From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932621Ab2GASZ0 (ORCPT ); Sun, 1 Jul 2012 14:25:26 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:46964 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755977Ab2GASQg (ORCPT ); Sun, 1 Jul 2012 14:16:36 -0400 Message-Id: <20120701172007.694144055@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Sun, 01 Jul 2012 18:20:13 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Pravin B Shelar , Amey Bhide , Christoph Lameter , Pekka Enberg , Andrea Arcangeli Subject: [ 07/48] mm: fix slab->page _count corruption when using slub In-Reply-To: <20120701172006.535271340@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pravin B Shelar commit abca7c4965845924f65d40e0aa1092bdd895e314 upstream. On arches that do not support this_cpu_cmpxchg_double() slab_lock is used to do atomic cmpxchg() on double word which contains page->_count. The page count can be changed from get_page() or put_page() without taking slab_lock. That corrupts page counter. Fix it by moving page->_count out of cmpxchg_double data. So that slub does no change it while updating slub meta-data in struct page. [akpm@linux-foundation.org: use standard comment layout, tweak comment text] Reported-by: Amey Bhide Signed-off-by: Pravin B Shelar Acked-by: Christoph Lameter Cc: Pekka Enberg Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- include/linux/mm_types.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index dad95bd..704a626 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -57,8 +57,18 @@ struct page { }; union { +#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ + defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) /* Used for cmpxchg_double in slub */ unsigned long counters; +#else + /* + * Keep _count separate from slub cmpxchg_double data. + * As the rest of the double word is protected by + * slab_lock but _count is not. + */ + unsigned counters; +#endif struct {