netdev - Re: [syzbot] [net?] [bpf?] possible deadlock in xsk_diag

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Message-ID: <20250411153822.2ff97d57@kernel.org>
Date: Fri, 11 Apr 2025 15:38:22 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: syzbot <syzbot+4ebb06d5f6e3597279c0@...kaller.appspotmail.com>
Cc: andrii@...nel.org, ast@...nel.org, bjorn@...nel.org,
 bpf@...r.kernel.org, daniel@...earbox.net, davem@...emloft.net,
 edumazet@...gle.com, horms@...nel.org, jonathan.lemon@...il.com,
 linux-kernel@...r.kernel.org, maciej.fijalkowski@...el.com,
 magnus.karlsson@...el.com, netdev@...r.kernel.org, pabeni@...hat.com,
 syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] [bpf?] possible deadlock in xsk_diag_dump

On Tue, 08 Apr 2025 04:53:35 -0700 syzbot wrote:
> Chain exists of:
>   &xs->mutex --> &rdev->wiphy.mtx --> &net->xdp.lock
> 
>  Possible unsafe locking scenario:
> 
>        CPU0                    CPU1
>        ----                    ----
>   lock(&net->xdp.lock);
>                                lock(&rdev->wiphy.mtx);
>                                lock(&net->xdp.lock);
>   lock(&xs->mutex);

After looking at it with Stanislav our best guess is that we're mixing
normal and ops locked devices in close_many. Will send a fix over the
weekend.