[PATCH 6.18 046/641] md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout

Greg Kroah-Hartman
2026-02-25T01:43:23Z

6.18-stable review patch. If anyone has any objections, please let me know.

------------------

From: Yu Kuai <yukuai@fnnas.com>

[ Upstream commit d119bd2e1643cc023210ff3c6f0657e4f914e71d ]

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.

Link: https://lore.kernel.org/linux-raid/20260123182623.3718551-3-yukuai@fnnas.com
Fixes: 5ab829f1971d ("md/md-llbitmap: introduce new lockless bitmap")
Signed-off-by: Yu Kuai <yukuai@fnnas.com>
Reviewed-by: Li Nan <linan122@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 1eb434306162a..bcb6eae1c711f 100644
--- a/drivers/md/md-llbitmap.c
+++ b/drivers/md/md-llbitmap.c
@@ -712,8 +712,10 @@ 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