From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE327C432BE for ; Thu, 26 Aug 2021 22:53:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 957E760ED5 for ; Thu, 26 Aug 2021 22:53:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243834AbhHZWx4 (ORCPT ); Thu, 26 Aug 2021 18:53:56 -0400 Received: from out0.migadu.com ([94.23.1.103]:44384 "EHLO out0.migadu.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231307AbhHZWxz (ORCPT ); Thu, 26 Aug 2021 18:53:55 -0400 Date: Fri, 27 Aug 2021 06:53:51 +0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1630018384; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=erq1XqrY8ZVsMbLH+bOTHYcfIujF9uYA/N4nT8HFyFo=; b=Lh57LYjeZZhENIdAMjgBYwRj/m21dqYay8a3yO6Wu3VikEz+eTpTlpOXFNbptmkbvkNkxz okyZOOihNDt85VzogX3T+1lYXmYgipQ/R1T0wVNQ5oxu1uDsoqqmjeCTeW9nuMH9nv9i6C yXoFveRQKl0INhbz0tc/ffp9z+vVEAY= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Tao Zhou To: Thomas Gleixner Cc: Sebastian Andrzej Siewior , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , linux-kernel@vger.kernel.org, tao.zhou@linux.dev Subject: Re: [PATCH] sched: Fix get_push_task() vs migrate_disable() Message-ID: References: <20210826133738.yiotqbtdaxzjsnfj@linutronix.de> <87k0k82dzq.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87k0k82dzq.ffs@tglx> X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: tao.zhou@linux.dev Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Thomas, On Thu, Aug 26, 2021 at 09:38:17PM +0200, Thomas Gleixner wrote: > Tao, > > On Fri, Aug 27 2021 at 00:24, Tao Zhou wrote: > > On Thu, Aug 26, 2021 at 03:37:38PM +0200, Sebastian Andrzej Siewior wrote: > >> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > >> index e205b63d6db07..32a4945730a9b 100644 > >> --- a/kernel/sched/sched.h > >> +++ b/kernel/sched/sched.h > >> @@ -2259,6 +2259,9 @@ static inline struct task_struct *get_push_task(struct rq *rq) > >> if (p->nr_cpus_allowed == 1) > >> return NULL; > >> > >> + if (p->migration_disabled) > >> + return NULL; > > > > Not much I can restore here.. > > > > Is is_migration_disabled(p) be more correct to check migration > > disable. > > Kinda, but it's not an issue here because get_push_task() is only available when > CONFIG_SMP=y which makes p->migration_disabled available as well. > > > And get_push_task() being called in pull_rt_task() has checked migration > > disable first and then call get_push_task(). That means this check in > > get_push_task() in patch is a second repeatly check. > > No. The checks are for two different tasks... Aha, yes. I lost here. Thanks for your reply. > Thanks, > > tglx Thanks, Tao