Previously, we wanted to shrink the pages of freed objects before they
were finally RCU collected. However, by removing the struct_mutex
serialisation around the active reference, we need to acquire an extra
reference around the wait. Unfortunately this means that we have to skip
objects that are waiting RCU collection.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110937Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190618074153.16055-2-chris@chris-wilson.co.uk