From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [RFC] allow skb->head to point/alias to first skb frag
Date: Thu, 26 Apr 2012 05:18:00 -0400 (EDT)
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From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 26 Apr 2012 11:10:02 +0200

> The 'frag' would have a known size : 2048 bytes
> 
> But the end of it would be used by struct skb_shared_info
> 
> so data_len would be 0 in fact.
> 
> This would look like a regular linear skb.
> 
> Just a bit set in skb to say : Warning, skb->head was not kmalloced :
> replace kfree(head) by put_page(...)
> 
> And this bit would be tested in GRO or tcp merge to 'upgrade' this
> skb->head to proper page/frag

And what happens if this ends up in a piece of code which wants to
append a page frag?

Or a piece of code which copies an SKB, including page frag parts?

All I'm saying is that the number of tests necessary to make this work
properly might become prohibitive.