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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 67066C433E9 for ; Sat, 26 Dec 2020 01:51:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F58B207CC for ; Sat, 26 Dec 2020 01:51:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729025AbgLZBvg (ORCPT ); Fri, 25 Dec 2020 20:51:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726164AbgLZBvg (ORCPT ); Fri, 25 Dec 2020 20:51:36 -0500 Received: from mail-pl1-x62a.google.com (mail-pl1-x62a.google.com [IPv6:2607:f8b0:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3C13FC0613CF for ; Fri, 25 Dec 2020 17:50:56 -0800 (PST) Received: by mail-pl1-x62a.google.com with SMTP id t6so2956479plq.1 for ; Fri, 25 Dec 2020 17:50:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=KeFih4MTBIL/G6+GX/5b1Bj376aPNpZ/6ClQ33D9BkI=; b=frogcNXKsAY2YbN+7JDxcCr8mY8dTV8OwH+OQ/7e/siAIdrDcoCFA54EbyZ5H2km3m ucbTa6IsKGgkW6t+VXhzcln8MXHcG8ffB83THEfm8+b4h94WFN57Mb9hSC45v7indhUR DWEiNG9SXAvm+rmc5CD2QRjxiG9KROaYSNF9+4z1NeM1v32DiogPdSTrPx2HkdEkjxCF cSLkwRs/BjkHIeTkXziBf9GQx3GTSrhGActmd2Sj5gAqLE1ZxX1EcxrUy5VMVHZ0xgIS kWwBEpoOvOWU/M1Jbr/H2/kg0Hyu9r4mkbSIf9cJ3/JfI3VAzFVjx4w3TW+JjZ9LWQ47 XjTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=KeFih4MTBIL/G6+GX/5b1Bj376aPNpZ/6ClQ33D9BkI=; b=NmeELz+yi34t3cDNrMM4iimg6ySg6XQZ2BaQDpEn7EIOvihKJ0kT2ogxYsUW5Ajcmd nsQdb2VEitwKr4YOQ84vkr5UtSN1Bik39b+xFlUXXiarereIAEcVdRrwu9Gsrm9vuSTr kB4m9/K5xs2HTFCXeEkAs6Q5NPkYXE+g1c/kWsasBux/ygv+NhXomONfd0zRnonxaAaR Z+ieCWFyYtl2HDjMY+PMKj6W4jzjHVtEHcTX2u5ptpcC79uThpcZsE1IrNxwUKGlrz05 xJK+UjDY9mxDUIlvBA1CQOCpf309KSb0KStwxt8FBNAZ+DUHZrNRmSLx9HTtKzr2ZbyH IjWg== X-Gm-Message-State: AOAM5316ON3RZF2HWLwiviw0fMici5lB6J45VBvgPfuuZLH552SYbIhz 3a6BjLr049kGG9CZxrd9p/bWke4yOhU= X-Google-Smtp-Source: ABdhPJxghyKpbHGf+UiYTjG4ornBqf1HBn3Qy7E7Exop4nuSNd0azsCh/gQPZS7cDmpK0DQFLgXeEg== X-Received: by 2002:a17:90a:eac5:: with SMTP id ev5mr10710088pjb.65.1608947455692; Fri, 25 Dec 2020 17:50:55 -0800 (PST) Received: from localhost ([47.251.3.230]) by smtp.gmail.com with ESMTPSA id r68sm29376769pfr.113.2020.12.25.17.50.54 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 25 Dec 2020 17:50:55 -0800 (PST) From: Lai Jiangshan To: linux-kernel@vger.kernel.org Cc: Valentin Schneider , Peter Zijlstra , Qian Cai , Vincent Donnefort , Dexuan Cui , Lai Jiangshan , Tejun Heo , Lai Jiangshan , Daniel Bristot de Oliveira Subject: [PATCH -tip V3 2/8] workqueue: Manually break affinity on pool detachment Date: Sat, 26 Dec 2020 10:51:10 +0800 Message-Id: <20201226025117.2770-3-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20201226025117.2770-1-jiangshanlai@gmail.com> References: <20201226025117.2770-1-jiangshanlai@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lai Jiangshan The pool->attrs->cpumask might be a single CPU and it may go down after detachment, and the scheduler won't force to break affinity for us since it is a per-cpu-ktrhead. So we have to do it on our own and unbind this worker which can't be unbound by workqueue_offline_cpu() since it doesn't belong to any pool after detachment. Do it unconditionally for there is no harm to break affinity for non-per-cpu-ktrhead and we don't need to rely on the scheduler's policy on when to break affinity. Fixes: 06249738a41a ("workqueue: Manually break affinity on hotplug") Acked-by: Tejun Heo Signed-off-by: Lai Jiangshan --- kernel/workqueue.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index f2b8f3d458d1..ccbceacaea1b 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1885,6 +1885,19 @@ static void worker_detach_from_pool(struct worker *worker) if (list_empty(&pool->workers)) detach_completion = pool->detach_completion; + + /* + * The pool->attrs->cpumask might be a single CPU and it may go + * down after detachment, and the scheduler won't force to break + * affinity for us since it is a per-cpu-ktrhead. So we have to + * do it on our own and unbind this worker which can't be unbound + * by workqueue_offline_cpu() since it doesn't belong to any pool + * after detachment. Do it unconditionally for there is no harm + * to break affinity for non-per-cpu-ktrhead and we don't need to + * rely on the scheduler's policy on when to break affinity. + */ + set_cpus_allowed_ptr(worker->task, cpu_possible_mask); + mutex_unlock(&wq_pool_attach_mutex); /* clear leftover flags without pool->lock after it is detached */ -- 2.19.1.6.gb485710b