ideapad: pass ideapad_priv as argument (part 2)

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

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7a22b41..00bb8a6 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1925,19 +1925,18 @@ again:
 
                rcu_read_lock();
                p = rcu_dereference(mm->owner);
-               VM_BUG_ON(!p);
                /*
-                * because we don't have task_lock(), "p" can exit while
-                * we're here. In that case, "mem" can point to root
-                * cgroup but never be NULL. (and task_struct itself is freed
-                * by RCU, cgroup itself is RCU safe.) Then, we have small
-                * risk here to get wrong cgroup. But such kind of mis-account
-                * by race always happens because we don't have cgroup_mutex().
-                * It's overkill and we allow that small race, here.
+                * Because we don't have task_lock(), "p" can exit.
+                * In that case, "mem" can point to root or p can be NULL with
+                * race with swapoff. Then, we have small risk of mis-accouning.
+                * But such kind of mis-account by race always happens because
+                * we don't have cgroup_mutex(). It's overkill and we allo that
+                * small race, here.
+                * (*) swapoff at el will charge against mm-struct not against
+                * task-struct. So, mm->owner can be NULL.
                 */
                mem = mem_cgroup_from_task(p);
-               VM_BUG_ON(!mem);
-               if (mem_cgroup_is_root(mem)) {
+               if (!mem || mem_cgroup_is_root(mem)) {
                        rcu_read_unlock();
                        goto done;
                }