Re: [patch 1/2] x86_64 page fault NMI-safe

H. Peter Anvin
2010-07-14T20:10:59Z

On 07/14/2010 01:07 PM, Andi Kleen wrote:
>>> In fact I'm pretty sure it worked originally. Perhaps it regressed?
>>
>> I'd first ask the obvious to Perf authors: does perf issue vmalloc_sync_all()
>> between percpu data allocation and tracing activation ? The generic ring buffer
>> library I posted last week does it already as a precaution for this very
>> specific reason (making sure NMIs never trigger page faults).
>
> I suspect the low level per cpu allocation functions should
> just call it.
>

Yes, specifically the point at which we allocate new per cpu memory blocks.

-hpa