mm: compaction: encapsulate defer reset logic

[firefly-linux-kernel-4.4.55.git] / mm / ksm.c

diff --git a/mm/ksm.c b/mm/ksm.c
index 646d45a6b6c8404ddee0cefe7bad144d6acecdcc..3df141e5f3e04a3b377971d0e69b214aafbb4b49 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1891,61 +1891,6 @@ struct page *ksm_might_need_to_copy(struct page *page,
        return new_page;
 }
 
-int page_referenced_ksm(struct page *page, struct mem_cgroup *memcg,
-                       unsigned long *vm_flags)
-{
-       struct stable_node *stable_node;
-       struct rmap_item *rmap_item;
-       unsigned int mapcount = page_mapcount(page);
-       int referenced = 0;
-       int search_new_forks = 0;
-
-       VM_BUG_ON(!PageKsm(page));
-       VM_BUG_ON(!PageLocked(page));
-
-       stable_node = page_stable_node(page);
-       if (!stable_node)
-               return 0;
-again:
-       hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) {
-               struct anon_vma *anon_vma = rmap_item->anon_vma;
-               struct anon_vma_chain *vmac;
-               struct vm_area_struct *vma;
-
-               anon_vma_lock_read(anon_vma);
-               anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root,
-                                              0, ULONG_MAX) {
-                       vma = vmac->vma;
-                       if (rmap_item->address < vma->vm_start ||
-                           rmap_item->address >= vma->vm_end)
-                               continue;
-                       /*
-                        * Initially we examine only the vma which covers this
-                        * rmap_item; but later, if there is still work to do,
-                        * we examine covering vmas in other mms: in case they
-                        * were forked from the original since ksmd passed.
-                        */
-                       if ((rmap_item->mm == vma->vm_mm) == search_new_forks)
-                               continue;
-
-                       if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
-                               continue;
-
-                       referenced += page_referenced_one(page, vma,
-                               rmap_item->address, &mapcount, vm_flags);
-                       if (!search_new_forks || !mapcount)
-                               break;
-               }
-               anon_vma_unlock_read(anon_vma);
-               if (!mapcount)
-                       goto out;
-       }
-       if (!search_new_forks++)
-               goto again;
-out:
-       return referenced;
-}
-
 int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
 {
        struct stable_node *stable_node;
@@ -1954,6 +1899,11 @@ int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
        int search_new_forks = 0;
 
        VM_BUG_ON(!PageKsm(page));
+
+       /*
+        * Rely on the page lock to protect against concurrent modifications
+        * to that page's node of the stable tree.
+        */
        VM_BUG_ON(!PageLocked(page));
 
        stable_node = page_stable_node(page);