mm: prepare page_referenced() and page_idle to new THP refcounting
Both page_referenced() and page_idle_clear_pte_refs_one() assume that
THP can only be mapped with PMD, so there's no reason to look on PTEs
for PageTransHuge() pages. That's no true anymore: THP can be mapped
with PTEs too.
The patch removes PageTransHuge() test from the functions and opencode
page table check.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page_idle.c b/mm/page_idle.c
index 1c245d9..2c553ba 100644
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -56,23 +56,70 @@
{
struct mm_struct *mm = vma->vm_mm;
spinlock_t *ptl;
+ pgd_t *pgd;
+ pud_t *pud;
pmd_t *pmd;
pte_t *pte;
bool referenced = false;
- if (unlikely(PageTransHuge(page))) {
- pmd = page_check_address_pmd(page, mm, addr, &ptl);
- if (pmd) {
- referenced = pmdp_clear_young_notify(vma, addr, pmd);
+ pgd = pgd_offset(mm, addr);
+ if (!pgd_present(*pgd))
+ return SWAP_AGAIN;
+ pud = pud_offset(pgd, addr);
+ if (!pud_present(*pud))
+ return SWAP_AGAIN;
+ pmd = pmd_offset(pud, addr);
+
+ if (pmd_trans_huge(*pmd)) {
+ ptl = pmd_lock(mm, pmd);
+ if (!pmd_present(*pmd))
+ goto unlock_pmd;
+ if (unlikely(!pmd_trans_huge(*pmd))) {
spin_unlock(ptl);
+ goto map_pte;
}
+
+ if (pmd_page(*pmd) != page)
+ goto unlock_pmd;
+
+ referenced = pmdp_clear_young_notify(vma, addr, pmd);
+ spin_unlock(ptl);
+ goto found;
+unlock_pmd:
+ spin_unlock(ptl);
+ return SWAP_AGAIN;
} else {
- pte = page_check_address(page, mm, addr, &ptl, 0);
- if (pte) {
- referenced = ptep_clear_young_notify(vma, addr, pte);
- pte_unmap_unlock(pte, ptl);
- }
+ pmd_t pmde = *pmd;
+
+ barrier();
+ if (!pmd_present(pmde) || pmd_trans_huge(pmde))
+ return SWAP_AGAIN;
+
}
+map_pte:
+ pte = pte_offset_map(pmd, addr);
+ if (!pte_present(*pte)) {
+ pte_unmap(pte);
+ return SWAP_AGAIN;
+ }
+
+ ptl = pte_lockptr(mm, pmd);
+ spin_lock(ptl);
+
+ if (!pte_present(*pte)) {
+ pte_unmap_unlock(pte, ptl);
+ return SWAP_AGAIN;
+ }
+
+ /* THP can be referenced by any subpage */
+ if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) {
+ pte_unmap_unlock(pte, ptl);
+ return SWAP_AGAIN;
+ }
+
+ referenced = ptep_clear_young_notify(vma, addr, pte);
+ pte_unmap_unlock(pte, ptl);
+found:
if (referenced) {
clear_page_idle(page);
/*