From: Daniel Borkmann <daniel@iogearbox.net>
To: Maninder Singh <maninder1.s@samsung.com>
Cc: davem@davemloft.net, willemb@google.com, edumazet@google.com,
eyal.birger@gmail.com, tklauser@distanz.ch,
fruggeri@aristanetworks.com, dwmw2@infradead.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
pankaj.m@samsung.com, gh007.kim@samsung.com,
hakbong5.lee@samsung.com, Vaneet Narang <v.narang@samsung.com>
Subject: Re: [PATCH] af_packet: Raw socket destruction warning fix
Date: Mon, 18 Jan 2016 10:44:57 +0100 [thread overview]
Message-ID: <569CB419.6050102@iogearbox.net> (raw)
In-Reply-To: <1453099068-39022-1-git-send-email-maninder1.s@samsung.com>
On 01/18/2016 07:37 AM, Maninder Singh wrote:
> Receieve queue is not purged when socket dectruction is called
> results in kernel warning because of non zero sk_rmem_alloc.
>
> WARNING: at net/packet/af_packet.c:1142 packet_sock_destruct
>
> Backtrace:
> WARN_ON(atomic_read(&sk->sk_rmem_alloc)
> packet_sock_destruct
> __sk_free
> sock_wfree
> skb_release_head_state
> skb_release_all
> __kfree_skb
> net_tx_action
> __do_softirq
> run_ksoftirqd
>
> Signed-off-by: Vaneet Narang <v.narang@samsung.com>
> Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Thanks for the fix. While it fixes the WARN_ON(), I believe some more
investigation is needed here on why it is happening:
We call first into packet_release(), which removes the socket hook from
the kernel (unregister_prot_hook()), later calls synchronize_net() to
make sure no more skbs will come in. The receive queue is purged right
after the synchronize_net() already.
packet_sock_destruct() will be called afterwards, when there are no more
refs on the socket anymore and no af_packet skbs in tx waiting for completion.
Only then, in sk_destruct(), we'll call into packet_sock_destruct().
So, eventually double purging the sk_receive_queue seems not the right
thing to do at first look, and w/o any deeper analysis in the commit description.
Could you look a bit further into the issue? Do you have a reproducer to
trigger it?
Thanks,
Daniel
> ---
> net/packet/af_packet.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> index 81b4b81..bcb37ba 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
> @@ -1310,6 +1310,7 @@ static bool packet_rcv_has_room(struct packet_sock *po, struct sk_buff *skb)
>
> static void packet_sock_destruct(struct sock *sk)
> {
> + skb_queue_purge(&sk->sk_receive_queue);
> skb_queue_purge(&sk->sk_error_queue);
>
> WARN_ON(atomic_read(&sk->sk_rmem_alloc));
>
next prev parent reply other threads:[~2016-01-18 9:45 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-18 6:37 [PATCH] af_packet: Raw socket destruction warning fix Maninder Singh
2016-01-18 9:44 ` Daniel Borkmann [this message]
2016-01-18 10:29 ` Daniel Borkmann
2016-02-05 11:26 ` Eric Dumazet
-- strict thread matches above, loose matches on Subject: below --
2016-01-18 10:11 Vaneet Narang
2016-01-18 11:08 ` Daniel Borkmann
2016-01-21 11:40 Maninder Singh
2016-01-26 0:13 ` Daniel Borkmann
2016-02-05 5:23 Vaneet Narang
2016-02-10 12:43 Vaneet Narang
2016-02-10 14:56 ` Eric Dumazet
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