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Subject: Re: [PATCH v9 01/24] mm: Introduce CONFIG_SPECULATIVE_PAGE_FAULT
To:     David Rientjes <rientjes@google.com>,
        Thomas Gleixner <tglx@linutronix.de>
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From:   Laurent Dufour <ldufour@linux.vnet.ibm.com>
Date:   Wed, 28 Mar 2018 09:49:29 +0200
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Hi David,

Thanks a lot for your deep review on this series.

On 25/03/2018 23:50, David Rientjes wrote:
> On Tue, 13 Mar 2018, Laurent Dufour wrote:
> 
>> This configuration variable will be used to build the code needed to
>> handle speculative page fault.
>>
>> By default it is turned off, and activated depending on architecture
>> support.
>>
>> Suggested-by: Thomas Gleixner <tglx@linutronix.de>
>> Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
>> ---
>>  mm/Kconfig | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/mm/Kconfig b/mm/Kconfig
>> index abefa573bcd8..07c566c88faf 100644
>> --- a/mm/Kconfig
>> +++ b/mm/Kconfig
>> @@ -759,3 +759,6 @@ config GUP_BENCHMARK
>>  	  performance of get_user_pages_fast().
>>  
>>  	  See tools/testing/selftests/vm/gup_benchmark.c
>> +
>> +config SPECULATIVE_PAGE_FAULT
>> +       bool
> 
> Should this be configurable even if the arch supports it?

Actually, this is not configurable unless by manually editing the .config file.

I made it this way on the Thomas's request :
https://lkml.org/lkml/2018/1/15/969

That sounds to be the smarter way to achieve that, isn't it ?

Laurent.