Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752104AbaJBT5k (ORCPT ); Thu, 2 Oct 2014 15:57:40 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:42513 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751334AbaJBT5j (ORCPT ); Thu, 2 Oct 2014 15:57:39 -0400 Date: Thu, 2 Oct 2014 21:57:27 +0200 From: Peter Zijlstra To: Oleg Nesterov Cc: Peter Hurley , Fengguang Wu , Jet Chen , Su Tao , Yuanhan Liu , LKP , linux-kernel@vger.kernel.org, Marcel Holtmann Subject: Re: [rfcomm_run] WARNING: CPU: 1 PID: 79 at kernel/sched/core.c:7156 __might_sleep() Message-ID: <20141002195727.GD10583@worktop.programming.kicks-ass.net> References: <20140930080228.GD9561@wfg-t540p.sh.intel.com> <20141002110927.GE2849@worktop.programming.kicks-ass.net> <20141002123150.GC6324@worktop.programming.kicks-ass.net> <20141002124247.GD6324@worktop.programming.kicks-ass.net> <542D57D0.4030904@hurleysoftware.com> <20141002135250.GB10583@worktop.programming.kicks-ass.net> <20141002135805.GF6324@worktop.programming.kicks-ass.net> <20141002191114.GA30606@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141002191114.GA30606@redhat.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 02, 2014 at 09:11:14PM +0200, Oleg Nesterov wrote: > On 10/02, Peter Zijlstra wrote: > > > > On Thu, Oct 02, 2014 at 03:52:50PM +0200, Peter Zijlstra wrote: > > > > If yes, then wakeups from signals don't work either, right? > > > > > > Its a kthread, there should not be any signals. > > > > That said, in the tty patch we do appear to have this problem. > > > > Oleg, do we want something like the below on top to make that work > > again? > > > > --- > > --- a/kernel/sched/wait.c > > +++ b/kernel/sched/wait.c > > @@ -326,8 +326,10 @@ long wait_woken(wait_queue_t *wait, unsi > > * woken_wake_function() such that if we observe WQ_FLAG_WOKEN we must > > * also observe all state before the wakeup. > > */ > > - if (!(wait->flags & WQ_FLAG_WOKEN)) > > - timeout = schedule_timeout(timeout); > > + if (!(wait->flags & WQ_FLAG_WOKEN)) { > > + if (___wait_is_interruptible(mode) && !signal_pending_state(mode, current)) > > + timeout = schedule_timeout(timeout); > > + } > > __set_current_state(TASK_RUNNING); > > I am a bit confused... but for what? > > schedule() won't sleep if signal_pending_state(mode) anyway, so we > do not need this correctness-wise. And the caller needs to check > signal_pending() anyway. Urgh, I always forget how all that signal stuff works. Yes you're right, we check that right in __schedule(). I'll just make all what I did go away and we'll keep it simple like it was. Sorry for the confusion. -- 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/