Re: kdump hangs up by Sysrq+C trigger in high load.

[Yoshihiro Takahashi]

Ingo. Thank you, your reply.

I will serch it again.

On Tue, 16 Dec 2008 12:09:49 +0100
Ingo Molnar <mingo@xxxxxxx> wrote:

> 
> * Yoshihiro Takahashi <ytakahashi@xxxxxxxxxxxxxxxx> wrote:
> 
> > Hi.
> > 
> > kdump hangs up by Sysrq+C trigger once in about 10 times in high load. 
> > After the above occurs, kdump cannot collect vmcores with NMI button. 
> > When waiting_for_crash_ipi does case more than 0, mdelay seem to make a 
> > stall.
> > 
> > While nmi_shootdown_cpus(), mdelay may not work since interruption is 
> > disable.  (ex. when crashing kernel by NMI interruption, all 
> > interruption may be disabled.).
> > 
> > So I think that it should use other way (TSC) instead of mdelay() in 
> > nmi_shootdown_cpus().
> 
> mdelay uses either the tsc or CPU loops - neither stop while IRQs are 
> disabled.
> 
> Could you figure out exactly why it hangs in your case?
> 
> 	Ingo
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