From: Tejun Heo <tj@kernel.org>
To: Tao Yu <tao1.yu@intel.com>
Cc: hannes@cmpxchg.org, mkoutny@suse.com, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org,
syzbot+bb2e19a1190a556c01b1@syzkaller.appspotmail.com
Subject: Re: [PATCH] cgroup: reject controller re-enable while css teardown is pending
Date: Wed, 02 Sep 2026 13:07:35 -1000 [thread overview]
Message-ID: <e959dbda2f689ed524e2a83d4affdfe0@kernel.org> (raw)
In-Reply-To: <20260901012342.855056-1-tao1.yu@intel.com>
Hello,
On Tue, Sep 01, 2026 at 09:23:42AM +0800, Tao Yu wrote:
> Stop draining offline csses from subtree_control and cgroup.type writes.
> Instead, reject the operation with -EBUSY if it would reuse a subsystem which
> still has dying csses in the target subtree.
Failing the re-enable isn't the right trade-off. "-cpu" followed by "+cpu"
has always succeeded eventually, and nr_dying_subsys stays non-zero until
the css is released, so it also counts removed cgroups and offlined but
still pinned csses. The -EBUSY would persist well past the actual conflict.
The writer shouldn't be sitting in D state waiting for exiting tasks in the
first place, so I posted a patchset which makes the drain interruptible
instead:
https://lore.kernel.org/all/20260902230313.530839-1-tj@kernel.org/
Thanks.
--
tejun
prev parent reply other threads:[~2026-09-02 23:07 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-01 1:23 [PATCH] cgroup: reject controller re-enable while css teardown is pending Tao Yu
2026-09-02 23:07 ` Tejun Heo [this message]
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