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Commit 2509ef26 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

badpage: zap print_bad_pte on swap and file 



Complete zap_pte_range()'s coverage of bad pagetable entries by calling
print_bad_pte() on a pte_file in a linear vma and on a bad swap entry.
That needs free_swap_and_cache() to tell it, which will also have shown
one of those "swap_free" errors (but with much less information).

Similar checks in fork's copy_one_pte()?  No, that would be more noisy
than helpful: we'll see them when parent and child exec or exit.

Where do_nonlinear_fault() calls print_bad_pte(): omit !VM_CAN_NONLINEAR
case, that could only be a bug in sys_remap_file_pages(), not a bad pte.
VM_FAULT_OOM rather than VM_FAULT_SIGBUS?  Well, okay, that is consistent
with what happens if do_swap_page() operates a bad swap entry; but don't
we have patches to be more careful about killing when VM_FAULT_OOM?

Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 22b31eec

include/linux/swap.h

+3 −9
Original line number Diff line number Diff line
@@ -302,7 +302,7 @@ extern swp_entry_t get_swap_page_of_type(int); 
extern int swap_duplicate(swp_entry_t);

extern int valid_swaphandles(swp_entry_t, unsigned long *);

extern void swap_free(swp_entry_t);

extern void free_swap_and_cache(swp_entry_t);

extern int free_swap_and_cache(swp_entry_t);

extern int swap_type_of(dev_t, sector_t, struct block_device **);

extern unsigned int count_swap_pages(int, int);

extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
@@ -352,14 +352,8 @@ static inline void show_swap_cache_info(void) 
{

}



static inline void free_swap_and_cache(swp_entry_t swp)

{

}



static inline int swap_duplicate(swp_entry_t swp)

{

	return 0;

}

#define free_swap_and_cache(swp)	is_migration_entry(swp)

#define swap_duplicate(swp)		is_migration_entry(swp)



static inline void swap_free(swp_entry_t swp)

{

mm/memory.c

+7 −4
Original line number Diff line number Diff line
@@ -810,8 +810,12 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, 
		 */

		if (unlikely(details))

			continue;

		if (!pte_file(ptent))

			free_swap_and_cache(pte_to_swp_entry(ptent));

		if (pte_file(ptent)) {

			if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))

				print_bad_pte(vma, addr, ptent, NULL);

		} else if

		  (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent))))

			print_bad_pte(vma, addr, ptent, NULL);

		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);

	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
@@ -2707,8 +2711,7 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))

		return 0;



	if (unlikely(!(vma->vm_flags & VM_NONLINEAR) ||

			!(vma->vm_flags & VM_CAN_NONLINEAR))) {

	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {

		/*

		 * Page table corrupted: show pte and kill process.

		 */

mm/swapfile.c

+4 −3
Original line number Diff line number Diff line
@@ -571,13 +571,13 @@ int try_to_free_swap(struct page *page) 
 * Free the swap entry like above, but also try to

 * free the page cache entry if it is the last user.

 */

void free_swap_and_cache(swp_entry_t entry)

int free_swap_and_cache(swp_entry_t entry)

{

	struct swap_info_struct *p;

	struct page *page = NULL;



	if (is_migration_entry(entry))

		return;

		return 1;



	p = swap_info_get(entry);

	if (p) {
@@ -603,6 +603,7 @@ void free_swap_and_cache(swp_entry_t entry) 
		unlock_page(page);

		page_cache_release(page);

	}

	return p != NULL;

}



#ifdef CONFIG_HIBERNATION