From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751256AbcEJQkn (ORCPT ); Tue, 10 May 2016 12:40:43 -0400 Received: from mail-yw0-f178.google.com ([209.85.161.178]:35050 "EHLO mail-yw0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750910AbcEJQkl (ORCPT ); Tue, 10 May 2016 12:40:41 -0400 Date: Tue, 10 May 2016 12:36:25 -0400 From: Tejun Heo To: Konstantin Khlebnikov Cc: "linux-kernel@vger.kernel.org" , Sasha Levin Subject: Re: workqueue: race in mod_delayed_work_on? Message-ID: <20160510163625.GM7110@mtj.duckdns.org> References: <57319A12.2020403@yandex-team.ru> <57320C18.3000909@yandex-team.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57320C18.3000909@yandex-team.ru> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Tue, May 10, 2016 at 07:28:08PM +0300, Konstantin Khlebnikov wrote: > On 10.05.2016 11:21, Konstantin Khlebnikov wrote: > >I've got plenty warnings, bugs and oops around trivial use of mod_delayed_work in drivers/infiniband/core/addr.c > > Looks like problem in mod_delayed_work_on was hidden because add_timer is equal to mod_timer The timer usages are gated behind PENDING bit, so whether add_timer() is equal to mod_timer() shouldn't matter. > but Sasha accidentally backported 874bbfe600a660cba9c776b3957b1ce393151b76 > (workqueue: make sure delayed work run in local cpu) into 3.18.25 > > I don't see reason why that commit could break delayed work, > most likely it highlighted some other problem. What are you running? Can you reproduce the issue on upstream kernel? -- tejun