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 A1EFAC2BBD5 for ; Fri, 18 Dec 2020 16:09:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 758AC23B75 for ; Fri, 18 Dec 2020 16:09:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730294AbgLRQJu (ORCPT ); Fri, 18 Dec 2020 11:09:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727608AbgLRQJt (ORCPT ); Fri, 18 Dec 2020 11:09:49 -0500 Received: from mail-pj1-x102f.google.com (mail-pj1-x102f.google.com [IPv6:2607:f8b0:4864:20::102f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4DA6BC061285 for ; Fri, 18 Dec 2020 08:09:09 -0800 (PST) Received: by mail-pj1-x102f.google.com with SMTP id v1so1535002pjr.2 for ; Fri, 18 Dec 2020 08:09:09 -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=HILaepP1L4LkoXGwjGc6/8JBQvrDdhltwxNiKtQLYyE=; b=a8y/QEyVo+S8aK85CvirEM0AMNRs75MWjiQVcmcwXD6eKV5Mh1AQ3f128Hj447yKXX sApwzn+GpoWpXPMvvRm+NybbV5kfHRUri80bgjlUJrdPc9imbVr5ui1ytyfB9H0uDZnq OdwyIVnhlccLrpVDRfT8H4hsaidkVazfRWzwRChMVntthXcRt5ClKP4YTCo3WU22tCnG mnBT/nBZJPDz6LCxU5x31OkorCk8JfCTfqPlrf4s5KzkR6W04MbTkzsHfT027cLEzWuR LwEB7cN2TlSufEdKKNTzL3SRIedhR7jBl4hRMn98O8R9ljyEb0Jq3XP9Lh5K/NeqMIVl HYOA== 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=HILaepP1L4LkoXGwjGc6/8JBQvrDdhltwxNiKtQLYyE=; b=MpJ4NuTaTkjSZc6Yuxo2CLphoVSu00Bv5GK6rYZGhPg5NuAZV8wegisnRCoRmby/4f 9tiKlAGdADdAvzGI99X6A27CQSHWGgKxrWpqFFH4ca5G5e2MdGD6DzEkQ0wc/fhdEvHc mkLSDCbCIuJPvtEc85Xq9BAyWwY0YpwJTFELRUDJZmBNXLgwLPoKeVDunnSkcPcYuOBE TpB7PTpHBu8N40JXvt/LCVJqlsDDhEyCqh+qS2gb+XM9Dphz7nEf69gX+qNMT4lPCIGe zooX8tcyr4jFxJlu/0ZIAqTuzAUpv3Tt5lFNlL0MHKBO8jTtRCuQb4O7jlDmHKkHh9O7 YGIA== X-Gm-Message-State: AOAM532dksoPMOFCSQkdggtgBidA5t2Lf1Li4DA8McS+UeoREASKKB/s IyCLamh7IFE+fwz31kW9908el3tizHA= X-Google-Smtp-Source: ABdhPJweZzlLDxl8M6kOxmpStgmtqZh/iRGCgjiUE3aMiAcJLBkT38JR3XDVyWlogphH65gTeb4DMA== X-Received: by 2002:a17:90a:c592:: with SMTP id l18mr4962949pjt.228.1608307748677; Fri, 18 Dec 2020 08:09:08 -0800 (PST) Received: from localhost ([47.251.4.198]) by smtp.gmail.com with ESMTPSA id t5sm7956672pjr.22.2020.12.18.08.09.07 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 18 Dec 2020 08:09:08 -0800 (PST) From: Lai Jiangshan To: linux-kernel@vger.kernel.org Cc: Valentin Schneider , Peter Zijlstra , Qian Cai , Vincent Donnefort , Lai Jiangshan , Tejun Heo , Lai Jiangshan , Daniel Bristot de Oliveira Subject: [PATCH -tip V2 03/10] workqueue: Manually break affinity on pool detachment Date: Sat, 19 Dec 2020 01:09:12 +0800 Message-Id: <20201218170919.2950-4-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20201218170919.2950-1-jiangshanlai@gmail.com> References: <20201218170919.2950-1-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 fa71520822f0..4d7575311198 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