe
->address
, fe
->pte
);
3551 * This is needed only for protection faults but the arch code
3552 * is not yet telling us if this is a protection fault or not.
3553 * This still avoids useless tlb flushes for .text page faults
3556 if (fe
->flags
& FAULT_FLAG_WRITE
)
3557 flush_tlb_fix_spurious_fault(fe
->vma
, fe
->address
);
3560 pte_unmap_unlock(fe
->pte
, fe
->ptl
);
3565 * By the time we get here, we already hold the mm semaphore
3567 * The mmap_sem may have been released depending on flags and our
3568 * return value. See filemap_fault() and __lock_page_or_retry().
3570 static int __handle_mm_fault(struct vm_area_struct
*vma
, unsigned long address
,
3573 struct fault_env fe
= {
3578 struct mm_struct
*mm
= vma
->vm_mm
;
3582 pgd
= pgd_offset(mm
, address
);
3583 pud
= pud_alloc(mm
, pgd
, address
);
3585 return VM_FAULT_OOM
;
3586 fe
.pmd
= pmd_alloc(mm
, pud
, address
);
3588 return VM_FAULT_OOM
;
3589 if (pmd_none(*fe
.pmd
) && transparent_hugepage_enabled(vma
)) {
3590 int ret
= create_huge_pmd(&fe
);
3591 if (!(ret
& VM_FAULT_FALLBACK
))
3594 pmd_t orig_pmd
= *fe
.pmd
;
3598 if (pmd_trans_huge(orig_pmd
) || pmd_devmap(orig_pmd
)) {
3599 if (pmd_protnone(orig_pmd
) && vma_is_accessible(vma
))
3600 return do_huge_pmd_numa_page(&fe
, orig_pmd
);
3602 if ((fe
.flags
& FAULT_FLAG_WRITE
) &&
3603 !pmd_write(orig_pmd
)) {
3604 ret
= wp_huge_pmd(&fe
, orig_pmd
);
3605 if (!(ret
& VM_FAULT_FALLBACK
))
3608 huge_pmd_set_accessed(&fe
, orig_pmd
);
3614 return handle_pte_fault(&fe
);
3618 * By the time we get here, we already hold the mm semaphore
3620 * The mmap_sem may have been released depending on flags and our
3621 * return value. See filemap_fault() and __lock_page_or_retry().
3623 int handle_mm_fault(struct vm_area_struct
*vma
, unsigned long address
,
3628 __set_current_state(TASK_RUNNING
);
3630 count_vm_event(PGFAULT
);
3631 mem_cgroup_count_vm_event(vma
->vm_mm
, PGFAULT
);
3633 /* do counter updates before entering really critical section. */
3634 check_sync_rss_stat(current
);
3637 * Enable the memcg OOM handling for faults triggered in user
3638 * space. Kernel faults are handled more gracefully.
3640 if (flags
& FAULT_FLAG_USER
)
3641 mem_cgroup_oom_enable();
3643 if (!arch_vma_access_permitted(vma
, flags
& FAULT_FLAG_WRITE
,
3644 flags
& FAULT_FLAG_INSTRUCTION
,
3645 flags
& FAULT_FLAG_REMOTE
))
3646 return VM_FAULT_SIGSEGV
;
3648 if (unlikely(is_vm_hugetlb_page(vma
)))
3649 ret
= hugetlb_fault(vma
->vm_mm
, vma
, address
, flags
);
3651 ret
= __handle_mm_fault(vma
, address
, flags
);
3653 if (flags
& FAULT_FLAG_USER
) {
3654 mem_cgroup_oom_disable();
3656 * The task may have entered a memcg OOM situation but
3657 * if the allocation error was handled gracefully (no
3658 * VM_FAULT_OOM), there is no need to kill anything.
3659 * Just clean up the OOM state peacefully.
3661 if (task_in_memcg_oom(current
) && !(ret
& VM_FAULT_OOM
))
3662 mem_cgroup_oom_synchronize(false);
3666 * This mm has been already reaped by the oom reaper and so the
3667 * refault cannot be trusted in general. Anonymous refaults would
3668 * lose data and give a zero page instead e.g. This is especially
3669 * problem for use_mm() because regular tasks will just die and
3670 * the corrupted data will not be visible anywhere while kthread
3671 * will outlive the oom victim and potentially propagate the date
3674 if (unlikely((current
->flags
& PF_KTHREAD
) && !(ret
& VM_FAULT_ERROR
)
3675 && test_bit(MMF_UNSTABLE
, &vma
->vm_mm
->flags
)))
3676 ret
= VM_FAULT_SIGBUS
;
3680 EXPORT_SYMBOL_GPL(handle_mm_fault
);
3682 #ifndef __PAGETABLE_PUD_FOLDED
3684 * Allocate page upper directory.
3685 * We've already handled the fast-path in-line.
3687 int __pud_alloc(struct mm_struct
*mm
, pgd_t
*pgd
, unsigned long address
)
3689 pud_t
*new = pud_alloc_one(mm
, address
);
3693 smp_wmb(); /* See comment in __pte_alloc */
3695 spin_lock(&mm
->page_table_lock
);
3696 if (pgd_present(*pgd
)) /* Another has populated it */
3699 pgd_populate(mm
, pgd
, new);
3700 spin_unlock(&mm
->page_table_lock
);
3703 #endif /* __PAGETABLE_PUD_FOLDED */
3705 #ifndef __PAGETABLE_PMD_FOLDED
3707 * Allocate page middle directory.
3708 * We've already handled the fast-path in-line.
3710 int __pmd_alloc(struct mm_struct
*mm
, pud_t
*pud
, unsigned long address
)
3712 pmd_t
*new = pmd_alloc_one(mm
, address
);
3716 smp_wmb(); /* See comment in __pte_alloc */
3718 spin_lock(&mm
->page_table_lock
);
3719 #ifndef __ARCH_HAS_4LEVEL_HACK
3720 if (!pud_present(*pud
)) {
3722 pud_populate(mm
, pud
, new);
3723 } else /* Another has populated it */
3726 if (!pgd_present(*pud
)) {
3728 pgd_populate(mm
, pud
, new);
3729 } else /* Another has populated it */
3731 #endif /* __ARCH_HAS_4LEVEL_HACK */
3732 spin_unlock(&mm
->page_table_lock
);
3735 #endif /* __PAGETABLE_PMD_FOLDED */
3737 static int __follow_pte(struct mm_struct
*mm
, unsigned long address
,
3738 pte_t
**ptepp
, spinlock_t
**ptlp
)
3745 pgd
= pgd_offset(mm
, address
);
3746 if (pgd_none(*pgd
) || unlikely(pgd_bad(*pgd
)))
3749 pud
= pud_offset(pgd
, address
);
3750 if (pud_none(*pud
) || unlikely(pud_bad(*pud
)))
3753 pmd
= pmd_offset(pud
, address
);
3754 VM_BUG_ON(pmd_trans_huge(*pmd
));
3755 if (pmd_none(*pmd
) || unlikely(pmd_bad(*pmd
)))
3758 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3762 ptep
= pte_offset_map_lock(mm
, pmd
, address
, ptlp
);
3765 if (!pte_present(*ptep
))
3770 pte_unmap_unlock(ptep
, *ptlp
);
3775 static inline int follow_pte(struct mm_struct
*mm
, unsigned long address
,
3776 pte_t
**ptepp
, spinlock_t
**ptlp
)
3780 /* (void) is needed to make gcc happy */
3781 (void) __cond_lock(*ptlp
,
3782 !(res
= __follow_pte(mm
, address
, ptepp
, ptlp
)));
3787 * follow_pfn - look up PFN at a user virtual address
3788 * @vma: memory mapping
3789 * @address: user virtual address
3790 * @pfn: location to store found PFN
3792 * Only IO mappings and raw PFN mappings are allowed.
3794 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3796 int follow_pfn(struct vm_area_struct
*vma
, unsigned long address
,
3803 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
3806 ret
= follow_pte(vma
->vm_mm
, address
, &ptep
, &ptl
);
3809 *pfn
= pte_pfn(*ptep
);
3810 pte_unmap_unlock(ptep
, ptl
);
3813 EXPORT_SYMBOL(follow_pfn
);
3815 #ifdef CONFIG_HAVE_IOREMAP_PROT
3816 int follow_phys(struct vm_area_struct
*vma
,
3817 unsigned long address
, unsigned int flags
,
3818 unsigned long *prot
, resource_size_t
*phys
)
3824 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
3827 if (follow_pte(vma
->vm_mm
, address
, &ptep
, &ptl
))
3831 if ((flags
& FOLL_WRITE
) && !pte_write(pte
))
3834 *prot
= pgprot_val(pte_pgprot(pte
));
3835 *phys
= (resource_size_t
)pte_pfn(pte
) << PAGE_SHIFT
;
3839 pte_unmap_unlock(ptep
, ptl
);
3844 int generic_access_phys(struct vm_area_struct
*vma
, unsigned long addr
,
3845 void *buf
, int len
, int write
)
3847 resource_size_t phys_addr
;
3848 unsigned long prot
= 0;
3849 void __iomem
*maddr
;
3850 int offset
= addr
& (PAGE_SIZE
-1);
3852 if (follow_phys(vma
, addr
, write
, &prot
, &phys_addr
))
3855 maddr
= ioremap_prot(phys_addr
, PAGE_ALIGN(len
+ offset
), prot
);
3857 memcpy_toio(maddr
+ offset
, buf
, len
);
3859 memcpy_fromio(buf
, maddr
+ offset
, len
);
3864 EXPORT_SYMBOL_GPL(generic_access_phys
);
3868 * Access another process' address space as given in mm. If non-NULL, use the
3869 * given task for page fault accounting.
3871 static int __access_remote_vm(struct task_struct
*tsk
, struct mm_struct
*mm
,
3872 unsigned long addr
, void *buf
, int len
, unsigned int gup_flags
)
3874 struct vm_area_struct
*vma
;
3875 void *old_buf
= buf
;
3876 int write
= gup_flags
& FOLL_WRITE
;
3878 down_read(&mm
->mmap_sem
);
3879 /* ignore errors, just check how much was successfully transferred */
3881 int bytes
, ret
, offset
;
3883 struct page
*page
= NULL
;
3885 ret
= get_user_pages_remote(tsk
, mm
, addr
, 1,
3886 gup_flags
, &page
, &vma
);
3888 #ifndef CONFIG_HAVE_IOREMAP_PROT
3892 * Check if this is a VM_IO | VM_PFNMAP VMA, which
3893 * we can access using slightly different code.
3895 vma
= find_vma(mm
, addr
);
3896 if (!vma
|| vma
->vm_start
> addr
)
3898 if (vma
->vm_ops
&& vma
->vm_ops
->access
)
3899 ret
= vma
->vm_ops
->access(vma
, addr
, buf
,
3907 offset
= addr
& (PAGE_SIZE
-1);
3908 if (bytes
> PAGE_SIZE
-offset
)
3909 bytes
= PAGE_SIZE
-offset
;
3913 copy_to_user_page(vma
, page
, addr
,
3914 maddr
+ offset
, buf
, bytes
);
3915 set_page_dirty_lock(page
);
3917 copy_from_user_page(vma
, page
, addr
,
3918 buf
, maddr
+ offset
, bytes
);
3927 up_read(&mm
->mmap_sem
);
3929 return buf
- old_buf
;
3933 * access_remote_vm - access another process' address space
3934 * @mm: the mm_struct of the target address space
3935 * @addr: start address to access
3936 * @buf: source or destination buffer
3937 * @len: number of bytes to transfer
3938 * @write: whether the access is a write
3940 * The caller must hold a reference on @mm.
3942 int access_remote_vm(struct mm_struct
*mm
, unsigned long addr
,
3943 void *buf
, int len
, int write
)
3945 unsigned int flags
= FOLL_FORCE
;
3948 flags
|= FOLL_WRITE
;
3950 return __access_remote_vm(NULL
, mm
, addr
, buf
, len
, flags
);
3954 * Access another process' address space.
3955 * Source/target buffer must be kernel space,
3956 * Do not walk the page table directly, use get_user_pages
3958 int access_process_vm(struct task_struct
*tsk
, unsigned long addr
,
3959 void *buf
, int len
, int write
)
3961 struct mm_struct
*mm
;
3963 unsigned int flags
= FOLL_FORCE
;
3965 mm
= get_task_mm(tsk
);
3970 flags
|= FOLL_WRITE
;
3972 ret
= __access_remote_vm(tsk
, mm
, addr
, buf
, len
, flags
);
3980 * Print the name of a VMA.
3982 void print_vma_addr(char *prefix
, unsigned long ip
)
3984 struct mm_struct
*mm
= current
->mm
;
3985 struct vm_area_struct
*vma
;
3988 * Do not print if we are in atomic
3989 * contexts (in exception stacks, etc.):
3991 if (preempt_count())
3994 down_read(&mm
->mmap_sem
);
3995 vma
= find_vma(mm
, ip
);
3996 if (vma
&& vma
->vm_file
) {
3997 struct file
*f
= vma
->vm_file
;
3998 char *buf
= (char *)__get_free_page(GFP_KERNEL
);
4002 p
= file_path(f
, buf
, PAGE_SIZE
);
4005 printk("%s%s[%lx+%lx]", prefix
, kbasename(p
),
4007 vma
->vm_end
- vma
->vm_start
);
4008 free_page((unsigned long)buf
);
4011 up_read(&mm
->mmap_sem
);
4014 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4015 void __might_fault(const char *file
, int line
)
4018 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4019 * holding the mmap_sem, this is safe because kernel memory doesn't
4020 * get paged out, therefore we'll never actually fault, and the
4021 * below annotations will generate false positives.
4023 if (segment_eq(get_fs(), KERNEL_DS
))
4025 if (pagefault_disabled())
4027 __might_sleep(file
, line
, 0);
4028 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4030 might_lock_read(¤t
->mm
->mmap_sem
);
4033 EXPORT_SYMBOL(__might_fault
);
4036 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4037 static void clear_gigantic_page(struct page
*page
,
4039 unsigned int pages_per_huge_page
)
4042 struct page
*p
= page
;
4045 for (i
= 0; i
< pages_per_huge_page
;
4046 i
++, p
= mem_map_next(p
, page
, i
)) {
4048 clear_user_highpage(p
, addr
+ i
* PAGE_SIZE
);
4051 void clear_huge_page(struct page
*page
,
4052 unsigned long addr
, unsigned int pages_per_huge_page
)
4056 if (unlikely(pages_per_huge_page
> MAX_ORDER_NR_PAGES
)) {
4057 clear_gigantic_page(page
, addr
, pages_per_huge_page
);
4062 for (i
= 0; i
< pages_per_huge_page
; i
++) {
4064 clear_user_highpage(page
+ i
, addr
+ i
* PAGE_SIZE
);
4068 static void copy_user_gigantic_page(struct page
*dst
, struct page
*src
,
4070 struct vm_area_struct
*vma
,
4071 unsigned int pages_per_huge_page
)
4074 struct page
*dst_base
= dst
;
4075 struct page
*src_base
= src
;
4077 for (i
= 0; i
< pages_per_huge_page
; ) {
4079 copy_user_highpage(dst
, src
, addr
+ i
*PAGE_SIZE
, vma
);
4082 dst
= mem_map_next(dst
, dst_base
, i
);
4083 src
= mem_map_next(src
, src_base
, i
);
4087 void copy_user_huge_page(struct page
*dst
, struct page
*src
,
4088 unsigned long addr
, struct vm_area_struct
*vma
,
4089 unsigned int pages_per_huge_page
)
4093 if (unlikely(pages_per_huge_page
> MAX_ORDER_NR_PAGES
)) {
4094 copy_user_gigantic_page(dst
, src
, addr
, vma
,
4095 pages_per_huge_page
);
4100 for (i
= 0; i
< pages_per_huge_page
; i
++) {
4102 copy_user_highpage(dst
+ i
, src
+ i
, addr
+ i
*PAGE_SIZE
, vma
);
4105 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4107 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4109 static struct kmem_cache
*page_ptl_cachep
;
4111 void __init
ptlock_cache_init(void)
4113 page_ptl_cachep
= kmem_cache_create("page->ptl", sizeof(spinlock_t
), 0,
4117 bool ptlock_alloc(struct page
*page
)
4121 ptl
= kmem_cache_alloc(page_ptl_cachep
, GFP_KERNEL
);
4128 void ptlock_free(struct page
*page
)
4130 kmem_cache_free(page_ptl_cachep
, page
->ptl
);