This can disrupt userspace signal management.

Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>