Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758181Ab0HDCg2 (ORCPT ); Tue, 3 Aug 2010 22:36:28 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:48872 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756860Ab0HDCg0 (ORCPT ); Tue, 3 Aug 2010 22:36:26 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Wed, 4 Aug 2010 11:31:22 +0900 From: KAMEZAWA Hiroyuki To: KAMEZAWA Hiroyuki Cc: Andrea Gelmini , "Rafael J. Wysocki" , Ondrej Zary , Kernel development list , Andrew Morton , Balbir Singh , nigel@tuxonice.net, stable@kernel.org, Hugh Dickins Subject: Re: [BUGFIX][PATCH] fix corruption of hibernation caused by reusing swap at saving image Message-Id: <20100804113122.071a6b8c.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100804105054.af68ee5c.kamezawa.hiroyu@jp.fujitsu.com> References: <201007282320.39528.linux@rainbow-software.org> <201007282334.08063.rjw@sisk.pl> <20100729132325.59871484.kamezawa.hiroyu@jp.fujitsu.com> <20100804083652.92b5b2df.kamezawa.hiroyu@jp.fujitsu.com> <20100804105054.af68ee5c.kamezawa.hiroyu@jp.fujitsu.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.0.3 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2598 Lines: 73 On Wed, 4 Aug 2010 10:50:54 +0900 KAMEZAWA Hiroyuki wrote: > This patch is created against 2.6.35. CC'ed stable. > Thank you for all helps. > I'm sorry I now doubt this patch is wrong. What should be done is stop swap-reuse before hibernation_snapshot(). But, hmm, this one can't. Maybe what really happens is someone (kswapd?) reuses swap while swsusp_alloc() is on going. please allow me to retry.. Thanks, -Kame > = > From: KAMEZAWA Hiroyuki > > 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 by the commit > c9e444103b5e7a5a3519f9913f59767f92e33baf. > > But this caused deta corruption at hibernation. Considering how > the image is saved, the calls of try_to_reclaim_swap() changes the > status of memory and there will be inconsitency between saved-memory-image's > swap_map[] / memmap / swapper_space because memory is saved per page with > swap-allocation per page. > > This patch is for avoiding bug by not reclaiming swap-entry at hibernation. > This is a quick fix for backporting. > > Cc: stable@kernel.org > Cc: Rafael J. Wysocki > Reported-by: Ondreg Zary > Tested-by: Andrea Gelmini > Acked-by: Hugh Dickins > Signed-off-by: KAMEZAWA Hiroyuki > --- > mm/swapfile.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > Index: linux-2.6.35.org/mm/swapfile.c > =================================================================== > --- linux-2.6.35.org.orig/mm/swapfile.c > +++ linux-2.6.35.org/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/