rcu: Awaken grace-period kthread when stalled

Recent kernels can fail to awaken the grace-period kthread for
quiescent-state forcing.  This commit is a crude hack that does
a wakeup any time a stall is detected.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 531a328076bdd82c61bd6e4c509225c9d450d1c4..a327a253c178ed61bdd7157035fcc1cdb8e1ff79 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1224,8 +1224,10 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
                       rsp->gp_flags,
                       gp_state_getname(rsp->gp_state), rsp->gp_state,
                       rsp->gp_kthread ? rsp->gp_kthread->state : ~0);
-               if (rsp->gp_kthread)
+               if (rsp->gp_kthread) {
                        sched_show_task(rsp->gp_kthread);
+                       wake_up_process(rsp->gp_kthread);
+               }
        }
 }