From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-il1-f173.google.com (mail-il1-f173.google.com [209.85.166.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EAF052F1FEE; Thu, 26 Jun 2025 00:24:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750897495; cv=none; b=OUUIcZJkDqjm4I3tpgfTANZ8ccwRst0ssgLTQJ8ShVCyBNDm1h2LFklKk30efYAMbbzkFdFhdJuQU9Rw071vMFW/3DxZgFxTnJ//YsMqfbqvkxVsxNh9ygPF9a9t23RzC8J5NJWv5SyO1/31YdRiK5vupvO/R3469S7fOVdYQXE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750897495; c=relaxed/simple; bh=3RUBDXcCOOdlEWGj394RlJKkuphbNDVZPadUh0UHBNc=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=EuT+Tk3PFAgqlxEARS4Sj7QMIu6h5IkYeEIV+9Qo+/Bysrsv8EO6WywzHSDGncxy/gdegLL7ctGFvHyBs9ND0Vnr8wagCHeaK/aOKU+DT3+SI6lGuXWZtWkBvmipnE+KzMi0bcXZmFkAWhM9HtMbUE4IaZomVQMF8wI1YJzYe40= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=JxYkyVRi; arc=none smtp.client-ip=209.85.166.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="JxYkyVRi" Received: by mail-il1-f173.google.com with SMTP id e9e14a558f8ab-3da82c6c5d4so3564005ab.1; Wed, 25 Jun 2025 17:24:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1750897493; x=1751502293; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=8DpDcu8odICYcSvPG11YgRezz0sdLDRgeHofe1ELDoU=; b=JxYkyVRiWHXBBYCr3SShKWyM29q9FUnRpYjAfchNV2rwRTIbgiSVc2totr5aU6W9cn ngVq6SMGFMkWIO2xIC4spUkvcENFazVtLQxcIep/hmh11RjmaHnMgg7p4nDdfNUl9Fog 459fP3gk/QqRPjGSvwavLOo1GbPzXEeb8Mpd5BCkBKWoRRT6LTV/6EaJq/+YVu+V7M8y nYIVEqSpQnc5E4J2ez2soZEvihvzdiTHaBRSFUb92OVy5kBIdteWHOdquIgYD+kKRKYq V+35rdTAxp271BdS3JWGHI1KH4c8tAru0VdJFmXJ9/uOSN2dWVlDvIj5Xf8ZtBjaE0Gv QdEg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750897493; x=1751502293; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=8DpDcu8odICYcSvPG11YgRezz0sdLDRgeHofe1ELDoU=; b=Uyql8qbdHoBqQI5z62TvJ+3oIwPbl4rCbSqW2fJplH03PWdLrKxbi4vKTDliQI8DWR cAX/XZ1xlGt3OBdoJQmkvGXU8aCh+1idVKHusk1QLc1cECuLC6RiHaLeyGKZpb5367sO 2KXkQdkSUZT6rpQpV6xHNZV+jou1M1144Zx/oPReoqCBp9mo8QNSwT9CEL9H4T2l0NIK 17rOjBeeq07o01SzJoZOaWlaqJpc0BGkLgHGVYX/3n0LfxWqY3J/5CefcRzpX2DJvbSc I+csxOH4QOVdB+Z6G4JDgHPwDhibyDGBFgUOB4dLr72q8FjGY5KkgiAeP/AO4bNeAk8g cTeg== X-Forwarded-Encrypted: i=1; AJvYcCUPnQwQqTBL6Xg2YAo5dH8mw8H3EAMed4CYwhRxfm7XDk6gRDHcV809ZoMFuJ/DoW4ead0=@vger.kernel.org, AJvYcCVyEsoMHXf5bAl2majzblRPxfTa8fxXnEOvUyunZJMduEotkge0j66cacqsAYjvXEhKfXNiHXyf@vger.kernel.org, AJvYcCWFu363SXdHZFDv/gEabQb89+/r/NK6OcH+MLOxDYnbTUOHqqoKy6WfQy4hrY+ZMUCijbRc8BXLVI1yvjpq@vger.kernel.org X-Gm-Message-State: AOJu0YxIq4C6veJqSxdA7RRC84zNNteTElk74Rh/oTBUJF2vVIWvjcxN AKl0qmX/10RF30VeMj4xNwb7C8ilHoG4Rmc9mUx2I7Udxd+jcJrEfeeSfv4Z7S+UPoMnSL1Hbfa yYibd3rdle0G5ONvnfn15ImGzmT4Y5mlsdyow+0k= X-Gm-Gg: ASbGncuV11xnh7Dg72NjJ/bFXq41/oY3gYHVr0W0x/LgHnqR+QJpl/rvvAErd97bdEX Jevp3CaZKPEic3PjLrbJHW74Nk26/yJQAnIWs6DYa20ItVoXMGByqILnMjvoO4gNQAC1/ml8GFz Zx/aTUSaUQ1aZf4fJkoJmbKdh0SrTOjRzGVWfhyQ/H5g== X-Google-Smtp-Source: AGHT+IHtHZaMbuHXKnztiu9cs2xdpESBu0dN6VQeV3lqpz2a3TdX5SwmtdYGOSge9cKK8qiIbygUpjoUG8TS68we2io= X-Received: by 2002:a05:6e02:1a82:b0:3df:2cd1:f61b with SMTP id e9e14a558f8ab-3df327de62cmr62782435ab.0.1750897492975; Wed, 25 Jun 2025 17:24:52 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <685af3b1.a00a0220.2e5631.0091.GAE@google.com> <20250625140357.6203d0af@kernel.org> In-Reply-To: From: Jason Xing Date: Thu, 26 Jun 2025 08:24:16 +0800 X-Gm-Features: Ac12FXzGwQs2zmklf2_XcL1cpsjKfoR8Pt8xDZ7LtAzluD81WRF_rGvoLqid8-c Message-ID: Subject: Re: [syzbot] [bpf?] [net?] possible deadlock in xsk_notifier (3) To: Stanislav Fomichev Cc: Jakub Kicinski , syzbot , andrii@kernel.org, ast@kernel.org, bjorn@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, davem@davemloft.net, edumazet@google.com, horms@kernel.org, jonathan.lemon@gmail.com, linux-kernel@vger.kernel.org, maciej.fijalkowski@intel.com, magnus.karlsson@intel.com, netdev@vger.kernel.org, pabeni@redhat.com, sdf@fomichev.me, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, Jun 26, 2025 at 7:37=E2=80=AFAM Stanislav Fomichev wrote: > > On 06/25, Jakub Kicinski wrote: > > On Wed, 25 Jun 2025 13:48:03 -0700 Stanislav Fomichev wrote: > > > > > I'm still learning the af_xdp. Sure, I'm interested in it, just a= bit > > > > > worried if I'm capable of completing it. I will try then. > > > > > > > > SG, thanks! If you need more details lmk, but basically we need to = reorder > > > > netdev_lock_ops() and mutex_lock(lock: &xs->mutex)+XSK_READY check. > > > > And similarly for cleanup (out_unlock/out_release) path. > > > > > > Jakub just told me that I'm wrong and it looks similar to commit > > > f0433eea4688 ("net: don't mix device locking in dev_close_many() > > > calls"). So this is not as easy as flipping the lock ordering :-( > > > > I don't think registering a netdev from NETDEV_UP even of another > > netdev is going to play way with instance locks and lockdep. > > This is likely a false positive but if syzbot keeps complaining > > we could: > > > > diff --git a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c > > index 995a7207bdf8..f357a7ac70ac 100644 > > --- a/drivers/net/wan/lapbether.c > > +++ b/drivers/net/wan/lapbether.c > > @@ -81,7 +81,7 @@ static struct lapbethdev *lapbeth_get_x25_dev(struct = net_device *dev) > > > > static __inline__ int dev_is_ethdev(struct net_device *dev) > > { > > - return dev->type =3D=3D ARPHRD_ETHER && strncmp(dev->name, "dum= my", 5); > > + return dev->type =3D=3D ARPHRD_ETHER && !netdev_need_ops_lock(d= ev); > > } > > > > IDK what the dummy hack is there for, it's been like that since > > git begun.. > > Agreed. The driver itlself looks interesting. IIUC, when loaded, it > unconditionally creates virtual netdev for any eth device in the init > ns. A bit surprised that syzbot enables it, none of my machines have it > enabled. Interesting case I find. Thank you both for the detailed explanation :) Thanks, Jason