diff options
| author | Eric Dumazet <edumazet@google.com> | 2026-06-13 04:26:19 +0000 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-06-13 06:34:34 -0600 |
| commit | d532cddb6c6049ced414d64d83c6ce7149a6421a (patch) | |
| tree | 8f6571fb1cf0c7087ab584a07828a1e3f993ee44 /drivers/block | |
| parent | e8dcf2d142bd720c8334233ad6cfdf00f0e76b7f (diff) | |
nbd: Reclassify sockets to avoid lockdep circular dependency
syzbot reported a possible circular locking dependency in udp_sendmsg()
where fs_reclaim can be triggered while holding sk_lock, and fs_reclaim
can eventually depend on another sk_lock (e.g., if NBD is used for swap
or writeback and NBD uses TLS/TCP which acquires sk_lock).
Since the UDP socket and the NBD TCP/TLS socket are different, this is a
false positive. Fix this by reclassifying NBD sockets to a separate lock
class when they are added to the NBD device.
This is similar to what nvme-tcp and other network block devices do.
Fixes: ffa1e7ada456 ("block: Make request_queue lockdep splats show up earlier")
Reported-by: syzbot+607cdcf978b3e79da878@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/6a2cdafe.428ffe26.258b27.0161.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260613042619.1108126-1-edumazet@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/nbd.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index e2fe9e3308fc..3a585a0c882a 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1238,6 +1238,42 @@ static struct socket *nbd_get_socket(struct nbd_device *nbd, unsigned long fd, return sock; } +#ifdef CONFIG_DEBUG_LOCK_ALLOC +static struct lock_class_key nbd_key[3]; +static struct lock_class_key nbd_slock_key[3]; + +static void nbd_reclassify_socket(struct socket *sock) +{ + struct sock *sk = sock->sk; + + if (WARN_ON_ONCE(!sock_allow_reclassification(sk))) + return; + + switch (sk->sk_family) { + case AF_INET: + sock_lock_init_class_and_name(sk, "slock-AF_INET-NBD", + &nbd_slock_key[0], + "sk_lock-AF_INET-NBD", + &nbd_key[0]); + break; + case AF_INET6: + sock_lock_init_class_and_name(sk, "slock-AF_INET6-NBD", + &nbd_slock_key[1], + "sk_lock-AF_INET6-NBD", + &nbd_key[1]); + break; + case AF_UNIX: + sock_lock_init_class_and_name(sk, "slock-AF_UNIX-NBD", + &nbd_slock_key[2], + "sk_lock-AF_UNIX-NBD", + &nbd_key[2]); + break; + } +} +#else +static inline void nbd_reclassify_socket(struct socket *sock) {} +#endif + static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg, bool netlink) { @@ -1254,6 +1290,7 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg, sock = nbd_get_socket(nbd, arg, &err); if (!sock) return err; + nbd_reclassify_socket(sock); /* * We need to make sure we don't get any errant requests while we're |