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SubjectRe: [PATCH net V2 2/2] macvtap: limit head length of skb allocated
From: Jason Wang <>
Date: Wed, 13 Nov 2013 14:00:40 +0800

> We currently use hdr_len as a hint of head length which is advertised by
> guest. But when guest advertise a very big value, it can lead to an 64K+
> allocating of kmalloc() which has a very high possibility of failure when host
> memory is fragmented or under heavy stress. The huge hdr_len also reduce the
> effect of zerocopy or even disable if a gso skb is linearized in guest.
> To solves those issues, this patch introduces an upper limit (PAGE_SIZE) of the
> head, which guarantees an order 0 allocation each time.
> Cc: Stefan Hajnoczi <>
> Cc: Michael S. Tsirkin <>
> Signed-off-by: Jason Wang <>

Applied and queued up for -stable.

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