From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id 220EB6B0069 for ; Wed, 27 Sep 2017 06:45:45 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id r83so22569579pfj.5 for ; Wed, 27 Sep 2017 03:45:45 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id h69si7376339pge.187.2017.09.27.03.45.43 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 27 Sep 2017 03:45:44 -0700 (PDT) Date: Wed, 27 Sep 2017 12:45:37 +0200 From: Michal Hocko Subject: Re: [PATCH 2/3] mm: oom: show unreclaimable slab info when kernel panic Message-ID: <20170927104537.r42javxhnyqlxnqm@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1506473616-88120-3-git-send-email-yang.s@alibaba-inc.com> 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 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. 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? -- 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