2.6.15-mm4 failure on power5

[Ingo Molnar]

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

> > Yes, which would be why this code never triggered a warning when
> > cpucontrol was a semaphore.
> 
> Yup.  Perhaps a sane fix which preserves the unpleasant semantics is 
> to do irqsave in the mutex debug code.

i'd much rather remove that ugly hack from __might_sleep(). How many 
other bugs does it hide? Does it hide bugs that dont normally trigger 
during bootups on real hardware, but which could trigger on e.g. UML or 
on Xen? I really think such ugly workarounds are not justified, if other 
arches can get their act together. Would you make such an exception for 
other arches too, like ARM?

an irqsave in the mutex debug code will uglify the kernel/mutex.c code - 
i'd have to add extra "unsigned long flags" lines. [It will also slow 
down the debug code a bit - an extra PUSHF has to be done.]

	Ingo