From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: [PATCH 10/15] HWPOISON: check and isolate corrupted free pages v3 Date: Sat, 20 Jun 2009 11:16:18 +0800 Message-ID: <20090620031625.977050921@intel.com> References: <20090620031608.624240019@intel.com> Return-path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 4FAA46B0083 for ; Fri, 19 Jun 2009 23:19:31 -0400 (EDT) Content-Disposition: inline; filename=free-pages-poison Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: LKML , Wu Fengguang , Andi Kleen , Ingo Molnar , Minchan Kim , Mel Gorman , Thomas Gleixner , "H. Peter Anvin" , Peter Zijlstra , Nick Piggin , Hugh Dickins , Andi Kleen , "riel@redhat.com" , "chris.mason@oracle.com" , "linux-mm@kvack.org" List-Id: linux-mm.kvack.org From: Wu Fengguang 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. v3: Fengguang: But still taint the kernel: PG_hwpoison might be set by a software bug. Signed-off-by: Wu Fengguang Signed-off-by: Andi Kleen --- mm/page_alloc.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) --- sound-2.6.orig/mm/page_alloc.c +++ sound-2.6/mm/page_alloc.c @@ -233,6 +233,10 @@ 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)) + goto out; + /* * Allow a burst of 60 reports, then keep quiet for that minute; * or allow a steady drip of one report per second. @@ -646,7 +650,7 @@ 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 +659,18 @@ 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); -- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org