Re: [PATCH] Increase default MLOCK_LIMIT to 8 MiB

David Hildenbrand
2021-11-24T13:31:22Z

On 24.11.21 14:28, Jason Gunthorpe wrote:
> On Wed, Nov 24, 2021 at 02:25:09PM +0100, David Hildenbrand wrote:
>> On 24.11.21 14:23, Jason Gunthorpe wrote:
>>> On Wed, Nov 24, 2021 at 09:57:32AM +0100, David Hildenbrand wrote:
>>>
>>>> Unfortunately it will only be a band aid AFAIU. I can rewrite my
>>>> reproducer fairly easily to pin the whole 2M range first, pin a second
>>>> time only a single page, and then unpin the 2M range, resulting in the
>>>> very same way to block THP. (I can block some THP less because I always
>>>> need the possibility to memlock 2M first, though).
>>>
>>> Oh!
>>>
>>> The issue is GUP always pins an entire compound, no matter how little
>>> the user requests.
>>
>> That's a different issue. I make sure to split the compound page before
>> pinning anything :)
>
> ?? Where is that done in GUP?

It's done in my reproducer manually.

--
Thanks,

David / dhildenb