Re: [PATCH v1 3/8] riscv: hugetlb: Convert set_huge_pte_at() to take vma

From: Alexandre Ghiti
Date: Fri Sep 22 2023 - 03:54:43 EST


Hi Ryan,

On 21/09/2023 18:20, Ryan Roberts wrote:
In order to fix a bug, arm64 needs access to the vma inside it's
implementation of set_huge_pte_at(). Provide for this by converting the
mm parameter to be a vma. Any implementations that require the mm can
access it via vma->vm_mm.

This commit makes the required riscv modifications. Separate commits
update the other arches and core code, before the actual bug is fixed in
arm64.

No behavioral changes intended.

Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
---
arch/riscv/include/asm/hugetlb.h | 2 +-
arch/riscv/mm/hugetlbpage.c | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/hugetlb.h b/arch/riscv/include/asm/hugetlb.h
index 34e24f078cc1..be1ac8582bc2 100644
--- a/arch/riscv/include/asm/hugetlb.h
+++ b/arch/riscv/include/asm/hugetlb.h
@@ -17,7 +17,7 @@ void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, unsigned long sz);
#define __HAVE_ARCH_HUGE_SET_HUGE_PTE_AT
-void set_huge_pte_at(struct mm_struct *mm,
+void set_huge_pte_at(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep, pte_t pte);
#define __HAVE_ARCH_HUGE_PTEP_GET_AND_CLEAR
diff --git a/arch/riscv/mm/hugetlbpage.c b/arch/riscv/mm/hugetlbpage.c
index 96225a8533ad..7cdbf0960772 100644
--- a/arch/riscv/mm/hugetlbpage.c
+++ b/arch/riscv/mm/hugetlbpage.c
@@ -177,11 +177,12 @@ pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags)
return entry;
}
-void set_huge_pte_at(struct mm_struct *mm,
+void set_huge_pte_at(struct vm_area_struct *vma,
unsigned long addr,
pte_t *ptep,
pte_t pte)
{
+ struct mm_struct *mm = vma->vm_mm;
int i, pte_num;
if (!pte_napot(pte)) {


You can add:

Reviewed-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>

I realize that we may have the same issue with our contig pte implementation (called napot in riscv) as we don't handle swap/migration entries at all. So I guess we need something similar, and I'll implement it (unless you want to do it of course, but I guess it's easier for me to test). One (maybe stupid) question though: wouldn't it be possible to extract the contig pte size from the value of ptep instead of using a vma?

Thanks,

Alex