2022-05-20 19:44:15

by Schspa Shi

[permalink] [raw]
Subject: [PATCH] sched: Dump stacktrace when some task failed to stop

Some processes may not be stopped, such as workqueue workers.

Add this dump_stack to easily figure out which process caused the problems.

Before this change:

<4>[ 517.545889] ------------[ cut here ]------------
<4>[ 517.545901] Dying CPU not properly vacated!
<4>[ 517.546366] ---[ end trace 0000000000000002 ]---
<4>[ 518.546831] CPU6 enqueued tasks (2 total):
<4>[ 518.546855] pid: 49, name: migration/6
<4>[ 518.547010] pid: 6231, name: kworker/6:0

Signed-off-by: Schspa Shi <[email protected]>
---
kernel/sched/core.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 53596842f0d8..de6b5320e4d7 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9416,7 +9416,14 @@ static void dump_rq_tasks(struct rq *rq, const char *loglvl)
continue;

printk("%s\tpid: %d, name: %s\n", loglvl, p->pid, p->comm);
+ if (p != current)
+ sched_show_task(p);
}
+ /*
+ * We need the stack of each cpu to analyze who is blocking the
+ * current cpu scheduling
+ */
+ trigger_all_cpu_backtrace();
}

int sched_cpu_dying(unsigned int cpu)
--
2.24.3 (Apple Git-128)