From: Kunwu Chan <kunwu.chan@linux.dev>
To: paulmck@kernel.org, frederic@kernel.org,
neeraj.upadhyay@kernel.org, joelagnelf@nvidia.com,
josh@joshtriplett.org, boqun@kernel.org, urezki@gmail.com,
rostedt@goodmis.org, mathieu.desnoyers@efficios.com,
jiangshanlai@gmail.com, qiang.zhang@linux.dev, dave@stgolabs.net
Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
Kunwu Chan <kunwu.chan@gmail.com>,
Wang Lian <lianux.mm@gmail.com>
Subject: [PATCH v2 1/3] rcu: Use task_state_to_char() in stall-warning prints
Date: Fri, 12 Jun 2026 10:34:12 +0800 [thread overview]
Message-ID: <20260612023414.679618-2-kunwu.chan@linux.dev> (raw)
In-Reply-To: <20260612023414.679618-1-kunwu.chan@linux.dev>
From: Kunwu Chan <kunwu.chan@gmail.com>
RCU stall warnings currently print task states as raw hexadecimal
values, requiring developers to manually decode them.
Use task_state_to_char() so that stall warnings show the same symbolic
task-state representation used elsewhere in the kernel.
For example:
->state=0x402 becomes ->state=I
->state=0x0 becomes ->state=R
->state=0x2 becomes ->state=D
This improves readability while preserving the underlying diagnostic
information.
Suggested-by: Zqiang <qiang.zhang@linux.dev>
Co-developed-by: Wang Lian <lianux.mm@gmail.com>
Signed-off-by: Wang Lian <lianux.mm@gmail.com>
Signed-off-by: Kunwu Chan <kunwu.chan@gmail.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 317ef91b1..7ca434b08 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -596,13 +596,13 @@ static void rcu_check_gp_kthread_starvation(void)
if (rcu_is_gp_kthread_starving(&j)) {
cpu = gpk ? task_cpu(gpk) : -1;
- pr_err("%s kthread starved for %ld jiffies! g%ld f%#x %s(%d) ->state=%#x ->cpu=%d\n",
+ pr_err("%s kthread starved for %ld jiffies! g%ld f%#x %s(%d) ->state=%c ->cpu=%d\n",
rcu_state.name, j,
(long)rcu_seq_current(&rcu_state.gp_seq),
data_race(READ_ONCE(rcu_state.gp_flags)),
gp_state_getname(rcu_state.gp_state),
data_race(READ_ONCE(rcu_state.gp_state)),
- gpk ? data_race(READ_ONCE(gpk->__state)) : ~0, cpu);
+ gpk ? task_state_to_char(gpk) : '?', cpu);
if (gpk) {
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
@@ -639,12 +639,12 @@ static void rcu_check_gp_kthread_expired_fqs_timer(void)
time_after(jiffies, jiffies_fqs + RCU_STALL_MIGHT_MIN) &&
gpk && !READ_ONCE(gpk->on_rq)) {
cpu = task_cpu(gpk);
- pr_err("%s kthread timer wakeup didn't happen for %ld jiffies! g%ld f%#x %s(%d) ->state=%#x\n",
+ pr_err("%s kthread timer wakeup didn't happen for %ld jiffies! g%ld f%#x %s(%d) ->state=%c\n",
rcu_state.name, (jiffies - jiffies_fqs),
(long)rcu_seq_current(&rcu_state.gp_seq),
data_race(READ_ONCE(rcu_state.gp_flags)), // Diagnostic read
gp_state_getname(RCU_GP_WAIT_FQS), RCU_GP_WAIT_FQS,
- data_race(READ_ONCE(gpk->__state)));
+ task_state_to_char(gpk));
pr_err("\tPossible timer handling issue on cpu=%d timer-softirq=%u\n",
cpu, kstat_softirqs_cpu(TIMER_SOFTIRQ, cpu));
}
@@ -971,10 +971,10 @@ void show_rcu_gp_kthreads(void)
jr = j - data_race(READ_ONCE(rcu_state.gp_req_activity));
js = j - data_race(READ_ONCE(rcu_state.gp_start));
jw = j - data_race(READ_ONCE(rcu_state.gp_wake_time));
- pr_info("%s: wait state: %s(%d) ->state: %#x ->rt_priority %u delta ->gp_start %lu ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_max %lu ->gp_flags %#x\n",
+ pr_info("%s: wait state: %s(%d) ->state: %c ->rt_priority %u delta ->gp_start %lu ->gp_activity %lu ->gp_req_activity %lu ->gp_wake_time %lu ->gp_wake_seq %ld ->gp_seq %ld ->gp_seq_needed %ld ->gp_max %lu ->gp_flags %#x\n",
rcu_state.name, gp_state_getname(rcu_state.gp_state),
data_race(READ_ONCE(rcu_state.gp_state)),
- t ? data_race(READ_ONCE(t->__state)) : 0x1ffff, t ? t->rt_priority : 0xffU,
+ t ? task_state_to_char(t) : '?', t ? t->rt_priority : 0xffU,
js, ja, jr, jw, (long)data_race(READ_ONCE(rcu_state.gp_wake_seq)),
(long)data_race(READ_ONCE(rcu_state.gp_seq)),
(long)data_race(READ_ONCE(rcu_get_root()->gp_seq_needed)),
--
2.43.0
next prev parent reply other threads:[~2026-06-12 2:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-12 2:34 [PATCH v2 0/3] rcu: Improve task-state reporting readability Kunwu Chan
2026-06-12 2:34 ` Kunwu Chan [this message]
2026-06-12 2:34 ` [PATCH v2 2/3] rcutorture: Use task_state_to_char() for task-state reporting Kunwu Chan
2026-06-12 2:34 ` [PATCH v2 3/3] hazptrtorture: " Kunwu Chan
2026-06-15 18:14 ` [PATCH v2 0/3] rcu: Improve task-state reporting readability Paul E. McKenney
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