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SubjectRe: [bug] SLUB + mm/slab.c boot crash in -rc9
Ingo Molnar wrote:
> * Christoph Lameter <clameter@sgi.com> wrote:
>
>> On Tue, 15 Apr 2008, Ingo Molnar wrote:
>>
>>> and the bug pattern seems to be memory corruption - not memory
>>> exhaustion.
>> SLUB does not do a memory allocation where it fails here but simply
>> accesses per cpu information that is expected to be already zeroed.
>>
>>> i.e. we allocated RAM but it got corrupted after allocation.
>> In some situations we are screwing up the per cpu data handling on 32
>> bit x86? Adding Mike. This looks like the per cpu area overlaps with
>> something else?
>
> yep, that was my other theory - and i doubled CONFIG_NR_CPUS to reduce
> that chance.
>
> in hindsight ... that wont save us from any overlap, right?
>
> what's the best way to artificially increase the size of the allocated
> per cpu area? (say double it)
>
> Ingo

I don't know that there is a boot option. If modules are defined it
adds an extra 8k. The size is defined in include/linux/percpu.h
(PERCPU_ENOUGH_ROOM).

Otherwise define a really large per_cpu variable...?

-Mike


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