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=-9.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,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 69FC5C433F5 for ; Mon, 13 Sep 2021 18:06:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4BD72610CE for ; Mon, 13 Sep 2021 18:06:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346341AbhIMSHP (ORCPT ); Mon, 13 Sep 2021 14:07:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235056AbhIMSHN (ORCPT ); Mon, 13 Sep 2021 14:07:13 -0400 Received: from mail-pj1-x102b.google.com (mail-pj1-x102b.google.com [IPv6:2607:f8b0:4864:20::102b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E32A8C061574; Mon, 13 Sep 2021 11:05:57 -0700 (PDT) Received: by mail-pj1-x102b.google.com with SMTP id g13-20020a17090a3c8d00b00196286963b9so49103pjc.3; Mon, 13 Sep 2021 11:05:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=lTZVobgM/3IcweDVBRrPU9HP9E4rGk6Uc/SK3CeJgbs=; b=hz+MNqFoGnCqooN4pC0ZNqbr8/ZDMZ29FkRELhIRuC5hKGL9L9J9cPYqbJJJ9EeVlD uieVwHvuZtCzWv2i9+5nUuSYWc6YHpCTvW/uCVKVWanM3bGO9clHLlZDJTRQdh+vStXT JebR147UMte2xKNSG766+KWPqjmormL7wvrfV4Oo6q7tYf9OBdp3Q9Sgyp+cXVXKPhd2 LZbVzW+nhGFJ8DywljsBashi5kxWlbVV3SrTxrThfU+pfx9HknFRDPUv/2nBqsbfr0kF mIB2JcID3JCKEdZYv1v67prapGM5itGUbWpzNfCUP+Gqx5xyBuRbv2pPH1Nx8ieaI2kr VBnQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=lTZVobgM/3IcweDVBRrPU9HP9E4rGk6Uc/SK3CeJgbs=; b=o+L+HeTT+4nDG++RZe2DkiGASmrOV4JgHtpG+TzpPcF9lQYZf3wWHtCMJ7WteUPdaa cOaawNpa6t3sqS42UMvJAKlc2OzPeMyWpWaq1fRkqFSFahnPKCbTk4ukLqAMw3MssUBk molGsGdILJwrR9a8jNxUR9jW89ZxThxGF6uZ+fdMRbckt05e5DOGcwt/EL3lbM+sck/T /UfjMtjrEjDgOcaPtu7dZosKLh5b2Db9ZIlHkGCM+5A5f+Zl/5AQueGslPkq/asOnOhr c5K8wiR1rAPIUYd6zUf9CI5LRNUtFePT/6t6rDQOEhb4slppwtePbAAdjNpWRCEvf7ms gNag== X-Gm-Message-State: AOAM532AuTmUNGTmZtcAPt0Fj8kx0VcvoDgbPfMHy8umnKFC+04AvNoa t63Gq6ksCWWjMCUm8YJoTA8= X-Google-Smtp-Source: ABdhPJwyUpLIfNUMvoWs8sNgwzlqizBHfnN+mQ+oZCTgPHX/7QjouVw56wymPnKahxjrFxQSQ7uEuQ== X-Received: by 2002:a17:902:8494:b0:13b:9365:6f12 with SMTP id c20-20020a170902849400b0013b93656f12mr6143553plo.19.1631556357279; Mon, 13 Sep 2021 11:05:57 -0700 (PDT) Received: from localhost (2603-800c-1a02-1bae-e24f-43ff-fee6-449f.res6.spectrum.com. [2603:800c:1a02:1bae:e24f:43ff:fee6:449f]) by smtp.gmail.com with ESMTPSA id ch19sm7823993pjb.33.2021.09.13.11.05.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Sep 2021 11:05:56 -0700 (PDT) Sender: Tejun Heo Date: Mon, 13 Sep 2021 08:05:55 -1000 From: Tejun Heo To: Waiman Long Cc: Zefan Li , Johannes Weiner , Juri Lelli , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] cgroup: Fix incorrect warning from cgroup_apply_control_disable() Message-ID: References: <20210910024256.7615-1-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210910024256.7615-1-longman@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Thu, Sep 09, 2021 at 10:42:55PM -0400, Waiman Long wrote: > diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c > index 881ce1470beb..e31bca9fcd46 100644 > --- a/kernel/cgroup/cgroup.c > +++ b/kernel/cgroup/cgroup.c > @@ -3140,7 +3140,16 @@ static void cgroup_apply_control_disable(struct cgroup *cgrp) > if (!css) > continue; > > - WARN_ON_ONCE(percpu_ref_is_dying(&css->refcnt)); > + /* > + * A kill_css() might have been called previously, but > + * the css may still linger for a while before being > + * removed. Skip it in this case. > + */ > + if (percpu_ref_is_dying(&css->refcnt)) { > + WARN_ON_ONCE(css->parent && > + cgroup_ss_mask(dsct) & (1 << ss->id)); > + continue; > + } This warning did help me catch some gnarly bugs. Any chance we can keep it for normal cases and elide it just for remounting? Thanks. -- tejun