From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id 403086B0005 for ; Thu, 26 Apr 2018 09:28:49 -0400 (EDT) Received: by mail-wr0-f198.google.com with SMTP id q3-v6so1678910wrn.3 for ; Thu, 26 Apr 2018 06:28:49 -0700 (PDT) Received: from pegase1.c-s.fr (pegase1.c-s.fr. [93.17.236.30]) by mx.google.com with ESMTPS id d13-v6si15815380wri.245.2018.04.26.06.28.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 Apr 2018 06:28:47 -0700 (PDT) Subject: Re: OOM killer invoked while still one forth of mem is available References: <296ea83c-2c00-f1d2-3f62-d8ab8b8fb73c@c-s.fr> <20180426131154.GQ17484@dhcp22.suse.cz> From: Christophe LEROY Message-ID: <2706829f-6207-89f7-46e6-d32244305ccb@c-s.fr> Date: Thu, 26 Apr 2018 15:28:46 +0200 MIME-Version: 1.0 In-Reply-To: <20180426131154.GQ17484@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: David Rientjes , linux-mm@kvack.org, "linuxppc-dev@lists.ozlabs.org" Le 26/04/2018 A 15:11, Michal Hocko a A(C)critA : > On Thu 26-04-18 08:10:30, Christophe LEROY wrote: >> >> >> Le 25/04/2018 A 21:57, David Rientjes a A(C)critA : >>> On Tue, 24 Apr 2018, christophe leroy wrote: >>> >>>> Hi >>>> >>>> Allthough there is still about one forth of memory available (7976kB >>>> among 32MB), oom-killer is invoked and makes a victim. >>>> >>>> What could be the reason and how could it be solved ? >>>> >>>> [ 54.400754] S99watchdogd-ap invoked oom-killer: >>>> gfp_mask=0x27000c0(GFP_KERNEL_ACCOUNT|__GFP_NOTRACK), nodemask=0, >>>> order=1, oom_score_adj=0 >>>> [ 54.400815] CPU: 0 PID: 777 Comm: S99watchdogd-ap Not tainted >>>> 4.9.85-local-knld-998 #5 >>>> [ 54.400830] Call Trace: >>>> [ 54.400910] [c1ca5d10] [c0327d28] dump_header.isra.4+0x54/0x17c >>>> (unreliable) >>>> [ 54.400998] [c1ca5d50] [c0079d88] oom_kill_process+0xc4/0x414 >>>> [ 54.401067] [c1ca5d90] [c007a5c8] out_of_memory+0x35c/0x37c >>>> [ 54.401220] [c1ca5dc0] [c007d68c] __alloc_pages_nodemask+0x8ec/0x9a8 >>>> [ 54.401318] [c1ca5e70] [c00169d4] copy_process.isra.9.part.10+0xdc/0x10d0 >>>> [ 54.401398] [c1ca5f00] [c0017b30] _do_fork+0xcc/0x2a8 >>>> [ 54.401473] [c1ca5f40] [c000a660] ret_from_syscall+0x0/0x38 >>> >>> Looks like this is because the allocation is order-1, likely the >>> allocation of a struct task_struct for a new process on fork. >> >> I'm not sure I understand what you mean. The allocation is order 1, yes, >> does it explains why OOM killer is invoked ? > > Well, not really > [ 54.437414] DMA: 460*4kB (UH) 201*8kB (UH) 121*16kB (UH) 43*32kB (UH) 10*64kB (U) 4*128kB (UH) 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB 0*8192kB = 7912kB` > > You should have enough order-1+ pages to proceed. > So, order is 1 so order - 1 is 0, what's wrong then ? Do the (UH) and (U) means anything special ? Otherwise, just above it says 'free:1994', so with 1994 pages free I should have enough to proceed, shouldn't I ? Am I missing something ? Christophe