From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753068AbbLYLmG (ORCPT ); Fri, 25 Dec 2015 06:42:06 -0500 Received: from mail-wm0-f53.google.com ([74.125.82.53]:34773 "EHLO mail-wm0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752187AbbLYLmD (ORCPT ); Fri, 25 Dec 2015 06:42:03 -0500 Date: Fri, 25 Dec 2015 12:41:59 +0100 From: Michal Hocko To: Tetsuo Handa Cc: zwisler@gmail.com, akpm@linux-foundation.org, mgorman@suse.de, rientjes@google.com, torvalds@linux-foundation.org, oleg@redhat.com, hughd@google.com, andrea@kernel.org, riel@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ross.zwisler@linux.intel.com Subject: Re: [PATCH 1/2] mm, oom: introduce oom reaper Message-ID: <20151225114159.GB6754@dhcp22.suse.cz> References: <1450204575-13052-1-git-send-email-mhocko@kernel.org> <20151224094758.GA22760@dhcp22.suse.cz> <201512242006.CGJ81784.SVMHOOQtLFFFOJ@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201512242006.CGJ81784.SVMHOOQtLFFFOJ@I-love.SAKURA.ne.jp> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 24-12-15 20:06:50, Tetsuo Handa wrote: > Michal Hocko wrote: > > This is VM_BUG_ON_PAGE(page_mapped(page), page), right? Could you attach > > the full kernel log? It all smells like a race when OOM reaper tears > > down the mapping and there is a truncate still in progress. But hitting > > the BUG_ON just because of that doesn't make much sense to me. OOM > > reaper is essentially MADV_DONTNEED. I have to think about this some > > more, though, but I am in a holiday mode until early next year so please > > bear with me. > > I don't know whether the OOM killer was invoked just before this > VM_BUG_ON_PAGE(). > > > Is this somehow DAX related? > > 4.4.0-rc6-next-20151223_new_fsync_v6+ suggests that this kernel > has "[PATCH v6 0/7] DAX fsync/msync support" applied. But I think > http://marc.info/?l=linux-mm&m=145068666428057 should be applied > when retesting. (20151223 does not have this fix.) Hmm, I think you are right! Very well spotted! If ignore_dirty ends up being true then we would simply skip over dirty page and wouldn't end up doing page_remove_rmap. I can see that the truncation code can later trip over this page. Thanks! -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f52.google.com (mail-wm0-f52.google.com [74.125.82.52]) by kanga.kvack.org (Postfix) with ESMTP id 283066B02F2 for ; Fri, 25 Dec 2015 06:42:02 -0500 (EST) Received: by mail-wm0-f52.google.com with SMTP id p187so201295566wmp.1 for ; Fri, 25 Dec 2015 03:42:02 -0800 (PST) Received: from mail-wm0-f54.google.com (mail-wm0-f54.google.com. [74.125.82.54]) by mx.google.com with ESMTPS id yv10si31212194wjc.217.2015.12.25.03.42.01 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 25 Dec 2015 03:42:01 -0800 (PST) Received: by mail-wm0-f54.google.com with SMTP id p187so199070730wmp.0 for ; Fri, 25 Dec 2015 03:42:01 -0800 (PST) Date: Fri, 25 Dec 2015 12:41:59 +0100 From: Michal Hocko Subject: Re: [PATCH 1/2] mm, oom: introduce oom reaper Message-ID: <20151225114159.GB6754@dhcp22.suse.cz> References: <1450204575-13052-1-git-send-email-mhocko@kernel.org> <20151224094758.GA22760@dhcp22.suse.cz> <201512242006.CGJ81784.SVMHOOQtLFFFOJ@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201512242006.CGJ81784.SVMHOOQtLFFFOJ@I-love.SAKURA.ne.jp> Sender: owner-linux-mm@kvack.org List-ID: To: Tetsuo Handa Cc: zwisler@gmail.com, akpm@linux-foundation.org, mgorman@suse.de, rientjes@google.com, torvalds@linux-foundation.org, oleg@redhat.com, hughd@google.com, andrea@kernel.org, riel@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ross.zwisler@linux.intel.com On Thu 24-12-15 20:06:50, Tetsuo Handa wrote: > Michal Hocko wrote: > > This is VM_BUG_ON_PAGE(page_mapped(page), page), right? Could you attach > > the full kernel log? It all smells like a race when OOM reaper tears > > down the mapping and there is a truncate still in progress. But hitting > > the BUG_ON just because of that doesn't make much sense to me. OOM > > reaper is essentially MADV_DONTNEED. I have to think about this some > > more, though, but I am in a holiday mode until early next year so please > > bear with me. > > I don't know whether the OOM killer was invoked just before this > VM_BUG_ON_PAGE(). > > > Is this somehow DAX related? > > 4.4.0-rc6-next-20151223_new_fsync_v6+ suggests that this kernel > has "[PATCH v6 0/7] DAX fsync/msync support" applied. But I think > http://marc.info/?l=linux-mm&m=145068666428057 should be applied > when retesting. (20151223 does not have this fix.) Hmm, I think you are right! Very well spotted! If ignore_dirty ends up being true then we would simply skip over dirty page and wouldn't end up doing page_remove_rmap. I can see that the truncation code can later trip over this page. Thanks! -- Michal Hocko SUSE Labs -- 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