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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260123182623.3718551-3-yukuai@fnnas.com>
Date: Sat, 24 Jan 2026 02:26:23 +0800
From: Yu Kuai <yukuai@...as.com>
To: axboe@...nel.dk,
	linux-block@...r.kernel.org,
	linux-raid@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	yukuai@...as.com,
	linan122@...wei.com,
	xni@...hat.com
Subject: [PATCH 2/2] md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout

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;
 }
-- 
2.51.0