They are 64K and result in order-4 allocations, even with SLUB.

Therefore, just like we always have for the deflate buffers, use
vmalloc.
Reported-by: NMartin Jackson <mjackson220.list@gmail.com>
Acked-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>