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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 6187AC4CECD for ; Tue, 17 Sep 2019 15:24:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 420A021881 for ; Tue, 17 Sep 2019 15:24:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729186AbfIQPYE (ORCPT ); Tue, 17 Sep 2019 11:24:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60120 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728127AbfIQPYE (ORCPT ); Tue, 17 Sep 2019 11:24:04 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B550E8A1CA6; Tue, 17 Sep 2019 15:24:01 +0000 (UTC) Received: from ovpn-117-172.phx2.redhat.com (ovpn-117-172.phx2.redhat.com [10.3.117.172]) by smtp.corp.redhat.com (Postfix) with ESMTP id 69AC726E66; Tue, 17 Sep 2019 15:23:59 +0000 (UTC) Message-ID: <1bcdec32b7a8165935cffbb2547c3d977c93f26d.camel@redhat.com> Subject: Re: [PATCH RT 2/8] sched: __set_cpus_allowed_ptr: Check cpus_mask, not cpus_ptr From: Scott Wood To: Sebastian Andrzej Siewior Cc: Thomas Gleixner , Steven Rostedt , Peter Zijlstra , Juri Lelli , Daniel Bristot de Oliveira , Clark Williams , linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Date: Tue, 17 Sep 2019 10:23:58 -0500 In-Reply-To: <20190917145729.pul3dmbrdnshne6m@linutronix.de> References: <20190727055638.20443-1-swood@redhat.com> <20190727055638.20443-3-swood@redhat.com> <20190917145729.pul3dmbrdnshne6m@linutronix.de> Organization: Red Hat Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.69]); Tue, 17 Sep 2019 15:24:04 +0000 (UTC) Sender: linux-rt-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org On Tue, 2019-09-17 at 16:57 +0200, Sebastian Andrzej Siewior wrote: > On 2019-07-27 00:56:32 [-0500], Scott Wood wrote: > > This function is concerned with the long-term cpu mask, not the > > transitory mask the task might have while migrate disabled. Before > > this patch, if a task was migrate disabled at the time > > __set_cpus_allowed_ptr() was called, and the new mask happened to be > > equal to the cpu that the task was running on, then the mask update > > would be lost. > > lost as in "would not be carried out" I assume. Right. The old mask would be restored upon migrate_enable() even though that's no longer the policy that was requested. -Scott