tree 8c6c163cd3914426873843c0fdb1c850dd5fe053
parent 6115c11fe1a5a636ac99fc823b00df4ff3c0674e
author Jason Wang <jasowang@redhat.com> 1384322439 +0800
committer David S. Miller <davem@davemloft.net> 1384463127 -0500

tuntap: limit head length of skb allocated

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 <stefanha@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>