netdev - Re: [PATCH net v2] l2tp: Don't sleep and disable BH under writer-side sk_callback

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Date:   Wed, 23 Nov 2022 12:50:15 +0000
From:   patchwork-bot+netdevbpf@...nel.org
To:     Jakub Sitnicki <jakub@...udflare.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, tparkin@...alix.com,
        penguin-kernel@...ove.sakura.ne.jp,
        syzbot+703d9e154b3b58277261@...kaller.appspotmail.com,
        syzbot+50680ced9e98a61f7698@...kaller.appspotmail.com,
        syzbot+de987172bb74a381879b@...kaller.appspotmail.com
Subject: Re: [PATCH net v2] l2tp: Don't sleep and disable BH under writer-side
 sk_callback_lock

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@...emloft.net>:

On Mon, 21 Nov 2022 09:54:26 +0100 you wrote:
> When holding a reader-writer spin lock we cannot sleep. Calling
> setup_udp_tunnel_sock() with write lock held violates this rule, because we
> end up calling percpu_down_read(), which might sleep, as syzbot reports
> [1]:
> 
>  __might_resched.cold+0x222/0x26b kernel/sched/core.c:9890
>  percpu_down_read include/linux/percpu-rwsem.h:49 [inline]
>  cpus_read_lock+0x1b/0x140 kernel/cpu.c:310
>  static_key_slow_inc+0x12/0x20 kernel/jump_label.c:158
>  udp_tunnel_encap_enable include/net/udp_tunnel.h:187 [inline]
>  setup_udp_tunnel_sock+0x43d/0x550 net/ipv4/udp_tunnel_core.c:81
>  l2tp_tunnel_register+0xc51/0x1210 net/l2tp/l2tp_core.c:1509
>  pppol2tp_connect+0xcdc/0x1a10 net/l2tp/l2tp_ppp.c:723
> 
> [...]

Here is the summary with links:
  - [net,v2] l2tp: Don't sleep and disable BH under writer-side sk_callback_lock
    https://git.kernel.org/netdev/net/c/af295e854a4e

You are awesome, thank you!
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