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Date:   Wed, 1 Jun 2022 10:42:32 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Jan Kara <jack@suse.cz>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        Christoph Hellwig <hch@infradead.org>,
        Tejun Heo <tj@kernel.org>,
        Paolo Valente <paolo.valente@linaro.org>,
        Logan Gunthorpe <logang@deltatee.com>,
        Donald Buczek <buczek@molgen.mpg.de>, stable@vger.kernel.org
Subject: Re: [PATCH] block: fix bio_clone_blkg_association() to associate
 with proper blkcg_gq
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On Wed, Jun 01, 2022 at 06:34:05PM +0200, Jan Kara wrote:
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -1975,10 +1975,9 @@ EXPORT_SYMBOL_GPL(bio_associate_blkg);
>  void bio_clone_blkg_association(struct bio *dst, struct bio *src)
>  {
>  	if (src->bi_blkg) {
> +		rcu_read_lock();
> +		bio_associate_blkg_from_css(dst, bio_blkcg_css(src));
> +		rcu_read_unlock();

What do we even need the rcu critical section here?

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>