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/rmap.h>
49 #include <linux/module.h>
50 #include <linux/init.h>
52 #include <asm/pgalloc.h>
53 #include <asm/uaccess.h>
55 #include <asm/tlbflush.h>
56 #include <asm/pgtable.h>
58 #include <linux/swapops.h>
59 #include <linux/elf.h>
61 #ifndef CONFIG_NEED_MULTIPLE_NODES
62 /* use the per-pgdat data instead for discontigmem - mbligh */
63 unsigned long max_mapnr
;
66 EXPORT_SYMBOL(max_mapnr
);
67 EXPORT_SYMBOL(mem_map
);
70 unsigned long num_physpages
;
72 * A number of key systems in x86 including ioremap() rely on the assumption
73 * that high_memory defines the upper bound on direct map memory, then end
74 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
75 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
79 unsigned long vmalloc_earlyreserve
;
81 EXPORT_SYMBOL(num_physpages
);
82 EXPORT_SYMBOL(high_memory
);
83 EXPORT_SYMBOL(vmalloc_earlyreserve
);
86 * If a p?d_bad entry is found while walking page tables, report
87 * the error, before resetting entry to p?d_none. Usually (but
88 * very seldom) called out from the p?d_none_or_clear_bad macros.
91 void pgd_clear_bad(pgd_t
*pgd
)
97 void pud_clear_bad(pud_t
*pud
)
103 void pmd_clear_bad(pmd_t
*pmd
)
110 * Note: this doesn't free the actual pages themselves. That
111 * has been handled earlier when unmapping all the memory regions.
113 static void free_pte_range(struct mmu_gather
*tlb
, pmd_t
*pmd
)
115 struct page
*page
= pmd_page(*pmd
);
117 pte_free_tlb(tlb
, page
);
118 dec_page_state(nr_page_table_pages
);
122 static inline void free_pmd_range(struct mmu_gather
*tlb
, pud_t
*pud
,
123 unsigned long addr
, unsigned long end
,
124 unsigned long floor
, unsigned long ceiling
)
131 pmd
= pmd_offset(pud
, addr
);
133 next
= pmd_addr_end(addr
, end
);
134 if (pmd_none_or_clear_bad(pmd
))
136 free_pte_range(tlb
, pmd
);
137 } while (pmd
++, addr
= next
, addr
!= end
);
147 if (end
- 1 > ceiling
- 1)
150 pmd
= pmd_offset(pud
, start
);
152 pmd_free_tlb(tlb
, pmd
);
155 static inline void free_pud_range(struct mmu_gather
*tlb
, pgd_t
*pgd
,
156 unsigned long addr
, unsigned long end
,
157 unsigned long floor
, unsigned long ceiling
)
164 pud
= pud_offset(pgd
, addr
);
166 next
= pud_addr_end(addr
, end
);
167 if (pud_none_or_clear_bad(pud
))
169 free_pmd_range(tlb
, pud
, addr
, next
, floor
, ceiling
);
170 } while (pud
++, addr
= next
, addr
!= end
);
176 ceiling
&= PGDIR_MASK
;
180 if (end
- 1 > ceiling
- 1)
183 pud
= pud_offset(pgd
, start
);
185 pud_free_tlb(tlb
, pud
);
189 * This function frees user-level page tables of a process.
191 * Must be called with pagetable lock held.
193 void free_pgd_range(struct mmu_gather
**tlb
,
194 unsigned long addr
, unsigned long end
,
195 unsigned long floor
, unsigned long ceiling
)
202 * The next few lines have given us lots of grief...
204 * Why are we testing PMD* at this top level? Because often
205 * there will be no work to do at all, and we'd prefer not to
206 * go all the way down to the bottom just to discover that.
208 * Why all these "- 1"s? Because 0 represents both the bottom
209 * of the address space and the top of it (using -1 for the
210 * top wouldn't help much: the masks would do the wrong thing).
211 * The rule is that addr 0 and floor 0 refer to the bottom of
212 * the address space, but end 0 and ceiling 0 refer to the top
213 * Comparisons need to use "end - 1" and "ceiling - 1" (though
214 * that end 0 case should be mythical).
216 * Wherever addr is brought up or ceiling brought down, we must
217 * be careful to reject "the opposite 0" before it confuses the
218 * subsequent tests. But what about where end is brought down
219 * by PMD_SIZE below? no, end can't go down to 0 there.
221 * Whereas we round start (addr) and ceiling down, by different
222 * masks at different levels, in order to test whether a table
223 * now has no other vmas using it, so can be freed, we don't
224 * bother to round floor or end up - the tests don't need that.
238 if (end
- 1 > ceiling
- 1)
244 pgd
= pgd_offset((*tlb
)->mm
, addr
);
246 next
= pgd_addr_end(addr
, end
);
247 if (pgd_none_or_clear_bad(pgd
))
249 free_pud_range(*tlb
, pgd
, addr
, next
, floor
, ceiling
);
250 } while (pgd
++, addr
= next
, addr
!= end
);
253 flush_tlb_pgtables((*tlb
)->mm
, start
, end
);
256 void free_pgtables(struct mmu_gather
**tlb
, struct vm_area_struct
*vma
,
257 unsigned long floor
, unsigned long ceiling
)
260 struct vm_area_struct
*next
= vma
->vm_next
;
261 unsigned long addr
= vma
->vm_start
;
263 if (is_hugepage_only_range(vma
->vm_mm
, addr
, HPAGE_SIZE
)) {
264 hugetlb_free_pgd_range(tlb
, addr
, vma
->vm_end
,
265 floor
, next
? next
->vm_start
: ceiling
);
268 * Optimization: gather nearby vmas into one call down
270 while (next
&& next
->vm_start
<= vma
->vm_end
+ PMD_SIZE
271 && !is_hugepage_only_range(vma
->vm_mm
, next
->vm_start
,
276 free_pgd_range(tlb
, addr
, vma
->vm_end
,
277 floor
, next
? next
->vm_start
: ceiling
);
283 pte_t fastcall
*pte_alloc_map(struct mm_struct
*mm
, pmd_t
*pmd
,
284 unsigned long address
)
286 if (!pmd_present(*pmd
)) {
289 spin_unlock(&mm
->page_table_lock
);
290 new = pte_alloc_one(mm
, address
);
291 spin_lock(&mm
->page_table_lock
);
295 * Because we dropped the lock, we should re-check the
296 * entry, as somebody else could have populated it..
298 if (pmd_present(*pmd
)) {
303 inc_page_state(nr_page_table_pages
);
304 pmd_populate(mm
, pmd
, new);
307 return pte_offset_map(pmd
, address
);
310 pte_t fastcall
* pte_alloc_kernel(struct mm_struct
*mm
, pmd_t
*pmd
, unsigned long address
)
312 if (!pmd_present(*pmd
)) {
315 spin_unlock(&mm
->page_table_lock
);
316 new = pte_alloc_one_kernel(mm
, address
);
317 spin_lock(&mm
->page_table_lock
);
322 * Because we dropped the lock, we should re-check the
323 * entry, as somebody else could have populated it..
325 if (pmd_present(*pmd
)) {
326 pte_free_kernel(new);
329 pmd_populate_kernel(mm
, pmd
, new);
332 return pte_offset_kernel(pmd
, address
);
336 * copy one vm_area from one task to the other. Assumes the page tables
337 * already present in the new task to be cleared in the whole range
338 * covered by this vma.
340 * dst->page_table_lock is held on entry and exit,
341 * but may be dropped within p[mg]d_alloc() and pte_alloc_map().
345 copy_one_pte(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
346 pte_t
*dst_pte
, pte_t
*src_pte
, unsigned long vm_flags
,
349 pte_t pte
= *src_pte
;
353 /* pte contains position in swap or file, so copy. */
354 if (unlikely(!pte_present(pte
))) {
355 if (!pte_file(pte
)) {
356 swap_duplicate(pte_to_swp_entry(pte
));
357 /* make sure dst_mm is on swapoff's mmlist. */
358 if (unlikely(list_empty(&dst_mm
->mmlist
))) {
359 spin_lock(&mmlist_lock
);
360 list_add(&dst_mm
->mmlist
, &src_mm
->mmlist
);
361 spin_unlock(&mmlist_lock
);
364 set_pte_at(dst_mm
, addr
, dst_pte
, pte
);
369 /* the pte points outside of valid memory, the
370 * mapping is assumed to be good, meaningful
371 * and not mapped via rmap - duplicate the
376 page
= pfn_to_page(pfn
);
378 if (!page
|| PageReserved(page
)) {
379 set_pte_at(dst_mm
, addr
, dst_pte
, pte
);
384 * If it's a COW mapping, write protect it both
385 * in the parent and the child
387 if ((vm_flags
& (VM_SHARED
| VM_MAYWRITE
)) == VM_MAYWRITE
) {
388 ptep_set_wrprotect(src_mm
, addr
, src_pte
);
393 * If it's a shared mapping, mark it clean in
396 if (vm_flags
& VM_SHARED
)
397 pte
= pte_mkclean(pte
);
398 pte
= pte_mkold(pte
);
401 inc_mm_counter(dst_mm
, anon_rss
);
403 inc_mm_counter(dst_mm
, file_rss
);
404 set_pte_at(dst_mm
, addr
, dst_pte
, pte
);
408 static int copy_pte_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
409 pmd_t
*dst_pmd
, pmd_t
*src_pmd
, struct vm_area_struct
*vma
,
410 unsigned long addr
, unsigned long end
)
412 pte_t
*src_pte
, *dst_pte
;
413 unsigned long vm_flags
= vma
->vm_flags
;
417 dst_pte
= pte_alloc_map(dst_mm
, dst_pmd
, addr
);
420 src_pte
= pte_offset_map_nested(src_pmd
, addr
);
422 spin_lock(&src_mm
->page_table_lock
);
425 * We are holding two locks at this point - either of them
426 * could generate latencies in another task on another CPU.
428 if (progress
>= 32) {
430 if (need_resched() ||
431 need_lockbreak(&src_mm
->page_table_lock
) ||
432 need_lockbreak(&dst_mm
->page_table_lock
))
435 if (pte_none(*src_pte
)) {
439 copy_one_pte(dst_mm
, src_mm
, dst_pte
, src_pte
, vm_flags
, addr
);
441 } while (dst_pte
++, src_pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
442 spin_unlock(&src_mm
->page_table_lock
);
444 pte_unmap_nested(src_pte
- 1);
445 pte_unmap(dst_pte
- 1);
446 cond_resched_lock(&dst_mm
->page_table_lock
);
452 static inline int copy_pmd_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
453 pud_t
*dst_pud
, pud_t
*src_pud
, struct vm_area_struct
*vma
,
454 unsigned long addr
, unsigned long end
)
456 pmd_t
*src_pmd
, *dst_pmd
;
459 dst_pmd
= pmd_alloc(dst_mm
, dst_pud
, addr
);
462 src_pmd
= pmd_offset(src_pud
, addr
);
464 next
= pmd_addr_end(addr
, end
);
465 if (pmd_none_or_clear_bad(src_pmd
))
467 if (copy_pte_range(dst_mm
, src_mm
, dst_pmd
, src_pmd
,
470 } while (dst_pmd
++, src_pmd
++, addr
= next
, addr
!= end
);
474 static inline int copy_pud_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
475 pgd_t
*dst_pgd
, pgd_t
*src_pgd
, struct vm_area_struct
*vma
,
476 unsigned long addr
, unsigned long end
)
478 pud_t
*src_pud
, *dst_pud
;
481 dst_pud
= pud_alloc(dst_mm
, dst_pgd
, addr
);
484 src_pud
= pud_offset(src_pgd
, addr
);
486 next
= pud_addr_end(addr
, end
);
487 if (pud_none_or_clear_bad(src_pud
))
489 if (copy_pmd_range(dst_mm
, src_mm
, dst_pud
, src_pud
,
492 } while (dst_pud
++, src_pud
++, addr
= next
, addr
!= end
);
496 int copy_page_range(struct mm_struct
*dst_mm
, struct mm_struct
*src_mm
,
497 struct vm_area_struct
*vma
)
499 pgd_t
*src_pgd
, *dst_pgd
;
501 unsigned long addr
= vma
->vm_start
;
502 unsigned long end
= vma
->vm_end
;
505 * Don't copy ptes where a page fault will fill them correctly.
506 * Fork becomes much lighter when there are big shared or private
507 * readonly mappings. The tradeoff is that copy_page_range is more
508 * efficient than faulting.
510 if (!(vma
->vm_flags
& (VM_HUGETLB
|VM_NONLINEAR
|VM_RESERVED
))) {
515 if (is_vm_hugetlb_page(vma
))
516 return copy_hugetlb_page_range(dst_mm
, src_mm
, vma
);
518 dst_pgd
= pgd_offset(dst_mm
, addr
);
519 src_pgd
= pgd_offset(src_mm
, addr
);
521 next
= pgd_addr_end(addr
, end
);
522 if (pgd_none_or_clear_bad(src_pgd
))
524 if (copy_pud_range(dst_mm
, src_mm
, dst_pgd
, src_pgd
,
527 } while (dst_pgd
++, src_pgd
++, addr
= next
, addr
!= end
);
531 static void zap_pte_range(struct mmu_gather
*tlb
, pmd_t
*pmd
,
532 unsigned long addr
, unsigned long end
,
533 struct zap_details
*details
)
537 pte
= pte_offset_map(pmd
, addr
);
542 if (pte_present(ptent
)) {
543 struct page
*page
= NULL
;
544 unsigned long pfn
= pte_pfn(ptent
);
545 if (pfn_valid(pfn
)) {
546 page
= pfn_to_page(pfn
);
547 if (PageReserved(page
))
550 if (unlikely(details
) && page
) {
552 * unmap_shared_mapping_pages() wants to
553 * invalidate cache without truncating:
554 * unmap shared but keep private pages.
556 if (details
->check_mapping
&&
557 details
->check_mapping
!= page
->mapping
)
560 * Each page->index must be checked when
561 * invalidating or truncating nonlinear.
563 if (details
->nonlinear_vma
&&
564 (page
->index
< details
->first_index
||
565 page
->index
> details
->last_index
))
568 ptent
= ptep_get_and_clear_full(tlb
->mm
, addr
, pte
,
570 tlb_remove_tlb_entry(tlb
, pte
, addr
);
573 if (unlikely(details
) && details
->nonlinear_vma
574 && linear_page_index(details
->nonlinear_vma
,
575 addr
) != page
->index
)
576 set_pte_at(tlb
->mm
, addr
, pte
,
577 pgoff_to_pte(page
->index
));
579 dec_mm_counter(tlb
->mm
, anon_rss
);
581 if (pte_dirty(ptent
))
582 set_page_dirty(page
);
583 if (pte_young(ptent
))
584 mark_page_accessed(page
);
585 dec_mm_counter(tlb
->mm
, file_rss
);
587 page_remove_rmap(page
);
588 tlb_remove_page(tlb
, page
);
592 * If details->check_mapping, we leave swap entries;
593 * if details->nonlinear_vma, we leave file entries.
595 if (unlikely(details
))
597 if (!pte_file(ptent
))
598 free_swap_and_cache(pte_to_swp_entry(ptent
));
599 pte_clear_full(tlb
->mm
, addr
, pte
, tlb
->fullmm
);
600 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
604 static inline void zap_pmd_range(struct mmu_gather
*tlb
, pud_t
*pud
,
605 unsigned long addr
, unsigned long end
,
606 struct zap_details
*details
)
611 pmd
= pmd_offset(pud
, addr
);
613 next
= pmd_addr_end(addr
, end
);
614 if (pmd_none_or_clear_bad(pmd
))
616 zap_pte_range(tlb
, pmd
, addr
, next
, details
);
617 } while (pmd
++, addr
= next
, addr
!= end
);
620 static inline void zap_pud_range(struct mmu_gather
*tlb
, pgd_t
*pgd
,
621 unsigned long addr
, unsigned long end
,
622 struct zap_details
*details
)
627 pud
= pud_offset(pgd
, addr
);
629 next
= pud_addr_end(addr
, end
);
630 if (pud_none_or_clear_bad(pud
))
632 zap_pmd_range(tlb
, pud
, addr
, next
, details
);
633 } while (pud
++, addr
= next
, addr
!= end
);
636 static void unmap_page_range(struct mmu_gather
*tlb
, struct vm_area_struct
*vma
,
637 unsigned long addr
, unsigned long end
,
638 struct zap_details
*details
)
643 if (details
&& !details
->check_mapping
&& !details
->nonlinear_vma
)
647 tlb_start_vma(tlb
, vma
);
648 pgd
= pgd_offset(vma
->vm_mm
, addr
);
650 next
= pgd_addr_end(addr
, end
);
651 if (pgd_none_or_clear_bad(pgd
))
653 zap_pud_range(tlb
, pgd
, addr
, next
, details
);
654 } while (pgd
++, addr
= next
, addr
!= end
);
655 tlb_end_vma(tlb
, vma
);
658 #ifdef CONFIG_PREEMPT
659 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
661 /* No preempt: go for improved straight-line efficiency */
662 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
666 * unmap_vmas - unmap a range of memory covered by a list of vma's
667 * @tlbp: address of the caller's struct mmu_gather
668 * @mm: the controlling mm_struct
669 * @vma: the starting vma
670 * @start_addr: virtual address at which to start unmapping
671 * @end_addr: virtual address at which to end unmapping
672 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
673 * @details: details of nonlinear truncation or shared cache invalidation
675 * Returns the end address of the unmapping (restart addr if interrupted).
677 * Unmap all pages in the vma list. Called under page_table_lock.
679 * We aim to not hold page_table_lock for too long (for scheduling latency
680 * reasons). So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to
681 * return the ending mmu_gather to the caller.
683 * Only addresses between `start' and `end' will be unmapped.
685 * The VMA list must be sorted in ascending virtual address order.
687 * unmap_vmas() assumes that the caller will flush the whole unmapped address
688 * range after unmap_vmas() returns. So the only responsibility here is to
689 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
690 * drops the lock and schedules.
692 unsigned long unmap_vmas(struct mmu_gather
**tlbp
, struct mm_struct
*mm
,
693 struct vm_area_struct
*vma
, unsigned long start_addr
,
694 unsigned long end_addr
, unsigned long *nr_accounted
,
695 struct zap_details
*details
)
697 unsigned long zap_bytes
= ZAP_BLOCK_SIZE
;
698 unsigned long tlb_start
= 0; /* For tlb_finish_mmu */
699 int tlb_start_valid
= 0;
700 unsigned long start
= start_addr
;
701 spinlock_t
*i_mmap_lock
= details
? details
->i_mmap_lock
: NULL
;
702 int fullmm
= (*tlbp
)->fullmm
;
704 for ( ; vma
&& vma
->vm_start
< end_addr
; vma
= vma
->vm_next
) {
707 start
= max(vma
->vm_start
, start_addr
);
708 if (start
>= vma
->vm_end
)
710 end
= min(vma
->vm_end
, end_addr
);
711 if (end
<= vma
->vm_start
)
714 if (vma
->vm_flags
& VM_ACCOUNT
)
715 *nr_accounted
+= (end
- start
) >> PAGE_SHIFT
;
717 while (start
!= end
) {
720 if (!tlb_start_valid
) {
725 if (is_vm_hugetlb_page(vma
)) {
727 unmap_hugepage_range(vma
, start
, end
);
729 block
= min(zap_bytes
, end
- start
);
730 unmap_page_range(*tlbp
, vma
, start
,
731 start
+ block
, details
);
736 if ((long)zap_bytes
> 0)
739 tlb_finish_mmu(*tlbp
, tlb_start
, start
);
741 if (need_resched() ||
742 need_lockbreak(&mm
->page_table_lock
) ||
743 (i_mmap_lock
&& need_lockbreak(i_mmap_lock
))) {
745 /* must reset count of rss freed */
746 *tlbp
= tlb_gather_mmu(mm
, fullmm
);
749 spin_unlock(&mm
->page_table_lock
);
751 spin_lock(&mm
->page_table_lock
);
754 *tlbp
= tlb_gather_mmu(mm
, fullmm
);
756 zap_bytes
= ZAP_BLOCK_SIZE
;
760 return start
; /* which is now the end (or restart) address */
764 * zap_page_range - remove user pages in a given range
765 * @vma: vm_area_struct holding the applicable pages
766 * @address: starting address of pages to zap
767 * @size: number of bytes to zap
768 * @details: details of nonlinear truncation or shared cache invalidation
770 unsigned long zap_page_range(struct vm_area_struct
*vma
, unsigned long address
,
771 unsigned long size
, struct zap_details
*details
)
773 struct mm_struct
*mm
= vma
->vm_mm
;
774 struct mmu_gather
*tlb
;
775 unsigned long end
= address
+ size
;
776 unsigned long nr_accounted
= 0;
778 if (is_vm_hugetlb_page(vma
)) {
779 zap_hugepage_range(vma
, address
, size
);
784 spin_lock(&mm
->page_table_lock
);
785 tlb
= tlb_gather_mmu(mm
, 0);
786 end
= unmap_vmas(&tlb
, mm
, vma
, address
, end
, &nr_accounted
, details
);
787 tlb_finish_mmu(tlb
, address
, end
);
788 spin_unlock(&mm
->page_table_lock
);
793 * Do a quick page-table lookup for a single page.
794 * mm->page_table_lock must be held.
796 static struct page
*__follow_page(struct mm_struct
*mm
, unsigned long address
,
797 int read
, int write
, int accessed
)
806 page
= follow_huge_addr(mm
, address
, write
);
810 pgd
= pgd_offset(mm
, address
);
811 if (pgd_none(*pgd
) || unlikely(pgd_bad(*pgd
)))
814 pud
= pud_offset(pgd
, address
);
815 if (pud_none(*pud
) || unlikely(pud_bad(*pud
)))
818 pmd
= pmd_offset(pud
, address
);
819 if (pmd_none(*pmd
) || unlikely(pmd_bad(*pmd
)))
822 return follow_huge_pmd(mm
, address
, pmd
, write
);
824 ptep
= pte_offset_map(pmd
, address
);
830 if (pte_present(pte
)) {
831 if (write
&& !pte_write(pte
))
833 if (read
&& !pte_read(pte
))
836 if (pfn_valid(pfn
)) {
837 page
= pfn_to_page(pfn
);
839 if (write
&& !pte_dirty(pte
) &&!PageDirty(page
))
840 set_page_dirty(page
);
841 mark_page_accessed(page
);
852 follow_page(struct mm_struct
*mm
, unsigned long address
, int write
)
854 return __follow_page(mm
, address
, 0, write
, 1);
858 * check_user_page_readable() can be called frm niterrupt context by oprofile,
859 * so we need to avoid taking any non-irq-safe locks
861 int check_user_page_readable(struct mm_struct
*mm
, unsigned long address
)
863 return __follow_page(mm
, address
, 1, 0, 0) != NULL
;
865 EXPORT_SYMBOL(check_user_page_readable
);
868 untouched_anonymous_page(struct mm_struct
* mm
, struct vm_area_struct
*vma
,
869 unsigned long address
)
875 /* Check if the vma is for an anonymous mapping. */
876 if (vma
->vm_ops
&& vma
->vm_ops
->nopage
)
879 /* Check if page directory entry exists. */
880 pgd
= pgd_offset(mm
, address
);
881 if (pgd_none(*pgd
) || unlikely(pgd_bad(*pgd
)))
884 pud
= pud_offset(pgd
, address
);
885 if (pud_none(*pud
) || unlikely(pud_bad(*pud
)))
888 /* Check if page middle directory entry exists. */
889 pmd
= pmd_offset(pud
, address
);
890 if (pmd_none(*pmd
) || unlikely(pmd_bad(*pmd
)))
893 /* There is a pte slot for 'address' in 'mm'. */
897 int get_user_pages(struct task_struct
*tsk
, struct mm_struct
*mm
,
898 unsigned long start
, int len
, int write
, int force
,
899 struct page
**pages
, struct vm_area_struct
**vmas
)
905 * Require read or write permissions.
906 * If 'force' is set, we only require the "MAY" flags.
908 flags
= write
? (VM_WRITE
| VM_MAYWRITE
) : (VM_READ
| VM_MAYREAD
);
909 flags
&= force
? (VM_MAYREAD
| VM_MAYWRITE
) : (VM_READ
| VM_WRITE
);
913 struct vm_area_struct
* vma
;
915 vma
= find_extend_vma(mm
, start
);
916 if (!vma
&& in_gate_area(tsk
, start
)) {
917 unsigned long pg
= start
& PAGE_MASK
;
918 struct vm_area_struct
*gate_vma
= get_gate_vma(tsk
);
923 if (write
) /* user gate pages are read-only */
924 return i
? : -EFAULT
;
926 pgd
= pgd_offset_k(pg
);
928 pgd
= pgd_offset_gate(mm
, pg
);
929 BUG_ON(pgd_none(*pgd
));
930 pud
= pud_offset(pgd
, pg
);
931 BUG_ON(pud_none(*pud
));
932 pmd
= pmd_offset(pud
, pg
);
934 return i
? : -EFAULT
;
935 pte
= pte_offset_map(pmd
, pg
);
936 if (pte_none(*pte
)) {
938 return i
? : -EFAULT
;
941 pages
[i
] = pte_page(*pte
);
953 if (!vma
|| (vma
->vm_flags
& VM_IO
)
954 || !(flags
& vma
->vm_flags
))
955 return i
? : -EFAULT
;
957 if (is_vm_hugetlb_page(vma
)) {
958 i
= follow_hugetlb_page(mm
, vma
, pages
, vmas
,
962 spin_lock(&mm
->page_table_lock
);
964 int write_access
= write
;
967 cond_resched_lock(&mm
->page_table_lock
);
968 while (!(page
= follow_page(mm
, start
, write_access
))) {
972 * Shortcut for anonymous pages. We don't want
973 * to force the creation of pages tables for
974 * insanely big anonymously mapped areas that
975 * nobody touched so far. This is important
976 * for doing a core dump for these mappings.
978 if (!write
&& untouched_anonymous_page(mm
,vma
,start
)) {
979 page
= ZERO_PAGE(start
);
982 spin_unlock(&mm
->page_table_lock
);
983 ret
= __handle_mm_fault(mm
, vma
, start
, write_access
);
986 * The VM_FAULT_WRITE bit tells us that do_wp_page has
987 * broken COW when necessary, even if maybe_mkwrite
988 * decided not to set pte_write. We can thus safely do
989 * subsequent page lookups as if they were reads.
991 if (ret
& VM_FAULT_WRITE
)
994 switch (ret
& ~VM_FAULT_WRITE
) {
1001 case VM_FAULT_SIGBUS
:
1002 return i
? i
: -EFAULT
;
1004 return i
? i
: -ENOMEM
;
1008 spin_lock(&mm
->page_table_lock
);
1012 flush_dcache_page(page
);
1013 if (!PageReserved(page
))
1014 page_cache_get(page
);
1021 } while (len
&& start
< vma
->vm_end
);
1022 spin_unlock(&mm
->page_table_lock
);
1026 EXPORT_SYMBOL(get_user_pages
);
1028 static int zeromap_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
1029 unsigned long addr
, unsigned long end
, pgprot_t prot
)
1033 pte
= pte_alloc_map(mm
, pmd
, addr
);
1037 pte_t zero_pte
= pte_wrprotect(mk_pte(ZERO_PAGE(addr
), prot
));
1038 BUG_ON(!pte_none(*pte
));
1039 set_pte_at(mm
, addr
, pte
, zero_pte
);
1040 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
1045 static inline int zeromap_pmd_range(struct mm_struct
*mm
, pud_t
*pud
,
1046 unsigned long addr
, unsigned long end
, pgprot_t prot
)
1051 pmd
= pmd_alloc(mm
, pud
, addr
);
1055 next
= pmd_addr_end(addr
, end
);
1056 if (zeromap_pte_range(mm
, pmd
, addr
, next
, prot
))
1058 } while (pmd
++, addr
= next
, addr
!= end
);
1062 static inline int zeromap_pud_range(struct mm_struct
*mm
, pgd_t
*pgd
,
1063 unsigned long addr
, unsigned long end
, pgprot_t prot
)
1068 pud
= pud_alloc(mm
, pgd
, addr
);
1072 next
= pud_addr_end(addr
, end
);
1073 if (zeromap_pmd_range(mm
, pud
, addr
, next
, prot
))
1075 } while (pud
++, addr
= next
, addr
!= end
);
1079 int zeromap_page_range(struct vm_area_struct
*vma
,
1080 unsigned long addr
, unsigned long size
, pgprot_t prot
)
1084 unsigned long end
= addr
+ size
;
1085 struct mm_struct
*mm
= vma
->vm_mm
;
1088 BUG_ON(addr
>= end
);
1089 pgd
= pgd_offset(mm
, addr
);
1090 flush_cache_range(vma
, addr
, end
);
1091 spin_lock(&mm
->page_table_lock
);
1093 next
= pgd_addr_end(addr
, end
);
1094 err
= zeromap_pud_range(mm
, pgd
, addr
, next
, prot
);
1097 } while (pgd
++, addr
= next
, addr
!= end
);
1098 spin_unlock(&mm
->page_table_lock
);
1103 * maps a range of physical memory into the requested pages. the old
1104 * mappings are removed. any references to nonexistent pages results
1105 * in null mappings (currently treated as "copy-on-access")
1107 static int remap_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
1108 unsigned long addr
, unsigned long end
,
1109 unsigned long pfn
, pgprot_t prot
)
1113 pte
= pte_alloc_map(mm
, pmd
, addr
);
1117 BUG_ON(!pte_none(*pte
));
1118 if (!pfn_valid(pfn
) || PageReserved(pfn_to_page(pfn
)))
1119 set_pte_at(mm
, addr
, pte
, pfn_pte(pfn
, prot
));
1121 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
1126 static inline int remap_pmd_range(struct mm_struct
*mm
, pud_t
*pud
,
1127 unsigned long addr
, unsigned long end
,
1128 unsigned long pfn
, pgprot_t prot
)
1133 pfn
-= addr
>> PAGE_SHIFT
;
1134 pmd
= pmd_alloc(mm
, pud
, addr
);
1138 next
= pmd_addr_end(addr
, end
);
1139 if (remap_pte_range(mm
, pmd
, addr
, next
,
1140 pfn
+ (addr
>> PAGE_SHIFT
), prot
))
1142 } while (pmd
++, addr
= next
, addr
!= end
);
1146 static inline int remap_pud_range(struct mm_struct
*mm
, pgd_t
*pgd
,
1147 unsigned long addr
, unsigned long end
,
1148 unsigned long pfn
, pgprot_t prot
)
1153 pfn
-= addr
>> PAGE_SHIFT
;
1154 pud
= pud_alloc(mm
, pgd
, addr
);
1158 next
= pud_addr_end(addr
, end
);
1159 if (remap_pmd_range(mm
, pud
, addr
, next
,
1160 pfn
+ (addr
>> PAGE_SHIFT
), prot
))
1162 } while (pud
++, addr
= next
, addr
!= end
);
1166 /* Note: this is only safe if the mm semaphore is held when called. */
1167 int remap_pfn_range(struct vm_area_struct
*vma
, unsigned long addr
,
1168 unsigned long pfn
, unsigned long size
, pgprot_t prot
)
1172 unsigned long end
= addr
+ PAGE_ALIGN(size
);
1173 struct mm_struct
*mm
= vma
->vm_mm
;
1177 * Physically remapped pages are special. Tell the
1178 * rest of the world about it:
1179 * VM_IO tells people not to look at these pages
1180 * (accesses can have side effects).
1181 * VM_RESERVED tells swapout not to try to touch
1184 vma
->vm_flags
|= VM_IO
| VM_RESERVED
;
1186 BUG_ON(addr
>= end
);
1187 pfn
-= addr
>> PAGE_SHIFT
;
1188 pgd
= pgd_offset(mm
, addr
);
1189 flush_cache_range(vma
, addr
, end
);
1190 spin_lock(&mm
->page_table_lock
);
1192 next
= pgd_addr_end(addr
, end
);
1193 err
= remap_pud_range(mm
, pgd
, addr
, next
,
1194 pfn
+ (addr
>> PAGE_SHIFT
), prot
);
1197 } while (pgd
++, addr
= next
, addr
!= end
);
1198 spin_unlock(&mm
->page_table_lock
);
1201 EXPORT_SYMBOL(remap_pfn_range
);
1204 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when
1205 * servicing faults for write access. In the normal case, do always want
1206 * pte_mkwrite. But get_user_pages can cause write faults for mappings
1207 * that do not have writing enabled, when used by access_process_vm.
1209 static inline pte_t
maybe_mkwrite(pte_t pte
, struct vm_area_struct
*vma
)
1211 if (likely(vma
->vm_flags
& VM_WRITE
))
1212 pte
= pte_mkwrite(pte
);
1217 * This routine handles present pages, when users try to write
1218 * to a shared page. It is done by copying the page to a new address
1219 * and decrementing the shared-page counter for the old page.
1221 * Note that this routine assumes that the protection checks have been
1222 * done by the caller (the low-level page fault routine in most cases).
1223 * Thus we can safely just mark it writable once we've done any necessary
1226 * We also mark the page dirty at this point even though the page will
1227 * change only once the write actually happens. This avoids a few races,
1228 * and potentially makes it more efficient.
1230 * We hold the mm semaphore and the page_table_lock on entry and exit
1231 * with the page_table_lock released.
1233 static int do_wp_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1234 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
1237 struct page
*old_page
, *new_page
;
1238 unsigned long pfn
= pte_pfn(orig_pte
);
1240 int ret
= VM_FAULT_MINOR
;
1242 if (unlikely(!pfn_valid(pfn
))) {
1244 * Page table corrupted: show pte and kill process.
1246 pte_ERROR(orig_pte
);
1250 old_page
= pfn_to_page(pfn
);
1252 if (PageAnon(old_page
) && !TestSetPageLocked(old_page
)) {
1253 int reuse
= can_share_swap_page(old_page
);
1254 unlock_page(old_page
);
1256 flush_cache_page(vma
, address
, pfn
);
1257 entry
= pte_mkyoung(orig_pte
);
1258 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1259 ptep_set_access_flags(vma
, address
, page_table
, entry
, 1);
1260 update_mmu_cache(vma
, address
, entry
);
1261 lazy_mmu_prot_update(entry
);
1262 ret
|= VM_FAULT_WRITE
;
1268 * Ok, we need to copy. Oh, well..
1270 if (!PageReserved(old_page
))
1271 page_cache_get(old_page
);
1272 pte_unmap(page_table
);
1273 spin_unlock(&mm
->page_table_lock
);
1275 if (unlikely(anon_vma_prepare(vma
)))
1277 if (old_page
== ZERO_PAGE(address
)) {
1278 new_page
= alloc_zeroed_user_highpage(vma
, address
);
1282 new_page
= alloc_page_vma(GFP_HIGHUSER
, vma
, address
);
1285 copy_user_highpage(new_page
, old_page
, address
);
1289 * Re-check the pte - we dropped the lock
1291 spin_lock(&mm
->page_table_lock
);
1292 page_table
= pte_offset_map(pmd
, address
);
1293 if (likely(pte_same(*page_table
, orig_pte
))) {
1294 if (PageReserved(old_page
))
1295 inc_mm_counter(mm
, anon_rss
);
1297 page_remove_rmap(old_page
);
1298 if (!PageAnon(old_page
)) {
1299 inc_mm_counter(mm
, anon_rss
);
1300 dec_mm_counter(mm
, file_rss
);
1303 flush_cache_page(vma
, address
, pfn
);
1304 entry
= mk_pte(new_page
, vma
->vm_page_prot
);
1305 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1306 ptep_establish(vma
, address
, page_table
, entry
);
1307 update_mmu_cache(vma
, address
, entry
);
1308 lazy_mmu_prot_update(entry
);
1310 lru_cache_add_active(new_page
);
1311 page_add_anon_rmap(new_page
, vma
, address
);
1313 /* Free the old page.. */
1314 new_page
= old_page
;
1315 ret
|= VM_FAULT_WRITE
;
1317 page_cache_release(new_page
);
1318 page_cache_release(old_page
);
1320 pte_unmap(page_table
);
1321 spin_unlock(&mm
->page_table_lock
);
1324 page_cache_release(old_page
);
1325 return VM_FAULT_OOM
;
1329 * Helper functions for unmap_mapping_range().
1331 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1333 * We have to restart searching the prio_tree whenever we drop the lock,
1334 * since the iterator is only valid while the lock is held, and anyway
1335 * a later vma might be split and reinserted earlier while lock dropped.
1337 * The list of nonlinear vmas could be handled more efficiently, using
1338 * a placeholder, but handle it in the same way until a need is shown.
1339 * It is important to search the prio_tree before nonlinear list: a vma
1340 * may become nonlinear and be shifted from prio_tree to nonlinear list
1341 * while the lock is dropped; but never shifted from list to prio_tree.
1343 * In order to make forward progress despite restarting the search,
1344 * vm_truncate_count is used to mark a vma as now dealt with, so we can
1345 * quickly skip it next time around. Since the prio_tree search only
1346 * shows us those vmas affected by unmapping the range in question, we
1347 * can't efficiently keep all vmas in step with mapping->truncate_count:
1348 * so instead reset them all whenever it wraps back to 0 (then go to 1).
1349 * mapping->truncate_count and vma->vm_truncate_count are protected by
1352 * In order to make forward progress despite repeatedly restarting some
1353 * large vma, note the restart_addr from unmap_vmas when it breaks out:
1354 * and restart from that address when we reach that vma again. It might
1355 * have been split or merged, shrunk or extended, but never shifted: so
1356 * restart_addr remains valid so long as it remains in the vma's range.
1357 * unmap_mapping_range forces truncate_count to leap over page-aligned
1358 * values so we can save vma's restart_addr in its truncate_count field.
1360 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1362 static void reset_vma_truncate_counts(struct address_space
*mapping
)
1364 struct vm_area_struct
*vma
;
1365 struct prio_tree_iter iter
;
1367 vma_prio_tree_foreach(vma
, &iter
, &mapping
->i_mmap
, 0, ULONG_MAX
)
1368 vma
->vm_truncate_count
= 0;
1369 list_for_each_entry(vma
, &mapping
->i_mmap_nonlinear
, shared
.vm_set
.list
)
1370 vma
->vm_truncate_count
= 0;
1373 static int unmap_mapping_range_vma(struct vm_area_struct
*vma
,
1374 unsigned long start_addr
, unsigned long end_addr
,
1375 struct zap_details
*details
)
1377 unsigned long restart_addr
;
1381 restart_addr
= vma
->vm_truncate_count
;
1382 if (is_restart_addr(restart_addr
) && start_addr
< restart_addr
) {
1383 start_addr
= restart_addr
;
1384 if (start_addr
>= end_addr
) {
1385 /* Top of vma has been split off since last time */
1386 vma
->vm_truncate_count
= details
->truncate_count
;
1391 restart_addr
= zap_page_range(vma
, start_addr
,
1392 end_addr
- start_addr
, details
);
1395 * We cannot rely on the break test in unmap_vmas:
1396 * on the one hand, we don't want to restart our loop
1397 * just because that broke out for the page_table_lock;
1398 * on the other hand, it does no test when vma is small.
1400 need_break
= need_resched() ||
1401 need_lockbreak(details
->i_mmap_lock
);
1403 if (restart_addr
>= end_addr
) {
1404 /* We have now completed this vma: mark it so */
1405 vma
->vm_truncate_count
= details
->truncate_count
;
1409 /* Note restart_addr in vma's truncate_count field */
1410 vma
->vm_truncate_count
= restart_addr
;
1415 spin_unlock(details
->i_mmap_lock
);
1417 spin_lock(details
->i_mmap_lock
);
1421 static inline void unmap_mapping_range_tree(struct prio_tree_root
*root
,
1422 struct zap_details
*details
)
1424 struct vm_area_struct
*vma
;
1425 struct prio_tree_iter iter
;
1426 pgoff_t vba
, vea
, zba
, zea
;
1429 vma_prio_tree_foreach(vma
, &iter
, root
,
1430 details
->first_index
, details
->last_index
) {
1431 /* Skip quickly over those we have already dealt with */
1432 if (vma
->vm_truncate_count
== details
->truncate_count
)
1435 vba
= vma
->vm_pgoff
;
1436 vea
= vba
+ ((vma
->vm_end
- vma
->vm_start
) >> PAGE_SHIFT
) - 1;
1437 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1438 zba
= details
->first_index
;
1441 zea
= details
->last_index
;
1445 if (unmap_mapping_range_vma(vma
,
1446 ((zba
- vba
) << PAGE_SHIFT
) + vma
->vm_start
,
1447 ((zea
- vba
+ 1) << PAGE_SHIFT
) + vma
->vm_start
,
1453 static inline void unmap_mapping_range_list(struct list_head
*head
,
1454 struct zap_details
*details
)
1456 struct vm_area_struct
*vma
;
1459 * In nonlinear VMAs there is no correspondence between virtual address
1460 * offset and file offset. So we must perform an exhaustive search
1461 * across *all* the pages in each nonlinear VMA, not just the pages
1462 * whose virtual address lies outside the file truncation point.
1465 list_for_each_entry(vma
, head
, shared
.vm_set
.list
) {
1466 /* Skip quickly over those we have already dealt with */
1467 if (vma
->vm_truncate_count
== details
->truncate_count
)
1469 details
->nonlinear_vma
= vma
;
1470 if (unmap_mapping_range_vma(vma
, vma
->vm_start
,
1471 vma
->vm_end
, details
) < 0)
1477 * unmap_mapping_range - unmap the portion of all mmaps
1478 * in the specified address_space corresponding to the specified
1479 * page range in the underlying file.
1480 * @mapping: the address space containing mmaps to be unmapped.
1481 * @holebegin: byte in first page to unmap, relative to the start of
1482 * the underlying file. This will be rounded down to a PAGE_SIZE
1483 * boundary. Note that this is different from vmtruncate(), which
1484 * must keep the partial page. In contrast, we must get rid of
1486 * @holelen: size of prospective hole in bytes. This will be rounded
1487 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
1489 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1490 * but 0 when invalidating pagecache, don't throw away private data.
1492 void unmap_mapping_range(struct address_space
*mapping
,
1493 loff_t
const holebegin
, loff_t
const holelen
, int even_cows
)
1495 struct zap_details details
;
1496 pgoff_t hba
= holebegin
>> PAGE_SHIFT
;
1497 pgoff_t hlen
= (holelen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1499 /* Check for overflow. */
1500 if (sizeof(holelen
) > sizeof(hlen
)) {
1502 (holebegin
+ holelen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1503 if (holeend
& ~(long long)ULONG_MAX
)
1504 hlen
= ULONG_MAX
- hba
+ 1;
1507 details
.check_mapping
= even_cows
? NULL
: mapping
;
1508 details
.nonlinear_vma
= NULL
;
1509 details
.first_index
= hba
;
1510 details
.last_index
= hba
+ hlen
- 1;
1511 if (details
.last_index
< details
.first_index
)
1512 details
.last_index
= ULONG_MAX
;
1513 details
.i_mmap_lock
= &mapping
->i_mmap_lock
;
1515 spin_lock(&mapping
->i_mmap_lock
);
1517 /* serialize i_size write against truncate_count write */
1519 /* Protect against page faults, and endless unmapping loops */
1520 mapping
->truncate_count
++;
1522 * For archs where spin_lock has inclusive semantics like ia64
1523 * this smp_mb() will prevent to read pagetable contents
1524 * before the truncate_count increment is visible to
1528 if (unlikely(is_restart_addr(mapping
->truncate_count
))) {
1529 if (mapping
->truncate_count
== 0)
1530 reset_vma_truncate_counts(mapping
);
1531 mapping
->truncate_count
++;
1533 details
.truncate_count
= mapping
->truncate_count
;
1535 if (unlikely(!prio_tree_empty(&mapping
->i_mmap
)))
1536 unmap_mapping_range_tree(&mapping
->i_mmap
, &details
);
1537 if (unlikely(!list_empty(&mapping
->i_mmap_nonlinear
)))
1538 unmap_mapping_range_list(&mapping
->i_mmap_nonlinear
, &details
);
1539 spin_unlock(&mapping
->i_mmap_lock
);
1541 EXPORT_SYMBOL(unmap_mapping_range
);
1544 * Handle all mappings that got truncated by a "truncate()"
1547 * NOTE! We have to be ready to update the memory sharing
1548 * between the file and the memory map for a potential last
1549 * incomplete page. Ugly, but necessary.
1551 int vmtruncate(struct inode
* inode
, loff_t offset
)
1553 struct address_space
*mapping
= inode
->i_mapping
;
1554 unsigned long limit
;
1556 if (inode
->i_size
< offset
)
1559 * truncation of in-use swapfiles is disallowed - it would cause
1560 * subsequent swapout to scribble on the now-freed blocks.
1562 if (IS_SWAPFILE(inode
))
1564 i_size_write(inode
, offset
);
1565 unmap_mapping_range(mapping
, offset
+ PAGE_SIZE
- 1, 0, 1);
1566 truncate_inode_pages(mapping
, offset
);
1570 limit
= current
->signal
->rlim
[RLIMIT_FSIZE
].rlim_cur
;
1571 if (limit
!= RLIM_INFINITY
&& offset
> limit
)
1573 if (offset
> inode
->i_sb
->s_maxbytes
)
1575 i_size_write(inode
, offset
);
1578 if (inode
->i_op
&& inode
->i_op
->truncate
)
1579 inode
->i_op
->truncate(inode
);
1582 send_sig(SIGXFSZ
, current
, 0);
1589 EXPORT_SYMBOL(vmtruncate
);
1592 * Primitive swap readahead code. We simply read an aligned block of
1593 * (1 << page_cluster) entries in the swap area. This method is chosen
1594 * because it doesn't cost us any seek time. We also make sure to queue
1595 * the 'original' request together with the readahead ones...
1597 * This has been extended to use the NUMA policies from the mm triggering
1600 * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
1602 void swapin_readahead(swp_entry_t entry
, unsigned long addr
,struct vm_area_struct
*vma
)
1605 struct vm_area_struct
*next_vma
= vma
? vma
->vm_next
: NULL
;
1608 struct page
*new_page
;
1609 unsigned long offset
;
1612 * Get the number of handles we should do readahead io to.
1614 num
= valid_swaphandles(entry
, &offset
);
1615 for (i
= 0; i
< num
; offset
++, i
++) {
1616 /* Ok, do the async read-ahead now */
1617 new_page
= read_swap_cache_async(swp_entry(swp_type(entry
),
1618 offset
), vma
, addr
);
1621 page_cache_release(new_page
);
1624 * Find the next applicable VMA for the NUMA policy.
1630 if (addr
>= vma
->vm_end
) {
1632 next_vma
= vma
? vma
->vm_next
: NULL
;
1634 if (vma
&& addr
< vma
->vm_start
)
1637 if (next_vma
&& addr
>= next_vma
->vm_start
) {
1639 next_vma
= vma
->vm_next
;
1644 lru_add_drain(); /* Push any new pages onto the LRU now */
1648 * We hold the mm semaphore and the page_table_lock on entry and
1649 * should release the pagetable lock on exit..
1651 static int do_swap_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1652 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
1653 int write_access
, pte_t orig_pte
)
1658 int ret
= VM_FAULT_MINOR
;
1660 pte_unmap(page_table
);
1661 spin_unlock(&mm
->page_table_lock
);
1663 entry
= pte_to_swp_entry(orig_pte
);
1664 page
= lookup_swap_cache(entry
);
1666 swapin_readahead(entry
, address
, vma
);
1667 page
= read_swap_cache_async(entry
, vma
, address
);
1670 * Back out if somebody else faulted in this pte while
1671 * we released the page table lock.
1673 spin_lock(&mm
->page_table_lock
);
1674 page_table
= pte_offset_map(pmd
, address
);
1675 if (likely(pte_same(*page_table
, orig_pte
)))
1680 /* Had to read the page from swap area: Major fault */
1681 ret
= VM_FAULT_MAJOR
;
1682 inc_page_state(pgmajfault
);
1686 mark_page_accessed(page
);
1690 * Back out if somebody else faulted in this pte while we
1691 * released the page table lock.
1693 spin_lock(&mm
->page_table_lock
);
1694 page_table
= pte_offset_map(pmd
, address
);
1695 if (unlikely(!pte_same(*page_table
, orig_pte
))) {
1696 ret
= VM_FAULT_MINOR
;
1700 if (unlikely(!PageUptodate(page
))) {
1701 ret
= VM_FAULT_SIGBUS
;
1705 /* The page isn't present yet, go ahead with the fault. */
1707 inc_mm_counter(mm
, anon_rss
);
1708 pte
= mk_pte(page
, vma
->vm_page_prot
);
1709 if (write_access
&& can_share_swap_page(page
)) {
1710 pte
= maybe_mkwrite(pte_mkdirty(pte
), vma
);
1714 flush_icache_page(vma
, page
);
1715 set_pte_at(mm
, address
, page_table
, pte
);
1716 page_add_anon_rmap(page
, vma
, address
);
1720 remove_exclusive_swap_page(page
);
1724 if (do_wp_page(mm
, vma
, address
,
1725 page_table
, pmd
, pte
) == VM_FAULT_OOM
)
1730 /* No need to invalidate - it was non-present before */
1731 update_mmu_cache(vma
, address
, pte
);
1732 lazy_mmu_prot_update(pte
);
1734 pte_unmap(page_table
);
1735 spin_unlock(&mm
->page_table_lock
);
1739 pte_unmap(page_table
);
1740 spin_unlock(&mm
->page_table_lock
);
1742 page_cache_release(page
);
1747 * We are called with the MM semaphore and page_table_lock
1748 * spinlock held to protect against concurrent faults in
1749 * multithreaded programs.
1751 static int do_anonymous_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1752 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
1757 /* Mapping of ZERO_PAGE - vm_page_prot is readonly */
1758 entry
= mk_pte(ZERO_PAGE(addr
), vma
->vm_page_prot
);
1763 /* Allocate our own private page. */
1764 pte_unmap(page_table
);
1765 spin_unlock(&mm
->page_table_lock
);
1767 if (unlikely(anon_vma_prepare(vma
)))
1769 page
= alloc_zeroed_user_highpage(vma
, address
);
1773 spin_lock(&mm
->page_table_lock
);
1774 page_table
= pte_offset_map(pmd
, address
);
1776 if (!pte_none(*page_table
)) {
1777 page_cache_release(page
);
1780 inc_mm_counter(mm
, anon_rss
);
1781 entry
= mk_pte(page
, vma
->vm_page_prot
);
1782 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1783 lru_cache_add_active(page
);
1784 SetPageReferenced(page
);
1785 page_add_anon_rmap(page
, vma
, address
);
1788 set_pte_at(mm
, address
, page_table
, entry
);
1790 /* No need to invalidate - it was non-present before */
1791 update_mmu_cache(vma
, address
, entry
);
1792 lazy_mmu_prot_update(entry
);
1794 pte_unmap(page_table
);
1795 spin_unlock(&mm
->page_table_lock
);
1796 return VM_FAULT_MINOR
;
1798 return VM_FAULT_OOM
;
1802 * do_no_page() tries to create a new page mapping. It aggressively
1803 * tries to share with existing pages, but makes a separate copy if
1804 * the "write_access" parameter is true in order to avoid the next
1807 * As this is called only for pages that do not currently exist, we
1808 * do not need to flush old virtual caches or the TLB.
1810 * This is called with the MM semaphore held and the page table
1811 * spinlock held. Exit with the spinlock released.
1813 static int do_no_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1814 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
1817 struct page
*new_page
;
1818 struct address_space
*mapping
= NULL
;
1820 unsigned int sequence
= 0;
1821 int ret
= VM_FAULT_MINOR
;
1824 pte_unmap(page_table
);
1825 spin_unlock(&mm
->page_table_lock
);
1828 mapping
= vma
->vm_file
->f_mapping
;
1829 sequence
= mapping
->truncate_count
;
1830 smp_rmb(); /* serializes i_size against truncate_count */
1833 new_page
= vma
->vm_ops
->nopage(vma
, address
& PAGE_MASK
, &ret
);
1835 * No smp_rmb is needed here as long as there's a full
1836 * spin_lock/unlock sequence inside the ->nopage callback
1837 * (for the pagecache lookup) that acts as an implicit
1838 * smp_mb() and prevents the i_size read to happen
1839 * after the next truncate_count read.
1842 /* no page was available -- either SIGBUS or OOM */
1843 if (new_page
== NOPAGE_SIGBUS
)
1844 return VM_FAULT_SIGBUS
;
1845 if (new_page
== NOPAGE_OOM
)
1846 return VM_FAULT_OOM
;
1849 * Should we do an early C-O-W break?
1851 if (write_access
&& !(vma
->vm_flags
& VM_SHARED
)) {
1854 if (unlikely(anon_vma_prepare(vma
)))
1856 page
= alloc_page_vma(GFP_HIGHUSER
, vma
, address
);
1859 copy_user_highpage(page
, new_page
, address
);
1860 page_cache_release(new_page
);
1865 spin_lock(&mm
->page_table_lock
);
1867 * For a file-backed vma, someone could have truncated or otherwise
1868 * invalidated this page. If unmap_mapping_range got called,
1869 * retry getting the page.
1871 if (mapping
&& unlikely(sequence
!= mapping
->truncate_count
)) {
1872 spin_unlock(&mm
->page_table_lock
);
1873 page_cache_release(new_page
);
1875 sequence
= mapping
->truncate_count
;
1879 page_table
= pte_offset_map(pmd
, address
);
1882 * This silly early PAGE_DIRTY setting removes a race
1883 * due to the bad i386 page protection. But it's valid
1884 * for other architectures too.
1886 * Note that if write_access is true, we either now have
1887 * an exclusive copy of the page, or this is a shared mapping,
1888 * so we can make it writable and dirty to avoid having to
1889 * handle that later.
1891 /* Only go through if we didn't race with anybody else... */
1892 if (pte_none(*page_table
)) {
1893 flush_icache_page(vma
, new_page
);
1894 entry
= mk_pte(new_page
, vma
->vm_page_prot
);
1896 entry
= maybe_mkwrite(pte_mkdirty(entry
), vma
);
1897 set_pte_at(mm
, address
, page_table
, entry
);
1899 inc_mm_counter(mm
, anon_rss
);
1900 lru_cache_add_active(new_page
);
1901 page_add_anon_rmap(new_page
, vma
, address
);
1902 } else if (!PageReserved(new_page
)) {
1903 inc_mm_counter(mm
, file_rss
);
1904 page_add_file_rmap(new_page
);
1907 /* One of our sibling threads was faster, back out. */
1908 page_cache_release(new_page
);
1912 /* no need to invalidate: a not-present page shouldn't be cached */
1913 update_mmu_cache(vma
, address
, entry
);
1914 lazy_mmu_prot_update(entry
);
1916 pte_unmap(page_table
);
1917 spin_unlock(&mm
->page_table_lock
);
1920 page_cache_release(new_page
);
1921 return VM_FAULT_OOM
;
1925 * Fault of a previously existing named mapping. Repopulate the pte
1926 * from the encoded file_pte if possible. This enables swappable
1929 static int do_file_page(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1930 unsigned long address
, pte_t
*page_table
, pmd_t
*pmd
,
1931 int write_access
, pte_t orig_pte
)
1936 pte_unmap(page_table
);
1937 spin_unlock(&mm
->page_table_lock
);
1939 if (unlikely(!(vma
->vm_flags
& VM_NONLINEAR
))) {
1941 * Page table corrupted: show pte and kill process.
1943 pte_ERROR(orig_pte
);
1944 return VM_FAULT_OOM
;
1946 /* We can then assume vm->vm_ops && vma->vm_ops->populate */
1948 pgoff
= pte_to_pgoff(orig_pte
);
1949 err
= vma
->vm_ops
->populate(vma
, address
& PAGE_MASK
, PAGE_SIZE
,
1950 vma
->vm_page_prot
, pgoff
, 0);
1952 return VM_FAULT_OOM
;
1954 return VM_FAULT_SIGBUS
;
1955 return VM_FAULT_MAJOR
;
1959 * These routines also need to handle stuff like marking pages dirty
1960 * and/or accessed for architectures that don't do it in hardware (most
1961 * RISC architectures). The early dirtying is also good on the i386.
1963 * There is also a hook called "update_mmu_cache()" that architectures
1964 * with external mmu caches can use to update those (ie the Sparc or
1965 * PowerPC hashed page tables that act as extended TLBs).
1967 * Note the "page_table_lock". It is to protect against kswapd removing
1968 * pages from under us. Note that kswapd only ever _removes_ pages, never
1969 * adds them. As such, once we have noticed that the page is not present,
1970 * we can drop the lock early.
1972 * The adding of pages is protected by the MM semaphore (which we hold),
1973 * so we don't need to worry about a page being suddenly been added into
1976 * We enter with the pagetable spinlock held, we are supposed to
1977 * release it when done.
1979 static inline int handle_pte_fault(struct mm_struct
*mm
,
1980 struct vm_area_struct
*vma
, unsigned long address
,
1981 pte_t
*pte
, pmd_t
*pmd
, int write_access
)
1986 if (!pte_present(entry
)) {
1987 if (pte_none(entry
)) {
1988 if (!vma
->vm_ops
|| !vma
->vm_ops
->nopage
)
1989 return do_anonymous_page(mm
, vma
, address
,
1990 pte
, pmd
, write_access
);
1991 return do_no_page(mm
, vma
, address
,
1992 pte
, pmd
, write_access
);
1994 if (pte_file(entry
))
1995 return do_file_page(mm
, vma
, address
,
1996 pte
, pmd
, write_access
, entry
);
1997 return do_swap_page(mm
, vma
, address
,
1998 pte
, pmd
, write_access
, entry
);
2002 if (!pte_write(entry
))
2003 return do_wp_page(mm
, vma
, address
, pte
, pmd
, entry
);
2004 entry
= pte_mkdirty(entry
);
2006 entry
= pte_mkyoung(entry
);
2007 ptep_set_access_flags(vma
, address
, pte
, entry
, write_access
);
2008 update_mmu_cache(vma
, address
, entry
);
2009 lazy_mmu_prot_update(entry
);
2011 spin_unlock(&mm
->page_table_lock
);
2012 return VM_FAULT_MINOR
;
2016 * By the time we get here, we already hold the mm semaphore
2018 int __handle_mm_fault(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
2019 unsigned long address
, int write_access
)
2026 __set_current_state(TASK_RUNNING
);
2028 inc_page_state(pgfault
);
2030 if (unlikely(is_vm_hugetlb_page(vma
)))
2031 return hugetlb_fault(mm
, vma
, address
, write_access
);
2034 * We need the page table lock to synchronize with kswapd
2035 * and the SMP-safe atomic PTE updates.
2037 pgd
= pgd_offset(mm
, address
);
2038 spin_lock(&mm
->page_table_lock
);
2040 pud
= pud_alloc(mm
, pgd
, address
);
2044 pmd
= pmd_alloc(mm
, pud
, address
);
2048 pte
= pte_alloc_map(mm
, pmd
, address
);
2052 return handle_pte_fault(mm
, vma
, address
, pte
, pmd
, write_access
);
2055 spin_unlock(&mm
->page_table_lock
);
2056 return VM_FAULT_OOM
;
2059 #ifndef __PAGETABLE_PUD_FOLDED
2061 * Allocate page upper directory.
2063 * We've already handled the fast-path in-line, and we own the
2066 pud_t fastcall
*__pud_alloc(struct mm_struct
*mm
, pgd_t
*pgd
, unsigned long address
)
2070 spin_unlock(&mm
->page_table_lock
);
2071 new = pud_alloc_one(mm
, address
);
2072 spin_lock(&mm
->page_table_lock
);
2077 * Because we dropped the lock, we should re-check the
2078 * entry, as somebody else could have populated it..
2080 if (pgd_present(*pgd
)) {
2084 pgd_populate(mm
, pgd
, new);
2086 return pud_offset(pgd
, address
);
2088 #endif /* __PAGETABLE_PUD_FOLDED */
2090 #ifndef __PAGETABLE_PMD_FOLDED
2092 * Allocate page middle directory.
2094 * We've already handled the fast-path in-line, and we own the
2097 pmd_t fastcall
*__pmd_alloc(struct mm_struct
*mm
, pud_t
*pud
, unsigned long address
)
2101 spin_unlock(&mm
->page_table_lock
);
2102 new = pmd_alloc_one(mm
, address
);
2103 spin_lock(&mm
->page_table_lock
);
2108 * Because we dropped the lock, we should re-check the
2109 * entry, as somebody else could have populated it..
2111 #ifndef __ARCH_HAS_4LEVEL_HACK
2112 if (pud_present(*pud
)) {
2116 pud_populate(mm
, pud
, new);
2118 if (pgd_present(*pud
)) {
2122 pgd_populate(mm
, pud
, new);
2123 #endif /* __ARCH_HAS_4LEVEL_HACK */
2126 return pmd_offset(pud
, address
);
2128 #endif /* __PAGETABLE_PMD_FOLDED */
2130 int make_pages_present(unsigned long addr
, unsigned long end
)
2132 int ret
, len
, write
;
2133 struct vm_area_struct
* vma
;
2135 vma
= find_vma(current
->mm
, addr
);
2138 write
= (vma
->vm_flags
& VM_WRITE
) != 0;
2141 if (end
> vma
->vm_end
)
2143 len
= (end
+PAGE_SIZE
-1)/PAGE_SIZE
-addr
/PAGE_SIZE
;
2144 ret
= get_user_pages(current
, current
->mm
, addr
,
2145 len
, write
, 0, NULL
, NULL
);
2148 return ret
== len
? 0 : -1;
2152 * Map a vmalloc()-space virtual address to the physical page.
2154 struct page
* vmalloc_to_page(void * vmalloc_addr
)
2156 unsigned long addr
= (unsigned long) vmalloc_addr
;
2157 struct page
*page
= NULL
;
2158 pgd_t
*pgd
= pgd_offset_k(addr
);
2163 if (!pgd_none(*pgd
)) {
2164 pud
= pud_offset(pgd
, addr
);
2165 if (!pud_none(*pud
)) {
2166 pmd
= pmd_offset(pud
, addr
);
2167 if (!pmd_none(*pmd
)) {
2168 ptep
= pte_offset_map(pmd
, addr
);
2170 if (pte_present(pte
))
2171 page
= pte_page(pte
);
2179 EXPORT_SYMBOL(vmalloc_to_page
);
2182 * Map a vmalloc()-space virtual address to the physical page frame number.
2184 unsigned long vmalloc_to_pfn(void * vmalloc_addr
)
2186 return page_to_pfn(vmalloc_to_page(vmalloc_addr
));
2189 EXPORT_SYMBOL(vmalloc_to_pfn
);
2192 * update_mem_hiwater
2193 * - update per process rss and vm high water data
2195 void update_mem_hiwater(struct task_struct
*tsk
)
2198 unsigned long rss
= get_mm_rss(tsk
->mm
);
2200 if (tsk
->mm
->hiwater_rss
< rss
)
2201 tsk
->mm
->hiwater_rss
= rss
;
2202 if (tsk
->mm
->hiwater_vm
< tsk
->mm
->total_vm
)
2203 tsk
->mm
->hiwater_vm
= tsk
->mm
->total_vm
;
2207 #if !defined(__HAVE_ARCH_GATE_AREA)
2209 #if defined(AT_SYSINFO_EHDR)
2210 static struct vm_area_struct gate_vma
;
2212 static int __init
gate_vma_init(void)
2214 gate_vma
.vm_mm
= NULL
;
2215 gate_vma
.vm_start
= FIXADDR_USER_START
;
2216 gate_vma
.vm_end
= FIXADDR_USER_END
;
2217 gate_vma
.vm_page_prot
= PAGE_READONLY
;
2218 gate_vma
.vm_flags
= 0;
2221 __initcall(gate_vma_init
);
2224 struct vm_area_struct
*get_gate_vma(struct task_struct
*tsk
)
2226 #ifdef AT_SYSINFO_EHDR
2233 int in_gate_area_no_task(unsigned long addr
)
2235 #ifdef AT_SYSINFO_EHDR
2236 if ((addr
>= FIXADDR_USER_START
) && (addr
< FIXADDR_USER_END
))
2242 #endif /* __HAVE_ARCH_GATE_AREA */