2.6.15-mm4 failure on power5

[Nathan Lynch]

Ingo Molnar wrote:
> 
> * Nathan Lynch <ntl at pobox.com> wrote:
> 
> > Dave C Boutcher wrote:
> > > On Tue, Jan 17, 2006 at 10:52:44AM -0600, Dave C Boutcher wrote:
> > > > Well, it turns out that I've been running with CONFIG_DEBUG_MUTEXES all
> > > > along...so no noise.  My console output is a little different that
> > > > Serge's, so I think this is timing related.  Also note that I'm dying in
> > > > the timer interrupt...
> > > 
> > > duh... here's the backtrace
> > > 0:mon> t
> > > [c000000000577890] c0000000000034b4 decrementer_common+0xb4/0x100
> > > --- Exception: 901 (Decrementer) at c0000000004627ec
> > > .__mutex_lock_interruptible_slowpath+0x3bc/0x4c4
> > > [c000000000577c60] c000000000075064 .__lock_cpu_hotplug+0x44/0xa8
> > > [c000000000577ce0] c000000000075600 .register_cpu_notifier+0x24/0x68
> > > [c000000000577d70] c00000000052cd7c .do_init_bootmem+0x68c/0xab0
> > > [c000000000577e50] c000000000522c84 .setup_arch+0x21c/0x2c0
> > > [c000000000577ef0] c00000000051a538 .start_kernel+0x40/0x280
> > > [c000000000577f90] c000000000008574 .hmt_init+0x0/0x8c
> > 
> > The mutex debug code (debug_spin_unlock in kernel/mutex-debug.h) is 
> > doing a local_irq_enable way before we're ready.
> > 
> > BTW: I couldn't build powerpc without mutex debugging until I changed 
> > the SYNC_ON_SMP in include/asm-powerpc/mutex.h:__mutex_fastpath_unlock 
> > to ISYNC_ON_SMP.
> > 
> > With that change, I was able to boot semi-successfully with mutex 
> > debugging off -- the system got hung up when udev started, apparently 
> > (or maybe I was too impatient).
> 
> ugh! Does the patch below get you a working system with DEBUG_MUTEXES=n?


Yes, this gets me to a login prompt, thanks.