From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id E7A696B00F7 for ; Wed, 3 Jun 2009 14:47:12 -0400 (EDT) From: Andi Kleen References: <20090603846.816684333@firstfloor.org> In-Reply-To: <20090603846.816684333@firstfloor.org> Subject: [PATCH] [11/16] HWPOISON: check and isolate corrupted free pages v2 Message-Id: <20090603184645.68FA21D0286@basil.firstfloor.org> Date: Wed, 3 Jun 2009 20:46:45 +0200 (CEST) Sender: owner-linux-mm@kvack.org To: fengguang.wu@intel.com, akpm@linux-foundation.org, npiggin@suse.de, linux-kernel@vger.kernel.org, linux-mm@kvack.orgfengguang.wu@intel.com List-ID: 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. Signed-off-by: Wu Fengguang Signed-off-by: Andi Kleen --- mm/page_alloc.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) Index: linux/mm/page_alloc.c =================================================================== --- linux.orig/mm/page_alloc.c 2009-06-03 19:37:39.000000000 +0200 +++ linux/mm/page_alloc.c 2009-06-03 20:13:43.000000000 +0200 @@ -237,6 +237,12 @@ 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. @@ -650,7 +656,7 @@ /* * 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) | @@ -659,6 +665,18 @@ 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