Re: git: 89eddfb4b9f5 - main - linux: fix panic on kldunload

From: John Baldwin <jhb_at_FreeBSD.org>
Date: Wed, 10 Dec 2025 20:24:00 UTC 
On 12/10/25 14:22, Gleb Smirnoff wrote:
> The branch main has been updated by glebius:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=89eddfb4b9f5d744623ce0ee8ea966b0d33456e5
> 
> commit 89eddfb4b9f5d744623ce0ee8ea966b0d33456e5
> Author:     Gleb Smirnoff <glebius@FreeBSD.org>
> AuthorDate: 2025-12-10 19:20:14 +0000
> Commit:     Gleb Smirnoff <glebius@FreeBSD.org>
> CommitDate: 2025-12-10 19:20:14 +0000
> 
>      linux: fix panic on kldunload
>      
>      The vnet_deregister_sysuninit() that is called by linker unload sequence also
>      calls every registered destructor before unregistering it.  IMHO, this is
>      not correct in principle, but for now plug the regression right in the code
>      that introduced the panic.
>      
>      Fixes:  607f11055d2d421770963162a4d9a99cdd136152
> ---
>   sys/compat/linux/linux_if.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/sys/compat/linux/linux_if.c b/sys/compat/linux/linux_if.c
> index 1281207c1c84..b342b07a6722 100644
> --- a/sys/compat/linux/linux_if.c
> +++ b/sys/compat/linux/linux_if.c
> @@ -105,6 +105,13 @@ VNET_SYSINIT(linux_ifnet_vnet_init, SI_SUB_PROTO_IF, SI_ORDER_ANY,
>   static void
>   linux_ifnet_vnet_uninit(void *arg __unused)
>   {
> +	/*
> +	 * At a normal vnet shutdown all interfaces are gone at this point.
> +	 * But when we kldunload linux.ko, the vnet_deregister_sysuninit()
> +	 * would call this function for the default vnet.
> +	 */
> +	if (IS_DEFAULT_VNET(curvnet))
> +		clear_unrhdr(V_linux_eth_unr);
>   	delete_unrhdr(V_linux_eth_unr);
>   }
>   VNET_SYSUNINIT(linux_ifnet_vnet_uninit, SI_SUB_PROTO_IF, SI_ORDER_ANY,

Don't you also want to make this SYSUNINIT enabled for the !VIMAGE case
so you don't leak this on unload for the !VIMAGE case?

-- 
John Baldwin