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| author | Zqiang <qiang.zhang@linux.dev> | 2026-07-16 17:57:54 +0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2026-07-24 17:00:47 -0700 |
| commit | 7a455d3caef8c1cae44b0b0ea103d1d9fb197aa6 (patch) | |
| tree | 68780087ad39fc766a05a358ec0fa1a946b3bbce /kernel/rcu | |
| parent | 5976694882f6ebccd0cf7c81a6fdf5c1e08d9d67 (diff) | |
| download | lwn-7a455d3caef8c1cae44b0b0ea103d1d9fb197aa6.tar.gz lwn-7a455d3caef8c1cae44b0b0ea103d1d9fb197aa6.zip | |
rcu-tasks: Dump rtpcp->lazy_timer status in show_rcu_tasks_generic_gp_kthread()
Add 'P' flag to the diagnostic line to indicate whether any per-cpu
rtpcp's lazy_timer is pending. this helps diagnose stalls where
rcu-task callbacks are queued but the kthread stay sleep because
the lazy_timer has not yet fired and no grace period has started.
The output is as follows:
[ 31.319540][ T77] call_rcu_tasks() has failed boot-time tests.
[ 31.320205][ T77] rcu_tasks: RTGS_WAIT_CBS(11) since 7518 g:4 i:0 kCuUP l:150000
Signed-off-by: Zqiang <qiang.zhang@linux.dev>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tasks.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index bc49698a3bcc..0306a0568f01 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -723,6 +723,7 @@ static void show_rcu_tasks_generic_gp_kthread(struct rcu_tasks *rtp, char *s) bool havecbs = false; bool haveurgent = false; bool haveurgentcbs = false; + bool havependtimer = false; for_each_possible_cpu(cpu) { struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu); @@ -733,10 +734,12 @@ static void show_rcu_tasks_generic_gp_kthread(struct rcu_tasks *rtp, char *s) haveurgent = true; if (!data_race(rcu_segcblist_empty(&rtpcp->cblist)) && data_race(rtpcp->urgent_gp)) haveurgentcbs = true; - if (havecbs && haveurgent && haveurgentcbs) + if (data_race(timer_pending(&rtpcp->lazy_timer))) + havependtimer = true; + if (havecbs && haveurgent && haveurgentcbs && havependtimer) break; } - pr_info("%s: %s(%d) since %lu g:%lu i:%lu %c%c%c%c l:%lu %s\n", + pr_info("%s: %s(%d) since %lu g:%lu i:%lu %c%c%c%c%c l:%lu %s\n", rtp->kname, tasks_gp_state_getname(rtp), data_race(rtp->gp_state), jiffies - data_race(rtp->gp_jiffies), @@ -746,6 +749,7 @@ static void show_rcu_tasks_generic_gp_kthread(struct rcu_tasks *rtp, char *s) ".C"[havecbs], ".u"[haveurgent], ".U"[haveurgentcbs], + ".P"[havependtimer], rtp->lazy_jiffies, s); } |