mm: don't dump the zero page

If someone reads untouched page, the kernel maps the zero page
to this address. This page will not have the SOFT_DIRTY bit and it must
not be dumped.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
kerndat: Close pagemap fd after getting zero page pfn

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
maps007: check "stop" with "delta"

We don't need to wait if a stop signal has been received.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: add more logging messages

Tests fail sometimes, but logs don't contain enough information:
Execute zdtm/live/static/umask00
./umask00 --pidfile=umask00.pid --outfile=umask00.out --mask=0345
make[3]: *** [umask00.pid] Error 1
ERROR: fail to start zdtm/live/static/umask00

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>