Messages in this thread | | | Date | Fri, 13 Jan 2023 14:43:53 +0100 | From | Petr Mladek <> | Subject | Re: [RFC PATCH] hung_task: show sysctl_hung_task_warnings |
| |
On Thu 2023-01-12 17:17:45, Weiping Zhang wrote: > This patch try to add more debug info to detect lost kernel log or no > hung task was detected. > > The user set 10 to the hung_task_timeout_secs, the kernel log: > > [ 3942.642220] INFO: task mount:19066 blocked for more than 10 seconds. > [ 3952.876768] INFO: task kworker/u81:0:7 blocked for more than 10 seconds. > [ 3952.877088] INFO: task scsi_eh_0:506 blocked for more than 10 seconds. > [ 3952.878212] INFO: task mount:19066 blocked for more than 10 seconds. > [ 3963.116805] INFO: task kworker/u81:0:7 blocked for more than 10 seconds. > [ 3963.117137] INFO: task scsi_eh_0:506 blocked for more than 10 seconds. > [ 3963.118275] INFO: task mount:19066 blocked for more than 10 seconds. > [ 3973.356837] INFO: task kworker/u81:0:7 blocked for more than 10 seconds. > [ 3973.357148] INFO: task scsi_eh_0:506 blocked for more than 10 seconds. > [ 3973.358247] INFO: task mount:19066 blocked for more than 10 seconds. > [ 3993.836899] INFO: task kworker/u81:0:7 blocked for more than 10 seconds. > [ 3993.837238] INFO: task scsi_eh_0:506 blocked for more than 10 seconds. > [ 3993.838356] INFO: task mount:19066 blocked for more than 10 seconds. > > There is no any log at about 3983, it's hard to know if kernel log was > lost or there is no hung task was detected at that moment. So this patch > print sysctl_hung_task_warnings to distinguish the above two cases. > > Signed-off-by: Weiping Zhang <zhangweiping@didiglobal.com> > --- > kernel/hung_task.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/kernel/hung_task.c b/kernel/hung_task.c > index c71889f3f3fc..ca917931473d 100644 > --- a/kernel/hung_task.c > +++ b/kernel/hung_task.c > @@ -127,8 +127,11 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout) > * complain: > */ > if (sysctl_hung_task_warnings) { > - if (sysctl_hung_task_warnings > 0) > + if (sysctl_hung_task_warnings > 0) { > sysctl_hung_task_warnings--; > + pr_err("sysctl_hung_task_warnings: %d\n", > + sysctl_hung_task_warnings); > + }
It is too much noise. But it might make sense to report it when the counter gets down to zero. Something like:
if (sysctl_hung_task_warnings) pr_info("Future hung task reports are suppressed, see sysctl kernel.hung_task_warnings\n");
and move this down after printing all the details for this hung task report.
> pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n", > t->comm, t->pid, (jiffies - t->last_switch_time) / HZ); > pr_err(" %s %s %.*s\n",
Best Regards, Petr
| |