[PATCH tip/core/rcu 11/15] rcu: Add more debug info on "kthread starved" RCU CPU stall warnings

From: Paul E. McKenney
Date: Tue May 12 2015 - 17:47:09 EST

From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>

This commit adds grace number and command-flags information to the
"kthread starved" message that is sometimes printed out as part of
RCU CPU stall warnings. This message is caused by the corresponding
RCU grace-period kthread not having run for at least two seconds, and
this added information can be helpful when debugging.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
kernel/rcu/tree.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index a7615a0b684f..5b573e75e0f8 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1133,8 +1133,9 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
j = jiffies;
gpa = READ_ONCE(rsp->gp_activity);
if (j - gpa > 2 * HZ)
- pr_err("%s kthread starved for %ld jiffies!\n",
- rsp->name, j - gpa);
+ pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x\n",
+ rsp->name, j - gpa,
+ rsp->gpnum, rsp->completed, rsp->gp_flags);


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