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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 35AE0C433F5 for ; Sun, 10 Apr 2022 22:06:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242990AbiDJWIf (ORCPT ); Sun, 10 Apr 2022 18:08:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239481AbiDJWIb (ORCPT ); Sun, 10 Apr 2022 18:08:31 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4AFC526AE2; Sun, 10 Apr 2022 15:06:20 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BA42DED1; Sun, 10 Apr 2022 15:06:19 -0700 (PDT) Received: from airbuntu (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7DCF33F70D; Sun, 10 Apr 2022 15:06:18 -0700 (PDT) Date: Sun, 10 Apr 2022 23:06:08 +0100 From: Qais Yousef To: Greg KH Cc: linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org, Abhijeet Dharmapurikar , Valentin Schneider , "Peter Zijlstra (Intel)" , "Steven Rostedt (Google)" , x86@kernel.org, stable@vger.kernel.org Subject: Re: [tip: sched/core] sched/tracing: Don't re-read p->state when emitting sched_switch event Message-ID: <20220410220608.cdf6hmf5mwcqzwun@airbuntu> References: <20220120162520.570782-2-valentin.schneider@arm.com> <164614827941.16921.4995078681021904041.tip-bot2@tip-bot2> <20220308180240.qivyjdn4e3te3urm@wubuntu> <20220308185138.ldxfqd242uxowymd@wubuntu> <20220409233829.o2s6tffuzujkx6w2@airbuntu> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220409233829.o2s6tffuzujkx6w2@airbuntu> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/10/22 00:38, Qais Yousef wrote: > On 03/08/22 18:51, Qais Yousef wrote: > > On 03/08/22 19:10, Greg KH wrote: > > > On Tue, Mar 08, 2022 at 06:02:40PM +0000, Qais Yousef wrote: > > > > +CC stable > > > > > > > > On 03/01/22 15:24, tip-bot2 for Valentin Schneider wrote: > > > > > The following commit has been merged into the sched/core branch of tip: > > > > > > > > > > Commit-ID: fa2c3254d7cfff5f7a916ab928a562d1165f17bb > > > > > Gitweb: https://git.kernel.org/tip/fa2c3254d7cfff5f7a916ab928a562d1165f17bb > > > > > Author: Valentin Schneider > > > > > AuthorDate: Thu, 20 Jan 2022 16:25:19 > > > > > Committer: Peter Zijlstra > > > > > CommitterDate: Tue, 01 Mar 2022 16:18:39 +01:00 > > > > > > > > > > sched/tracing: Don't re-read p->state when emitting sched_switch event > > > > > > > > > > As of commit > > > > > > > > > > c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu") > > > > > > > > > > the following sequence becomes possible: > > > > > > > > > > p->__state = TASK_INTERRUPTIBLE; > > > > > __schedule() > > > > > deactivate_task(p); > > > > > ttwu() > > > > > READ !p->on_rq > > > > > p->__state=TASK_WAKING > > > > > trace_sched_switch() > > > > > __trace_sched_switch_state() > > > > > task_state_index() > > > > > return 0; > > > > > > > > > > TASK_WAKING isn't in TASK_REPORT, so the task appears as TASK_RUNNING in > > > > > the trace event. > > > > > > > > > > Prevent this by pushing the value read from __schedule() down the trace > > > > > event. > > > > > > > > > > Reported-by: Abhijeet Dharmapurikar > > > > > Signed-off-by: Valentin Schneider > > > > > Signed-off-by: Peter Zijlstra (Intel) > > > > > Reviewed-by: Steven Rostedt (Google) > > > > > Link: https://lore.kernel.org/r/20220120162520.570782-2-valentin.schneider@arm.com > > > > > > > > Any objection to picking this for stable? I'm interested in this one for some > > > > Android users but prefer if it can be taken by stable rather than backport it > > > > individually. > > > > > > > > I think it makes sense to pick the next one in the series too. > > > > > > What commit does this fix in Linus's tree? > > > > It should be this one: c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu") > > Should this be okay to be picked up by stable now? I can see AUTOSEL has picked > it up for v5.15+, but it impacts v5.10 too. commit: fa2c3254d7cfff5f7a916ab928a562d1165f17bb subject: sched/tracing: Don't re-read p->state when emitting sched_switch event This patch has an impact on Android 5.10 users who experience tooling breakage. Is it possible to include in 5.10 LTS please? It was already picked up for 5.15+ by AUTOSEL and only 5.10 is missing. Thanks -- Qais Yousef