From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Thu, 31 Dec 2015 16:48:36 +0000 (-0800)
Subject: rcu: Awaken grace-period kthread when stalled
X-Git-Tag: v4.7-rc1~196^2^2^3~4
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=86057b80ae31d37fcbdb5f57d15aaf1148c69f96;p=linux.git

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 531a328076bd..a327a253c178 100644
--- 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);
+		}
 	}
 }