From nobody Sun Apr 12 04:21:06 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0592C00140 for ; Tue, 2 Aug 2022 08:42:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236440AbiHBIma (ORCPT ); Tue, 2 Aug 2022 04:42:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231859AbiHBImZ (ORCPT ); Tue, 2 Aug 2022 04:42:25 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id CAB7C1BEB0 for ; Tue, 2 Aug 2022 01:42:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1659429744; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4gzLDvQ7aWaj23CMbC0REd/onn9CKJJFu3RV6mIazrs=; b=Xp1UPP5ii4iyXaAydigSfRar46EdUQPO7gmNfsjGS+rfXTQAVXIj7cjBdvxIrwkhg/Ilxc j1UFdoXDG9HLU0N0BPz7uk423JkcJZOziBaMdbt5Z7Fc6c+gl61w0VCTq6aS54cAGlT4Il 9uuuQMXnnNLlwIevTRhGrdHkTIBdc5g= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-457-J1vX1i_rNjGZGR7kmqvMsQ-1; Tue, 02 Aug 2022 04:42:23 -0400 X-MC-Unique: J1vX1i_rNjGZGR7kmqvMsQ-1 Received: by mail-wr1-f72.google.com with SMTP id s24-20020adf9798000000b0021ed3f3dd75so3254033wrb.15 for ; Tue, 02 Aug 2022 01:42:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc; bh=4gzLDvQ7aWaj23CMbC0REd/onn9CKJJFu3RV6mIazrs=; b=eUbS/yaAgNCSbC1+YVLDR7BQrvxhQ++ZZn4dk4O17z1ZtA2c5c9szIGWnMRDJ4XhbJ qUKMc1EuchElX5IvP9YLNp5Qcev8bW0i5Ub8ywL3jHPRGqOWojM+2rnmWb4sdk67q3DU 7VIDashNHo6X0rv7s+q5UHPvRrnfUw6TpMkgddkSTnW1+jHjAgKLAUBLexF+yXP9q+jC mBwErAFXHQ6VhsT5+bHR4tT9eOp8gjku8TUVZ2YBBvuQQs84qEdvmyIf0JGAOMY/ZQqJ r2WljJAU0sbtn6CdbXOo5RB92VZzWPg97NpVSSm/kMF+IkDHl0QPyeIY1Xk1uvI2Zz5w l1MA== X-Gm-Message-State: AJIora88xsILnoRFGxinErcMdIYc5yCj1yC/C7daqbU1dle7k9EPxsMl 63DhFdiqTtkowQa8ChUkLjbbpvoZyYQlx4wz4EnNMI1ka2xEtHxtSokt3o5GODpDDO6P8ZAMJqk SeLGtm3uo9qOpuX5B20DQoIOlG2L7v1817THXiMBCZZ2rzJFOQ7BLHcFnN7cRoSvPPrzuVbXDax Bj X-Received: by 2002:a05:600c:a146:b0:3a3:1e79:4446 with SMTP id ib6-20020a05600ca14600b003a31e794446mr13768018wmb.158.1659429741610; Tue, 02 Aug 2022 01:42:21 -0700 (PDT) X-Google-Smtp-Source: AGRyM1te439EFrpVNkzNpR1rWgVUPi8JRsLzt6WMfD4BOYnGxBzLvyGLBPnePuCREG7Vbdo+SsE81w== X-Received: by 2002:a05:600c:a146:b0:3a3:1e79:4446 with SMTP id ib6-20020a05600ca14600b003a31e794446mr13768000wmb.158.1659429741412; Tue, 02 Aug 2022 01:42:21 -0700 (PDT) Received: from vschneid.remote.csb ([185.11.37.247]) by smtp.gmail.com with ESMTPSA id f12-20020a05600c154c00b003a31169a7f4sm24825800wmg.12.2022.08.02.01.42.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Aug 2022 01:42:20 -0700 (PDT) From: Valentin Schneider To: linux-kernel@vger.kernel.org Cc: Tejun Heo , Lai Jiangshan , Peter Zijlstra , Frederic Weisbecker , Juri Lelli , Phil Auld , Marcelo Tosatti Subject: [RFC PATCH v3 1/3] workqueue: Hold wq_pool_mutex while affining tasks to wq_unbound_cpumask Date: Tue, 2 Aug 2022 09:41:44 +0100 Message-Id: <20220802084146.3922640-2-vschneid@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220802084146.3922640-1-vschneid@redhat.com> References: <20220802084146.3922640-1-vschneid@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" When unbind_workers() reads wq_unbound_cpumask to set the affinity of freshly-unbound kworkers, it only holds wq_pool_attach_mutex. This isn't sufficient as wq_unbound_cpumask is only protected by wq_pool_mutex. This is made more obvious as of recent commit 46a4d679ef88 ("workqueue: Avoid a false warning in unbind_workers()") e.g. unbind_workers() workqueue_set_unbound_cpumask() kthread_set_per_cpu(p, -1); if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask)) cpumask_copy(wq_unbound_cpumask, cpumask); WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0= ); Make workqueue_offline_cpu() invoke unbind_workers() with wq_pool_mutex held. Fixes: 10a5a651e3af ("workqueue: Restrict kworker in the offline CPU pool r= unning on housekeeping CPUs") Signed-off-by: Valentin Schneider Reported-by: Valentin Schneider --- kernel/workqueue.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index aa8a82bc6738..97cc41430a76 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -5143,14 +5143,15 @@ int workqueue_offline_cpu(unsigned int cpu) if (WARN_ON(cpu !=3D smp_processor_id())) return -1; =20 + mutex_lock(&wq_pool_mutex); + unbind_workers(cpu); =20 /* update NUMA affinity of unbound workqueues */ - mutex_lock(&wq_pool_mutex); list_for_each_entry(wq, &workqueues, list) wq_update_unbound_numa(wq, cpu, false); - mutex_unlock(&wq_pool_mutex); =20 + mutex_unlock(&wq_pool_mutex); return 0; } =20 --=20 2.31.1