Re: [RFC V2] mm: Generalize notify_page_fault()

Anshuman Khandual
2019-06-06T02:52:28Z

On 06/05/2019 04:53 PM, Matthew Wilcox wrote:
> On Wed, Jun 05, 2019 at 09:19:22PM +1000, Michael Ellerman wrote:
>> Anshuman Khandual <anshuman.khandual@arm.com> writes:
>>> Similar notify_page_fault() definitions are being used by architectures
>>> duplicating much of the same code. This attempts to unify them into a
>>> single implementation, generalize it and then move it to a common place.
>>> kprobes_built_in() can detect CONFIG_KPROBES, hence notify_page_fault()
>>> need not be wrapped again within CONFIG_KPROBES. Trap number argument can
>>> now contain upto an 'unsigned int' accommodating all possible platforms.
>> ...
>>
>> You've changed several of the architectures from something like above,
>> where it disables preemption around the call into the below:
>>
>>
>> Which skips everything if we're preemptible. Is that an equivalent
>> change? If so can you please explain why in more detail.
>
> See the discussion in v1 of this patch, which you were cc'd on.
>
> I agree the description here completely fails to mention why the change.
> It should mention commit a980c0ef9f6d8c.

I will update the commit message to include an explanation for this new
preempt behavior in the generic definition.