Re: sched domains bringup race?

[Nathan Lynch <nathanl@austin.ibm.com>]

On Mon, 2004-07-19 at 02:31, Nick Piggin wrote:
> Keshavamurthy Anil S wrote:
> > Even on my system which is Intel 865 chipset (P4 with HT enabled system) 
> > I see a bug check somewhere in the schedular_tick during boot.
> > However if I move the sched_init_smp() after do_basic_setup() the
> > kernel boots without any problem. Any clue here?
> 
> There shouldn't be any problem doing that if we have to, obviously we
> need to know why. Is it possible that cpu_sibling_map, or one of the
> CPU masks isn't set up correctly at the time of the call?

In 2.6.8-rc1-mm1 at least, backing this patch out fixed it for me on
ppc64:

http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.8-rc1/2.6.8-rc1-mm1/broken-out/detect-too-early-schedule-attempts.patch

Code with statements of the form:

if (system_state == SYSTEM_BOOTING)
	/* do something boot-specific */
else
	/* do something assuming system_state == SYSTEM_RUNNING */

is broken by this change.  Parts of the cpu bringup code in arch/ppc64
do this (and thus need to be fixed if the above change is kept). 
Chances are there is similar code in some x86 setups.

Nathan