Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031013AbaDJNdH (ORCPT ); Thu, 10 Apr 2014 09:33:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40868 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030980AbaDJNdB (ORCPT ); Thu, 10 Apr 2014 09:33:01 -0400 Date: Thu, 10 Apr 2014 15:33:05 +0200 From: Oleg Nesterov To: Steven Rostedt Cc: Mathieu Desnoyers , Frederic Weisbecker , LKML , Andrew Morton , Ingo Molnar Subject: Re: [PATCH RESEND 1/2] tracing: syscall_*regfunc() can race with copy_process() Message-ID: <20140410133305.GA12228@redhat.com> References: <1397059882-23063-1-git-send-email-fweisbec@gmail.com> <1397059882-23063-3-git-send-email-fweisbec@gmail.com> <360091921.1294.1397060915052.JavaMail.zimbra@efficios.com> <20140409124249.4081e665@gandalf.local.home> <20140409170505.GA27638@redhat.com> <20140409170542.GB27638@redhat.com> <20140410090452.6b7677fc@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140410090452.6b7677fc@gandalf.local.home> 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 04/10, Steven Rostedt wrote: > > On Wed, 9 Apr 2014 19:05:42 +0200 > Oleg Nesterov wrote: > > > syscall_regfunc() and syscall_unregfunc() should set/clear > > TIF_SYSCALL_TRACEPOINT system-wide, but do_each_thread() can race > > with copy_process() and miss the new child which was not added to > > init_task.tasks list yet. > > > > Change copy_process() to update the child's TIF_SYSCALL_TRACEPOINT > > under tasklist. > > > > While at it, > > > > - remove _irqsafe from syscall_regfunc/syscall_unregfunc, > > read_lock(tasklist) doesn't need to disable irqs. > > > > - change syscall_unregfunc() to check PF_KTHREAD to skip > > the kernel threads, ->mm != NULL is the common mistake. > > > > Note: probably this check should be simply removed, needs > > another patch. > > > > Signed-off-by: Oleg Nesterov > > BTW, how important is this fix? Something we should aim for the current > merge window? stable? Or can it wait till 3.16? I think this all can wait till 3.16. The problem is really minor. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/