mm: compaction: fix COMPACTPAGEFAILED counting

Presently update_nr_listpages() doesn't have a role.  That's because lists
passed is always empty just after calling migrate_pages.  The
migrate_pages cleans up page list which have failed to migrate before
returning by aaa994b3.

 [PATCH] page migration: handle freeing of pages in migrate_pages()

 Do not leave pages on the lists passed to migrate_pages().  Seems that we will
 not need any postprocessing of pages.  This will simplify the handling of
 pages by the callers of migrate_pages().

At that time, we thought we don't need any postprocessing of pages.  But
the situation is changed.  The compaction need to know the number of
failed to migrate for COMPACTPAGEFAILED stat

This patch makes new rule for caller of migrate_pages to call
putback_lru_pages.  So caller need to clean up the lists so it has a
chance to postprocess the pages.  [suggested by Christoph Lameter]
Signed-off-by: NMinchan Kim <minchan.kim@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andi Kleen <andi@firstfloor.org>
Reviewed-by: NMel Gorman <mel@csn.ul.ie>
Reviewed-by: NWu Fengguang <fengguang.wu@intel.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/memory-failure.c

@@ -1292,6 +1292,7 @@ static int soft_offline_huge_page(struct page *page, int flags)
 	list_add(&hpage->lru, &pagelist);
 	ret = migrate_huge_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0);
 	if (ret) {
+			putback_lru_pages(&pagelist);
 		pr_debug("soft offline: %#lx: migration failed %d, type %lx\n",
 			 pfn, ret, page->flags);
 		if (ret > 0)

mm/memory_hotplug.c

@@ -731,6 +731,8 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
 		goto out;
 	/* this function returns # of failed pages */
 	ret = migrate_pages(&source, hotremove_migrate_alloc, 0, 1);
+	if (ret)
+		putback_lru_pages(&source);
 
 out:
 	return ret;

mm/mempolicy.c

@@ -931,8 +931,11 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
 	check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
 			flags | MPOL_MF_DISCONTIG_OK, &pagelist);
 
-	if (!list_empty(&pagelist))
+	if (!list_empty(&pagelist)) {
 		err = migrate_pages(&pagelist, new_node_page, dest, 0);
+		if (err)
+			putback_lru_pages(&pagelist);
+	}
 
 	return err;
 }
@@ -1147,9 +1150,12 @@ static long do_mbind(unsigned long start, unsigned long len,
 
 		err = mbind_range(mm, start, end, new);
 
-		if (!list_empty(&pagelist))
+		if (!list_empty(&pagelist)) {
 			nr_failed = migrate_pages(&pagelist, new_vma_page,
 						(unsigned long)vma, 0);
+			if (nr_failed)
+				putback_lru_pages(&pagelist);
+		}
 
 		if (!err && nr_failed && (flags & MPOL_MF_STRICT))
 			err = -EIO;

mm/migrate.c

@@ -883,8 +883,9 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
  *
  * The function returns after 10 attempts or if no pages
  * are movable anymore because to has become empty
- * or no retryable pages exist anymore. All pages will be
- * returned to the LRU or freed.
+ * or no retryable pages exist anymore.
+ * Caller should call putback_lru_pages to return pages to the LRU
+ * or free list.
  *
  * Return: Number of pages not migrated or error code.
  */
@@ -931,8 +932,6 @@ int migrate_pages(struct list_head *from,
 	if (!swapwrite)
 		current->flags &= ~PF_SWAPWRITE;
 
-	putback_lru_pages(from);
-
 	if (rc)
 		return rc;
 
@@ -1087,9 +1086,12 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
 	}
 
 	err = 0;
-	if (!list_empty(&pagelist))
+	if (!list_empty(&pagelist)) {
 		err = migrate_pages(&pagelist, new_page_node,
 				(unsigned long)pm, 0);
+		if (err)
+			putback_lru_pages(&pagelist);
+	}
 
 	up_read(&mm->mmap_sem);
 	return err;