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=-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 A6F17C6369E for ; Thu, 19 Nov 2020 09:55:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3AEB0221FB for ; Thu, 19 Nov 2020 09:55:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="EovJ6buN"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="p/8SD9Do" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727007AbgKSJzJ (ORCPT ); Thu, 19 Nov 2020 04:55:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726974AbgKSJzH (ORCPT ); Thu, 19 Nov 2020 04:55:07 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 032D5C0613D4; Thu, 19 Nov 2020 01:55:07 -0800 (PST) Date: Thu, 19 Nov 2020 09:55:04 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1605779705; 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=lanMMzq8f95P2MRv1w3fMei1JqZrJujk1xOsUupIJvk=; b=EovJ6buNejQm8xrvQhPFUJ1KXl6ORYMzAXxy5+6+HXvfV85WaliCols4JrXnP3Mtc/PyTB B/zSCxhMl/vK1nLg8HzG5VIz3CbKYmh2bQh605PdU3A1KcoSoMWwOpZApauPdqbWUZFtjC gS+zjpvQ9PU8SHPP4qvgUgxiBMr0zHfYrJvCpskszbqnYqtry3qNxVTPh6XuM2TYkpUhM+ t+3iwMZCWQs82wkp4wCDxbo1gh7JCUKe+HbwY6KTGrDEZHEqKVp4sGqYVgyKQFzt8F4SB/ FhEsVW183xG6FelDOXsMFUKEIsAi0Ob5Ehb+kFcKCQ4/bszn9/9oKHZIGajVpg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1605779705; 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=lanMMzq8f95P2MRv1w3fMei1JqZrJujk1xOsUupIJvk=; b=p/8SD9DoikdFF3dtL5NgNdKf6k9OrMyY2xY6Wz8caycmHfjbKXeA0Ub6UAUorYGjOZ37jl Kx83vmhmU3zkAFCw== From: "tip-bot2 for Peter Zijlstra" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/urgent] sched: Fix rq->nr_iowait ordering Cc: Tejun Heo , "Peter Zijlstra (Intel)" , Mel Gorman , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20201117093829.GD3121429@hirez.programming.kicks-ass.net> References: <20201117093829.GD3121429@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Message-ID: <160577970455.11244.7243891330140821350.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/urgent branch of tip: Commit-ID: ec618b84f6e15281cc3660664d34cd0dd2f2579e Gitweb: https://git.kernel.org/tip/ec618b84f6e15281cc3660664d34cd0dd2f2579e Author: Peter Zijlstra AuthorDate: Thu, 24 Sep 2020 13:50:42 +02:00 Committer: Peter Zijlstra CommitterDate: Tue, 17 Nov 2020 13:15:28 +01:00 sched: Fix rq->nr_iowait ordering schedule() ttwu() deactivate_task(); if (p->on_rq && ...) // false atomic_dec(&task_rq(p)->nr_iowait); if (prev->in_iowait) atomic_inc(&rq->nr_iowait); Allows nr_iowait to be decremented before it gets incremented, resulting in more dodgy IO-wait numbers than usual. Note that because we can now do ttwu_queue_wakelist() before p->on_cpu==0, we lose the natural ordering and have to further delay the decrement. Fixes: c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu") Reported-by: Tejun Heo Signed-off-by: Peter Zijlstra (Intel) Acked-by: Mel Gorman Link: https://lkml.kernel.org/r/20201117093829.GD3121429@hirez.programming.kicks-ass.net --- kernel/sched/core.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d2003a7..9f0ebfb 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2501,7 +2501,12 @@ ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags, #ifdef CONFIG_SMP if (wake_flags & WF_MIGRATED) en_flags |= ENQUEUE_MIGRATED; + else #endif + if (p->in_iowait) { + delayacct_blkio_end(p); + atomic_dec(&task_rq(p)->nr_iowait); + } activate_task(rq, p, en_flags); ttwu_do_wakeup(rq, p, wake_flags, rf); @@ -2888,11 +2893,6 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) if (READ_ONCE(p->on_rq) && ttwu_runnable(p, wake_flags)) goto unlock; - if (p->in_iowait) { - delayacct_blkio_end(p); - atomic_dec(&task_rq(p)->nr_iowait); - } - #ifdef CONFIG_SMP /* * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be @@ -2963,6 +2963,11 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags); if (task_cpu(p) != cpu) { + if (p->in_iowait) { + delayacct_blkio_end(p); + atomic_dec(&task_rq(p)->nr_iowait); + } + wake_flags |= WF_MIGRATED; psi_ttwu_dequeue(p); set_task_cpu(p, cpu);