Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault

Avi Kivity
2010-07-16T17:54:59Z

On 07/16/2010 07:58 PM, Mathieu Desnoyers wrote:
>
>> Why is that kernel code calling vmalloc_sync_all()? If it is only NMI
>> which cannot take vmalloc faults, why bother? If not, why not?
>>
> Modules come as yet another example of stuff that is loaded in vmalloc'd space
> and can be accesses from NMI context. That would include oprofile, tracers, and
> probably others I'm forgetting about.
>

Module loading can certainly take a vmalloc_sync_all() (though I agree
it's unpleasant). Anything else?

Note perf is not modular at this time, but could be made so with
preempt/sched notifiers to hook the context switch.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.