Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759214AbbLCMg5 (ORCPT ); Thu, 3 Dec 2015 07:36:57 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:44811 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751756AbbLCMg4 (ORCPT ); Thu, 3 Dec 2015 07:36:56 -0500 Date: Thu, 3 Dec 2015 13:36:50 +0100 From: Peter Zijlstra To: Sasha Levin Cc: mingo@redhat.com, linux-kernel@vger.kernel.org, oleg@redhat.com, torvalds@linux-foundation.org Subject: Re: [PATCH] sched: remove false-positive warning from wake_up_process() Message-ID: <20151203123650.GZ3816@twins.programming.kicks-ass.net> References: <1448933660-23082-1-git-send-email-sasha.levin@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1448933660-23082-1-git-send-email-sasha.levin@oracle.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1593 Lines: 44 On Mon, Nov 30, 2015 at 08:34:20PM -0500, Sasha Levin wrote: > Futex can have a spurious wake up before we actually wake it up on our own, > which will trigger this warning if the task is still stopped. I've edited the changelog like so, please let me know if that is fine with you. Thanks. --- Subject: sched: Remove false-positive warning from wake_up_process() From: Sasha Levin Date: Mon, 30 Nov 2015 20:34:20 -0500 Because wakeups can (fundamentally) be late, a task might not be in the expected state. Therefore testing against a task's state is racy, and can yield false positives. Fixes: 9067ac85d533 ("wake_up_process() should be never used to wakeup a TASK_STOPPED/TRACED task") Cc: oleg@redhat.com Cc: torvalds@linux-foundation.org Cc: mingo@redhat.com Signed-off-by: Sasha Levin Signed-off-by: Peter Zijlstra (Intel) Link: http://lkml.kernel.org/r/1448933660-23082-1-git-send-email-sasha.levin@oracle.com --- kernel/sched/core.c | 1 - 1 file changed, 1 deletion(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2160,7 +2160,6 @@ static void try_to_wake_up_local(struct */ int wake_up_process(struct task_struct *p) { - WARN_ON(task_is_stopped_or_traced(p)); return try_to_wake_up(p, TASK_NORMAL, 0); } EXPORT_SYMBOL(wake_up_process); -- 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/