netlink: use kvmalloc() in netlink_alloc_large_skb()

This is a followup of commit 234ec0b6034b ("netlink: fix potential
sleeping issue in mqueue_flush_file"), because vfree_atomic()
overhead is unfortunate for medium sized allocations.

1) If the allocation is smaller than PAGE_SIZE, do not bother
   with vmalloc() at all. Some arches have 64KB PAGE_SIZE,
   while NLMSG_GOODSIZE is smaller than 8KB.

2) Use kvmalloc(), which might allocate one high order page
   instead of vmalloc if memory is not too fragmented.

Signed-off-by: Eric Dumazet <[email protected]>
Reviewed-by: Zhengchao Shao <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

0 files changed, 0 insertions, 0 deletions