From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752155AbdFUWEm (ORCPT ); Wed, 21 Jun 2017 18:04:42 -0400 Received: from mail-yw0-f169.google.com ([209.85.161.169]:34995 "EHLO mail-yw0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751667AbdFUWEl (ORCPT ); Wed, 21 Jun 2017 18:04:41 -0400 Date: Wed, 21 Jun 2017 18:04:38 -0400 From: Tejun Heo To: Waiman Long Cc: Li Zefan , Johannes Weiner , Peter Zijlstra , Ingo Molnar , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, efault@gmx.de, torvalds@linux-foundation.org Subject: Re: [RFC PATCH-cgroup 5/6] cgroup: Skip dying css in cgroup_apply_control_{enable,disable} Message-ID: <20170621220438.GB18600@htj.duckdns.org> References: <1497452737-11125-1-git-send-email-longman@redhat.com> <1497452737-11125-6-git-send-email-longman@redhat.com> <20170621214216.GE14720@htj.duckdns.org> <81c62822-8bb6-ae68-112a-dad49414e3f1@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <81c62822-8bb6-ae68-112a-dad49414e3f1@redhat.com> User-Agent: Mutt/1.8.2 (2017-04-18) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, Jun 21, 2017 at 06:01:56PM -0400, Waiman Long wrote: > I do think that it can happen with existing code because CSS killing is > asynchronous, I think. So the command can complete before the CSS is > actually gone. If the next command to reactivate it happens fast enough, > we can trigger that. When I added more checking to my test script > essentially increasing the latency between successive tests, I couldn't > trigger it anymore. While disabling is asynchronous, there's a flushing logic before starting reenabling things, so the existing code shouldn't trigger that condition. But then there's should and the reality. :) Thanks. -- tejun