slub: Potential stack overflow
[linux-2.6.git] / mm / page_cgroup.c
index 3d535d5..6c00814 100644 (file)
@@ -284,6 +284,7 @@ static DEFINE_MUTEX(swap_cgroup_mutex);
 struct swap_cgroup_ctrl {
        struct page **map;
        unsigned long length;
+       spinlock_t      lock;
 };
 
 struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];
@@ -335,6 +336,43 @@ not_enough_page:
 }
 
 /**
+ * swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry.
+ * @end: swap entry to be cmpxchged
+ * @old: old id
+ * @new: new id
+ *
+ * Returns old id at success, 0 at failure.
+ * (There is no mem_cgroup useing 0 as its id)
+ */
+unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
+                                       unsigned short old, unsigned short new)
+{
+       int type = swp_type(ent);
+       unsigned long offset = swp_offset(ent);
+       unsigned long idx = offset / SC_PER_PAGE;
+       unsigned long pos = offset & SC_POS_MASK;
+       struct swap_cgroup_ctrl *ctrl;
+       struct page *mappage;
+       struct swap_cgroup *sc;
+       unsigned long flags;
+       unsigned short retval;
+
+       ctrl = &swap_cgroup_ctrl[type];
+
+       mappage = ctrl->map[idx];
+       sc = page_address(mappage);
+       sc += pos;
+       spin_lock_irqsave(&ctrl->lock, flags);
+       retval = sc->id;
+       if (retval == old)
+               sc->id = new;
+       else
+               retval = 0;
+       spin_unlock_irqrestore(&ctrl->lock, flags);
+       return retval;
+}
+
+/**
  * swap_cgroup_record - record mem_cgroup for this swp_entry.
  * @ent: swap entry to be recorded into
  * @mem: mem_cgroup to be recorded
@@ -352,14 +390,17 @@ unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id)
        struct page *mappage;
        struct swap_cgroup *sc;
        unsigned short old;
+       unsigned long flags;
 
        ctrl = &swap_cgroup_ctrl[type];
 
        mappage = ctrl->map[idx];
        sc = page_address(mappage);
        sc += pos;
+       spin_lock_irqsave(&ctrl->lock, flags);
        old = sc->id;
        sc->id = id;
+       spin_unlock_irqrestore(&ctrl->lock, flags);
 
        return old;
 }
@@ -411,6 +452,7 @@ int swap_cgroup_swapon(int type, unsigned long max_pages)
        mutex_lock(&swap_cgroup_mutex);
        ctrl->length = length;
        ctrl->map = array;
+       spin_lock_init(&ctrl->lock);
        if (swap_cgroup_prepare(type)) {
                /* memory shortage */
                ctrl->map = NULL;