From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756253AbYE0Dbx (ORCPT ); Mon, 26 May 2008 23:31:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754310AbYE0Dbp (ORCPT ); Mon, 26 May 2008 23:31:45 -0400 Received: from rv-out-0506.google.com ([209.85.198.233]:5059 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754224AbYE0Dbo (ORCPT ); Mon, 26 May 2008 23:31:44 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=Ucp6u/q1RsdH8FPJ/+VJqC2Epkgl5Hm3svAnBT+naiXRVIlV5+5Ew7LUX+fPdt4cnS5g1L1JLdK9lUYsW0YyqM6cBYPmb2oUUmXH/iz0my1SOXZl3jXDovtAkBMkJmxKhWfIOVGNE0IJtGOaNqUWV8Ki3NKdk2392/HKrvCpTrc= Message-ID: <3877989d0805262031i29db16bcjfa31652afc746b49@mail.gmail.com> Date: Tue, 27 May 2008 11:31:43 +0800 From: "Luming Yu" To: "Roland McGrath" Subject: Re: [RFC PATCH] set TASK_TRACED before arch_ptrace code to fix a race Cc: "Petr Tesarik" , LKML , linux-ia64@vger.kernel.org In-Reply-To: <3877989d0805251830w70f19e4cu46fbc32148217749@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <3877989d0805211947i54bacc7cv619541e9b40824fb@mail.gmail.com> <3877989d0805220216o5add20ddye2a1fde98a0c1e69@mail.gmail.com> <20080522111826.BB90326FA24@magilla.localdomain> <3877989d0805220624i259a9d1j708795c65c636ca0@mail.gmail.com> <20080522203428.835D626FA24@magilla.localdomain> <3877989d0805222042p176da844k384ea512b1cfb0da@mail.gmail.com> <20080523041940.39E8726FA24@magilla.localdomain> <3877989d0805222224n77ce36b6wdf15c4bab330a0f8@mail.gmail.com> <20080526001527.81E1126FA9E@magilla.localdomain> <3877989d0805251830w70f19e4cu46fbc32148217749@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > if happens, it should be a bug, right? It does happen!! Call Trace: [] show_stack+0x50/0xa0 sp=e000000146bbfbb0 bsp=e000000146bb0e08 [] dump_stack+0x30/0x60 sp=e000000146bbfd80 bsp=e000000146bb0de8 [] get_signal_to_deliver+0x60/0x6e0 sp=e000000146bbfd80 bsp=e000000146bb0d80 [] ia64_do_signal+0xb0/0xd00 sp=e000000146bbfd80 bsp=e000000146bb0cd8 [] do_notify_resume_user+0xf0/0x140 sp=e000000146bbfe20 bsp=e000000146bb0ca8 [] notify_resume_user+0x40/0x60 sp=e000000146bbfe20 bsp=e000000146bb0c58 [] skip_rbs_switch+0xe0/0x110 sp=e000000146bbfe30 bsp=e000000146bb0c58 [] __kernel_syscall_via_break+0x0/0x20 sp=e000000146bc0000 bsp=e000000146bb0c58 >> > I will try to customize kernel to capture call trace for a precise code path. I applied the following patch , and got the call trace above.. If apply my RFC patch as antidote, I don't see "deliver" ... Is the problem clear now? I will serve you until every thing is clear to you. Thanks, Luming Signed-off-by: Yu Luming diff -Bru 1/kernel/signal.c 0/kernel/signal.c --- 1/kernel/signal.c 2008-05-27 15:18:48.000000000 +0800 +++ 0/kernel/signal.c 2008-05-27 15:08:51.000000000 +0800 @@ -38,6 +38,7 @@ */ static struct kmem_cache *sigqueue_cachep; +unsigned long global_arch_ptrace_stop_flag =0; static int __sig_ignored(struct task_struct *t, int sig) { @@ -1501,9 +1502,12 @@ * siglock. That must prevent us from sleeping in TASK_TRACED. * So after regaining the lock, we must check for SIGKILL. */ + global_arch_ptrace_stop_flag = 1; spin_unlock_irq(¤t->sighand->siglock); arch_ptrace_stop(exit_code, info); + spin_lock_irq(¤t->sighand->siglock); + global_arch_ptrace_stop_flag = 0; killed = sigkill_pending(current); } @@ -1701,6 +1705,8 @@ struct signal_struct *signal = current->signal; int signr; + if (global_arch_ptrace_stop_flag) + dump_stack(); relock: /* * We'll jump back here after any time we were stopped in TASK_STOPPED.