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badpage: keep any bad page out of circulation

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Until now the bad_page() checkers have special-cased PageReserved, keeping
those pages out of circulation thereafter.  Now extend the special case to
all: we want to keep ANY page with bad state out of circulation - the
"free" page may well be in use by something.

Leave the bad state of those pages untouched, for examination by
debuggers; except for PageBuddy - leaving that set would risk bringing the
page back.

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 14:40:06 -08:00 committed by Linus Torvalds
parent 79f4b7bf39
commit 8cc3b39221
1 changed files with 24 additions and 28 deletions
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52
mm/page_alloc.c
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@ -231,9 +231,9 @@ static void bad_page(struct page *page)
printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n"
KERN_EMERG "Backtrace:\n");
dump_stack();
set_page_count(page, 0);
reset_page_mapcount(page);
page->mapping = NULL;
/* Leave bad fields for debug, except PageBuddy could make trouble */
__ClearPageBuddy(page);
add_taint(TAINT_BAD_PAGE);
}
@ -290,25 +290,31 @@ void prep_compound_gigantic_page(struct page *page, unsigned long order)
}
#endif
static void destroy_compound_page(struct page *page, unsigned long order)
static int destroy_compound_page(struct page *page, unsigned long order)
{
int i;
int nr_pages = 1 << order;
int bad = 0;
if (unlikely(compound_order(page) != order))
if (unlikely(compound_order(page) != order) ||
unlikely(!PageHead(page))) {
bad_page(page);
bad++;
}
if (unlikely(!PageHead(page)))
bad_page(page);
__ClearPageHead(page);
for (i = 1; i < nr_pages; i++) {
struct page *p = page + i;
if (unlikely(!PageTail(p) |
(p->first_page != page)))
if (unlikely(!PageTail(p) | (p->first_page != page))) {
bad_page(page);
bad++;
}
__ClearPageTail(p);
}
return bad;
}
static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
@ -428,7 +434,8 @@ static inline void __free_one_page(struct page *page,
int migratetype = get_pageblock_migratetype(page);
if (unlikely(PageCompound(page)))
destroy_compound_page(page, order);
if (unlikely(destroy_compound_page(page, order)))
return;
page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
@ -465,15 +472,10 @@ static inline int free_pages_check(struct page *page)
if (unlikely(page_mapcount(page) |
(page->mapping != NULL) |
(page_count(page) != 0) |
(page->flags & PAGE_FLAGS_CHECK_AT_FREE)))
(page->flags & PAGE_FLAGS_CHECK_AT_FREE))) {
bad_page(page);
/*
* 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
* to do more, for when the ZERO_PAGE count wraps negative.
*/
if (PageReserved(page))
return 1;
}
if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
return 0;
@ -521,11 +523,11 @@ static void __free_pages_ok(struct page *page, unsigned int order)
{
unsigned long flags;
int i;
int reserved = 0;
int bad = 0;
for (i = 0 ; i < (1 << order) ; ++i)
reserved += free_pages_check(page + i);
if (reserved)
bad += free_pages_check(page + i);
if (bad)
return;
if (!PageHighMem(page)) {
@ -610,17 +612,11 @@ static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
if (unlikely(page_mapcount(page) |
(page->mapping != NULL) |
(page_count(page) != 0) |
(page->flags & PAGE_FLAGS_CHECK_AT_PREP)))
(page->flags & PAGE_FLAGS_CHECK_AT_PREP))) {
bad_page(page);
/*
* For now, we report if PG_reserved was found set, but do not
* clear it, and do not allocate the page: as a safety net.
*/
if (PageReserved(page))
return 1;
}
page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
set_page_private(page, 0);
set_page_refcounted(page);