From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 3CA5C6B005D for ; Fri, 29 May 2009 17:35:24 -0400 (EDT) From: Andi Kleen References: <200905291135.124267638@firstfloor.org> In-Reply-To: <200905291135.124267638@firstfloor.org> Subject: [PATCH] [12/16] HWPOISON: check and isolate corrupted free pages Message-Id: <20090529213538.318C61D0295@basil.firstfloor.org> Date: Fri, 29 May 2009 23:35:38 +0200 (CEST) Sender: owner-linux-mm@kvack.org To: fengguang.wu@intel.com, akpm@linux-foundation.org, 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] Signed-off-by: Wu Fengguang Signed-off-by: Andi Kleen --- mm/page_alloc.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) Index: linux/mm/page_alloc.c =================================================================== --- linux.orig/mm/page_alloc.c 2009-05-29 23:32:08.000000000 +0200 +++ linux/mm/page_alloc.c 2009-05-29 23:32:11.000000000 +0200 @@ -633,12 +633,22 @@ */ 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))) { - bad_page(page); - return 1; + int i; + + for (i = 0; i < (1 << order); i++) { + struct page *p = page + i; + + if (unlikely(page_mapcount(p) | + (p->mapping != NULL) | + (page_count(p) != 0) | + (p->flags & PAGE_FLAGS_CHECK_AT_PREP))) { + /* + * The whole array of pages will be dropped, + * hopefully this is a rare and abnormal event. + */ + bad_page(p); + return 1; + } } set_page_private(page, 0); -- 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