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Date:	Mon, 17 Nov 2014 12:22:54 +0200
From:	Denys Fedoryshchenko <nuclearcat@...learcat.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Neal Cardwell <ncardwell@...gle.com>,
	Yuchung Cheng <ycheng@...gle.com>, netdev@...r.kernel.org
Subject: Re: /proc/net/sockstat invalid memory accounting or memory leak in
 latest kernels? (trying to debug)

On 2014-11-17 07:01, Eric Dumazet wrote:
> On Sun, 2014-11-16 at 12:16 -0800, Eric Dumazet wrote:
> 
>> Thanks Denys !
>> 
>> Could you try following patch ?
>> 
>> Thanks !
> 
> Hmm.... I have an updated patch, sorry.
> 
> (A memcpy_fromiovec() has to be memcpy_fromiovecend() )
> 
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index a3d453b94747..c2bbfcd9c0db 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -2998,7 +2998,7 @@ static int tcp_send_syn_data(struct sock *sk,
> struct sk_buff *syn)
>  {
>  	struct tcp_sock *tp = tcp_sk(sk);
>  	struct tcp_fastopen_request *fo = tp->fastopen_req;
> -	int syn_loss = 0, space, i, err = 0, iovlen = fo->data->msg_iovlen;
> +	int syn_loss = 0, space, err = 0;
>  	struct sk_buff *syn_data = NULL, *data;
>  	unsigned long last_syn_loss = 0;
> 
> @@ -3031,25 +3031,19 @@ static int tcp_send_syn_data(struct sock *sk,
> struct sk_buff *syn)
>  	/* limit to order-0 allocations */
>  	space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER));
> 
> -	syn_data = skb_copy_expand(syn, MAX_TCP_HEADER, space,
> -				   sk->sk_allocation);
> -	if (syn_data == NULL)
> +	syn_data = sk_stream_alloc_skb(sk, space, sk->sk_allocation);
> +	if (!syn_data)
>  		goto fallback;
> 
> -	for (i = 0; i < iovlen && syn_data->len < space; ++i) {
> -		struct iovec *iov = &fo->data->msg_iov[i];
> -		unsigned char __user *from = iov->iov_base;
> -		int len = iov->iov_len;
> -
> -		if (syn_data->len + len > space)
> -			len = space - syn_data->len;
> -		else if (i + 1 == iovlen)
> -			/* No more data pending in inet_wait_for_connect() */
> -			fo->data = NULL;
> +	syn_data->ip_summed = CHECKSUM_PARTIAL;
> +	memcpy(syn_data->cb, syn->cb, sizeof(syn->cb));
> +	if (memcpy_fromiovecend(skb_put(syn_data, space),
> +				fo->data->msg_iov, 0, space))
> +		goto fallback;
> 
> -		if (skb_add_data(syn_data, from, len))
> -			goto fallback;
> -	}
> +	/* No more data pending in inet_wait_for_connect() */
> +	if (space == fo->size)
> +		fo->data = NULL;
> 
>  	/* Queue a data-only packet after the regular SYN for retransmission 
> */
>  	data = pskb_copy(syn_data, sk->sk_allocation);
> @@ -3101,13 +3095,10 @@ int tcp_connect(struct sock *sk)
>  		return 0;
>  	}
> 
> -	buff = alloc_skb_fclone(MAX_TCP_HEADER + 15, sk->sk_allocation);
> -	if (unlikely(buff == NULL))
> +	buff = sk_stream_alloc_skb(sk, 0, sk->sk_allocation);
> +	if (unlikely(!buff))
>  		return -ENOBUFS;
> 
> -	/* Reserve space for headers. */
> -	skb_reserve(buff, MAX_TCP_HEADER);
> -
>  	tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN);
>  	tp->retrans_stamp = tcp_time_stamp;
>  	tcp_connect_queue_skb(sk, buff);

Installed patch, but will have to wait a while (usually at least 
24hours), to be sure if it is stable.

Thanks a lot!


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