From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752977AbcJEJhH (ORCPT ); Wed, 5 Oct 2016 05:37:07 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:35559 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750807AbcJEJhF (ORCPT ); Wed, 5 Oct 2016 05:37:05 -0400 Date: Wed, 5 Oct 2016 11:37:02 +0200 From: Michal Hocko To: Oleg Nesterov Cc: linux-mm@kvack.org, David Rientjes , Tetsuo Handa , Johannes Weiner , Andrew Morton , LKML , Al Viro Subject: Re: [PATCH 3/4] mm, oom: do not rely on TIF_MEMDIE for exit_oom_victim Message-ID: <20161005093702.GB7138@dhcp22.suse.cz> References: <20161004090009.7974-1-mhocko@kernel.org> <20161004090009.7974-4-mhocko@kernel.org> <20161004162114.GB32428@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161004162114.GB32428@redhat.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 04-10-16 18:21:14, Oleg Nesterov wrote: [...] > so this can't detect the multi-threaded group exit, and ... > > > list_for_each_entry_safe(p, n, &dead, ptrace_entry) { > > list_del_init(&p->ptrace_entry); > > - release_task(p); > > + if (release_task(p) && p == tsk) > > + last = true; > > this can only happen if this process auto-reaps itself. Not to mention > that exit_notify() will never return true if traced. > > No, this doesn't look right. You are right. I should have noticed that. Especially when I was hunting the strace hang bug. I started to have a bad feeling about this patch but for some reason I just didn't put all the pieces together. So the patch is completely b0rked. Back to drawing board and start again. Oh well... Anyway thanks and sorry to waste your time. -- Michal Hocko SUSE Labs