RE: [外部邮件] Re: [PATCH] hung_task: Panic after fixed number of hung tasks

Li,Rongqing
2025-09-28T01:55:30Z

> > Signed-off-by: Li RongQing <lirongqing@baidu.com>
> > ---
> > Documentation/admin-guide/sysctl/kernel.rst | 6 ++++++
> > kernel/hung_task.c | 14 +++++++++++++-
> > 2 files changed, 19 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/admin-guide/sysctl/kernel.rst
> > b/Documentation/admin-guide/sysctl/kernel.rst
> > index 8b49eab..4240e7b 100644
> > --- a/Documentation/admin-guide/sysctl/kernel.rst
> > +++ b/Documentation/admin-guide/sysctl/kernel.rst
> > @@ -405,6 +405,12 @@ This file shows up if
> ``CONFIG_DETECT_HUNG_TASK`` is enabled.
> > 1 Panic immediately.
> > = =================================================
> >
> > +hung_task_count_to_panic
> > +=====================
> > +
> > +When set to a non-zero value, after the number of consecutive hung
> > +task occur, the kernel will triggers a panic
>
> Hmm... the documentation here seems a bit misleading.
>
> hung_task_panic=1 will always cause an immediate panic, regardless of the
> hung_task_count_to_panic setting, right?
>
> Perhaps something like this would be more accurate?
>
> ```
> hung_task_count_to_panic
> ========================
>
> When set to a non-zero value, a kernel panic will be triggered if the number of
> detected hung tasks reaches this value.
>
> Note that setting hung_task_panic=1 will still cause an immediate panic on the
> first hung task, overriding this setting.
> ```

I will rewrite this documentation as your suggestions

>
> >
> > hung_task_check_count
> > =====================
> > diff --git a/kernel/hung_task.c b/kernel/hung_task.c index
> > 8708a12..87a6421 100644
> > --- a/kernel/hung_task.c
> > +++ b/kernel/hung_task.c
> > @@ -83,6 +83,8 @@ static unsigned int __read_mostly
> sysctl_hung_task_all_cpu_backtrace;
> > static unsigned int __read_mostly sysctl_hung_task_panic =
> > IS_ENABLED(CONFIG_BOOTPARAM_HUNG_TASK_PANIC);
> >
> > +static unsigned int __read_mostly sysctl_hung_task_count_to_panic;
>
> Nit: while static variables are guaranteed to be zero-initialized, it's a good
> practice and clearer for readers to initialize them explicitly.
>
> static unsigned int __read_mostly sysctl_hung_task_count_to_panic = 0;
>

Ok, I will change it

Thanks

-Li

>
> Otherwise, this patch looks good to me!
> Acked-by: Lance Yang <lance.yang@linux.dev>
>
> > +
> > static int
> > hung_task_panic(struct notifier_block *this, unsigned long event, void *ptr)
> > {
> > @@ -219,7 +221,9 @@ static void check_hung_task(struct task_struct *t,
> > unsigned long timeout)
> >
> > trace_sched_process_hang(t);
> >
> > - if (sysctl_hung_task_panic) {
> > + if (sysctl_hung_task_panic ||
> > + (sysctl_hung_task_count_to_panic &&
> > + (sysctl_hung_task_detect_count >=
> > +sysctl_hung_task_count_to_panic))) {
> > console_verbose();
> > hung_task_show_lock = true;
> > hung_task_call_panic = true;
> > @@ -388,6 +392,14 @@ static const struct ctl_table hung_task_sysctls[] = {
> > .extra2 = SYSCTL_ONE,
> > },
> > {
> > + .procname = "hung_task_count_to_panic",
> > + .data = &sysctl_hung_task_count_to_panic,
> > + .maxlen = sizeof(int),
> > + .mode = 0644,
> > + .proc_handler = proc_dointvec_minmax,
> > + .extra1 = SYSCTL_ZERO,
> > + },
> > + {
> > .procname = "hung_task_check_count",
> > .data = &sysctl_hung_task_check_count,
> > .maxlen = sizeof(int),