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badpage: simplify page_alloc flag check+clear

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Simplify the PAGE_FLAGS checking and clearing when freeing and allocating
a page: check the same flags as before when freeing, clear ALL the flags
(unless PageReserved) when freeing, check ALL flags off when allocating.

Signed-off-by: Hugh 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2009-01-06 14:40:05 -08:00 committed by Linus Torvalds
parent 0f64415d42
commit 79f4b7bf39
2 changed files with 14 additions and 30 deletions
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25
include/linux/page-flags.h
View file

@ -373,31 +373,22 @@ static inline void __ClearPageTail(struct page *page)
#define __PG_MLOCKED 0 #define __PG_MLOCKED 0
#endif #endif
#define PAGE_FLAGS (1 << PG_lru | 1 << PG_private | 1 << PG_locked | \
1 << PG_buddy | 1 << PG_writeback | \
1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
__PG_UNEVICTABLE | __PG_MLOCKED)
/*
* Flags checked in bad_page(). Pages on the free list should not have
* these flags set. It they are, there is a problem.
*/
#define PAGE_FLAGS_CLEAR_WHEN_BAD (PAGE_FLAGS | \
1 << PG_reclaim | 1 << PG_dirty | 1 << PG_swapbacked)
/* /*
* Flags checked when a page is freed. Pages being freed should not have * Flags checked when a page is freed. Pages being freed should not have
* these flags set. It they are, there is a problem. * these flags set. It they are, there is a problem.
*/ */
#define PAGE_FLAGS_CHECK_AT_FREE (PAGE_FLAGS | 1 << PG_reserved) #define PAGE_FLAGS_CHECK_AT_FREE \
(1 << PG_lru | 1 << PG_private | 1 << PG_locked | \
1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \
1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
__PG_UNEVICTABLE | __PG_MLOCKED)
/* /*
* Flags checked when a page is prepped for return by the page allocator. * Flags checked when a page is prepped for return by the page allocator.
* Pages being prepped should not have these flags set. It they are, there * Pages being prepped should not have any flags set. It they are set,
* is a problem. * there has been a kernel bug or struct page corruption.
*/ */
#define PAGE_FLAGS_CHECK_AT_PREP (PAGE_FLAGS | \ #define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1)
1 << PG_reserved | 1 << PG_dirty | 1 << PG_swapbacked)
#endif /* !__GENERATING_BOUNDS_H */ #endif /* !__GENERATING_BOUNDS_H */
#endif /* PAGE_FLAGS_H */ #endif /* PAGE_FLAGS_H */

19
mm/page_alloc.c
View file

@ -231,7 +231,6 @@ static void bad_page(struct page *page)
printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n" printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n"
KERN_EMERG "Backtrace:\n"); KERN_EMERG "Backtrace:\n");
dump_stack(); dump_stack();
page->flags &= ~PAGE_FLAGS_CLEAR_WHEN_BAD;
set_page_count(page, 0); set_page_count(page, 0);
reset_page_mapcount(page); reset_page_mapcount(page);
page->mapping = NULL; page->mapping = NULL;
@ -468,16 +467,16 @@ static inline int free_pages_check(struct page *page)
(page_count(page) != 0) | (page_count(page) != 0) |
(page->flags & PAGE_FLAGS_CHECK_AT_FREE))) (page->flags & PAGE_FLAGS_CHECK_AT_FREE)))
bad_page(page); bad_page(page);
if (PageDirty(page))
__ClearPageDirty(page);
if (PageSwapBacked(page))
__ClearPageSwapBacked(page);
/* /*
* For now, we report if PG_reserved was found set, but do not * For now, we report if PG_reserved was found set, but do not
* clear it, and do not free the page. But we shall soon need * clear it, and do not free the page. But we shall soon need
* to do more, for when the ZERO_PAGE count wraps negative. * to do more, for when the ZERO_PAGE count wraps negative.
*/ */
return PageReserved(page); if (PageReserved(page))
return 1;
if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
return 0;
} }
/* /*
@ -621,13 +620,7 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
if (PageReserved(page)) if (PageReserved(page))
return 1; return 1;
page->flags &= ~(1 << PG_uptodate | 1 << PG_error | 1 << PG_reclaim | page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
1 << PG_referenced | 1 << PG_arch_1 |
1 << PG_owner_priv_1 | 1 << PG_mappedtodisk
#ifdef CONFIG_UNEVICTABLE_LRU
| 1 << PG_mlocked
#endif
);
set_page_private(page, 0); set_page_private(page, 0);
set_page_refcounted(page); set_page_refcounted(page);