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rcu: Add GP-kthread-starvation checks to CPU stall warnings

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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>
This commit is contained in:
Paul E. McKenney
2014-12-17 08:35:02 -08:00
parent 5cd37193ce
commit fb81a44b88
2 changed files with 29 additions and 1 deletions
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21
kernel/rcu/tree.c
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@@ -1072,6 +1072,21 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
rsp->n_force_qs_gpstart = ACCESS_ONCE(rsp->n_force_qs);
}
/*
* 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.
*/
@@ -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);