rcu: Detect stalls caused by failure to propagate up rcu_node tree
If all CPUs have passed through quiescent states, then stalls might be
due to starvation of the grace-period kthread or to failure to propagate
the quiescent states up the rcu_node combining tree. The current stall
warning messages do not differentiate, so this commit adds a printout
of the root rcu_node structure's ->qsmask field.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 98da632..3b7e413 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1196,9 +1196,10 @@
} else {
j = jiffies;
gpa = ACCESS_ONCE(rsp->gp_activity);
- pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld\n",
+ pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld, root ->qsmask %#lx\n",
rsp->name, j - gpa, j, gpa,
- jiffies_till_next_fqs);
+ jiffies_till_next_fqs,
+ rcu_get_root(rsp)->qsmask);
/* In this case, the current CPU might be at fault. */
sched_show_task(current);
}
