From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752494AbcBOUue (ORCPT ); Mon, 15 Feb 2016 15:50:34 -0500 Received: from mail-wm0-f65.google.com ([74.125.82.65]:34425 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751153AbcBOUud (ORCPT ); Mon, 15 Feb 2016 15:50:33 -0500 Date: Mon, 15 Feb 2016 21:50:29 +0100 From: Michal Hocko To: Tetsuo Handa Cc: akpm@linux-foundation.org, rientjes@google.com, mgorman@suse.de, oleg@redhat.com, torvalds@linux-foundation.org, hughd@google.com, andrea@kernel.org, riel@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/5] mm, oom: introduce oom reaper Message-ID: <20160215205028.GE9223@dhcp22.suse.cz> References: <1454505240-23446-1-git-send-email-mhocko@kernel.org> <1454505240-23446-2-git-send-email-mhocko@kernel.org> <201602062222.HJH86328.SMFVtFOJFHQOLO@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201602062222.HJH86328.SMFVtFOJFHQOLO@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 Sat 06-02-16 22:22:20, Tetsuo Handa wrote: > Michal Hocko wrote: > > There is one notable exception to this, though, if the OOM victim was > > in the process of coredumping the result would be incomplete. This is > > considered a reasonable constrain because the overall system health is > > more important than debugability of a particular application. > > Is it possible to clarify what "the result would be incomplete" mean? > > (1) The size of coredump file becomes smaller than it should be, and > data in reaped pages is not included into the file. > > (2) The size of coredump file does not change, and data in reaped pages > is included into the file as NUL byte. AFAIU this will be the case. We are not destroying VMAs we are just unmapping the page ranges. So what would happen is that the core dump will contain zero pages for anonymous mappings. This might change in future though because the oom repear might be extended to do more work (e.g. drop associated page tables when I would expect the core dumping could SEGV). -- Michal Hocko SUSE Labs