Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161144AbaDJNec (ORCPT ); Thu, 10 Apr 2014 09:34:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2009 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030842AbaDJNeb (ORCPT ); Thu, 10 Apr 2014 09:34:31 -0400 Date: Thu, 10 Apr 2014 15:34:35 +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: <20140410133435.GB12228@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> <20140410090643.46ca2226@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140410090643.46ca2226@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: > > > --- a/kernel/fork.c > > +++ b/kernel/fork.c > > @@ -1472,7 +1472,9 @@ static struct task_struct *copy_process(unsigned long clone_flags, > > > > total_forks++; > > spin_unlock(¤t->sighand->siglock); > > + syscall_tracepoint_update(p); > > write_unlock_irq(&tasklist_lock); > > + > > So this looks to be a fix that probably should go to stable? Not sure, this is up to you. > > @@ -732,33 +732,31 @@ static int sys_tracepoint_refcount; > > > > void syscall_regfunc(void) > > { > > - unsigned long flags; > > struct task_struct *g, *t; > > > > if (!sys_tracepoint_refcount) { > > - read_lock_irqsave(&tasklist_lock, flags); > > + read_lock(&tasklist_lock); > > do_each_thread(g, t) { > > /* Skip kernel threads. */ > > - if (t->mm) > > + if (!(t->flags & PF_KTHREAD)) > > set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); > > } while_each_thread(g, t); > > - read_unlock_irqrestore(&tasklist_lock, flags); > > + read_unlock(&tasklist_lock); > > } > > sys_tracepoint_refcount++; > > } > > > > void syscall_unregfunc(void) > > { > > - unsigned long flags; > > struct task_struct *g, *t; > > > > sys_tracepoint_refcount--; > > if (!sys_tracepoint_refcount) { > > - read_lock_irqsave(&tasklist_lock, flags); > > + read_lock(&tasklist_lock); > > do_each_thread(g, t) { > > clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); > > } while_each_thread(g, t); > > - read_unlock_irqrestore(&tasklist_lock, flags); > > + read_unlock(&tasklist_lock); > > These changes should be in a separate patch, as they can wait till 3.16. OK, I'll split this change. 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/