From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id E7BC96B01E3 for ; Thu, 22 Apr 2010 17:11:58 -0400 (EDT) Received: from hpaq3.eem.corp.google.com (hpaq3.eem.corp.google.com [10.3.21.3]) by smtp-out.google.com with ESMTP id o3MLBsvh011665 for ; Thu, 22 Apr 2010 23:11:54 +0200 Received: from pzk35 (pzk35.prod.google.com [10.243.19.163]) by hpaq3.eem.corp.google.com with ESMTP id o3MLBq5w030937 for ; Thu, 22 Apr 2010 23:11:53 +0200 Received: by pzk35 with SMTP id 35so1045129pzk.0 for ; Thu, 22 Apr 2010 14:11:52 -0700 (PDT) Date: Thu, 22 Apr 2010 14:11:48 -0700 (PDT) From: David Rientjes Subject: Re: [patch -mm] memcg: make oom killer a no-op when no killable task can be found In-Reply-To: <20100422192714.da3fdccf.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <20100407092050.48c8fc3d.kamezawa.hiroyu@jp.fujitsu.com> <20100407205418.FB90.A69D9226@jp.fujitsu.com> <20100421121758.af52f6e0.akpm@linux-foundation.org> <20100422072319.GW5683@laptop> <20100422162536.b904203e.kamezawa.hiroyu@jp.fujitsu.com> <20100422100944.GX5683@laptop> <20100422192714.da3fdccf.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Nick Piggin , Andrew Morton , KOSAKI Motohiro , anfei , nishimura@mxp.nes.nec.co.jp, Balbir Singh , linux-mm@kvack.org List-ID: On Thu, 22 Apr 2010, KAMEZAWA Hiroyuki wrote: > Hmm...checking again. > > Maybe related patches are: > 1: oom-remove-special-handling-for-pagefault-ooms.patch > 2: oom-default-to-killing-current-for-pagefault-ooms.patch > > IIUC, (1) doesn't make change. But (2)... > > Before(1) > - pagefault-oom kills someone by out_of_memory(). > After (1) > - pagefault-oom calls out_of_memory() only when someone isn't being killed. > > So, this patch helps to avoid double-kill and I like this change. > > Before (2) > At pagefault-out-of-memory > - panic_on_oom==2, panic always. > - panic_on_oom==1, panic when CONSITRAINT_NONE. > > After (2) > At pagefault-put-of-memory, if there is no running OOM-Kill, > current is killed always. In this case, panic_on_oom doesn't work. > > I think panic_on_oom==2 should work.. Hmm. why this behavior changes ? > We can readd the panic_on_oom code once Nick's patchset is merged that unifies all architectures in using pagefault_out_of_memory() for VM_FAULT_OOM. Otherwise, some architectures would panic in this case and others would not (while they allow tasks to be SIGKILL'd even when panic_on_oom == 2 is set, including OOM_DISABLE tasks!) so I think it's better to be entirely consistent with sysctl semantics across architectures. -- 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