netdev - Re: [PATCH net-next] sit: proper dev_{hold|put} in ndo

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Date:   Wed, 31 Mar 2021 07:53:50 +0200
From:   Eric Dumazet <edumazet@...gle.com>
To:     "Wong, Vee Khee" <vee.khee.wong@...el.com>
Cc:     "eric.dumazet@...il.com" <eric.dumazet@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "syzkaller@...glegroups.com" <syzkaller@...glegroups.com>,
        "Ismail, Mohammad Athari" <mohammad.athari.ismail@...el.com>
Subject: Re: [PATCH net-next] sit: proper dev_{hold|put} in ndo_[un]init methods

On Wed, Mar 31, 2021 at 2:05 AM Wong, Vee Khee <vee.khee.wong@...el.com> wrote:
>
> Hi all,
>
> This patch introduced the following massive warnings printouts on a
> Intel x86 Alderlake platform with STMMAC MAC and Marvell 88E2110 PHY.
>
> [  149.674232] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  159.930310] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  170.186205] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  180.434311] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  190.682309] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  200.690176] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  210.938310] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  221.186311] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  231.442311] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  241.690186] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  251.698288] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  261.946311] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  272.194181] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  282.442311] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  292.690310] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  302.938313] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  313.186255] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  323.442329] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  333.698309] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  343.946310] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  354.202166] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  364.450190] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
> [  374.706314] unregister_netdevice: waiting for sit0 to become free. Usage count = 2
>
> Is this an expected behavior?
>


Nope, I already have a fix, but it depends on a pending patch.

https://patchwork.kernel.org/project/netdevbpf/patch/20210330064551.545964-1-eric.dumazet@gmail.com/

(I need the patch being merged to add a corresponding Fixes: tag)

You can try the attached patch :

View attachment "0001-ipv6-remove-extra-dev_hold-for-fallback-tunnels.patch" of type "text/x-patch" (3126 bytes)