From patchwork Thu Sep 9 09:38:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: thermal-bot for Julien Panis X-Patchwork-Id: 508750 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=-20.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED 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 1715AC433F5 for ; Thu, 9 Sep 2021 09:38:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E5B216113E for ; Thu, 9 Sep 2021 09:38:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233080AbhIIJjr (ORCPT ); Thu, 9 Sep 2021 05:39:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229927AbhIIJjr (ORCPT ); Thu, 9 Sep 2021 05:39:47 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 02033C061575; Thu, 9 Sep 2021 02:38:37 -0700 (PDT) Date: Thu, 09 Sep 2021 09:38:34 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1631180315; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lcNaP07PKMAmOJRYwyE4hu2hgVbleeLOp79xPo503QA=; b=FnhyKhFH5VbglJwVrG886b43A+BIuM4Gs4i43SgnnD8RxLQIJtStnZPlyvz5MuudKysy6z pIfg2ggyOZ0+A9A0+WIxltii5vYtXOokYqU+Vv3cyO7uLjJ5Jl/UGv97t04l02FudCgyfc j7XuqG2ZT4KyFufuRGaB2QFs/DQ1GzSbiUx0lZPoPwVvYn0MAjJnWpPize25dw2yOM+UCm FnTb1IDJ8FUBqhiHMzvNarY8BXd+hlN6qSFdvYPGpm6ll6mvgrsiPBejdGq0nfEYtBaAiF xwAXp+nwJOlAUNCA2FpWKioZtAx2418qX4ayfyCNQ9dxnOVvAiq22Q9WOye6jQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1631180315; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lcNaP07PKMAmOJRYwyE4hu2hgVbleeLOp79xPo503QA=; b=emY8EWEWXfYbLaCfIQBpbkzvY4MF+U8nS/0zEkj9DaVZoWvkyHc4GUJOEOe7CPleBM5y3S CimKJo6QSL7wDPCQ== From: "tip-bot2 for Thomas Gleixner" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/urgent] sched: Prevent balance_push() on remote runqueues Cc: Sebastian Siewior , Thomas Gleixner , "Peter Zijlstra (Intel)" , stable@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <87zgt1hdw7.ffs@tglx> References: <87zgt1hdw7.ffs@tglx> MIME-Version: 1.0 Message-ID: <163118031401.25758.11404036783844944649.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The following commit has been merged into the sched/urgent branch of tip: Commit-ID: 868ad33bfa3bf39960982682ad3a0f8ebda1656e Gitweb: https://git.kernel.org/tip/868ad33bfa3bf39960982682ad3a0f8ebda1656e Author: Thomas Gleixner AuthorDate: Sat, 28 Aug 2021 15:55:52 +02:00 Committer: Peter Zijlstra CommitterDate: Thu, 09 Sep 2021 11:27:23 +02:00 sched: Prevent balance_push() on remote runqueues sched_setscheduler() and rt_mutex_setprio() invoke the run-queue balance callback after changing priorities or the scheduling class of a task. The run-queue for which the callback is invoked can be local or remote. That's not a problem for the regular rq::push_work which is serialized with a busy flag in the run-queue struct, but for the balance_push() work which is only valid to be invoked on the outgoing CPU that's wrong. It not only triggers the debug warning, but also leaves the per CPU variable push_work unprotected, which can result in double enqueues on the stop machine list. Remove the warning and validate that the function is invoked on the outgoing CPU. Fixes: ae7927023243 ("sched: Optimize finish_lock_switch()") Reported-by: Sebastian Siewior Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/87zgt1hdw7.ffs@tglx --- kernel/sched/core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index f3b27c6..b21a185 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8523,7 +8523,6 @@ static void balance_push(struct rq *rq) struct task_struct *push_task = rq->curr; lockdep_assert_rq_held(rq); - SCHED_WARN_ON(rq->cpu != smp_processor_id()); /* * Ensure the thing is persistent until balance_push_set(.on = false); @@ -8531,9 +8530,10 @@ static void balance_push(struct rq *rq) rq->balance_callback = &balance_push_callback; /* - * Only active while going offline. + * Only active while going offline and when invoked on the outgoing + * CPU. */ - if (!cpu_dying(rq->cpu)) + if (!cpu_dying(rq->cpu) || rq != this_rq()) return; /*