memory controller BUG_ON()

Move mem_controller_cache_charge() above radix_tree_preload().
radix_tree_preload() disables preemption, even though the gfp_mask passed
contains __GFP_WAIT, we cannot really do __GFP_WAIT allocations, thus we
hit a BUG_ON() in kmem_cache_alloc().

This patch moves mem_controller_cache_charge() to above radix_tree_preload()
for cache charging.
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/filemap.c

@@ -460,14 +460,12 @@ int filemap_write_and_wait_range(struct address_space *mapping,
 int add_to_page_cache(struct page *page, struct address_space *mapping,
 		pgoff_t offset, gfp_t gfp_mask)
 {
-	int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
+	int error = mem_cgroup_cache_charge(page, current->mm, gfp_mask);
+	if (error)
+		goto out;
 
+	error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
 	if (error == 0) {
-
-		error = mem_cgroup_cache_charge(page, current->mm, gfp_mask);
-		if (error)
-			goto out;
-
 		write_lock_irq(&mapping->tree_lock);
 		error = radix_tree_insert(&mapping->page_tree, offset, page);
 		if (!error) {
@@ -482,7 +480,8 @@ int add_to_page_cache(struct page *page, struct address_space *mapping,
 
 		write_unlock_irq(&mapping->tree_lock);
 		radix_tree_preload_end();
-	}
+	} else
+		mem_cgroup_uncharge_page(page);
 out:
 	return error;
 }

mm/swap_state.c

@@ -75,13 +75,13 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
 	BUG_ON(!PageLocked(page));
 	BUG_ON(PageSwapCache(page));
 	BUG_ON(PagePrivate(page));
-	error = radix_tree_preload(gfp_mask);
-	if (!error) {
 
-		error = mem_cgroup_cache_charge(page, current->mm, gfp_mask);
-		if (error)
-			goto out;
+	error = mem_cgroup_cache_charge(page, current->mm, gfp_mask);
+	if (error)
+		goto out;
 
+	error = radix_tree_preload(gfp_mask);
+	if (!error) {
 		write_lock_irq(&swapper_space.tree_lock);
 		error = radix_tree_insert(&swapper_space.page_tree,
 						entry.val, page);
@@ -97,7 +97,8 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
 		}
 		write_unlock_irq(&swapper_space.tree_lock);
 		radix_tree_preload_end();
-	}
+	} else
+		mem_cgroup_uncharge_page(page);
 out:
 	return error;
 }