mm/madvise: minor cleanup for swapin_walk_pmd_entry()

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.

[akpm@linux-foundation.org: reduce scope of `ptep']
Link: https://lkml.kernel.org/r/20220618090527.37843-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/madvise.c b/mm/madvise.c
index 0316bbc..e55108d 100644 (file)
--- a/mm/madvise.c
+++ b/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 *orig_pte;
        struct vm_area_struct *vma = walk->private;
        unsigned long index;
        struct swap_iocb *splug = NULL;
@@ -208,12 +207,13 @@ static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
                swp_entry_t entry;
                struct page *page;
                spinlock_t *ptl;
+               pte_t *ptep;
 
-               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)))