Le 22/09/2023 à 10:41, Ryan Roberts a écrit :

On 22/09/2023 09:10, Christophe Leroy wrote:

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I'm happy to take your proposed approach if that's your preference. Another
option is to use a dummy VMA, as I have done in the core code, for the one call
site that calls set_huge_pte_at() with init_mm:

struct vm_area_struct vma = TLB_FLUSH_VMA(&init_mm, 0);

This is an existing macro that creates a dummy vma with vma->vm_mm filled in.
Then I pass &vma to the function.

I don't like that, I prefer the solution I proposed. We already have a
couple places where powerpc do things based on whether vma is NULL or not.

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Or yet another option would be to keep the mm param as is in set_huge_pte_at(),
and add a size param to the function. But then all call sites have the burden of
figuring out the size of the huge pte (although I think most know already).

Indeed.

arch_make_huge_pte() used to take a vma until commit 79c1c594f49a
("mm/hugetlb: change parameters of arch_make_huge_pte()").

Should we try and have the same approach ? Or is it irrelevant ?

See [1]; I'm going to rework to pass mm + size parameter since the current
approach will break riscv.

Can you pass a shift parameter instead of a size, like 
arch_make_huge_pte() ? As far as I remember it is easier to handle a 
shift than a size.

Christophe