mm: convert remove_migration_pte() to use page_vma_mapped_walk()

remove_migration_pte() also can easily be converted to
page_vma_mapped_walk().

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170129173858.45174-13-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.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>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/migrate.c b/mm/migrate.c
index 6807174e0715fc9a5dffc3cb80307d23cb47db30..2c63ac06791bbdf0e382e669812fcca67bf3cc55 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -193,82 +193,62 @@ void putback_movable_pages(struct list_head *l)
 /*
  * Restore a potential migration pte to a working pte entry
  */
-static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
+static int remove_migration_pte(struct page *page, struct vm_area_struct *vma,
                                 unsigned long addr, void *old)
 {
-       struct mm_struct *mm = vma->vm_mm;
+       struct page_vma_mapped_walk pvmw = {
+               .page = old,
+               .vma = vma,
+               .address = addr,
+               .flags = PVMW_SYNC | PVMW_MIGRATION,
+       };
+       struct page *new;
+       pte_t pte;
        swp_entry_t entry;
-       pmd_t *pmd;
-       pte_t *ptep, pte;
-       spinlock_t *ptl;
 
-       if (unlikely(PageHuge(new))) {
-               ptep = huge_pte_offset(mm, addr);
-               if (!ptep)
-                       goto out;
-               ptl = huge_pte_lockptr(hstate_vma(vma), mm, ptep);
-       } else {
-               pmd = mm_find_pmd(mm, addr);
-               if (!pmd)
-                       goto out;
+       VM_BUG_ON_PAGE(PageTail(page), page);
+       while (page_vma_mapped_walk(&pvmw)) {
+               new = page - pvmw.page->index +
+                       linear_page_index(vma, pvmw.address);
 
-               ptep = pte_offset_map(pmd, addr);
+               get_page(new);
+               pte = pte_mkold(mk_pte(new, READ_ONCE(vma->vm_page_prot)));
+               if (pte_swp_soft_dirty(*pvmw.pte))
+                       pte = pte_mksoft_dirty(pte);
 
                /*
-                * Peek to check is_swap_pte() before taking ptlock?  No, we
-                * can race mremap's move_ptes(), which skips anon_vma lock.
+                * Recheck VMA as permissions can change since migration started
                 */
-
-               ptl = pte_lockptr(mm, pmd);
-       }
-
-       spin_lock(ptl);
-       pte = *ptep;
-       if (!is_swap_pte(pte))
-               goto unlock;
-
-       entry = pte_to_swp_entry(pte);
-
-       if (!is_migration_entry(entry) ||
-           migration_entry_to_page(entry) != old)
-               goto unlock;
-
-       get_page(new);
-       pte = pte_mkold(mk_pte(new, READ_ONCE(vma->vm_page_prot)));
-       if (pte_swp_soft_dirty(*ptep))
-               pte = pte_mksoft_dirty(pte);
-
-       /* Recheck VMA as permissions can change since migration started  */
-       if (is_write_migration_entry(entry))
-               pte = maybe_mkwrite(pte, vma);
+               entry = pte_to_swp_entry(*pvmw.pte);
+               if (is_write_migration_entry(entry))
+                       pte = maybe_mkwrite(pte, vma);
 
 #ifdef CONFIG_HUGETLB_PAGE
-       if (PageHuge(new)) {
-               pte = pte_mkhuge(pte);
-               pte = arch_make_huge_pte(pte, vma, new, 0);
-       }
+               if (PageHuge(new)) {
+                       pte = pte_mkhuge(pte);
+                       pte = arch_make_huge_pte(pte, vma, new, 0);
+               }
 #endif
-       flush_dcache_page(new);
-       set_pte_at(mm, addr, ptep, pte);
+               flush_dcache_page(new);
+               set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
 
-       if (PageHuge(new)) {
-               if (PageAnon(new))
-                       hugepage_add_anon_rmap(new, vma, addr);
+               if (PageHuge(new)) {
+                       if (PageAnon(new))
+                               hugepage_add_anon_rmap(new, vma, pvmw.address);
+                       else
+                               page_dup_rmap(new, true);
+               } else if (PageAnon(new))
+                       page_add_anon_rmap(new, vma, pvmw.address, false);
                else
-                       page_dup_rmap(new, true);
-       } else if (PageAnon(new))
-               page_add_anon_rmap(new, vma, addr, false);
-       else
-               page_add_file_rmap(new, false);
+                       page_add_file_rmap(new, false);
 
-       if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new))
-               mlock_vma_page(new);
+               if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new))
+                       mlock_vma_page(new);
+
+               /* No need to invalidate - it was non-present before */
+               update_mmu_cache(vma, pvmw.address, pvmw.pte);
+       }
 
-       /* No need to invalidate - it was non-present before */
-       update_mmu_cache(vma, addr, ptep);
-unlock:
-       pte_unmap_unlock(ptep, ptl);
-out:
        return SWAP_AGAIN;
 }