Messages in this thread Patch in this message | | | From | Andi Kleen <> | Subject | [PATCH] [10/15] HWPOISON: check and isolate corrupted free pages v2 | Date | Tue, 4 Aug 2009 23:53:09 +0200 (CEST) |
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From: Wu Fengguang <fengguang.wu@intel.com>
If memory corruption hits the free buddy pages, we can safely ignore them. No one will access them until page allocation time, then prep_new_page() will automatically check and isolate PG_hwpoison page for us (for 0-order allocation).
This patch expands prep_new_page() to check every component page in a high order page allocation, in order to completely stop PG_hwpoison pages from being recirculated.
Note that the common case -- only allocating a single page, doesn't do any more work than before. Allocating > order 0 does a bit more work, but that's relatively uncommon.
This simple implementation may drop some innocent neighbor pages, hopefully it is not a big problem because the event should be rare enough.
This patch adds some runtime costs to high order page users.
[AK: Improved description]
v2: Andi Kleen: Port to -mm code Move check into separate function. Don't dump stack in bad_pages for hwpoisoned pages. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andi Kleen <ak@linux.intel.com>
--- mm/page_alloc.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-)
Index: linux/mm/page_alloc.c =================================================================== --- linux.orig/mm/page_alloc.c +++ linux/mm/page_alloc.c @@ -234,6 +234,12 @@ static void bad_page(struct page *page) static unsigned long nr_shown; static unsigned long nr_unshown; + /* Don't complain about poisoned pages */ + if (PageHWPoison(page)) { + __ClearPageBuddy(page); + return; + } + /* * Allow a burst of 60 reports, then keep quiet for that minute; * or allow a steady drip of one report per second. @@ -646,7 +652,7 @@ static inline void expand(struct zone *z /* * This page is about to be returned from the page allocator */ -static int prep_new_page(struct page *page, int order, gfp_t gfp_flags) +static inline int check_new_page(struct page *page) { if (unlikely(page_mapcount(page) | (page->mapping != NULL) | @@ -655,6 +661,18 @@ static int prep_new_page(struct page *pa bad_page(page); return 1; } + return 0; +} + +static int prep_new_page(struct page *page, int order, gfp_t gfp_flags) +{ + int i; + + for (i = 0; i < (1 << order); i++) { + struct page *p = page + i; + if (unlikely(check_new_page(p))) + return 1; + } set_page_private(page, 0); set_page_refcounted(page);
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