Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751996AbaJETrx (ORCPT ); Sun, 5 Oct 2014 15:47:53 -0400 Received: from mail-qc0-f177.google.com ([209.85.216.177]:42004 "EHLO mail-qc0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751474AbaJETrv (ORCPT ); Sun, 5 Oct 2014 15:47:51 -0400 Date: Sun, 5 Oct 2014 15:47:48 -0400 From: Tejun Heo To: Joe Lawrence Cc: linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, jiri@resnulli.us, stable@vger.kernel.org Subject: Re: [PATCH v2 1/2] workqueue: add quiescent state between work items Message-ID: <20141005194748.GG8549@htj.dyndns.org> References: <1412529862-17954-1-git-send-email-joe.lawrence@stratus.com> <1412529862-17954-2-git-send-email-joe.lawrence@stratus.com> <20141005192119.GE8549@htj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141005192119.GE8549@htj.dyndns.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 05, 2014 at 03:21:19PM -0400, Tejun Heo wrote: > On Sun, Oct 05, 2014 at 01:24:21PM -0400, Joe Lawrence wrote: > > Similar to the stop_machine deadlock scenario on !PREEMPT kernels > > addressed in b22ce2785d97 "workqueue: cond_resched() after processing > > each work item", kworker threads requeueing back-to-back with zero jiffy > > delay can stall RCU. The cond_resched call introduced in that fix will > > yield only iff there are other higher priority tasks to run, so force a > > quiescent RCU state between work items. > > > > Signed-off-by: Joe Lawrence > > Link: https://lkml.kernel.org/r/20140926105227.01325697@jlaw-desktop.mno.stratus.com > > Link: https://lkml.kernel.org/r/20140929115445.40221d8e@jlaw-desktop.mno.stratus.com > > Fixes: b22ce2785d97 ("workqueue: cond_resched() after processing each work item") > > Cc: > > Applied to wq/for-3.17-fixes. If 3.17 comes out before this gets > merged, I'll send it as for-3.18. Oops, the rcu calls aren't in mainline yet. I think it'd be best to route these through the RCU tree. Paul, can you please route these two patches? Acked-by: Tejun Heo Thanks. -- tejun -- 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/