linux-kernel - Re: [PATCH 2/2] md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout

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Message-ID: <85477dfd-708c-44f8-26ee-19d3328fb9ae@huaweicloud.com>
Date: Sat, 24 Jan 2026 09:58:28 +0800
From: Li Nan <linan666@...weicloud.com>
To: Yu Kuai <yukuai@...as.com>, axboe@...nel.dk, linux-block@...r.kernel.org,
 linux-raid@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, xni@...hat.com
Subject: Re: [PATCH 2/2] md/md-llbitmap: fix percpu_ref not resurrected on
 suspend timeout



在 2026/1/24 2:26, Yu Kuai 写道:
> When llbitmap_suspend_timeout() times out waiting for percpu_ref to
> become zero, it returns -ETIMEDOUT without resurrecting the percpu_ref.
> The caller (md_llbitmap_daemon_fn) then continues to the next page
> without calling llbitmap_resume(), leaving the percpu_ref in a killed
> state permanently.
> 
> Fix this by resurrecting the percpu_ref before returning the error,
> ensuring the page control structure remains usable for subsequent
> operations.
> 
> Fixes: 5ab829f1971d ("md/md-llbitmap: introduce new lockless bitmap")
> Signed-off-by: Yu Kuai <yukuai@...as.com>
> ---
>   drivers/md/md-llbitmap.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/md/md-llbitmap.c b/drivers/md/md-llbitmap.c
> index b482a1db0861..7df15756142d 100644
> --- a/drivers/md/md-llbitmap.c
> +++ b/drivers/md/md-llbitmap.c
> @@ -779,8 +779,10 @@ static int llbitmap_suspend_timeout(struct llbitmap *llbitmap, int page_idx)
>   	percpu_ref_kill(&pctl->active);
>   
>   	if (!wait_event_timeout(pctl->wait, percpu_ref_is_zero(&pctl->active),
> -			llbitmap->mddev->bitmap_info.daemon_sleep * HZ))
> +			llbitmap->mddev->bitmap_info.daemon_sleep * HZ)) {
> +		percpu_ref_resurrect(&pctl->active);
>   		return -ETIMEDOUT;
> +	}
>   
>   	return 0;
>   }

LGTM

Reviewed-by: Li Nan <linan122@...wei.com>

-- 
Thanks,
Nan