Re: Huge memory takes too long time to initialize on 4TB ?

From: ethan zhao
Date: Wed May 23 2012 - 22:28:05 EST


Andrea,
The system didn't crash and died forever, just lockup on all cpus
too long time more than 21s and get to normal status.
there is race condition between stop_machine_cpu_stop() when switch to
TSC and the setup_per_zone_wmarks(void)
about irq. My guess right ?

Thanks,
Ethan


On Thu, May 24, 2012 at 7:32 AM, Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote:
> Hi,
>
> On Tue, May 22, 2012 at 08:38:04PM -0700, David Rientjes wrote:
>> On Wed, 23 May 2012, ethan zhao wrote:
>>
>> > Hi, aarcange
>> >
>> >    When I boot kernel 2.6.39-100.6.1.el6uek.x86_64(actually 3.0.26)on
>> > a 4TB memory machine, got following call trace,
>> > That shows huge memory take too long time to initialize ? any help ?,
>> > I compared the huge_memory.c code between 3.0.26 and the current
>> > 3.2.x, no change.
>> >
>>
>> This has nothing to do with mm/huge_memory.c, which is transparent
>> hugepages code, it's the lengthy iteration done for a very large
>> ZONE_NORMAL in setup_zone_migrate_reserve().
>>
>> This should be fixed by 938929f14cb5 ("mm: reduce the amount of work done
>> when updating min_free_kbytes") and was merged in 3.3.  Let us know if
>> there's still a problem after upgrading to either that or 3.4
>
> I thought that was only a performance optimization, so if the oops is
> generated by a timeout it can fix it, so good idea to try it. But a
> timeout watchdog triggering exactly in spin_unlock sounds a bit
> unlikely occurence, so I assumed too long time here meant "wait forever
> because it crashed".
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