Memory controller remove control_type feature

Based on the discussion at http://lkml.org/lkml/2007/12/20/383, it was felt
that control_type might not be a good thing to implement right away.  We
can add this flexibility at a later point when required.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 18 insertions, 79 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d87090eb14c0..9815951ec995 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -38,6 +38,7 @@ extern struct page_cgroup *page_get_page_cgroup(struct page *page);
 extern int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
                                 gfp_t gfp_mask);
 extern void mem_cgroup_uncharge(struct page_cgroup *pc);
+extern void mem_cgroup_uncharge_page(struct page *page);
 extern void mem_cgroup_move_lists(struct page_cgroup *pc, bool active);
 extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
                                         struct list_head *dst,
@@ -55,11 +56,6 @@ static inline struct mem_cgroup *mm_cgroup(const struct mm_struct *mm)
         return rcu_dereference(mm->mem_cgroup);
 }
 
-static inline void mem_cgroup_uncharge_page(struct page *page)
-{
-        mem_cgroup_uncharge(page_get_page_cgroup(page));
-}
-
 extern int mem_cgroup_prepare_migration(struct page *page);
 extern void mem_cgroup_end_migration(struct page *page);
 extern void mem_cgroup_page_migration(struct page *page, struct page *newpage);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 315dee180129..5c2c702af617 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -131,7 +131,6 @@ struct mem_cgroup {
          */
         struct mem_cgroup_lru_info info;
 
-        unsigned long control_type;     /* control RSS or RSS+Pagecache */
         int     prev_priority;  /* for recording reclaim priority */
         /*
          * statistics.
@@ -709,24 +708,17 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
                                 gfp_t gfp_mask)
 {
         int ret = 0;
-        struct mem_cgroup *mem;
         if (!mm)
                 mm = &init_mm;
 
-        rcu_read_lock();
-        mem = rcu_dereference(mm->mem_cgroup);
-        css_get(&mem->css);
-        rcu_read_unlock();
-        if (mem->control_type == MEM_CGROUP_TYPE_ALL)
-                ret = mem_cgroup_charge_common(page, mm, gfp_mask,
+        ret = mem_cgroup_charge_common(page, mm, gfp_mask,
                                 MEM_CGROUP_CHARGE_TYPE_CACHE);
-        css_put(&mem->css);
         return ret;
 }
 
 /*
  * Uncharging is always a welcome operation, we never complain, simply
- * uncharge.
+ * uncharge. This routine should be called with lock_page_cgroup held
  */
 void mem_cgroup_uncharge(struct page_cgroup *pc)
 {
@@ -736,8 +728,7 @@ void mem_cgroup_uncharge(struct page_cgroup *pc)
         unsigned long flags;
 
         /*
-         * This can handle cases when a page is not charged at all and we
-         * are switching between handling the control_type.
+         * Check if our page_cgroup is valid
          */
         if (!pc)
                 return;
@@ -749,6 +740,7 @@ void mem_cgroup_uncharge(struct page_cgroup *pc)
                  * get page->cgroup and clear it under lock.
                  * force_empty can drop page->cgroup without checking refcnt.
                  */
+                unlock_page_cgroup(page);
                 if (clear_page_cgroup(page, pc) == pc) {
                         mem = pc->mem_cgroup;
                         css_put(&mem->css);
@@ -758,9 +750,17 @@ void mem_cgroup_uncharge(struct page_cgroup *pc)
                         spin_unlock_irqrestore(&mz->lru_lock, flags);
                         kfree(pc);
                 }
+                lock_page_cgroup(page);
         }
 }
 
+void mem_cgroup_uncharge_page(struct page *page)
+{
+        lock_page_cgroup(page);
+        mem_cgroup_uncharge(page_get_page_cgroup(page));
+        unlock_page_cgroup(page);
+}
+
 /*
  * Returns non-zero if a page (under migration) has valid page_cgroup member.
  * Refcnt of page_cgroup is incremented.
@@ -780,8 +780,12 @@ int mem_cgroup_prepare_migration(struct page *page)
 
 void mem_cgroup_end_migration(struct page *page)
 {
-        struct page_cgroup *pc = page_get_page_cgroup(page);
+        struct page_cgroup *pc;
+
+        lock_page_cgroup(page);
+        pc = page_get_page_cgroup(page);
         mem_cgroup_uncharge(pc);
+        unlock_page_cgroup(page);
 }
 /*
  * We know both *page* and *newpage* are now not-on-LRU and Pg_locked.
@@ -936,61 +940,6 @@ static ssize_t mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
                                 mem_cgroup_write_strategy);
 }
 
-static ssize_t mem_control_type_write(struct cgroup *cont,
-                        struct cftype *cft, struct file *file,
-                        const char __user *userbuf,
-                        size_t nbytes, loff_t *pos)
-{
-        int ret;
-        char *buf, *end;
-        unsigned long tmp;
-        struct mem_cgroup *mem;
-
-        mem = mem_cgroup_from_cont(cont);
-        buf = kmalloc(nbytes + 1, GFP_KERNEL);
-        ret = -ENOMEM;
-        if (buf == NULL)
-                goto out;
-
-        buf[nbytes] = 0;
-        ret = -EFAULT;
-        if (copy_from_user(buf, userbuf, nbytes))
-                goto out_free;
-
-        ret = -EINVAL;
-        tmp = simple_strtoul(buf, &end, 10);
-        if (*end != '\0')
-                goto out_free;
-
-        if (tmp <= MEM_CGROUP_TYPE_UNSPEC || tmp >= MEM_CGROUP_TYPE_MAX)
-                goto out_free;
-
-        mem->control_type = tmp;
-        ret = nbytes;
-out_free:
-        kfree(buf);
-out:
-        return ret;
-}
-
-static ssize_t mem_control_type_read(struct cgroup *cont,
-                                struct cftype *cft,
-                                struct file *file, char __user *userbuf,
-                                size_t nbytes, loff_t *ppos)
-{
-        unsigned long val;
-        char buf[64], *s;
-        struct mem_cgroup *mem;
-
-        mem = mem_cgroup_from_cont(cont);
-        s = buf;
-        val = mem->control_type;
-        s += sprintf(s, "%lu\n", val);
-        return simple_read_from_buffer((void __user *)userbuf, nbytes,
-                        ppos, buf, s - buf);
-}
-
-
 static ssize_t mem_force_empty_write(struct cgroup *cont,
                                 struct cftype *cft, struct file *file,
                                 const char __user *userbuf,
@@ -1089,11 +1038,6 @@ static struct cftype mem_cgroup_files[] = {
                 .read = mem_cgroup_read,
         },
         {
-                .name = "control_type",
-                .write = mem_control_type_write,
-                .read = mem_control_type_read,
-        },
-        {
                 .name = "force_empty",
                 .write = mem_force_empty_write,
                 .read = mem_force_empty_read,
@@ -1161,7 +1105,6 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
 
         res_counter_init(&mem->res);
 
-        mem->control_type = MEM_CGROUP_TYPE_ALL;
         memset(&mem->info, 0, sizeof(mem->info));
 
         for_each_node_state(node, N_POSSIBLE)