Messages in this thread | | | Subject | Re: [PATCH v5 05/15] mm/frame-vector: Use FOLL_LONGTERM | From | John Hubbard <> | Date | Thu, 5 Nov 2020 20:08:10 -0800 |
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On 11/5/20 4:49 AM, Jason Gunthorpe wrote: > On Thu, Nov 05, 2020 at 10:25:24AM +0100, Daniel Vetter wrote: >>> /* >>> * If we can't determine whether or not a pte is special, then fail immediately >>> * for ptes. Note, we can still pin HugeTLB and THP as these are guaranteed not >>> * to be special. >>> * >>> * For a futex to be placed on a THP tail page, get_futex_key requires a >>> * get_user_pages_fast_only implementation that can pin pages. Thus it's still >>> * useful to have gup_huge_pmd even if we can't operate on ptes. >>> */ >> >> We support hugepage faults in gpu drivers since recently, and I'm not >> seeing a pud_mkhugespecial anywhere. So not sure this works, but probably >> just me missing something again. > > It means ioremap can't create an IO page PUD, it has to be broken up. > > Does ioremap even create anything larger than PTEs? >
From my reading, yes. See ioremap_try_huge_pmd().
thanks, -- John Hubbard NVIDIA
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