Received: by 2002:a05:6358:4e97:b0:b3:742d:4702 with SMTP id ce23csp2885350rwb; Mon, 15 Aug 2022 13:17:58 -0700 (PDT) X-Google-Smtp-Source: AA6agR5wN5oeoy3t3bruTRvFPKTAohv2JxzzddNjAatMzAXsUxcMoz65nWklr9E2AyZxNJg3lYbL X-Received: by 2002:a05:6402:2b98:b0:43e:107:183d with SMTP id fj24-20020a0564022b9800b0043e0107183dmr16084461edb.366.1660594677973; Mon, 15 Aug 2022 13:17:57 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1660594677; cv=none; d=google.com; s=arc-20160816; b=vv0h0F4hqLywbwALyfv725abtUJKqGt/SBH2MRtwtjhpmbzDIhUScZoY0fCRt6QtE4 E/f1A2iXpMG/IPheHF9S/PRDyKjWg6/qseCUBWXj6rdgEDcWq9gBcLTHW49ms0gjAcb5 iwG4Pc7eNAv5jHzg/NXnPeV+2yorG+xRmhXizzvNWzIwCv1Q+jhByCQRVJgXA+Ymtpc1 3KNJjFf4vszDI6JfetFzJOiM59O21MESgnKptVwuVD9iN8+VpDwOI0fL7SpB9+pk30rj AJM0NgMCuvrLF/4LPLgOMKgj2+UMwoo/yWTIeXl97dddDVGR7EvCBMPRI/XW4HEKJjxi AsjA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:message-id:date:subject:cc:to :from:dkim-signature; bh=bwq2RjuzFUzqUXzrxISJbwhVoHcqWfcdQOicKH97R4Q=; b=F7b0BcWFB2DrHXp5jlOl78ajx1KDEQOGt0yg+lR84Dr6IfoZGxr6XC8JA77IA90ACr QrvtwpLST+qKHKB/J7Zx5Bqb7VImW0e0y5MP4E+H2oOOgGif/KjPo2g8O1xYM93hekBs xn5hiU8emsocYP8iiRtXMHiBswx5jng+T55UOPlFCwJSvEmh4rFwzDI6blHr1dNnSIW1 EEP6s088onptyS45k6wr4Ymew03RVh3i6dZkJ3HHhb43mlb6369JYPPh/WRyq2uk+MCj rrCCSBidPvRtWBarBN/nwR1L8AjK8fvXJGVxQUMI+lsMuy/+UxPStq5qOfWOx6/M0HsU 5MPw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b="Nh/F6uun"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Return-Path: Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id hd11-20020a170907968b00b00732f74db437si7709522ejc.891.2022.08.15.13.17.30; Mon, 15 Aug 2022 13:17:57 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b="Nh/F6uun"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344618AbiHOTr1 (ORCPT + 99 others); Mon, 15 Aug 2022 15:47:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344965AbiHOTp5 (ORCPT ); Mon, 15 Aug 2022 15:45:57 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9DB06CD22; Mon, 15 Aug 2022 11:48:37 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 9405EB81082; Mon, 15 Aug 2022 18:48:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9935AC433D6; Mon, 15 Aug 2022 18:48:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660589314; bh=QY8H96EPvepEtFY3UWFxK8kekjXPXBDtFe/aU03yreA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Nh/F6uun1yAkAVVTguNMXyIEpH0b3mVu2+EB8L5hdDecgFDfJnz+MCIIo6yBJZhRr FlDSltOhR4Ug4slTuncY1XPKMjTqNwq2inS3sgSMauOfYSONeSpe3xj2jLnZrjTv37 y00w7YSpBWILWyvPCk3MjBfUlUCQly2vUNQbScYM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mel Gorman , Ingo Molnar , Sasha Levin Subject: [PATCH 5.15 662/779] sched/core: Do not requeue task on CPU excluded from cpus_mask Date: Mon, 15 Aug 2022 20:05:06 +0200 Message-Id: <20220815180405.648962572@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180337.130757997@linuxfoundation.org> References: <20220815180337.130757997@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mel Gorman [ Upstream commit 751d4cbc43879229dbc124afefe240b70fd29a85 ] The following warning was triggered on a large machine early in boot on a distribution kernel but the same problem should also affect mainline. WARNING: CPU: 439 PID: 10 at ../kernel/workqueue.c:2231 process_one_work+0x4d/0x440 Call Trace: rescuer_thread+0x1f6/0x360 kthread+0x156/0x180 ret_from_fork+0x22/0x30 Commit c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu") optimises ttwu by queueing a task that is descheduling on the wakelist, but does not check if the task descheduling is still allowed to run on that CPU. In this warning, the problematic task is a workqueue rescue thread which checks if the rescue is for a per-cpu workqueue and running on the wrong CPU. While this is early in boot and it should be possible to create workers, the rescue thread may still used if the MAYDAY_INITIAL_TIMEOUT is reached or MAYDAY_INTERVAL and on a sufficiently large machine, the rescue thread is being used frequently. Tracing confirmed that the task should have migrated properly using the stopper thread to handle the migration. However, a parallel wakeup from udev running on another CPU that does not share CPU cache observes p->on_cpu and uses task_cpu(p), queues the task on the old CPU and triggers the warning. Check that the wakee task that is descheduling is still allowed to run on its current CPU and if not, wait for the descheduling to complete and select an allowed CPU. Fixes: c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu") Signed-off-by: Mel Gorman Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20220804092119.20137-1-mgorman@techsingularity.net Signed-off-by: Sasha Levin --- kernel/sched/core.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4499b58ac2ca..85be684687b0 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3714,7 +3714,7 @@ bool cpus_share_cache(int this_cpu, int that_cpu) return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu); } -static inline bool ttwu_queue_cond(int cpu) +static inline bool ttwu_queue_cond(struct task_struct *p, int cpu) { /* * Do not complicate things with the async wake_list while the CPU is @@ -3723,6 +3723,10 @@ static inline bool ttwu_queue_cond(int cpu) if (!cpu_active(cpu)) return false; + /* Ensure the task will still be allowed to run on the CPU. */ + if (!cpumask_test_cpu(cpu, p->cpus_ptr)) + return false; + /* * If the CPU does not share cache, then queue the task on the * remote rqs wakelist to avoid accessing remote data. @@ -3752,7 +3756,7 @@ static inline bool ttwu_queue_cond(int cpu) static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags) { - if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu)) { + if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(p, cpu)) { sched_clock_cpu(cpu); /* Sync clocks across CPUs */ __ttwu_queue_wakelist(p, cpu, wake_flags); return true; -- 2.35.1