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Sender: Tejun Heo <htejun@gmail.com>
Date:   Wed, 7 Jul 2021 05:11:33 -1000
From:   Tejun Heo <tj@kernel.org>
To:     Yu Kuai <yukuai3@huawei.com>
Cc:     axboe@kernel.dk, cgroups@vger.kernel.org,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        yi.zhang@huawei.com
Subject: Re: [PATCH V2] blk-cgroup: prevent rcu_sched detected stalls
 warnings while iterating blkgs
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References: <20210707015649.1929797-1-yukuai3@huawei.com>
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On Wed, Jul 07, 2021 at 09:56:49AM +0800, Yu Kuai wrote:
> We run a test that create millions of cgroups and blkgs, and then trigger
> blkg_destroy_all(). blkg_destroy_all() will hold spin lock for a long
> time in such situation. Thus release the lock when a batch of blkgs are
> destroyed.
> 
> blkcg_activate_policy() and blkcg_deactivate_policy() might have the
> same problem, however, as they are basically only called from module
> init/exit paths, let's leave them alone for now.
> 
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun