From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755671AbZKWIgT (ORCPT ); Mon, 23 Nov 2009 03:36:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752845AbZKWIgS (ORCPT ); Mon, 23 Nov 2009 03:36:18 -0500 Received: from cantor.suse.de ([195.135.220.2]:42446 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751123AbZKWIgS (ORCPT ); Mon, 23 Nov 2009 03:36:18 -0500 Date: Mon, 23 Nov 2009 09:36:23 +0100 From: Nick Piggin To: Oleg Nesterov Cc: Linux Kernel Mailing List , Roland McGrath Subject: Re: Zombie process when ptracing Message-ID: <20091123083623.GD5602@wotan.suse.de> References: <20091119102543.GB5602@wotan.suse.de> <20091120012930.GA3985@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091120012930.GA3985@redhat.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 20, 2009 at 02:29:30AM +0100, Oleg Nesterov wrote: > Hi, > > On 11/19, Nick Piggin wrote: > > > > Running recent git kernel, I have a process stuck in Z state > > > > bash ? 0000000000000000 0 3188 3187 0x00000000 > > ffff88012e24fec8 0000000000000046 0000000000000000 0000000000000012 > > ffff88012e24fec8 ffff88012e24e000 ffff88012e24ffd8 ffff88012e24e000 > > 000000000000efc8 ffff88012e24e000 ffff88012ea82090 ffff88012ff78640 > > Call Trace: > > [] ? proc_clear_tty+0x5e/0x70 > > [] ? exit_ptrace+0xb8/0x140 > > [] do_exit+0x58a/0x7c0 > > [] do_group_exit+0x3d/0xb0 > > [] sys_exit_group+0x12/0x20 > > [] system_call_fastpath+0x16/0x1b > > > > This was after stracing a few test programs. > > > > It also seems to have lost job control (^C) at the same time. > > This can happen if the tracer (strace) itself hangs, zombies > should go away once the tracer is killed. Or its ->real_parent > is stopped or hangs... > > (I assume you didn't strace /sbin/init) No, I straced something else, and all straces seemed to be killed but bash remained. I was running a script that in turn launched another process, so I ran it via strace -ff bash ./script.sh > But, > > > Hmm, and the kernel just paniced with an nmi lockup while I was > > trying to get more info. > > this probably means we have a kernel bug ;) Hmm sorry that seemed like it _may_ have been an unrelated issue (with the ssh connection). > If you see a zombie again, could you look at its /ptoc/pid/status? OK, any other hints if I see it again? > And of course, which programs did you trace and how? It would be > great if we can reproduce the problem. At this stage I have not reproduced it, and I can't share the program which was being straced. If it does happen again and I cannot distil a simple test case, I will ask permission to distribute it. Thanks, Nick