Kmemleak can be tweaked at runtime by writing commands into debugfs
file.  Root can use it anyway, but without the write-bit this interface
isn't obvious.

Link: http://lkml.kernel.org/r/150728996582.744328.11541332857988399411.stgit@buzzSigned-off-by: NKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>