Re: sched domains bringup race?

From: Nick Piggin
Date: Thu Jul 22 2004 - 19:39:09 EST


Nathan Lynch wrote:

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.



That patch can be dropped AFAIKS.

sched-clean-init-idle.patch introduces a better check.


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