Steven Price <steven.price@xxxxxxx> 於 2019年10月19日 週六 下午4:12寫道：
>
> Since 48684a65b4e3: "mm: pagewalk: fix misbehavior of walk_page_range
> for vma(VM_PFNMAP)", page_table_walk() will report any kernel area as
> a hole, because it lacks a vma.
>
> This means each arch has re-implemented page table walking when needed,
> for example in the per-arch ptdump walker.
>
> Remove the requirement to have a vma except when trying to split huge
> pages.
>
> Signed-off-by: Steven Price <steven.price@xxxxxxx>
> ---
> mm/pagewalk.c | 25 +++++++++++++++++--------
> 1 file changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
> index fc4d98a3a5a0..4139e9163aee 100644
> --- a/mm/pagewalk.c
> +++ b/mm/pagewalk.c
> @@ -38,7 +38,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
> do {
> again:
> next = pmd_addr_end(addr, end);
> - if (pmd_none(*pmd) || !walk->vma) {
> + if (pmd_none(*pmd)) {
> if (ops->pte_hole)
> err = ops->pte_hole(addr, next, walk);
> if (err)
> @@ -61,9 +61,14 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
> if (!ops->pte_entry)
> continue;
>
> - split_huge_pmd(walk->vma, pmd, addr);
> - if (pmd_trans_unstable(pmd))
> - goto again;
> + if (walk->vma) {
> + split_huge_pmd(walk->vma, pmd, addr);
> + if (pmd_trans_unstable(pmd))
> + goto again;
> + } else if (pmd_leaf(*pmd)) {
> + continue;
> + }
> +
> err = walk_pte_range(pmd, addr, next, walk);
> if (err)
> break;
> @@ -84,7 +89,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
> do {
> again:
> next = pud_addr_end(addr, end);
> - if (pud_none(*pud) || !walk->vma) {
> + if (pud_none(*pud)) {
> if (ops->pte_hole)
> err = ops->pte_hole(addr, next, walk);
> if (err)
> @@ -98,9 +103,13 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
> break;
> }
>
> - split_huge_pud(walk->vma, pud, addr);
> - if (pud_none(*pud))
> - goto again;
> + if (walk->vma) {
> + split_huge_pud(walk->vma, pud, addr);
> + if (pud_none(*pud))
> + goto again;
> + } else if (pud_leaf(*pud)) {
> + continue;
> + }
>
> if (ops->pmd_entry || ops->pte_entry)
> err = walk_pmd_range(pud, addr, next, walk);
> --
> 2.20.1
>
It's good to me.
Tested-by: Zong Li <zong.li@xxxxxxxxxx>
