Re: [PATCH v2 1/3] hugetlb: Convert hugetlb_fault() to use struct vm_fault

Oscar Salvador
2024-04-04T12:26:22Z

On Mon, Apr 01, 2024 at 01:26:49PM -0700, Vishal Moola (Oracle) wrote:
> Now that hugetlb_fault() has a vm_fault available for fault tracking, use
> it throughout. This cleans up the code by removing 2 variables, and
> prepares hugetlb_fault() to take in a struct vm_fault argument.
>
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>

Reviewed-by: Oscar Salvador <osalvador@suse.de>

A question below:

> mm/hugetlb.c | 84 +++++++++++++++++++++++++---------------------------
> 1 file changed, 41 insertions(+), 43 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 8267e221ca5d..360b82374a89 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
...
> /*
> - * entry could be a migration/hwpoison entry at this point, so this
> - * check prevents the kernel from going below assuming that we have
> - * an active hugepage in pagecache. This goto expects the 2nd page
> - * fault, and is_hugetlb_entry_(migration|hwpoisoned) check will
> - * properly handle it.
> + * vmf.orig_pte could be a migration/hwpoison vmf.orig_pte at this

"vmf.orig_pte could be a migration/hwpoison entry at ..."

> - entry = pte_mkyoung(entry);
> - if (huge_ptep_set_access_flags(vma, haddr, ptep, entry,
> + vmf.orig_pte = pte_mkyoung(vmf.orig_pte);
> + if (huge_ptep_set_access_flags(vma, vmf.address, vmf.pte, vmf.orig_pte,
> flags & FAULT_FLAG_WRITE))

Would it make sense to teach huge_ptep_set_access_flags/set_huge_pte_at() to use
vm_fault struct as well? All info we are passing is stored there.
Maybe it is not worth the trouble though, just asking.

--
Oscar Salvador
SUSE Labs