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>

1 files changed, 19 insertions, 54 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f283cb7..ab544b1 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1649,46 +1649,6 @@ bool __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
 	return false;
 }
 
-/*
- * This function returns whether a given @page is mapped onto the @address
- * in the virtual space of @mm.
- *
- * When it's true, this function returns *pmd with holding the page table lock
- * and passing it back to the caller via @ptl.
- * If it's false, returns NULL without holding the page table lock.
- */
-pmd_t *page_check_address_pmd(struct page *page,
-			      struct mm_struct *mm,
-			      unsigned long address,
-			      spinlock_t **ptl)
-{
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd;
-
-	if (address & ~HPAGE_PMD_MASK)
-		return NULL;
-
-	pgd = pgd_offset(mm, address);
-	if (!pgd_present(*pgd))
-		return NULL;
-	pud = pud_offset(pgd, address);
-	if (!pud_present(*pud))
-		return NULL;
-	pmd = pmd_offset(pud, address);
-
-	*ptl = pmd_lock(mm, pmd);
-	if (!pmd_present(*pmd))
-		goto unlock;
-	if (pmd_page(*pmd) != page)
-		goto unlock;
-	if (pmd_trans_huge(*pmd))
-		return pmd;
-unlock:
-	spin_unlock(*ptl);
-	return NULL;
-}
-
 #define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE)
 
 int hugepage_madvise(struct vm_area_struct *vma,
@@ -3097,20 +3057,6 @@ static void unfreeze_page(struct anon_vma *anon_vma, struct page *page)
 	}
 }
 
-static int total_mapcount(struct page *page)
-{
-	int i, ret;
-
-	ret = compound_mapcount(page);
-	for (i = 0; i < HPAGE_PMD_NR; i++)
-		ret += atomic_read(&page[i]._mapcount) + 1;
-
-	if (PageDoubleMap(page))
-		ret -= HPAGE_PMD_NR;
-
-	return ret;
-}
-
 static int __split_huge_page_tail(struct page *head, int tail,
 		struct lruvec *lruvec, struct list_head *list)
 {
@@ -3211,6 +3157,25 @@ static void __split_huge_page(struct page *page, struct list_head *list)
 	}
 }
 
+int total_mapcount(struct page *page)
+{
+	int i, ret;
+
+	VM_BUG_ON_PAGE(PageTail(page), page);
+
+	if (likely(!PageCompound(page)))
+		return atomic_read(&page->_mapcount) + 1;
+
+	ret = compound_mapcount(page);
+	if (PageHuge(page))
+		return ret;
+	for (i = 0; i < HPAGE_PMD_NR; i++)
+		ret += atomic_read(&page[i]._mapcount) + 1;
+	if (PageDoubleMap(page))
+		ret -= HPAGE_PMD_NR;
+	return ret;
+}
+
 /*
  * This function splits huge page into normal pages. @page can point to any
  * subpage of huge page to split. Split doesn't change the position of @page.