From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net ([212.227.17.21]:60778 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932283AbcLRAfC (ORCPT ); Sat, 17 Dec 2016 19:35:02 -0500 MIME-Version: 1.0 Message-ID: From: "Xin Zhou" To: "Tetsuo Handa" Cc: linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org Subject: Re: OOM: Better, but still there on Content-Type: text/plain; charset=UTF-8 Date: Sun, 18 Dec 2016 01:28:15 +0100 In-Reply-To: <862a1ada-17f1-9cff-c89b-46c47432e89f@I-love.SAKURA.ne.jp> References: <20161216073941.GA26976@dhcp22.suse.cz> <20161216155808.12809-1-mhocko@kernel.org> <20161216184655.GA5664@boerne.fritz.box> <20161217000203.GC23392@dhcp22.suse.cz> <20161217125950.GA3321@boerne.fritz.box>, <862a1ada-17f1-9cff-c89b-46c47432e89f@I-love.SAKURA.ne.jp> Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi, The system supposes to have special memory reservation for coredump and other debug info when encountering panic, the size seems configurable. Thanks, Xin     Sent: Saturday, December 17, 2016 at 6:44 AM From: "Tetsuo Handa" To: "Nils Holland" , "Michal Hocko" Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Chris Mason" , "David Sterba" , linux-btrfs@vger.kernel.org Subject: Re: OOM: Better, but still there on On 2016/12/17 21:59, Nils Holland wrote: > On Sat, Dec 17, 2016 at 01:02:03AM +0100, Michal Hocko wrote: >> mount -t tracefs none /debug/trace >> echo 1 > /debug/trace/events/vmscan/enable >> cat /debug/trace/trace_pipe > trace.log >> >> should help >> [...] > > No problem! I enabled writing the trace data to a file and then tried > to trigger another OOM situation. That worked, this time without a > complete kernel panic, but with only my processes being killed and the > system becoming unresponsive. When that happened, I let it run for > another minute or two so that in case it was still logging something > to the trace file, it could continue to do so some time longer. Then I > rebooted with the only thing that still worked, i.e. by means of magic > SysRequest. Under OOM situation, writing to a file on disk unlikely works. Maybe logging via network ( "cat /debug/trace/trace_pipe > /dev/udp/$ip/$port" if your are using bash) works better. (I wish we can do it from kernel so that /bin/cat is not disturbed by delays due to page fault.) If you can configure netconsole for logging OOM killer messages and UDP socket for logging trace_pipe messages, udplogger at https://osdn.net/projects/akari/scm/svn/tree/head/branches/udplogger/ might fit for logging both output with timestamp into a single file. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html[http://vger.kernel.org/majordomo-info.html]