Fix ->vm_file accounting, mmap_region() may do do_munmap().
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>