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 28892C43381 for ; Sat, 26 Dec 2020 01:52:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1B3A224B1 for ; Sat, 26 Dec 2020 01:52:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729362AbgLZBwS (ORCPT ); Fri, 25 Dec 2020 20:52:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726164AbgLZBwS (ORCPT ); Fri, 25 Dec 2020 20:52:18 -0500 Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E354DC0613C1 for ; Fri, 25 Dec 2020 17:51:37 -0800 (PST) Received: by mail-pf1-x42e.google.com with SMTP id t8so3160620pfg.8 for ; Fri, 25 Dec 2020 17:51:37 -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=rmioAxNSR6MAY+J4fyGJ9OkjHtlBhIZAxyWFqSA2PTg=; b=a9fdtmJm9f3y1e4rkyLB6faMuZKB2ebBCjIGnVqjZBhwxo08r9rCzsflVdyudM2paC ohigfDgaJhNEW8bEMWSMLMV6RKZS5/14+6dWpaVWfbgOtSWtF8FYIfPOY/EoSdLN7LVH VwxZ32EJeEC15ekK6ybFW9Bc8gvWSUB/gP85fPSwhEoXLXapOi/8BRN31xdsrVXrSzUI utbWGDODU9jaG1r6dcP2LnEUxUA6TM6r/LacBx8Z2NPrQ7Cays4PBcU4e3b3UQiADFsV aqGCsP4MQmXI+CmeQXfSABTYHEwbjjU/bu4Nfm1dXlUUb5llGuqpsMAeXj5RJBs7OQeO iwDA== 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=rmioAxNSR6MAY+J4fyGJ9OkjHtlBhIZAxyWFqSA2PTg=; b=eZblD7uAiRKr/t2FdyGAAzsnZ75+chdl8saRcPonKdFd+uWo4UjUMt5xixqI/6dElf x7lw6LD7pDkcIaor6yLLiXpnBU+ikqSfMUTV5LLME9Y3EoTpf3aHEPjj8vSQJzMR6E2b +72G1CfBHDR82/kdIdVtqpVuPzfyqcXIifLDPmgvfoK9dyaB7rfKOnhvlErrthhpPPOL L5U9WFU03XOS7FhVY1gwY28vpVhiDogfENmheE+z6p3FstcIZa9OOae3xck0fcNriQaX XeuwWcXQQnjh7OFvExpw5ikKmzsVNWReEnnmgEjlpnCLd/JOkPCgjIHa8acJn4Nh9F5R f9uQ== X-Gm-Message-State: AOAM533QTDOEcvXlfJ1Jz7ILzU/JRnDV+7O+5496X9aLW3EZZtNtMIHt bp64RxscMp0yfntxMrDKjPcf1gfEvlE= X-Google-Smtp-Source: ABdhPJxoetehjnG0HHX1bUnfzEc2bPOTEN3/vDXN+FaQD2lo3rYrdg9TEcgH9saPYmDIPXH9u1yJcg== X-Received: by 2002:a63:5720:: with SMTP id l32mr22883358pgb.64.1608947497404; Fri, 25 Dec 2020 17:51:37 -0800 (PST) Received: from localhost ([47.251.3.230]) by smtp.gmail.com with ESMTPSA id y16sm21792055pgg.20.2020.12.25.17.51.36 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 25 Dec 2020 17:51:36 -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 Subject: [PATCH -tip V3 8/8] workqueue: Fix affinity of kworkers when attaching into pool Date: Sat, 26 Dec 2020 10:51:16 +0800 Message-Id: <20201226025117.2770-9-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 When worker_attach_to_pool() is called, we should not put the workers to pool->attrs->cpumask when there is not CPU online in it. We have to use wq_online_cpumask in worker_attach_to_pool() to check if pool->attrs->cpumask is valid rather than cpu_online_mask or cpu_active_mask due to gaps between stages in cpu hot[un]plug. So for that late-spawned per-CPU kworker case: the outgoing CPU should have already been cleared from wq_online_cpumask, so it gets its affinity reset to the possible mask and the subsequent wakeup will ensure it's put on an active CPU. To use wq_online_cpumask in worker_attach_to_pool(), we need to protect wq_online_cpumask in wq_pool_attach_mutex and we modify workqueue_online_cpu() and workqueue_offline_cpu() to enlarge wq_pool_attach_mutex protected region. We also put updating wq_online_cpumask and [re|un]bind_workers() in the same wq_pool_attach_mutex protected region to make the update for percpu workqueue atomically. Cc: Qian Cai Cc: Peter Zijlstra Cc: Vincent Donnefort Link: https://lore.kernel.org/lkml/20201210163830.21514-3-valentin.schneider@arm.com/ Reviewed-by: Valentin Schneider Acked-by: Tejun Heo Signed-off-by: Lai Jiangshan --- kernel/workqueue.c | 32 +++++++++++++++----------------- 1 file changed, 15 insertions(+), 17 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index dd32398edf55..25d50050257c 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -310,7 +310,7 @@ static bool workqueue_freezing; /* PL: have wqs started freezing? */ /* PL: allowable cpus for unbound wqs and work items */ static cpumask_var_t wq_unbound_cpumask; -/* PL: online cpus (cpu_online_mask with the going-down cpu cleared) */ +/* PL&A: online cpus (cpu_online_mask with the going-down cpu cleared) */ static cpumask_var_t wq_online_cpumask; /* CPU where unbound work was last round robin scheduled from this CPU */ @@ -1848,11 +1848,11 @@ static void worker_attach_to_pool(struct worker *worker, { mutex_lock(&wq_pool_attach_mutex); - /* - * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any - * online CPUs. It'll be re-applied when any of the CPUs come up. - */ - set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); + /* Is there any cpu in pool->attrs->cpumask online? */ + if (cpumask_intersects(pool->attrs->cpumask, wq_online_cpumask)) + WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask) < 0); + else + WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0); /* * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains @@ -5082,13 +5082,12 @@ int workqueue_online_cpu(unsigned int cpu) int pi; mutex_lock(&wq_pool_mutex); - cpumask_set_cpu(cpu, wq_online_cpumask); - for_each_cpu_worker_pool(pool, cpu) { - mutex_lock(&wq_pool_attach_mutex); + mutex_lock(&wq_pool_attach_mutex); + cpumask_set_cpu(cpu, wq_online_cpumask); + for_each_cpu_worker_pool(pool, cpu) rebind_workers(pool); - mutex_unlock(&wq_pool_attach_mutex); - } + mutex_unlock(&wq_pool_attach_mutex); /* update CPU affinity of workers of unbound pools */ for_each_pool(pool, pi) { @@ -5118,14 +5117,13 @@ int workqueue_offline_cpu(unsigned int cpu) if (WARN_ON(cpu != smp_processor_id())) return -1; - for_each_cpu_worker_pool(pool, cpu) { - mutex_lock(&wq_pool_attach_mutex); - unbind_workers(pool); - mutex_unlock(&wq_pool_attach_mutex); - } - mutex_lock(&wq_pool_mutex); + + mutex_lock(&wq_pool_attach_mutex); cpumask_clear_cpu(cpu, wq_online_cpumask); + for_each_cpu_worker_pool(pool, cpu) + unbind_workers(pool); + mutex_unlock(&wq_pool_attach_mutex); /* update CPU affinity of workers of unbound pools */ for_each_pool(pool, pi) { -- 2.19.1.6.gb485710b