Re: 2.6.15-mm4 failure on power5

[Dave C Boutcher <sleddog@us.ibm.com>]

On Tue, Jan 17, 2006 at 09:17:49AM +0100, Ingo Molnar wrote:
> 
> * 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?

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...

Please wait, loading kernel...
   Elf64 kernel loaded...
Loading ramdisk...
ramdisk loaded at 02600000, size: 1212 Kbytes
OF stdout device is: /vdevice/vty@30000000
Hypertas detected, assuming LPAR !
command line: root=/dev/sda3 selinux=0 elevator=cfq
memory layout at init:
  memory_limit : 0000000000000000 (16 MB aligned)
  alloc_bottom : 000000000272f000
  alloc_top    : 0000000008000000
  alloc_top_hi : 0000000100000000
  rmo_top      : 0000000008000000
  ram_top      : 0000000100000000
Looking for displays
found display   : /pci@800000020000002/pci@2,6/pci@1/display@0, opening
... doneinstantiating rtas at 0x0000000007734000 ... done
0000000000000000 : boot cpu     0000000000000000
0000000000000002 : starting cpu hw idx 0000000000000002... done
0000000000000004 : starting cpu hw idx 0000000000000004... done
0000000000000006 : starting cpu hw idx 0000000000000006... done
copying OF device tree ...
Building dt strings...
Building dt structure...
Device tree strings 0x0000000002a30000 -> 0x0000000002a313f5
Device tree struct  0x0000000002a32000 -> 0x0000000002a42000
Calling quiesce ...
returning from prom_init
Page orders: linear mapping = 24, others = 12
Found initrd at 0xc000000002600000:0xc00000000272f000
cpu 0x0: Vector: 300 (Data Access) at [c000000000577520]
    pc: c000000000021064: .timer_interrupt+0xf4/0x440
    lr: c000000000021020: .timer_interrupt+0xb0/0x440
    sp: c0000000005777a0
   msr: 8000000000001032
   dar: 10
 dsisr: 40000000
  current = 0xc0000000005c1150
  paca    = 0xc0000000005c1d00
    pid   = 0, comm = swapper
enter ? for help
0:mon>


-- 
Dave Boutcher
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