From: Zhaolong Zhang <zhangzl2013@126.com>
To: Zhaolong Zhang <zhangzl2013@126.com.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Joel Fernandes <joel@joelfernandes.org>
Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] rcu: Fix the (t=0 jiffies) false positive
Date: Thu, 5 Mar 2020 15:45:57 +0800 [thread overview]
Message-ID: <1583394357-11767-1-git-send-email-zhangzl2013@126.com> (raw)
Calculate 't' with the previously recorded 'gps' instead of 'gp_start'.
Signed-off-by: Zhaolong Zhang <zhangzl2013@126.com>
---
kernel/rcu/tree_stall.h | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 55f9b84..4223b8b 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -371,7 +371,7 @@ static void rcu_check_gp_kthread_starvation(void)
}
}
-static void print_other_cpu_stall(unsigned long gp_seq)
+static void print_other_cpu_stall(unsigned long gp_seq, unsigned long gps)
{
int cpu;
unsigned long flags;
@@ -408,7 +408,7 @@ static void print_other_cpu_stall(unsigned long gp_seq)
for_each_possible_cpu(cpu)
totqlen += rcu_get_n_cbs_cpu(cpu);
pr_cont("\t(detected by %d, t=%ld jiffies, g=%ld, q=%lu)\n",
- smp_processor_id(), (long)(jiffies - rcu_state.gp_start),
+ smp_processor_id(), (long)(jiffies - gps),
(long)rcu_seq_current(&rcu_state.gp_seq), totqlen);
if (ndetected) {
rcu_dump_cpu_stacks();
@@ -442,7 +442,7 @@ static void print_other_cpu_stall(unsigned long gp_seq)
rcu_force_quiescent_state(); /* Kick them all. */
}
-static void print_cpu_stall(void)
+static void print_cpu_stall(unsigned long gps)
{
int cpu;
unsigned long flags;
@@ -467,7 +467,7 @@ static void print_cpu_stall(void)
for_each_possible_cpu(cpu)
totqlen += rcu_get_n_cbs_cpu(cpu);
pr_cont("\t(t=%lu jiffies g=%ld q=%lu)\n",
- jiffies - rcu_state.gp_start,
+ jiffies - gps,
(long)rcu_seq_current(&rcu_state.gp_seq), totqlen);
rcu_check_gp_kthread_starvation();
@@ -546,7 +546,7 @@ static void check_cpu_stall(struct rcu_data *rdp)
cmpxchg(&rcu_state.jiffies_stall, js, jn) == js) {
/* We haven't checked in, so go dump stack. */
- print_cpu_stall();
+ print_cpu_stall(gps);
if (rcu_cpu_stall_ftrace_dump)
rcu_ftrace_dump(DUMP_ALL);
@@ -555,7 +555,7 @@ static void check_cpu_stall(struct rcu_data *rdp)
cmpxchg(&rcu_state.jiffies_stall, js, jn) == js) {
/* They had a few time units to dump stack, so complain. */
- print_other_cpu_stall(gs2);
+ print_other_cpu_stall(gs2, gps);
if (rcu_cpu_stall_ftrace_dump)
rcu_ftrace_dump(DUMP_ALL);
}
--
1.8.3.1
next reply other threads:[~2020-03-05 8:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-05 7:45 Zhaolong Zhang [this message]
2020-03-05 23:05 ` [PATCH] rcu: Fix the (t=0 jiffies) false positive Paul E. McKenney
2020-03-06 5:06 ` Zhaolong Zhang
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