cow01 uses /proc/pid/pagemap which has been protected by
CAP_SYS_ADMIN.

"""
	commit	ab676b7d6fbf4b294bf198fb27ade5b0e865c7ce
	pagemap: do not leak physical addresses to non-privileged userspace

	As pointed by recent post[1] on exploiting DRAM physical imperfection,
	/proc/PID/pagemap exposes sensitive information which can be used to do
	attacks.
"""
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>