mm: fix handling PTE-mapped THPs in page_idle_clear_pte_refs()

For PTE-mapped THP page_check_address_transhuge() is not adequate: it
cannot find all relevant PTEs, only the first one.i

Let's switch it to page_vma_mapped_walk().

I don't think it's subject for stable@: it's not fatal.

Link: http://lkml.kernel.org/r/20170129173858.45174-5-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
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 ae11aa914e5569afbd5ee67f5349b81912121d02..b0ee56c56b5850f32f5b3157f9b142788840f50f 100644 (file)
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -54,27 +54,27 @@ static int page_idle_clear_pte_refs_one(struct page *page,
                                        struct vm_area_struct *vma,
                                        unsigned long addr, void *arg)
 {
-       struct mm_struct *mm = vma->vm_mm;
-       pmd_t *pmd;
-       pte_t *pte;
-       spinlock_t *ptl;
+       struct page_vma_mapped_walk pvmw = {
+               .page = page,
+               .vma = vma,
+               .address = addr,
+       };
        bool referenced = false;
 
-       if (!page_check_address_transhuge(page, mm, addr, &pmd, &pte, &ptl))
-               return SWAP_AGAIN;
-
-       if (pte) {
-               referenced = ptep_clear_young_notify(vma, addr, pte);
-               pte_unmap(pte);
-       } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
-               referenced = pmdp_clear_young_notify(vma, addr, pmd);
-       } else {
-               /* unexpected pmd-mapped page? */
-               WARN_ON_ONCE(1);
+       while (page_vma_mapped_walk(&pvmw)) {
+               addr = pvmw.address;
+               if (pvmw.pte) {
+                       referenced = ptep_clear_young_notify(vma, addr,
+                                       pvmw.pte);
+               } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
+                       referenced = pmdp_clear_young_notify(vma, addr,
+                                       pvmw.pmd);
+               } else {
+                       /* unexpected pmd-mapped page? */
+                       WARN_ON_ONCE(1);
+               }
        }
 
-       spin_unlock(ptl);
-
        if (referenced) {
                clear_page_idle(page);
                /*