On 2022/6/19 2:59, Andrew Morton wrote:
> On Sat, 18 Jun 2022 17:05:27 +0800 Miaohe Lin <linmiaohe@xxxxxxxxxx> wrote:
>
>> Passing index to pte_offset_map_lock() directly so the below calculation
>> can be avoided. Rename orig_pte to ptep as it's not changed. Also use
>> helper is_swap_pte() to improve the readability. No functional change
>> intended.
>>
>> ...
>>
>> --- a/mm/madvise.c
>> +++ b/mm/madvise.c
>> @@ -195,7 +195,7 @@ static int madvise_update_vma(struct vm_area_struct *vma,
>> static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
>> unsigned long end, struct mm_walk *walk)
>> {
>> - pte_t *orig_pte;
>> + pte_t *ptep;
>> struct vm_area_struct *vma = walk->private;
>> unsigned long index;
>> struct swap_iocb *splug = NULL;
>> @@ -209,11 +209,11 @@ static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
>> struct page *page;
>> spinlock_t *ptl;
>>
>> - orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
>> - pte = *(orig_pte + ((index - start) / PAGE_SIZE));
>> - pte_unmap_unlock(orig_pte, ptl);
>> + ptep = pte_offset_map_lock(vma->vm_mm, pmd, index, &ptl);
>> + pte = *ptep;
>> + pte_unmap_unlock(ptep, ptl);
>>
>> - if (pte_present(pte) || pte_none(pte))
>> + if (!is_swap_pte(pte))
>> continue;
>> entry = pte_to_swp_entry(pte);
>> if (unlikely(non_swap_entry(entry)))
>
> Also...
>
> From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Subject: mm-madvise-minor-cleanup-for-swapin_walk_pmd_entry-fix
> Date: Sat Jun 18 11:58:03 AM PDT 2022
>
> reduce scope of `ptep'
Looks good to me. Thanks for doing this. :)
>
> Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
>
> mm/madvise.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/mm/madvise.c~mm-madvise-minor-cleanup-for-swapin_walk_pmd_entry-fix
> +++ a/mm/madvise.c
> @@ -195,7 +195,6 @@ success:
> static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
> unsigned long end, struct mm_walk *walk)
> {
> - pte_t *ptep;
> struct vm_area_struct *vma = walk->private;
> unsigned long index;
> struct swap_iocb *splug = NULL;
> @@ -208,6 +207,7 @@ static int swapin_walk_pmd_entry(pmd_t *
> swp_entry_t entry;
> struct page *page;
> spinlock_t *ptl;
> + pte_t *ptep;
>
> ptep = pte_offset_map_lock(vma->vm_mm, pmd, index, &ptl);
> pte = *ptep;
> _
>
> .
>
