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From: Eric Dumazet <edumazet@google.com>
Date: Tue, 20 Feb 2024 19:03:41 +0100
Message-ID: <CANn89iKn1U14L1u2w3VwenRt0S4QnXJhiA5PvMF0s41d8nS6Tw@mail.gmail.com>
Subject: Re: [PATCH net 03/13] mptcp: fix lockless access in subflow ULP diag
To: Paolo Abeni <pabeni@redhat.com>
Cc: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>, mptcp@lists.linux.dev, 
	Mat Martineau <martineau@kernel.org>, Geliang Tang <geliang@kernel.org>, 
	"David S. Miller" <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>, 
	Davide Caratti <dcaratti@redhat.com>, Shuah Khan <shuah@kernel.org>, netdev@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, 
	stable@vger.kernel.org, Boris Pismenny <borisp@nvidia.com>, 
	John Fastabend <john.fastabend@gmail.com>
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On Tue, Feb 20, 2024 at 6:33=E2=80=AFPM Paolo Abeni <pabeni@redhat.com> wro=
te:
>
> On Mon, 2024-02-19 at 19:33 +0100, Eric Dumazet wrote:
> > On Mon, Feb 19, 2024 at 7:04=E2=80=AFPM Paolo Abeni <pabeni@redhat.com>=
 wrote:
> > > Thanks for the head-up. This later option looks preferable, to avoid
> > > quit a bit of noise with _ONCE annotation. Is there a syzkaller splat=
 I
> > > could look at? if it landed on the ML, I missed it.
> > >
> >
> > Not landed yet, here is the splat :
> >
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
> > WARNING: possible circular locking dependency detected
> > 6.8.0-rc4-syzkaller-00212-g40b9385dd8e6 #0 Not tainted
> > ------------------------------------------------------
> > syz-executor.2/24141 is trying to acquire lock:
> > ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at:
> > tcp_diag_put_ulp net/ipv4/tcp_diag.c:100 [inline]
> > ffff888045870130 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at:
> > tcp_diag_get_aux+0x738/0x830 net/ipv4/tcp_diag.c:137
> >
> > but task is already holding lock:
> > ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at: spin_lock
> > include/linux/spinlock.h:351 [inline]
> > ffffc9000135e488 (&h->lhash2[i].lock){+.+.}-{2:2}, at:
> > inet_diag_dump_icsk+0x39f/0x1f80 net/ipv4/inet_diag.c:1038
>
> [Sorry for the latency]. Yes it looks like that checking the listener
> status will work. I can test and send the formal patch - with the due
> credits! - or do you prefer otherwise?

Sure, please send the formal patch, thank you.