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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-11-17 13:25:21 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-12-04 12:26:53 -0800
commit72611ab9f5d2d384a04e72d560c9c82463115cbf (patch)
tree46daecec76847f22b9cc89f80c222fa027122d04
parent73f36f9de8bed78bcda2704a348594c20518b455 (diff)
downloadlinux-sh-72611ab9f5d2d384a04e72d560c9c82463115cbf.tar.gz
rcu: Add more diagnostics to expedited stall warning messages.
This commit adds print statements that check the rcu_node structure to find which ->expmask bits and which ->exp_tasks structures are blocking the current expedited grace period. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
-rw-r--r--kernel/rcu/tree.c24
1 files changed, 21 insertions, 3 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index bc6b79716a86..6a652d1f3d7f 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3745,6 +3745,7 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
unsigned long jiffies_stall;
unsigned long jiffies_start;
unsigned long mask;
+ int ndetected;
struct rcu_node *rnp;
struct rcu_node *rnp_root = rcu_get_root(rsp);
int ret;
@@ -3767,14 +3768,16 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
}
pr_err("INFO: %s detected expedited stalls on CPUs/tasks: {",
rsp->name);
+ ndetected = 0;
rcu_for_each_leaf_node(rsp, rnp) {
- (void)rcu_print_task_exp_stall(rnp);
+ ndetected = rcu_print_task_exp_stall(rnp);
mask = 1;
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {
struct rcu_data *rdp;
if (!(rnp->expmask & mask))
continue;
+ ndetected++;
rdp = per_cpu_ptr(rsp->rda, cpu);
pr_cont(" %d-%c%c%c", cpu,
"O."[cpu_online(cpu)],
@@ -3783,8 +3786,23 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
}
mask <<= 1;
}
- pr_cont(" } %lu jiffies s: %lu\n",
- jiffies - jiffies_start, rsp->expedited_sequence);
+ pr_cont(" } %lu jiffies s: %lu root: %#lx/%c\n",
+ jiffies - jiffies_start, rsp->expedited_sequence,
+ rnp_root->expmask, ".T"[!!rnp_root->exp_tasks]);
+ if (!ndetected) {
+ pr_err("blocking rcu_node structures:");
+ rcu_for_each_node_breadth_first(rsp, rnp) {
+ if (rnp == rnp_root)
+ continue; /* printed unconditionally */
+ if (sync_rcu_preempt_exp_done(rnp))
+ continue;
+ pr_cont(" l=%u:%d-%d:%#lx/%c",
+ rnp->level, rnp->grplo, rnp->grphi,
+ rnp->expmask,
+ ".T"[!!rnp->exp_tasks]);
+ }
+ pr_cont("\n");
+ }
rcu_for_each_leaf_node(rsp, rnp) {
mask = 1;
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {