mm: add page_check_address_transhuge() helper
page_referenced_one() and page_idle_clear_pte_refs_one() duplicate the
code for looking up pte of a (possibly transhuge) page. Move this code
to a new helper function, page_check_address_transhuge(), and make the
above mentioned functions use it.
This is just a cleanup, no functional changes are intended.
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/rmap.c b/mm/rmap.c
index 6127c00..cdc2a88 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -798,6 +798,96 @@
return 1;
}
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/*
+ * Check that @page is mapped at @address into @mm. In contrast to
+ * page_check_address(), this function can handle transparent huge pages.
+ *
+ * On success returns true with pte mapped and locked. For PMD-mapped
+ * transparent huge pages *@ptep is set to NULL.
+ */
+bool page_check_address_transhuge(struct page *page, struct mm_struct *mm,
+ unsigned long address, pmd_t **pmdp,
+ pte_t **ptep, spinlock_t **ptlp)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+ spinlock_t *ptl;
+
+ if (unlikely(PageHuge(page))) {
+ /* when pud is not present, pte will be NULL */
+ pte = huge_pte_offset(mm, address);
+ if (!pte)
+ return false;
+
+ ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
+ pmd = NULL;
+ goto check_pte;
+ }
+
+ pgd = pgd_offset(mm, address);
+ if (!pgd_present(*pgd))
+ return false;
+ pud = pud_offset(pgd, address);
+ if (!pud_present(*pud))
+ return false;
+ pmd = pmd_offset(pud, address);
+
+ 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;
+
+ pte = NULL;
+ goto found;
+unlock_pmd:
+ spin_unlock(ptl);
+ return false;
+ } else {
+ pmd_t pmde = *pmd;
+
+ barrier();
+ if (!pmd_present(pmde) || pmd_trans_huge(pmde))
+ return false;
+ }
+map_pte:
+ pte = pte_offset_map(pmd, address);
+ if (!pte_present(*pte)) {
+ pte_unmap(pte);
+ return false;
+ }
+
+ ptl = pte_lockptr(mm, pmd);
+check_pte:
+ spin_lock(ptl);
+
+ if (!pte_present(*pte)) {
+ pte_unmap_unlock(pte, ptl);
+ return false;
+ }
+
+ /* 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 false;
+ }
+found:
+ *ptep = pte;
+ *pmdp = pmd;
+ *ptlp = ptl;
+ return true;
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
struct page_referenced_arg {
int mapcount;
int referenced;
@@ -811,108 +901,45 @@
unsigned long address, void *arg)
{
struct mm_struct *mm = vma->vm_mm;
- spinlock_t *ptl;
- int referenced = 0;
struct page_referenced_arg *pra = arg;
- pgd_t *pgd;
- pud_t *pud;
pmd_t *pmd;
pte_t *pte;
+ spinlock_t *ptl;
+ int referenced = 0;
- if (unlikely(PageHuge(page))) {
- /* when pud is not present, pte will be NULL */
- pte = huge_pte_offset(mm, address);
- if (!pte)
- return SWAP_AGAIN;
-
- ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
- goto check_pte;
- }
-
- pgd = pgd_offset(mm, address);
- if (!pgd_present(*pgd))
+ if (!page_check_address_transhuge(page, mm, address, &pmd, &pte, &ptl))
return SWAP_AGAIN;
- pud = pud_offset(pgd, address);
- if (!pud_present(*pud))
- return SWAP_AGAIN;
- pmd = pmd_offset(pud, address);
-
- if (pmd_trans_huge(*pmd)) {
- int ret = SWAP_AGAIN;
-
- 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;
-
- if (vma->vm_flags & VM_LOCKED) {
- pra->vm_flags |= VM_LOCKED;
- ret = SWAP_FAIL; /* To break the loop */
- goto unlock_pmd;
- }
-
- if (pmdp_clear_flush_young_notify(vma, address, pmd))
- referenced++;
- spin_unlock(ptl);
- goto found;
-unlock_pmd:
- spin_unlock(ptl);
- return ret;
- } else {
- pmd_t pmde = *pmd;
-
- barrier();
- if (!pmd_present(pmde) || pmd_trans_huge(pmde))
- return SWAP_AGAIN;
- }
-map_pte:
- pte = pte_offset_map(pmd, address);
- if (!pte_present(*pte)) {
- pte_unmap(pte);
- return SWAP_AGAIN;
- }
-
- ptl = pte_lockptr(mm, pmd);
-check_pte:
- 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;
- }
if (vma->vm_flags & VM_LOCKED) {
- pte_unmap_unlock(pte, ptl);
+ if (pte)
+ pte_unmap(pte);
+ spin_unlock(ptl);
pra->vm_flags |= VM_LOCKED;
return SWAP_FAIL; /* To break the loop */
}
- if (ptep_clear_flush_young_notify(vma, address, pte)) {
- /*
- * Don't treat a reference through a sequentially read
- * mapping as such. If the page has been used in
- * another mapping, we will catch it; if this other
- * mapping is already gone, the unmap path will have
- * set PG_referenced or activated the page.
- */
- if (likely(!(vma->vm_flags & VM_SEQ_READ)))
+ if (pte) {
+ if (ptep_clear_flush_young_notify(vma, address, pte)) {
+ /*
+ * Don't treat a reference through a sequentially read
+ * mapping as such. If the page has been used in
+ * another mapping, we will catch it; if this other
+ * mapping is already gone, the unmap path will have
+ * set PG_referenced or activated the page.
+ */
+ if (likely(!(vma->vm_flags & VM_SEQ_READ)))
+ referenced++;
+ }
+ pte_unmap(pte);
+ } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
+ if (pmdp_clear_flush_young_notify(vma, address, pmd))
referenced++;
+ } else {
+ /* unexpected pmd-mapped page? */
+ WARN_ON_ONCE(1);
}
- pte_unmap_unlock(pte, ptl);
+ spin_unlock(ptl);
-found:
if (referenced)
clear_page_idle(page);
if (test_and_clear_page_young(page))