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Message-ID: <ZieDYD5ibpGjlIRw@gmail.com>
Date: Tue, 23 Apr 2024 02:46:08 -0700
From: Breno Leitao <leitao@...ian.org>
To: Florian Westphal <fw@...len.de>
Cc: netdev@...r.kernel.org, Paolo Abeni <pabeni@...hat.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH net-next] ip6_vti: fix memleak on netns dismantle
Hello Florian,
On Mon, Apr 15, 2024 at 02:23:44PM +0200, Florian Westphal wrote:
> kmemleak reports net_device resources are no longer released, restore
> needs_free_netdev toggle. Sample backtrace:
>
> unreferenced object 0xffff88810874f000 (size 4096): [..]
> [<00000000a2b8af8b>] __kmalloc_node+0x209/0x290
> [<0000000040b0a1a9>] alloc_netdev_mqs+0x58/0x470
> [<00000000b4be1e78>] vti6_init_net+0x94/0x230
> [<000000008830c1ea>] ops_init+0x32/0xc0
> [<000000006a26fa8f>] setup_net+0x134/0x2e0
> [..]
>
> Cc: Breno Leitao <leitao@...ian.org>
> Fixes: a9b2d55a8f1e ("ip6_vti: Do not use custom stat allocator")
> Signed-off-by: Florian Westphal <fw@...len.de>
> ---
> net/ipv6/ip6_vti.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c
> index 4d68a0777b0c..78344cf3867e 100644
> --- a/net/ipv6/ip6_vti.c
> +++ b/net/ipv6/ip6_vti.c
> @@ -901,6 +901,7 @@ static void vti6_dev_setup(struct net_device *dev)
> {
> dev->netdev_ops = &vti6_netdev_ops;
> dev->header_ops = &ip_tunnel_header_ops;
> + dev->needs_free_netdev = true;
Thanks for the fix!
Could you help me to understand how needs_free_netdev will trigger the
free()here?
I _though_ that any device that is being unregistered would have the stats
freed.
This is the flow I am reading:
1) When the device is unregistered, then it is marked as todo:
unregister_netdevice_many_notify() {
list_for_each_entry(dev, head, unreg_list) {
net_set_todo(dev);
}
}
2) Then, "run_todo" will run later, and it does:
netdev_run_todo() {
list_for_each_entry_safe(dev, tmp, &list, todo_list) {
if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) {
netdev_WARN(dev, "run_todo but not unregistering\n");
list_del(&dev->todo_list);
continue;
}
while (!list_empty(&list)) {
netdev_do_free_pcpu_stats(dev);
}
}
Thank you!
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