mm: vmalloc improve vmallocinfo

If we do that, output of files like /proc/vmallocinfo will show things
like "vmalloc_32", "vmalloc_user", or whomever the caller was as the
caller.  This info is not as useful as the real caller of the allocation.

So, proposal is to call __vmalloc_node node directly, with matching
parameters to save the caller information

Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>