How do you investigate the cause of total hang? Is there some information that I should pay attention to in order to get some hint?

How do you investigate the cause of total hang? Is there some information that I should pay attention to in order to get some hint?

[孙世龙 sunshilong]

Hi, list

My x86 machine(linux4.19) sometimes hangs, suddenly not responding in
any way to the mouse or the keyboard.

How can I investigate why it hung up? Is there extra information I can
find for a clue? Is there anything less drastic than power-off to get
some kind of action, if only some limited shell or just beeps,
but might give a clue?

Thank you for your attention to this matter.

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Re: How do you investigate the cause of total hang? Is there some information that I should pay attention to in order to get some hint?

[Cong Wang]

On Tue, Jun 30, 2020 at 7:49 PM 孙世龙 sunshilong <sunshilong369@gmail.com> wrote:
>
> Hi, list
>
> My x86 machine(linux4.19) sometimes hangs, suddenly not responding in
> any way to the mouse or the keyboard.
>
> How can I investigate why it hung up? Is there extra information I can
> find for a clue? Is there anything less drastic than power-off to get
> some kind of action, if only some limited shell or just beeps,
> but might give a clue?
>

If the hang was a crash which you didn't get a chance to capture the
last kernel log, you can use kdump to collect them. The kernel log
tells what kind of crash it is, a NULL pointer deref, a kernel page fault
etc..

If the hang was a hard lockup, you have to turn on lockup detector
and also kdump to capture what the detector tells.

Thanks.

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Re: How do you investigate the cause of total hang? Is there some information that I should pay attention to in order to get some hint?

[孙世龙 sunshilong]

Hi, Cong Wang

Thank you for taking the time to respond to me.
Do you think the message(i.e. "RCU detect a stall on CPU 2") indicates
there is a lockup.

Cong Wang <xiyou.wangcong@gmail.com> 于2020年7月1日周三 下午2:07写道：


>
> On Tue, Jun 30, 2020 at 7:49 PM 孙世龙 sunshilong <sunshilong369@gmail.com> wrote:
> >
> > Hi, list
> >
> > My x86 machine(linux4.19) sometimes hangs, suddenly not responding in
> > any way to the mouse or the keyboard.
> >
> > How can I investigate why it hung up? Is there extra information I can
> > find for a clue? Is there anything less drastic than power-off to get
> > some kind of action, if only some limited shell or just beeps,
> > but might give a clue?
> >
>
> If the hang was a crash which you didn't get a chance to capture the
> last kernel log, you can use kdump to collect them. The kernel log
> tells what kind of crash it is, a NULL pointer deref, a kernel page fault
> etc..
>
> If the hang was a hard lockup, you have to turn on lockup detector
> and also kdump to capture what the detector tells.
>
> Thanks.

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