From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id 629AB6B0253 for ; Mon, 2 Oct 2017 03:26:10 -0400 (EDT) Received: by mail-wm0-f70.google.com with SMTP id i124so730574wmf.1 for ; Mon, 02 Oct 2017 00:26:10 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 32si8120935wrs.205.2017.10.02.00.26.09 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 02 Oct 2017 00:26:09 -0700 (PDT) Date: Mon, 2 Oct 2017 09:26:07 +0200 From: Michal Hocko Subject: Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel panic Message-ID: <20171002072607.sjikpsoaiyebmukd@dhcp22.suse.cz> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Yang Shi 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 On Thu 28-09-17 01:25:50, Yang Shi wrote: > > > 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. If that ever happens then we will eventually add it. But do not add proc knobs for theoretical usecases. We will have to maintain them and it can turn into a maint. pain. Like some others in the past. -- 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