6b706e5603
If the rcutree.rcu_min_cached_objs kernel boot parameter is set to zero, then krcp->page_cache_work will never be triggered to fill page cache. In addition, the put_cached_bnode() will not fill page cache. As a result krcp->bkvcache will always be empty, so there is no need to acquire krcp->lock to get page from krcp->bkvcache. This commit therefore makes drain_page_cache() return immediately if the rcu_min_cached_objs is zero. Signed-off-by: Zqiang <qiang1.zhang@intel.com> Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>