From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Wed, 17 Feb 2016 19:54:28 +0000 (-0800)
Subject: rcu: Dump ftrace buffer when kicking grace-period kthread
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=5dffed1e5721f6deae4fd67d32386ef037c5fc56;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git

rcu: Dump ftrace buffer when kicking grace-period kthread

If it is necessary to kick the grace-period kthread, that is a good
time to dump the trace buffer in order to learn why kicking was needed.
This commit therefore does the dump.

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

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index a739292be605..86edb92276d3 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1266,6 +1266,7 @@ static void rcu_stall_kick_kthreads(struct rcu_state *rsp)
 	j = READ_ONCE(rsp->jiffies_kick_kthreads);
 	if (time_after(jiffies, j) && rsp->gp_kthread) {
 		WARN_ONCE(1, "Kicking %s grace-period kthread\n", rsp->name);
+		rcu_ftrace_dump(DUMP_ALL);
 		wake_up_process(rsp->gp_kthread);
 		WRITE_ONCE(rsp->jiffies_kick_kthreads, j + HZ);
 	}