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From:   Jens Axboe <axboe@kernel.dk>
To:     jack@suse.cz, paolo.valente@linaro.org, tj@kernel.org,
        josef@toxicpanda.com, Yu Kuai <yukuai1@huaweicloud.com>
Cc:     linux-block@vger.kernel.org, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org, yukuai3@huawei.com,
        yi.zhang@huawei.com, yangerkun@huawei.com
In-Reply-To: <20230103084755.1256479-1-yukuai1@huaweicloud.com>
References: <20230103084755.1256479-1-yukuai1@huaweicloud.com>
Subject: Re: [PATCH] block, bfq: switch 'bfqg->ref' to use atomic refcount
 apis
Message-Id: <167384123010.165459.4491550988140898321.b4-ty@kernel.dk>
Date:   Sun, 15 Jan 2023 20:53:50 -0700
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On Tue, 03 Jan 2023 16:47:55 +0800, Yu Kuai wrote:
> The updating of 'bfqg->ref' should be protected by 'bfqd->lock', however,
> during code review, we found that bfq_pd_free() update 'bfqg->ref'
> without holding the lock, which is problematic:
> 
> 1) bfq_pd_free() triggered by removing cgroup is called asynchronously;
> 2) bfqq will grab bfqg reference, and exit bfqq will drop the reference,
> which can concurrent with 1).
> 
> [...]

Applied, thanks!

[1/1] block, bfq: switch 'bfqg->ref' to use atomic refcount apis
      commit: 216f764716f34fe68cedc7296ae2043a7727e640

Best regards,
-- 
Jens Axboe