On Thu, Oct 29, 2009 at 08:15:03PM +0100, Soeren Sandmann wrote:
> Hi,
> 
> This program
> 
>         http://www.daimi.au.dk/~sandmann/lockup.c
> 
> locks up hard for me on a Pentium 4 in 32 bit mode, with the hrtimer
> patches applied (-tip for example).
> 
> What the program does is spawn a thread that just spins, and then 400
> threads that each create a performance counter of type
> PERF_COUNT_SW_CPU_CLOCK and a sample period of 1000000 and a
> sample_type of
> 
>         PERF_SAMPLE_IP | PERF_SAMPLE_TID | PERF_SAMPLE_CALLCHAIN
> 
> These threads then map the event buffer and read it continuously.
> 
> It does not apparently lock up if SAMPLE_CALLCHAIN is removed; also I
> cannot get it to lock up on Core 2 Duo in either 32 or 64 bit mode.
> 
> 
> Soren



It locks up hard for me too, no more blinking cursor, nothing.
I've attached my config, it's against tip:master from yesterday.

Indeed it happens only with callchains enabled.
The nmi watchdog doesn't report anything. I will retry with
early_printk=vga (I don't have any serial line in my laptop).