Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751974AbdI0R0Z (ORCPT ); Wed, 27 Sep 2017 13:26:25 -0400 Received: from out0-248.mail.aliyun.com ([140.205.0.248]:52868 "EHLO out0-248.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750852AbdI0R0X (ORCPT ); Wed, 27 Sep 2017 13:26:23 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R131e4;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e02c03274;MF=yang.s@alibaba-inc.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---.9.2JoJe_1506533154; Subject: Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel panic To: Michal Hocko Cc: cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1506473616-88120-1-git-send-email-yang.s@alibaba-inc.com> <1506473616-88120-3-git-send-email-yang.s@alibaba-inc.com> <20170927104537.r42javxhnyqlxnqm@dhcp22.suse.cz> From: "Yang Shi" Message-ID: Date: Thu, 28 Sep 2017 01:25:50 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20170927104537.r42javxhnyqlxnqm@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1065 Lines: 30 On 9/27/17 3:45 AM, Michal Hocko wrote: > On Wed 27-09-17 08:53:35, Yang Shi wrote: >> Kernel may panic when oom happens without killable process sometimes it >> is caused by huge unreclaimable slabs used by kernel. >> >> Although kdump could help debug such problem, however, kdump is not >> available on all architectures and it might be malfunction sometime. >> And, since kernel already panic it is worthy capturing such information >> in dmesg to aid touble shooting. >> >> Print out unreclaimable slab info (used size and total size) which >> actual memory usage is not zero (num_objs * size != 0) when: >> - unreclaimable slabs : all user memory > unreclaim_slabs_oom_ratio >> - panic_on_oom is set or no killable process > > OK, this is better but I do not see why this should be tunable via proc. Just thought someone might want to dump unreclaimable slab info unconditionally. > Can we start with simple NR_SLAB_UNRECLAIMABLE > LRU_PAGES and place it > into dump_header so that we get the report also during regular OOM Yes. Thanks, Yang >