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authorHugh Dickins <hugh@veritas.com>2009-01-06 14:40:06 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-06 15:59:07 -0800
commit8cc3b39221b0ecbd83a338948a8396df097fc656 (patch)
tree8a8617590f6bc9842c28a0fc4e5e5fbc93e95780
parent79f4b7bf393e67bbffec807cc68caaefc72b82ee (diff)
badpage: keep any bad page out of circulation
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>
-rw-r--r--mm/page_alloc.c52
1 files changed, 24 insertions, 28 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b90a74d2848..bd330252fc7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -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);