Re: [PATCH v3 2/2] blk-mq: fix blk_mq_tags double free while nr_requests grown

[Li Nan]

在 2025/8/21 14:06, Yu Kuai 写道:
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> In the case user trigger tags grow by queue sysfs attribute nr_requests,
> hctx->sched_tags will be freed directly and replaced with a new
> allocated tags, see blk_mq_tag_update_depth().
>
> The problem is that hctx->sched_tags is from elevator->et->tags, while
> et->tags is still the freed tags, hence later elevator exit will try to
> free the tags again, causing kernel panic.
>
> Fix this problem by replacing et->tags with new allocated tags as well.
>
> Noted there are still some long term problems that will require some
> refactor to be fixed thoroughly[1].
>
> [1] https://lore.kernel.org/all/20250815080216.410665-1-yukuai1@xxxxxxxxxxxxxxx/
> Fixes: f5a6604f7a44 ("block: fix lockdep warning caused by lock dependency in elv_iosched_store")
>
> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
> Reviewed-by: Nilay Shroff<nilay@xxxxxxxxxxxxx>
> ---

LGTM

Reviewed-by: Li Nan <linan122@xxxxxxxxxx>

--
Thanks,
Nan