From: Simon Horman <horms@kernel•org>
To: Ido Schimmel <idosch@idosch•org>
Cc: Vlad Buslov <vladbu@nvidia•com>,
davem@davemloft•net, kuba@kernel•org, edumazet@google•com,
pabeni@redhat•com, netdev@vger•kernel.org,
amir.hanania@intel•com, jeffrey.t.kirsher@intel•com,
john.fastabend@gmail•com
Subject: Re: [PATCH net] vlan: Fix VLAN 0 memory leak
Date: Mon, 31 Jul 2023 11:52:19 +0200 [thread overview]
Message-ID: <ZMeEU/Aqq0ljY8NE@kernel.org> (raw)
In-Reply-To: <ZMaCB/Pek5c4baCn@shredder>
On Sun, Jul 30, 2023 at 06:30:15PM +0300, Ido Schimmel wrote:
> On Fri, Jul 28, 2023 at 06:31:52PM +0200, Vlad Buslov wrote:
> > The referenced commit intended to fix memleak of VLAN 0 that is implicitly
> > created on devices with NETIF_F_HW_VLAN_CTAG_FILTER feature. However, it
> > doesn't take into account that the feature can be re-set during the
> > netdevice lifetime which will cause memory leak if feature is disabled
> > during the device deletion as illustrated by [0]. Fix the leak by
> > unconditionally deleting VLAN 0 on NETDEV_DOWN event.
>
> Specifically, what happens is:
>
> >
> > [0]:
> > > modprobe 8021q
> > > ip l set dev eth2 up
>
> VID 0 is created with reference count of 1
>
> > > ethtool -k eth2 | grep rx-vlan-filter
> > rx-vlan-filter: on
> > > ethtool -K eth2 rx-vlan-filter off
> > > ip l set dev eth2 down
>
> Reference count is not dropped because the feature is off
>
> > > ip l set dev eth2 up
>
> Reference count is not increased because the feature is off. It could
> have been increased if this line was preceded by:
>
> ethtool -K eth2 rx-vlan-filter on
>
> > > modprobe -r mlx5_ib
> > > modprobe -r mlx5_core
>
> Reference count is not dropped during NETDEV_DOWN because the feature is
> off and NETDEV_UNREGISTER only dismantles upper VLAN devices, resulting
> in VID 0 being leaked.
Thanks Ido and Vlad,
perhaps it would be worth including the information added
by Ido above in the patch description. Not a hard requirement
from my side, just an idea.
next prev parent reply other threads:[~2023-07-31 9:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-28 16:31 [PATCH net] vlan: Fix VLAN 0 memory leak Vlad Buslov
2023-07-30 15:30 ` Ido Schimmel
2023-07-31 9:52 ` Simon Horman [this message]
2023-07-31 15:45 ` Ido Schimmel
2023-07-31 19:11 ` Vlad Buslov
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