[-rc7 regression] Buggy commit: "mm: use aligned zone start forpfn_to_bitidx calculation"

From: Ingo Molnar
Date: Fri Feb 15 2013 - 06:44:42 EST

[ Greg: -stable was Cc:-ed for this potentially buggy commit. ]

* Yinghai Lu <yinghai@xxxxxxxxxx> wrote:

> On Thu, Feb 14, 2013 at 7:08 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> > these three:
> >
> > 10d73e655cef mm: bootmem: fix free_all_bootmem_core() with odd bitmap alignment
> > c060f943d092 mm: use aligned zone start for pfn_to_bitidx calculation
> > c0232ae861df mm: memblock: fix wrong memmove size in memblock_merge_regions()
> >
> > might have highmem=512m boot parameter sensitivity.
> 10d73e655cef should not be related, as we are using nobootmem wrapper
> of memblock.
> c0232ae861df is copying less while using the blank slot in memblock
> memory or reserved array
> so it should be ok too.
> c060f943d092 may be related as you config does not have

Right, that's the commit causing the x86 regression:

c060f943d0929f3e429c5d9522290584f6281d6e is the first bad commit
commit c060f943d0929f3e429c5d9522290584f6281d6e
Date: Fri Jan 11 14:31:51 2013 -0800

mm: use aligned zone start for pfn_to_bitidx calculation

I've given 6d92d4f (its parent commit) quite a bit of testing so
I'm 99% sure in the validity of this bisection result.

Involved parties Cc:-ed.

Revert attached below - it reverts cleanly and I'll test this
today, to see whether this solves the sporadic lockups.