Lazy unmapping in the vmalloc code has now opened the possibility for use
after free bugs to go undetected.  We can catch those by forcing an unmap
and flush (which is going to be slow, but that's what happens).
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>