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

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Message-ID: <1426817846.25985.27.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Thu, 19 Mar 2015 19:17:26 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Josh Hunt <johunt@...mai.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com
Subject: Re: [PATCH] fix tcp fin memory accounting

On Thu, 2015-03-19 at 19:19 -0400, Josh Hunt wrote:
> 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>
> ---

Acked-by: Eric Dumazet <edumazet@...gle.com>


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