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>

1 files changed, 7 insertions, 6 deletions

diff --git a/mm/swap_state.c b/mm/swap_state.c
index 581b609e748d..6ce0669acedc 100644
--- a/mm/swap_state.c
+++ b/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;
 }