From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754135AbYJ3J7b (ORCPT ); Thu, 30 Oct 2008 05:59:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753027AbYJ3J7W (ORCPT ); Thu, 30 Oct 2008 05:59:22 -0400 Received: from mx2.redhat.com ([66.187.237.31]:35253 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752879AbYJ3J7V (ORCPT ); Thu, 30 Oct 2008 05:59:21 -0400 Date: Thu, 30 Oct 2008 12:00:00 +0100 From: Oleg Nesterov To: Michael Kerrisk Cc: lkml , Alan Cox , Bert Wesarg , Ingo Molnar , Roland McGrath , Linus Torvalds Subject: Re: Strange stop-signal behavior in multithreaded program with defunct main Message-ID: <20081030110000.GA3767@redhat.com> References: <4907E6B9.8080700@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4907E6B9.8080700@gmail.com> 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 10/28, Michael Kerrisk wrote: > > Bert Wesarg described a scenario that I quickly replicated on > 2.6.28-rc2 (and 2.6.25 -- it's not a regression in 2.6.28-rc) > using the program below: if we have a multithreaded process > with a defunct main thread running on a tty, and that > process is sent a stop signal (either ^Z (SIGTSTP) or a stop > signal sent from another terminal using kill(1)), then: > > a) the terminal is locked up; and > > b) the program is unresponsive to any other signal, except SIGKILL > or SIGCONT. Yes, known problem. Please look at [RFC,PATCH 3/3] do_wait: fix waiting for stopped group with dead leader http://marc.info/?t=119713920000003 Oleg.