[PATCH V2] nbd: Reclassify sockets in the reconnect path

[PATCH V2] nbd: Reclassify sockets in the reconnect path

[Guilherme Giacomo Simoes]

Commit d532cddb6c60 ("nbd: Reclassify sockets to avoid lockdep circular
dependency") introduced nbd_reclassify_socket() to prevent lockdep false
positives when NBD sockets are used in memory reclaim paths. While
nbd_add_socket() reclassifies newly added sockets,
nbd_genl_reconnect_sock_cb() omitted this call when replacing dead
sockets during reconnection. Consequently, reconnected sockets retain
the generic socket lockdep class and trigger false-positive lockdep
reports.

Fix this by reclassifying the replacement socket in
nbd_genl_reconnect_sock_cb().

Fixes: d532cddb6c60 ("nbd: Reclassify sockets to avoid lockdep circular dependency")
Reported-by: syzbot+d7d72f3d467710442af0@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d7d72f3d467710442af0
Signed-off-by: Guilherme Giacomo Simoes <trintaeoitogc@gmail.com>
---
v2:
- change previous patch to a single line addition of
  nbd_reclassify_socket()
- improve commit message

v1: 
https://lore.kernel.org/all/20261110215723.199948-1-trintaeoitogc@gmail.com/
---
 drivers/block/nbd.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index ffce519bf008..b2b27f90a7ed 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1356,6 +1356,7 @@ static int nbd_genl_reconnect_sock_cb(struct nbd_device *nbd, unsigned long arg)
 	sock = nbd_get_socket(nbd, arg, &err);
 	if (!sock)
 		return err;
+	nbd_reclassify_socket(sock);
 
 	args = kzalloc_obj(*args);
 	if (!args) {
-- 
2.52.0

Re: [PATCH V2] nbd: Reclassify sockets in the reconnect path

[Bart Van Assche]

On 11/12/26 2:59 AM, Guilherme Giacomo Simoes wrote:
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index ffce519bf008..b2b27f90a7ed 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -1356,6 +1356,7 @@ static int nbd_genl_reconnect_sock_cb(struct nbd_device *nbd, unsigned long arg)
>   	sock = nbd_get_socket(nbd, arg, &err);
>   	if (!sock)
>   		return err;
> +	nbd_reclassify_socket(sock);
>   
>   	args = kzalloc_obj(*args);
>   	if (!args) {

Reviewed-by: Bart Van Assche <bvanassche@acm.org>