From: Hillf Danton <hdanton@sina.com>
To: Eric Dumazet <edumazet@google.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, nbd@other.debian.org,
Kuniyuki Iwashima <kuniyu@google.com>,
netdev@vger.kernel.org,
syzbot+607cdcf978b3e79da878@syzkaller.appspotmail.com
Subject: Re: [PATCH] nbd: Reclassify sockets to avoid lockdep circular dependency
Date: Sat, 13 Jun 2026 18:12:13 +0800 [thread overview]
Message-ID: <20260613101214.1771-1-hdanton@sina.com> (raw)
In-Reply-To: <20260613042619.1108126-1-edumazet@google.com>
On Sat, 13 Jun 2026 04:26:19 +0000 Eric Dumazet wrote:
> 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")
Given the Fixes tag, can you specify anything wrong that commit added?
> 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>
> ---
next prev parent reply other threads:[~2026-06-13 10:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-13 4:26 [PATCH] nbd: Reclassify sockets to avoid lockdep circular dependency Eric Dumazet
2026-06-13 10:12 ` Hillf Danton [this message]
2026-06-13 12:34 ` Jens Axboe
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