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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 F297DC4743C for ; Wed, 23 Jun 2021 14:00:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CA93961076 for ; Wed, 23 Jun 2021 14:00:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230411AbhFWOCg (ORCPT ); Wed, 23 Jun 2021 10:02:36 -0400 Received: from vulcan.natalenko.name ([104.207.131.136]:59538 "EHLO vulcan.natalenko.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230274AbhFWOCg (ORCPT ); Wed, 23 Jun 2021 10:02:36 -0400 Received: from spock.localnet (unknown [151.237.229.131]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by vulcan.natalenko.name (Postfix) with ESMTPSA id 6BCE8AF3443; Wed, 23 Jun 2021 16:00:16 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=natalenko.name; s=dkim-20170712; t=1624456816; h=from:from: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=rQqup4RSADZYht0Tjo6YJfart8szjUekpTWg50N90zg=; b=iiBSiQTzNzNIsxPhqWjmqKJF7tmTZJY5Q/BidWx9FCs62wrCJhiaCYQVZkiRCLrSASONxZ H4lrMykgMh1LcGAUVxjofIFlyQq3NDycgDefrxAT2Yl5Me/auyB0nE1qGMoU5gF1t28wtI xixdIlLXYHgvej0KMo8u/iqe07PzqLw= From: Oleksandr Natalenko To: Johannes Weiner Cc: Greg KH , stable@vger.kernel.org, Peter Zijlstra Subject: Re: Backport d583d360a6 into 5.12 stable Date: Wed, 23 Jun 2021 16:00:14 +0200 Message-ID: <7592880.XtGZTbpMlS@spock> In-Reply-To: References: <11282373.oIR2C0Pl9h@spock> <5661831.TEGnOE2T3c@spock> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Hello. On =C3=BAter=C3=BD 22. =C4=8Dervna 2021 20:27:51 CEST Johannes Weiner wrote: > On Tue, Jun 22, 2021 at 07:24:56PM +0200, Oleksandr Natalenko wrote: > > On =C3=BAter=C3=BD 22. =C4=8Dervna 2021 18:47:59 CEST Greg KH wrote: > > > On Tue, Jun 22, 2021 at 06:30:46PM +0200, Oleksandr Natalenko wrote: > > > > I'd like to nominate d583d360a6 ("psi: Fix psi state corruption when > > > > schedule() races with cgroup move") for 5.12 stable tree. > > > >=20 > > > > Recently, I've hit this: > > > >=20 > > > > ``` > > > > kernel: psi: inconsistent task state! task=3D2667:clementine cpu=3D= 21 > > > > psi_flags=3D0 clear=3D1 set=3D0 > > > > ``` > > > >=20 > > > > and after that PSI IO went crazy high. That seems to match the > > > > symptoms > > > > described in the commit message. > > >=20 > > > But this says it fixes 4117cebf1a9f ("psi: Optimize task switch inside > > > shared cgroups") which did not show up until 5.13-rc1, so how are you > > > hitting this issue? > >=20 > > I'm not positive 4117cebf1a9f was a root cause of the race. To me it lo= oks > > like 4117cebf1a9f just made an older issue more likely to be hit. > >=20 > > Peter, Johannes, am I correct saying that it is still possible to hit a > > corruption described in d583d360a6 on 5.12? >=20 > I'm not aware of a previous issue, but it's possible you discovered > one that was incidentally fixed by this change. >=20 > That said, there haven't been many changes in this area prior to 5.12, > and I stared at the old code quite a bit to see if there are other > possible scenarios, so this gives me pause. Ack. > > > Did you try this patch on 5.12.y and see that it solved your problem? > >=20 > > Yes, I've built the kernel with this patch, and so far it runs fine. It > > can > > take a while until the condition is hit though since it seems to be very > > unlikely on 5.12. >=20 > Is your task moving / being moved between cgroups while it's doing > work? Likely, yes. IIUC, KDE spawns apps in separate cgroups so that in that very= =20 case Clementine should get its own one (?): ``` $ systemd-cgls =E2=80=A6 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=80app-clementine-df516e4181= f446ab869e723ea2ed6094.scope=20 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=802926 /bin/cleme= ntine -session=20 10de706f63000162437544200000015700012_1624379013_575845 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803059 /usr/bin/c= lementine-tagreader /tmp/clementine_735427711 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803060 /usr/bin/c= lementine-tagreader /tmp/clementine_557274898 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803062 /usr/bin/c= lementine-tagreader /tmp/clementine_1730944950 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803063 /usr/bin/c= lementine-tagreader /tmp/clementine_1509249421 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803065 /usr/bin/c= lementine-tagreader /tmp/clementine_1345386497 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803068 /usr/bin/c= lementine-tagreader /tmp/clementine_865255891 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803070 /usr/bin/c= lementine-tagreader /tmp/clementine_1782561441 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803072 /usr/bin/c= lementine-tagreader /tmp/clementine_421851305 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803073 /usr/bin/c= lementine-tagreader /tmp/clementine_175368243 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803075 /usr/bin/c= lementine-tagreader /tmp/clementine_1962830479 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803076 /usr/bin/c= lementine-tagreader /tmp/clementine_547573203 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803078 /usr/bin/c= lementine-tagreader /tmp/clementine_1819270047 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803079 /usr/bin/c= lementine-tagreader /tmp/clementine_1632862299 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803085 /usr/bin/c= lementine-tagreader /tmp/clementine_1279975869 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803095 /usr/bin/c= lementine-tagreader /tmp/clementine_1612119641 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803102 /usr/bin/c= lementine-tagreader /tmp/clementine_1789578483 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803103 /usr/bin/c= lementine-tagreader /tmp/clementine_1541442265 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803105 /usr/bin/c= lementine-tagreader /tmp/clementine_1418456770 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803106 /usr/bin/c= lementine-tagreader /tmp/clementine_1998684543 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803107 /usr/bin/c= lementine-tagreader /tmp/clementine_1349315391 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803108 /usr/bin/c= lementine-tagreader /tmp/clementine_231895572 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803110 /usr/bin/c= lementine-tagreader /tmp/clementine_492688785 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=9C=E2=94=803111 /usr/bin/c= lementine-tagreader /tmp/clementine_1492630900 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=82 =E2=94=94=E2=94=803112 /usr/bin/c= lementine-tagreader /tmp/clementine_2017490599 =E2=80=A6 ``` > How long does it usually take to trigger it? I don't know :(. I don't usually peer into dmesg, and noticed this by a pur= e=20 chance. Grepping the journal shows nothing else but only this occurrence, a= nd=20 also the journal is rotating, so some info might be already lost. > Would it be possible to share a simpler reproducer, or is this part of > a more complex application? This was triggered bu KDE's autostart of Clementine player, and I don't hav= e=20 any specific reproducer. If I find one, I'll share it of course. Thanks. =2D-=20 Oleksandr Natalenko (post-factum)