Merge branch 'rtnl_lock_killable'

Kirill Tkhai says:

====================
Introduce rtnl_lock_killable()

rtnl_lock() is widely used mutex in kernel. Some of kernel code
does memory allocations under it. In case of memory deficit this
may invoke OOM killer, but the problem is a killed task can't
exit if it's waiting for the mutex. This may be a reason of deadlock
and panic.

This patchset adds a new primitive, which responds on SIGKILL,
and it allows to use it in the places, where we don't want
to sleep forever. Also, the first place is made to use it.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>