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[72.235.129.167]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1ff58f26f4bsm144551635ad.34.2024.08.09.09.36.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Aug 2024 09:36:22 -0700 (PDT) Sender: Tejun Heo Date: Fri, 9 Aug 2024 06:36:21 -1000 From: Tejun Heo To: Waiman Long Cc: Zefan Li , Johannes Weiner , Michal =?iso-8859-1?Q?Koutn=FD?= , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Roman Gushchin , Kamalesh Babulal Subject: Re: [PATCH] cgroup: Fix incorrect WARN_ON_ONCE() in css_release_work_fn() Message-ID: References: <20240809032259.1233679-1-longman@redhat.com> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240809032259.1233679-1-longman@redhat.com> On Thu, Aug 08, 2024 at 11:22:59PM -0400, Waiman Long wrote: > It turns out that the WARN_ON_ONCE() call in css_release_work_fn > introduced by commit ab0312526867 ("cgroup: Show # of subsystem CSSes > in cgroup.stat") is incorrect. Although css->nr_descendants must be > 0 when a css is released and ready to be freed, the corresponding > cgrp->nr_dying_subsys[ss->id] may not be 0 if a subsystem is activated > and deactivated multiple times with one or more of its previous > activation leaving behind dying csses. > > Fix the incorrect warning by removing the cgrp->nr_dying_subsys check. > > Fixes: ab0312526867 ("cgroup: Show # of subsystem CSSes in cgroup.stat") > Closes: https://lore.kernel.org/cgroups/6f301773-2fce-4602-a391-8af7ef00b2fb@redhat.com/T/#t > Signed-off-by: Waiman Long Applied to cgroup/for-6.12. Thanks. -- tejun