netdev - Re: [PATCH] net: Add back alignment for size for __alloc

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Message-ID: <4EB1CEC4.3090909@gmail.com>
Date:	Thu, 03 Nov 2011 00:14:12 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
CC:	tony@...mide.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org
Subject: Re: [PATCH] net: Add back alignment for size for __alloc_skb

On 03/11/2011 00:09, David Miller wrote:

> From: Eric Dumazet <eric.dumazet@...il.com>
> Date: Wed, 02 Nov 2011 23:55:11 +0100
> 
>> There is a problem with your kmalloc() or alignments on your architecture.
>>
>> What is the SMP_CACHE_BYTES value ?
> 
> kmalloc() behavior doesn't have anything to do with this bug.
> 
> The issue is calculation of skb->end, which is based upon calculated
> 'size' variable.
> 
> skb->end determines alignment of skb_shared_info, which is where the
> alignment problem is occuring for Tony.
> 


I understood that David, but check the code, and you can see that exact
skb->end depends also on ksize()

So maybe the right fix is to make sure skb->end is properly aligned, say
with SLOB

So a more generic fix is welcomed.

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