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@fnnas.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;
 }
-- 
2.51.0

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@fnnas.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@huawei.com>

-- 
Thanks,
Nan