netdev - Re: [PATCH] fix tcp fin memory accounting

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Date:	Fri, 20 Mar 2015 13:20:29 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	johunt@...mai.com
Cc:	netdev@...r.kernel.org, edumazet@...gle.com
Subject: Re: [PATCH] fix tcp fin memory accounting

From: Josh Hunt <johunt@...mai.com>
Date: Thu, 19 Mar 2015 19:19:30 -0400

> tcp_send_fin() does not account for the memory it allocates properly, so
> sk_forward_alloc can be negative in cases where we've sent a FIN:
> 
> ss example output (ss -amn | grep -B1 f4294):
> tcp    FIN-WAIT-1 0      1            192.168.0.1:45520         192.0.2.1:8080
> 	skmem:(r0,rb87380,t0,tb87380,f4294966016,w1280,o0,bl0)
> --
> tcp    FIN-WAIT-1 0      1            192.168.0.1:8080          192.0.2.1:59710
> 	skmem:(r0,rb87380,t0,tb87380,f4294966016,w1280,o0,bl0)
> 
> This can be resolved by using sk_stream_alloc_skb() instead of calling alloc_skb_fclone()
> directly. The same fix was made in tcp_connect() in commit 355a901e6cf1 (tcp: make connect() mem charging friendly).
> 
> With this fix applied I no longer see the negative sk_forward_alloc values (or
> very large values repoted by ss) in my tests.
> 
> Signed-off-by: Josh Hunt <johunt@...mai.com>

Applied and queued up for -stable, thanks.
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