Re: kvm_intel: Could not allocate 42 bytes percpu data

From: Rusty Russell
Date: Tue Jul 02 2013 - 08:23:40 EST


Chegu Vinod <chegu_vinod@xxxxxx> writes:
> On 6/30/2013 11:22 PM, Rusty Russell wrote:
>> Chegu Vinod <chegu_vinod@xxxxxx> writes:
>>> Hello,
>>>
>>> Lots (~700+) of the following messages are showing up in the dmesg of a
>>> 3.10-rc1 based kernel (Host OS is running on a large socket count box
>>> with HT-on).
>>>
>>> [ 82.270682] PERCPU: allocation failed, size=42 align=16, alloc from
>>> reserved chunk failed
>>> [ 82.272633] kvm_intel: Could not allocate 42 bytes percpu data
>> Woah, weird....
>>
>> Oh. Shit. Um, this is embarrassing.
>>
>> Thanks,
>> Rusty.
>
>
> Thanks for your response!
>
>> ===
>> module: do percpu allocation after uniqueness check. No, really!
>>
>> v3.8-rc1-5-g1fb9341 was supposed to stop parallel kvm loads exhausting
>> percpu memory on large machines:
>>
>> Now we have a new state MODULE_STATE_UNFORMED, we can insert the
>> module into the list (and thus guarantee its uniqueness) before we
>> allocate the per-cpu region.
>>
>> In my defence, it didn't actually say the patch did this. Just that
>> we "can".
>>
>> This patch actually *does* it.
>>
>> Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
>> Tested-by: Noone it seems.
>
> Your following "updated" fix seems to be working fine on the larger
> socket count machine with HT-on.

OK, did you definitely revert every other workaround?

If so, please give me a Tested-by: line...

Thanks,
Rusty.
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