Re: Deadlock with linux kernel

["Sam Varshavchik" <mrsam@courier-mta.com>]

Mika Liljeberg writes: 

> Hi Jeff, 
> 
> I have the exact same symptoms on my PII SMP, 440BX chipset machine, and
> I believe it started around version 2.4.6 as you say. Prior to that, my
> machine would reboot randomly without warning. The latest kernel that
> neither reboots nor locks up is 2.4.0-test9. Sometimes it takes two
> hours, sometimes it takes two days, sometimes it takes longer.

A small SMP bug did indeed slip through in 2.4.6 that nails some SMP 
hardware dead cold.  It should be fixed in the -ac tree know.  Have no idea 
about the spontaneous reboots you were seeing with the earlier kernels. 

> The machine just freezes solid, nothing appears on the console, sysrq
> won't work, leds won't blink, and I suspect the CPUs are spinning (I can
> hear the CPU fans pick up speed, when it happens).

Yup.  If you have the right combination of hardware, in 2.4.6+ you could 
sometimes end up in an infinite loop while holding a spinlock.  I was able 
to hit the jackpot with dual P-IIIs on a 440GX with two aic7xxx HBAs. 

This wouldn't explain your spontaneous reboots, but try booting with 
"noapic". 

-- 
Sam