3 files changed, 51 insertions, 8 deletions

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 6a456ce6de20..616aa4d05f0a 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -235,10 +235,25 @@ struct anon_vma *page_lock_anon_vma_read(struct page *page);
 void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
 
+/*
+ * rmap_walk_control: To control rmap traversing for specific needs
+ *
+ * arg: passed to rmap_one() and invalid_vma()
+ * rmap_one: executed on each vma where page is mapped
+ * done: for checking traversing termination condition
+ * file_nonlinear: for handling file nonlinear mapping
+ * anon_lock: for getting anon_lock by optimized way rather than default
+ * invalid_vma: for skipping uninterested vma
+ */
 struct rmap_walk_control {
         void *arg;
         int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
                                         unsigned long addr, void *arg);
+        int (*done)(struct page *page);
+        int (*file_nonlinear)(struct page *, struct address_space *,
+                                        struct vm_area_struct *vma);
+        struct anon_vma *(*anon_lock)(struct page *page);
+        bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
 };
 
 /*
diff --git a/mm/ksm.c b/mm/ksm.c
index c3035fee8080..91b8cb35f7cc 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2032,12 +2032,19 @@ again:
                         if ((rmap_item->mm == vma->vm_mm) == search_new_forks)
                                 continue;
 
+                        if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
+                                continue;
+
                         ret = rwc->rmap_one(page, vma,
                                         rmap_item->address, rwc->arg);
                         if (ret != SWAP_AGAIN) {
                                 anon_vma_unlock_read(anon_vma);
                                 goto out;
                         }
+                        if (rwc->done && rwc->done(page)) {
+                                anon_vma_unlock_read(anon_vma);
+                                goto out;
+                        }
                 }
                 anon_vma_unlock_read(anon_vma);
         }
diff --git a/mm/rmap.c b/mm/rmap.c
index f8f10ad5d359..97bf8f0396f8 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1684,10 +1684,14 @@ void __put_anon_vma(struct anon_vma *anon_vma)
 }
 
 #ifdef CONFIG_MIGRATION
-static struct anon_vma *rmap_walk_anon_lock(struct page *page)
+static struct anon_vma *rmap_walk_anon_lock(struct page *page,
+                                        struct rmap_walk_control *rwc)
 {
         struct anon_vma *anon_vma;
 
+        if (rwc->anon_lock)
+                return rwc->anon_lock(page);
+
         /*
          * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
          * because that depends on page_mapped(); but not all its usages
@@ -1713,16 +1717,22 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
         struct anon_vma_chain *avc;
         int ret = SWAP_AGAIN;
 
-        anon_vma = rmap_walk_anon_lock(page);
+        anon_vma = rmap_walk_anon_lock(page, rwc);
         if (!anon_vma)
                 return ret;
 
         anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
                 struct vm_area_struct *vma = avc->vma;
                 unsigned long address = vma_address(page, vma);
+
+                if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
+                        continue;
+
                 ret = rwc->rmap_one(page, vma, address, rwc->arg);
                 if (ret != SWAP_AGAIN)
                         break;
+                if (rwc->done && rwc->done(page))
+                        break;
         }
         anon_vma_unlock_read(anon_vma);
         return ret;
@@ -1740,15 +1750,26 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
         mutex_lock(&mapping->i_mmap_mutex);
         vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
                 unsigned long address = vma_address(page, vma);
+
+                if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
+                        continue;
+
                 ret = rwc->rmap_one(page, vma, address, rwc->arg);
                 if (ret != SWAP_AGAIN)
-                        break;
+                        goto done;
+                if (rwc->done && rwc->done(page))
+                        goto done;
         }
-        /*
-         * No nonlinear handling: being always shared, nonlinear vmas
-         * never contain migration ptes.  Decide what to do about this
-         * limitation to linear when we need rmap_walk() on nonlinear.
-         */
+
+        if (!rwc->file_nonlinear)
+                goto done;
+
+        if (list_empty(&mapping->i_mmap_nonlinear))
+                goto done;
+
+        ret = rwc->file_nonlinear(page, mapping, vma);
+
+done:
         mutex_unlock(&mapping->i_mmap_mutex);
         return ret;
 }