Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758943Ab0HLARv (ORCPT ); Wed, 11 Aug 2010 20:17:51 -0400 Received: from kroah.org ([198.145.64.141]:60519 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933082Ab0HLAIO (ORCPT ); Wed, 11 Aug 2010 20:08:14 -0400 X-Mailbox-Line: From gregkh@clark.site Wed Aug 11 17:06:14 2010 Message-Id: <20100812000614.598946449@clark.site> User-Agent: quilt/0.48-11.2 Date: Wed, 11 Aug 2010 17:05:36 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, KAMEZAWA Hiroyuki , "Rafael J. Wysocki" , Hugh Dickins Subject: [21/67] mm: fix corruption of hibernation caused by reusing swap during image saving In-Reply-To: <20100812000641.GA6348@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2535 Lines: 71 2.6.35-stable review patch. If anyone has any objections, please let us know. ------------------ From: KAMEZAWA Hiroyuki commit 966cca029f739716fbcc8068b8c6dfe381f86fc3 upstream. Since 2.6.31, swap_map[]'s refcounting was changed to show that a used swap entry is just for swap-cache, can be reused. Then, while scanning free entry in swap_map[], a swap entry may be able to be reclaimed and reused. It was caused by commit c9e444103b5e7a5 ("mm: reuse unused swap entry if necessary"). But this caused deta corruption at resume. The scenario is - Assume a clean-swap cache, but mapped. - at hibernation_snapshot[], clean-swap-cache is saved as clean-swap-cache and swap_map[] is marked as SWAP_HAS_CACHE. - then, save_image() is called. And reuse SWAP_HAS_CACHE entry to save image, and break the contents. After resume: - the memory reclaim runs and finds clean-not-referenced-swap-cache and discards it because it's marked as clean. But here, the contents on disk and swap-cache is inconsistent. Hance memory is corrupted. This patch avoids the bug by not reclaiming swap-entry during hibernation. This is a quick fix for backporting. Signed-off-by: KAMEZAWA Hiroyuki Cc: Rafael J. Wysocki Reported-by: Ondreg Zary Tested-by: Ondreg Zary Tested-by: Andrea Gelmini Acked-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/swapfile.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -318,8 +318,10 @@ checks: if (offset > si->highest_bit) scan_base = offset = si->lowest_bit; - /* reuse swap entry of cache-only swap if not busy. */ - if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { + /* reuse swap entry of cache-only swap if not hibernation. */ + if (vm_swap_full() + && usage == SWAP_HAS_CACHE + && si->swap_map[offset] == SWAP_HAS_CACHE) { int swap_was_freed; spin_unlock(&swap_lock); swap_was_freed = __try_to_reclaim_swap(si, offset); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/