Re: 2.6.15-mm4 failure on power5

Ingo Molnar
2006-01-17T08:17:55Z

* Andrew Morton <akpm@osdl.org> wrote:

> > If I revert just that patch, mm4 boots fine. Its really not obvious to
> > me at all why that patch is breaking things though...
>
> Yes, that is strange. I do recall that if something accidentally
> enables interrupts too early in boot, ppc64 machines tend to go
> comatose. But if we'd been running that code under
> local_irq_disable(), down() would have spat a warning.

perhaps it was just luck it worked so far, and the bug could have had
worse incarnations that the current clear hang if a certain generic
codepath is touched in a perfectly valid way. Does CONFIG_DEBUG_MUTEXES
(or any of the other debugging options) make any noise?

Ingo