From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763735AbZE0TKM (ORCPT ); Wed, 27 May 2009 15:10:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761213AbZE0TJ7 (ORCPT ); Wed, 27 May 2009 15:09:59 -0400 Received: from mx2.redhat.com ([66.187.237.31]:37707 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756482AbZE0TJ7 (ORCPT ); Wed, 27 May 2009 15:09:59 -0400 Date: Wed, 27 May 2009 21:05:13 +0200 From: Oleg Nesterov To: Andi Kleen Cc: paul@mad-scientist.net, linux-kernel@vger.kernel.org, Andrew Morton , Roland McGrath Subject: Re: [2.6.27.24] Kernel coredump to a pipe is failing Message-ID: <20090527190513.GA32452@redhat.com> References: <1243355634.29250.331.camel@psmith-ubeta.netezza.com> <878wkjobbm.fsf@basil.nowhere.org> <20090527183109.GA30574@redhat.com> <20090527185056.GW1065@one.firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090527185056.GW1065@one.firstfloor.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/27, Andi Kleen wrote: > > > Actually, I think there is a strong reason to handle signals during > > core dumping. The coredump can take a lot of time/resources, not good > > it looks like unkillable procees to users. > > One problem with that is if you send a process a string of signals that cause > a core dump and then kill. In the old case you would just get a full core dump > on the first signal and be done. With your change it would process > the second signal too and stop the dumping and you get none or a partial > core dump. That might well break existing setups. I don't think we should worry about this particular case. Suppose a user does kill(pid, SIGQUIT); kill(pid, SIGKILL); In this case, most likely the core dump will not start. Because SIGKILL will set SIGNAL_GROUP_EXIT before the process dequeues SIGQUIT and start do_coredump() which checks signal_group_exit() in zap_threads(). But yes, I agree, this change is user-visible and should be discussed. Oleg.