On Mon, Mar 16, 2020 at 01:49:53PM +0100, Christoph Hellwig wrote:

On Mon, Mar 16, 2020 at 09:10:53AM -0300, Jason Gunthorpe wrote:

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On Mon, Mar 16, 2020 at 10:13:47AM +0100, Christoph Hellwig wrote:

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On Wed, Mar 11, 2020 at 03:35:06PM -0300, Jason Gunthorpe wrote:

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From: Jason Gunthorpe jgg@mellanox.com

Currently if a special PTE is encountered hmm_range_fault() immediately returns EFAULT and sets the HMM_PFN_SPECIAL error output (which nothing uses).

EFAULT should only be returned after testing with hmm_pte_need_fault().

Also pte_devmap() and pte_special() are exclusive, and there is no need to check IS_ENABLED, pte_special() is stubbed out to return false on unsupported architectures.

I think the right fix is to just kill HMM_PFN_SPECIAL and treat any fault on special ptes that aren't the zero page as an error.

I have another series that is doing that - this change is to make the next series make sense and not introduce new control logic too.

Ok. I had some cleanups like this based of older trees, but if you are active in this area I think I'll let you handle it.

You once said you wanted to loose the weird pfn flags scheme, so before putting hmm_range_fault in ODP I planned to do that.

If you have your series someplace send me a URL and I'll look on it

Thanks, Jason