Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753103AbaJGH3w (ORCPT ); Tue, 7 Oct 2014 03:29:52 -0400 Received: from mail-lb0-f174.google.com ([209.85.217.174]:37842 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751223AbaJGH3s (ORCPT ); Tue, 7 Oct 2014 03:29:48 -0400 Date: Tue, 7 Oct 2014 09:29:42 +0200 From: Jiri Pirko To: "Paul E. McKenney" Cc: Tejun Heo , Joe Lawrence , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2 1/2] workqueue: add quiescent state between work items Message-ID: <20141007072942.GA2088@nanopsycho.orion> 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> <20141005194748.GG8549@htj.dyndns.org> <20141006042158.GW5015@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141006042158.GW5015@linux.vnet.ibm.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 Mon, Oct 06, 2014 at 06:21:58AM CEST, paulmck@linux.vnet.ibm.com wrote: >On Sun, Oct 05, 2014 at 03:47:48PM -0400, Tejun Heo wrote: >> 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 > >Will do! > >I will try 3.17, failing that, 3.18. Paul, Tehun, how do you propose to fix this on older kernels which do not have rcu_note_voluntary_context_switch? I'm particullary interested in 3.10. Thanks. -- 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/