From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qe0-f54.google.com (mail-qe0-f54.google.com [209.85.128.54]) by kanga.kvack.org (Postfix) with ESMTP id 224726B0035 for ; Thu, 28 Nov 2013 13:36:33 -0500 (EST) Received: by mail-qe0-f54.google.com with SMTP id cy11so7571094qeb.41 for ; Thu, 28 Nov 2013 10:36:32 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTP id h17si21161216qej.3.2013.11.28.10.36.31 for ; Thu, 28 Nov 2013 10:36:31 -0800 (PST) Date: Thu, 28 Nov 2013 19:37:02 +0100 From: Oleg Nesterov Subject: Re: [PATCH] Fix race between oom kill and task exit Message-ID: <20131128183702.GC20740@redhat.com> References: <3917C05D9F83184EAA45CE249FF1B1DD0253093A@SHSMSX103.ccr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3917C05D9F83184EAA45CE249FF1B1DD0253093A@SHSMSX103.ccr.corp.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Ma, Xindong" , Sameer Nanda Cc: "akpm@linux-foundation.org" , "mhocko@suse.cz" , "rientjes@google.com" , "hannes@cmpxchg.org" , "rusty@rustcorp.com.au" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , 'Peter Zijlstra' , "'gregkh@linuxfoundation.org'" , "Tu, Xiaobing" On 11/28, Ma, Xindong wrote: > > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -412,16 +412,6 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, > static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL, > DEFAULT_RATELIMIT_BURST); > > - /* > - * If the task is already exiting, don't alarm the sysadmin or kill > - * its children or threads, just set TIF_MEMDIE so it can die quickly > - */ > - if (p->flags & PF_EXITING) { > - set_tsk_thread_flag(p, TIF_MEMDIE); > - put_task_struct(p); > - return; > - } > - > if (__ratelimit(&oom_rs)) > dump_header(p, gfp_mask, order, memcg, nodemask); > > @@ -437,6 +427,16 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, > * still freeing memory. > */ > read_lock(&tasklist_lock); > + /* > + * If the task is already exiting, don't alarm the sysadmin or kill > + * its children or threads, just set TIF_MEMDIE so it can die quickly > + */ > + if (p->flags & PF_EXITING) { > + set_tsk_thread_flag(p, TIF_MEMDIE); > + put_task_struct(p); > + read_unlock(&tasklist_lock); > + return; > + } I got lost... didn't we recently discussed the similar patch from Sameer? This one doesn't look right. find_lock_task_mm() after unlock(tasklist) can hit the same problem. I belive the patch from Sameer was correct. Oleg. -- 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