Boot failure on the powerstation with 2.6.30 latest

[James Bottomley]

On Mon, 2009-06-22 at 11:11 -0500, Brian King wrote:
> James,
> 
> I was running into a similar hang on one of my Power boxes as well.
> Reverting c868d550115b9ccc0027c67265b9520790f05601 allowed by system
> to boot. It looks like that patch injected a bug where we can end up
> waiting on an uninitialized mutex:
> 
> [c0000000009f3c30] c00000000052c7dc .mutex_lock+0x34/0x50
> [c0000000009f3cb0] c00000000008b190 .get_online_cpus+0x3c/0x74
> [c0000000009f3d40] c000000000146cd0 .kmem_cache_create+0xcc/0x548
> [c0000000009f3e50] c000000000032ae0 .pgtable_cache_init+0x28/0x6c
> [c0000000009f3ee0] c000000000780960 .start_kernel+0x1ec/0x520
> [c0000000009f3f90] c0000000000083d8 .start_here_common+0x1c/0x44
> 
> The mutex gets initialized in cpu_hotplug_init, which doesn't get called until
> after pgtable_cache_init.

Actually, no, reverting that one doesn't fix it.

A full run of git bisect turns up this commit as the culprit; I'll make
a fuss on lkml:

83b519e8b9572c319c8e0c615ee5dd7272856090 is first bad commit
commit 83b519e8b9572c319c8e0c615ee5dd7272856090
Author: Pekka Enberg <penberg at cs.helsinki.fi>
Date:   Wed Jun 10 19:40:04 2009 +0300

    slab: setup allocators earlier in the boot sequence

James