netdev - Re: [Bugme-new] [Bug 16083] New: swapper: Page allocation failure

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Date:	Thu, 03 Jun 2010 23:58:02 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [Bugme-new] [Bug 16083] New: swapper: Page allocation failure

Le jeudi 03 juin 2010 à 14:39 -0700, Andrew Morton a écrit :

> Well.  The presence of this warning does serve to remind us how sucky
> e1000[e] is :(
> 
> I'm not particularly fussed either way - I'm just wondering if you guys
> think this thing meets the noise-to-benefit test...
> 

Well, in this particular case, I think its a genuine bug in the ipv6
code, not on the e1000[e] driver :)

It allocates "a priori" dev->mtu sized skb that are filled by maybe one
hundred bytes by caller.

With MTU=9000, this means order-2 allocations. In an ideal world, it
would be fine, but in practice, we know only fools can trust high order
allocations.

Since code is prepared to chain skbs, just make sure we cap allocations
to smaller units (up to 0xe80 bytes on a 64bit kernel)

So in this particular case, the bugzilla report can point to a real
problem in our stack.

Failed allocations had been silent, we probably would never have
noticed.

Hmm...

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