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SubjectRe: [PATCH] net: Add back alignment for size for __alloc_skb
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From: Tony Lindgren <tony@atomide.com>
Date: Wed, 2 Nov 2011 16:19:17 -0700

> * 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.

Ok, so ksize(x) gives an odd value for whichever allocator you are
using. Which is the point Eric was trying to make. It becomes
clearernow.



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