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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-12-17 08:35:02 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-01-15 23:33:15 -0800
commitfb81a44b88e6173ed0f6e9d6a1afa5305fb63f6e (patch)
treefaa68798164b89dd6d37a9a591e62e9dfc7afdad /kernel/rcu
parent5cd37193ce8539be1e6ef76be226f4bcc984e0f5 (diff)
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rcu: Add GP-kthread-starvation checks to CPU stall warnings
This commit adds a message that is printed if the relevant grace-period kthread has not been able to run for the two seconds preceding the stall warning. (The two seconds is double the maximum interval between successive bouts of quiescent-state forcing.) Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tree.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index cb00e038c2f2..e335f33d0b9f 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1073,6 +1073,21 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
}
/*
+ * Complain about starvation of grace-period kthread.
+ */
+static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
+{
+ unsigned long gpa;
+ unsigned long j;
+
+ j = jiffies;
+ gpa = ACCESS_ONCE(rsp->gp_activity);
+ if (j - gpa > 2 * HZ)
+ pr_err("%s kthread starved for %ld jiffies!\n",
+ rsp->name, j - gpa);
+}
+
+/*
* Dump stacks of all tasks running on stalled CPUs.
*/
static void rcu_dump_cpu_stacks(struct rcu_state *rsp)
@@ -1169,9 +1184,10 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
}
/* Complain about tasks blocking the grace period. */
-
rcu_print_detail_task_stall(rsp);
+ rcu_check_gp_kthread_starvation(rsp);
+
force_quiescent_state(rsp); /* Kick them all. */
}
@@ -1196,6 +1212,9 @@ static void print_cpu_stall(struct rcu_state *rsp)
pr_cont(" (t=%lu jiffies g=%ld c=%ld q=%lu)\n",
jiffies - rsp->gp_start,
(long)rsp->gpnum, (long)rsp->completed, totqlen);
+
+ rcu_check_gp_kthread_starvation(rsp);
+
rcu_dump_cpu_stacks(rsp);
raw_spin_lock_irqsave(&rnp->lock, flags);