Noticed by Coverity checker.

(akpm: I stole this from Greg's tree and used the (IMO) tidier sizeof(*p)
construct).
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>