From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753713Ab3CRTcY (ORCPT ); Mon, 18 Mar 2013 15:32:24 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:6517 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751383Ab3CRTcX (ORCPT ); Mon, 18 Mar 2013 15:32:23 -0400 X-Authority-Analysis: v=2.0 cv=H5hZMpki c=1 sm=0 a=rXTBtCOcEpjy1lPqhTCpEQ==:17 a=mNMOxpOpBa8A:10 a=bGeQnFoGQusA:10 a=5SG0PmZfjMsA:10 a=IkcTkHD0fZMA:10 a=meVymXHHAAAA:8 a=mxv2HPhRFNcA:10 a=VwQbUJbxAAAA:8 a=Vl498xH2DZN-PoZfw4oA:9 a=QEXdDO2ut3YA:10 a=LI9Vle30uBYA:10 a=jeBq3FmKZ4MA:10 a=rXTBtCOcEpjy1lPqhTCpEQ==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 74.67.115.198 Message-ID: <1363635140.28194.10.camel@gandalf.local.home> Subject: Re: [PATCH] scheduler: convert BUG_ON()s in try_to_wake_up_local() to WARN_ON_ONCE()s From: Steven Rostedt To: Tejun Heo Cc: Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, Thomas Gleixner , Clark Williams Date: Mon, 18 Mar 2013 15:32:20 -0400 In-Reply-To: <20130318192234.GD3042@htj.dyndns.org> References: <20130318192234.GD3042@htj.dyndns.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.4-2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2013-03-18 at 12:22 -0700, Tejun Heo wrote: > try_to_wake_up_local() should only be invoked to wake up another task > in the same runqueue and BUG_ON()s are used to enforce the rule. > Missing try_to_wake_up_local() can stall workqueue execution but such > stalls are likely to be finite either by another work item being > queued or the one blocked getting unblocked. There's no reason to > trigger BUG while holding rq lock crashing the whole system. > > Convert BUG_ON()s in try_to_wake_up_local() to WARN_ON_ONCE()s. > > Signed-off-by: Tejun Heo > Cc: Steven Rostedt Acked-by: Steven Rostedt -- Steve > --- > kernel/sched/core.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 7f12624..a2eda4d 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -1498,8 +1498,10 @@ static void try_to_wake_up_local(struct task_struct *p) > { > struct rq *rq = task_rq(p); > > - BUG_ON(rq != this_rq()); > - BUG_ON(p == current); > + if (WARN_ON_ONCE(rq != this_rq()) || > + WARN_ON_ONCE(p == current)) > + return; > + > lockdep_assert_held(&rq->lock); > > if (!raw_spin_trylock(&p->pi_lock)) {