Re: [PATCH] IPoIB: fix skb truesize underestimatiom

From: Eric Dumazet <redacted>
Date: Tue, 10 Jul 2012 22:03:41 +0200

From: Eric Dumazet <edumazet@google.com>

Or Gerlitz reported triggering of WARN_ON_ONCE(delta < len); in
skb_try_coalesce()
This warning tracks drivers that incorrectly set skb->truesize

IPoIB indeed allocates a full page to store a fragment, but only
accounts in skb->truesize the used part of the page (frame length)

This patch fixes skb truesize underestimation, and
also fixes a performance issue, because RX skbs have not enough tailroom
to allow IP and TCP stacks to pull their header in skb linear part
without an expensive call to pskb_expand_head()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Or Gerlitz <redacted>

Applied to net, thanks.