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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 CCC35C43333 for ; Mon, 15 Mar 2021 14:45:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AEBFF64F33 for ; Mon, 15 Mar 2021 14:45:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238900AbhCOOpT (ORCPT ); Mon, 15 Mar 2021 10:45:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:51696 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234532AbhCOOEM (ORCPT ); Mon, 15 Mar 2021 10:04:12 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id DA0DB64E83; Mon, 15 Mar 2021 14:04:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1615817052; bh=WPjeWVA1ttw7p/Rkyh3FafAywGgPmhm9Sf7XLwNoQCM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Po3S2V0zf3Al2m16NlaF5ngr9RpO/kaaVXJDecGojJ0LBKai1YW8j2tL4OEBx5xlp 6iYktc/HdJeSrgjpNMNjNS/QMzb7w9uAKcBQR7m07aninMF261WL2PWMkabWPq8WYf iK75YkBdflbYHwHOTfusSuO9mH+brEE1pdPbFMOQ= From: gregkh@linuxfoundation.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, stable@kernel.org, "Peter Zijlstra (Intel)" , Ingo Molnar , Valentin Schneider Subject: [PATCH 5.11 276/306] sched: Optimize migration_cpu_stop() Date: Mon, 15 Mar 2021 14:55:39 +0100 Message-Id: <20210315135516.995722029@linuxfoundation.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210315135507.611436477@linuxfoundation.org> References: <20210315135507.611436477@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Greg Kroah-Hartman From: Peter Zijlstra commit 3f1bc119cd7fc987c8ed25ffb717f99403bb308c upstream. When the purpose of migration_cpu_stop() is to migrate the task to 'any' valid CPU, don't migrate the task when it's already running on a valid CPU. Fixes: 6d337eab041d ("sched: Fix migrate_disable() vs set_cpus_allowed_ptr()") Cc: stable@kernel.org Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Valentin Schneider Link: https://lkml.kernel.org/r/20210224131355.569238629@infradead.org Signed-off-by: Greg Kroah-Hartman --- kernel/sched/core.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1936,14 +1936,25 @@ static int migration_cpu_stop(void *data complete = true; } - if (dest_cpu < 0) + if (dest_cpu < 0) { + if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) + goto out; + dest_cpu = cpumask_any_distribute(&p->cpus_mask); + } if (task_on_rq_queued(p)) rq = __migrate_task(rq, &rf, p, dest_cpu); else p->wake_cpu = dest_cpu; + /* + * XXX __migrate_task() can fail, at which point we might end + * up running on a dodgy CPU, AFAICT this can only happen + * during CPU hotplug, at which point we'll get pushed out + * anyway, so it's probably not a big deal. + */ + } else if (pending) { /* * This happens when we get migrated between migrate_enable()'s