4 files changed, 86 insertions, 11 deletions

diff --git a/Documentation/controllers/memory.txt b/Documentation/controllers/memory.txt
index d71745cc2f00..e1501964df1e 100644
--- a/Documentation/controllers/memory.txt
+++ b/Documentation/controllers/memory.txt
@@ -314,6 +314,15 @@ will be charged as a new owner of it.
         showing for better debug please see the code for meanings.
 
 
+5.3 swappiness
+  Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.
+
+  Following cgroup's swapiness can't be changed.
+  - root cgroup (uses /proc/sys/vm/swappiness).
+  - a cgroup which uses hierarchy and it has child cgroup.
+  - a cgroup which uses hierarchy and not the root of hierarchy.
+
+
 6. Hierarchy support
 
 The memory controller supports a deep hierarchy and hierarchical accounting.
diff --git a/include/linux/swap.h b/include/linux/swap.h
index be938ce4895a..4ccca25d0f05 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -214,7 +214,8 @@ static inline void lru_cache_add_active_file(struct page *page)
 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
                                         gfp_t gfp_mask);
 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
-                                                gfp_t gfp_mask, bool noswap);
+                                                  gfp_t gfp_mask, bool noswap,
+                                                  unsigned int swappiness);
 extern int __isolate_lru_page(struct page *page, int mode, int file);
 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 extern int vm_swappiness;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 027c0dd7a83e..ab2ecbb95b8d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -164,6 +164,9 @@ struct mem_cgroup {
         int             obsolete;
         atomic_t        refcnt;
 
+        unsigned int    swappiness;
+
+
         unsigned int inactive_ratio;
 
         /*
@@ -636,6 +639,22 @@ static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
         return false;
 }
 
+static unsigned int get_swappiness(struct mem_cgroup *memcg)
+{
+        struct cgroup *cgrp = memcg->css.cgroup;
+        unsigned int swappiness;
+
+        /* root ? */
+        if (cgrp->parent == NULL)
+                return vm_swappiness;
+
+        spin_lock(&memcg->reclaim_param_lock);
+        swappiness = memcg->swappiness;
+        spin_unlock(&memcg->reclaim_param_lock);
+
+        return swappiness;
+}
+
 /*
  * Dance down the hierarchy if needed to reclaim memory. We remember the
  * last child we reclaimed from, so that we don't end up penalizing
@@ -656,7 +675,8 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
          * but there might be left over accounting, even after children
          * have left.
          */
-        ret = try_to_free_mem_cgroup_pages(root_mem, gfp_mask, noswap);
+        ret = try_to_free_mem_cgroup_pages(root_mem, gfp_mask, noswap,
+                                           get_swappiness(root_mem));
         if (mem_cgroup_check_under_limit(root_mem))
                 return 0;
         if (!root_mem->use_hierarchy)
@@ -672,7 +692,8 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
                         cgroup_unlock();
                         continue;
                 }
-                ret = try_to_free_mem_cgroup_pages(next_mem, gfp_mask, noswap);
+                ret = try_to_free_mem_cgroup_pages(next_mem, gfp_mask, noswap,
+                                                   get_swappiness(next_mem));
                 if (mem_cgroup_check_under_limit(root_mem))
                         return 0;
                 cgroup_lock();
@@ -1400,7 +1421,8 @@ int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
         rcu_read_unlock();
 
         do {
-                progress = try_to_free_mem_cgroup_pages(mem, gfp_mask, true);
+                progress = try_to_free_mem_cgroup_pages(mem, gfp_mask, true,
+                                                        get_swappiness(mem));
                 progress += mem_cgroup_check_under_limit(mem);
         } while (!progress && --retry);
 
@@ -1468,7 +1490,9 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
                         break;
 
                 progress = try_to_free_mem_cgroup_pages(memcg,
-                                GFP_KERNEL, false);
+                                                        GFP_KERNEL,
+                                                        false,
+                                                        get_swappiness(memcg));
                 if (!progress)                  retry_count--;
         }
 
@@ -1512,7 +1536,8 @@ int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
                         break;
 
                 oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
-                try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL, true);
+                try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL, true,
+                                             get_swappiness(memcg));
                 curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
                 if (curusage >= oldusage)
                         retry_count--;
@@ -1643,8 +1668,8 @@ try_to_free:
                         ret = -EINTR;
                         goto out;
                 }
-                progress = try_to_free_mem_cgroup_pages(mem,
-                                                  GFP_KERNEL, false);
+                progress = try_to_free_mem_cgroup_pages(mem, GFP_KERNEL,
+                                                false, get_swappiness(mem));
                 if (!progress) {
                         nr_retries--;
                         /* maybe some writeback is necessary */
@@ -1864,6 +1889,37 @@ static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
         return 0;
 }
 
+static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
+{
+        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+
+        return get_swappiness(memcg);
+}
+
+static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
+                                       u64 val)
+{
+        struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+        struct mem_cgroup *parent;
+        if (val > 100)
+                return -EINVAL;
+
+        if (cgrp->parent == NULL)
+                return -EINVAL;
+
+        parent = mem_cgroup_from_cont(cgrp->parent);
+        /* If under hierarchy, only empty-root can set this value */
+        if ((parent->use_hierarchy) ||
+            (memcg->use_hierarchy && !list_empty(&cgrp->children)))
+                return -EINVAL;
+
+        spin_lock(&memcg->reclaim_param_lock);
+        memcg->swappiness = val;
+        spin_unlock(&memcg->reclaim_param_lock);
+
+        return 0;
+}
+
 
 static struct cftype mem_cgroup_files[] = {
         {
@@ -1902,6 +1958,11 @@ static struct cftype mem_cgroup_files[] = {
                 .write_u64 = mem_cgroup_hierarchy_write,
                 .read_u64 = mem_cgroup_hierarchy_read,
         },
+        {
+                .name = "swappiness",
+                .read_u64 = mem_cgroup_swappiness_read,
+                .write_u64 = mem_cgroup_swappiness_write,
+        },
 };
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
@@ -2093,6 +2154,9 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
         mem->last_scanned_child = NULL;
         spin_lock_init(&mem->reclaim_param_lock);
 
+        if (parent)
+                mem->swappiness = get_swappiness(parent);
+
         return &mem->css;
 free_out:
         for_each_node_state(node, N_POSSIBLE)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f03c239440ad..ece2f405187f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1707,14 +1707,15 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 
 unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
-                                                gfp_t gfp_mask,
-                                           bool noswap)
+                                           gfp_t gfp_mask,
+                                           bool noswap,
+                                           unsigned int swappiness)
 {
         struct scan_control sc = {
                 .may_writepage = !laptop_mode,
                 .may_swap = 1,
                 .swap_cluster_max = SWAP_CLUSTER_MAX,
-                .swappiness = vm_swappiness,
+                .swappiness = swappiness,
                 .order = 0,
                 .mem_cgroup = mem_cont,
                 .isolate_pages = mem_cgroup_isolate_pages,