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Date: Wed, 2 Nov 2011 16:24:03 -0700
From: Tony Lindgren <tony@atomide.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org
Subject: Re: [PATCH] net: Add back alignment for size for __alloc_skb
Message-ID: <20111102232403.GO31337@atomide.com>
References: <4EB1CA4F.3090403@gmail.com>
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* Eric Dumazet <eric.dumazet@gmail.com> [111102 15:46]:
> On 03/11/2011 00:19, Tony Lindgren wrote:
> 
> > * David Miller <davem@davemloft.net> [111102 15:42]:
> >> c> 
> >>> 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.
> >>
> >> Right, and SMP_CACHE_BYTES setting should save us in any case.
> >>
> >> For ARM, SMP_CACHE_BYTES seems to be set to L1_CACHE_BYTES which in
> >> turn is set via ARM_L1_CACHE_SHIFT which can be set seemingly to any
> >> value but the defaults are 5 and 6 which should be OK.
> >>
> >> So unless Tony is using a non-standard setting of ARM_L1_CACHE_SHIFT,
> >> this report is a bit mysterious.
> > 
> > This is happening at least with omap1_defconfig. In that case we have
> > ARM_L1_CACHE_SHIFT=5.
> > 
> > Regards,
> > 
> > Tony
> 
> 
> Do you use SLOB, SLUB or SLAB ?

Seems to be SLOB for omap1_defconfig.

Tony