bci: some more code for testing

[pandora-kernel.git] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0f1f7a7..36896f3 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -250,6 +250,14 @@ static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
 
 struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
 {
+       /*
+        * mm_update_next_owner() may clear mm->owner to NULL
+        * if it races with swapoff, page migration, etc.
+        * So this can be called with p == NULL.
+        */
+       if (unlikely(!p))
+               return NULL;
+
        return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
                                struct mem_cgroup, css);
 }
@@ -549,6 +557,11 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
        if (likely(!memcg)) {
                rcu_read_lock();
                mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
+               if (unlikely(!mem)) {
+                       rcu_read_unlock();
+                       kmem_cache_free(page_cgroup_cache, pc);
+                       return 0;
+               }
                /*
                 * For every charge from the cgroup, increment reference count
                 */
@@ -801,11 +814,16 @@ int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
 
        rcu_read_lock();
        mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
+       if (unlikely(!mem)) {
+               rcu_read_unlock();
+               return 0;
+       }
        css_get(&mem->css);
        rcu_read_unlock();
 
        do {
                progress = try_to_free_mem_cgroup_pages(mem, gfp_mask);
+               progress += res_counter_check_under_limit(&mem->res);
        } while (!progress && --retry);
 
        css_put(&mem->css);