[PATCH] exynos: Put a stop to the userptr heresy.

[Daniel Vetter]

On Tue, Jul 8, 2014 at 6:20 PM, Inki Dae <inki.dae at samsung.com> wrote:
> 2014-07-08 22:37 GMT+09:00 Daniel Vetter <daniel at ffwll.ch>:
>> On Wed, Jul 02, 2014 at 11:25:19AM -0400, Jerome Glisse wrote:
>>> Anyway as this is upstream i guess you can keep it. This is just an horrible
>>> API that allow to circumvant any limit set by memcg for page locking and all.
>>> But anyway GPU driver never played in the same ballpark as other driver.
>>
>> I agree that exynos userptr as-is should be removed since as opposed to
>> the i915 implementation it doesn't play nice with the core mm
>
> Can you give me more details why you think so?

>From a very quick look there's two pieces:
- The implementation with the vma tricks looks _really_ scary. You'd
need to have Al Viro's opinion on it though.
- If I'm reading the code correctly userspace can pin unlimted amounts
of memory, but I've gotten a bit lost in the code. In i915 we have
shrinkers and mmu notifier to make sure that if the vm needs this
memory again we'll make it available.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch