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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 97A68C47082 for ; Thu, 3 Jun 2021 06:34:34 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 137876140B for ; Thu, 3 Jun 2021 06:33:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 137876140B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=tempfail smtp.mailfrom=dm-devel-bounces@redhat.com Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-274-UblY9Co9NieKQC3gO4JAfw-1; Thu, 03 Jun 2021 02:33:28 -0400 X-MC-Unique: UblY9Co9NieKQC3gO4JAfw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EDB208042C6; Thu, 3 Jun 2021 06:33:19 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8BDA65D76F; Thu, 3 Jun 2021 06:33:18 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 2AB7C44A5F; Thu, 3 Jun 2021 06:33:18 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 152EcVX2002892 for ; Wed, 2 Jun 2021 10:38:31 -0400 Received: by smtp.corp.redhat.com (Postfix) id 4BDD1114B307; Wed, 2 Jun 2021 14:38:31 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast01.extmail.prod.ext.rdu2.redhat.com [10.11.55.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 480CC103F279 for ; Wed, 2 Jun 2021 14:38:27 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-2.mimecast.com [207.211.31.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 99AAA90DE2F for ; Wed, 2 Jun 2021 14:38:27 +0000 (UTC) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by relay.mimecast.com with ESMTP id us-mta-191-W3Cs-bCFNVeZtp01ft4ZYQ-1; Wed, 02 Jun 2021 10:38:23 -0400 X-MC-Unique: W3Cs-bCFNVeZtp01ft4ZYQ-1 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 35C8D1042; Wed, 2 Jun 2021 07:30:32 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [10.57.31.212]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D16593F73D; Wed, 2 Jun 2021 07:30:19 -0700 (PDT) Date: Wed, 2 Jun 2021 15:30:16 +0100 From: Mark Rutland To: Peter Zijlstra Message-ID: <20210602143016.GE12753@C02TD0UTHF1T.local> References: <20210602131225.336600299@infradead.org> <20210602133040.398289363@infradead.org> <1873020549.5854.1622642347895.JavaMail.zimbra@efficios.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-loop: dm-devel@redhat.com X-Mailman-Approved-At: Thu, 03 Jun 2021 02:32:49 -0400 Cc: Juri Lelli , Pavel Machek , Mike Snitzer , Alexander Shishkin , kgdb-bugreport@lists.sourceforge.net, Lai Jiangshan , Oleg Nesterov , Ben Segall , linux-mm , dm-devel@redhat.com, Paolo Bonzini , Zefan Li , "H. Peter Anvin" , "Joel Fernandes, Google" , netdev , Jiri Olsa , Alasdair Kergon , Daniel Thompson , Davidlohr Bueso , Vincent Guittot , KVM list , Will Deacon , cgroups , x86 , Ingo Molnar , Mel Gorman , Jakub Kicinski , John Stultz , paulmck , linux-pm@vger.kernel.org, Boqun Feng , Jason Wessel , Josh Triplett , rostedt , linux-block@vger.kernel.org, linux-fsdevel , Mathieu Desnoyers , Alexander Viro , Waiman Long , Namhyung Kim , Thomas Gleixner , acme , Dietmar Eggemann , Jens Axboe , Felipe Balbi , Stephen Boyd , Greg Kroah-Hartman , linux-usb@vger.kernel.org, "Rafael J. Wysocki" , Douglas Anderson , linux-kernel , linux-perf-users@vger.kernel.org, Johannes Weiner , Tejun Heo , Borislav Petkov , Andrew Morton , rcu , bristot , "David S. Miller" Subject: Re: [dm-devel] [PATCH 3/6] sched, perf, kvm: Fix preemption condition X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Wed, Jun 02, 2021 at 04:10:29PM +0200, Peter Zijlstra wrote: > On Wed, Jun 02, 2021 at 09:59:07AM -0400, Mathieu Desnoyers wrote: > > ----- On Jun 2, 2021, at 9:12 AM, Peter Zijlstra peterz@infradead.org wrote: > > > > > When ran from the sched-out path (preempt_notifier or perf_event), > > > p->state is irrelevant to determine preemption. You can get preempted > > > with !task_is_running() just fine. > > > > > > The right indicator for preemption is if the task is still on the > > > runqueue in the sched-out path. > > > > > > Signed-off-by: Peter Zijlstra (Intel) > > > --- > > > kernel/events/core.c | 7 +++---- > > > virt/kvm/kvm_main.c | 2 +- > > > 2 files changed, 4 insertions(+), 5 deletions(-) > > > > > > --- a/kernel/events/core.c > > > +++ b/kernel/events/core.c > > > @@ -8568,13 +8568,12 @@ static void perf_event_switch(struct tas > > > }, > > > }; > > > > > > - if (!sched_in && task->state == TASK_RUNNING) > > > + if (!sched_in && current->on_rq) { > > > > This changes from checking task->state to current->on_rq, but this change > > from "task" to "current" is not described in the commit message, which is odd. > > > > Are we really sure that task == current here ? > > Yeah, @task == @prev == current at this point, but yes, not sure why I > changed that... lemme change that back to task. FWIW, with that: Acked-by: Mark Rutland I have no strong feelings either way w.r.t. the whitespace cleanup. ;) Thanks, Mark -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel