If SIGKILL does not have priority, we cannot instantly kill task before it
makes some unexpected job.  It can be critical, but we were unable to
reproduce this easily until Heiko Carstens <[email protected]>
reported this problem on LKML.

Signed-Off-By: Kirill Korotaev <[email protected]>
Signed-Off-By: Alexey Kuznetsov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>