1 files changed, 197 insertions, 0 deletions

diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index df1e54a5ed19..685e7c8e1fd6 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -8,6 +8,7 @@
 #include <linux/memory.h>
 #include <linux/vmalloc.h>
 #include <linux/cgroup.h>
+#include <linux/swapops.h>
 
 static void __meminit
 __init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
@@ -270,3 +271,199 @@ void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)
 }
 
 #endif
+
+
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
+
+static DEFINE_MUTEX(swap_cgroup_mutex);
+struct swap_cgroup_ctrl {
+        struct page **map;
+        unsigned long length;
+};
+
+struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];
+
+/*
+ * This 8bytes seems big..maybe we can reduce this when we can use "id" for
+ * cgroup rather than pointer.
+ */
+struct swap_cgroup {
+        struct mem_cgroup       *val;
+};
+#define SC_PER_PAGE     (PAGE_SIZE/sizeof(struct swap_cgroup))
+#define SC_POS_MASK     (SC_PER_PAGE - 1)
+
+/*
+ * SwapCgroup implements "lookup" and "exchange" operations.
+ * In typical usage, this swap_cgroup is accessed via memcg's charge/uncharge
+ * against SwapCache. At swap_free(), this is accessed directly from swap.
+ *
+ * This means,
+ *  - we have no race in "exchange" when we're accessed via SwapCache because
+ *    SwapCache(and its swp_entry) is under lock.
+ *  - When called via swap_free(), there is no user of this entry and no race.
+ * Then, we don't need lock around "exchange".
+ *
+ * TODO: we can push these buffers out to HIGHMEM.
+ */
+
+/*
+ * allocate buffer for swap_cgroup.
+ */
+static int swap_cgroup_prepare(int type)
+{
+        struct page *page;
+        struct swap_cgroup_ctrl *ctrl;
+        unsigned long idx, max;
+
+        if (!do_swap_account)
+                return 0;
+        ctrl = &swap_cgroup_ctrl[type];
+
+        for (idx = 0; idx < ctrl->length; idx++) {
+                page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+                if (!page)
+                        goto not_enough_page;
+                ctrl->map[idx] = page;
+        }
+        return 0;
+not_enough_page:
+        max = idx;
+        for (idx = 0; idx < max; idx++)
+                __free_page(ctrl->map[idx]);
+
+        return -ENOMEM;
+}
+
+/**
+ * swap_cgroup_record - record mem_cgroup for this swp_entry.
+ * @ent: swap entry to be recorded into
+ * @mem: mem_cgroup to be recorded
+ *
+ * Returns old value at success, NULL at failure.
+ * (Of course, old value can be NULL.)
+ */
+struct mem_cgroup *swap_cgroup_record(swp_entry_t ent, struct mem_cgroup *mem)
+{
+        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;
+        struct mem_cgroup *old;
+
+        if (!do_swap_account)
+                return NULL;
+
+        ctrl = &swap_cgroup_ctrl[type];
+
+        mappage = ctrl->map[idx];
+        sc = page_address(mappage);
+        sc += pos;
+        old = sc->val;
+        sc->val = mem;
+
+        return old;
+}
+
+/**
+ * lookup_swap_cgroup - lookup mem_cgroup tied to swap entry
+ * @ent: swap entry to be looked up.
+ *
+ * Returns pointer to mem_cgroup at success. NULL at failure.
+ */
+struct mem_cgroup *lookup_swap_cgroup(swp_entry_t ent)
+{
+        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;
+        struct mem_cgroup *ret;
+
+        if (!do_swap_account)
+                return NULL;
+
+        ctrl = &swap_cgroup_ctrl[type];
+        mappage = ctrl->map[idx];
+        sc = page_address(mappage);
+        sc += pos;
+        ret = sc->val;
+        return ret;
+}
+
+int swap_cgroup_swapon(int type, unsigned long max_pages)
+{
+        void *array;
+        unsigned long array_size;
+        unsigned long length;
+        struct swap_cgroup_ctrl *ctrl;
+
+        if (!do_swap_account)
+                return 0;
+
+        length = ((max_pages/SC_PER_PAGE) + 1);
+        array_size = length * sizeof(void *);
+
+        array = vmalloc(array_size);
+        if (!array)
+                goto nomem;
+
+        memset(array, 0, array_size);
+        ctrl = &swap_cgroup_ctrl[type];
+        mutex_lock(&swap_cgroup_mutex);
+        ctrl->length = length;
+        ctrl->map = array;
+        if (swap_cgroup_prepare(type)) {
+                /* memory shortage */
+                ctrl->map = NULL;
+                ctrl->length = 0;
+                vfree(array);
+                mutex_unlock(&swap_cgroup_mutex);
+                goto nomem;
+        }
+        mutex_unlock(&swap_cgroup_mutex);
+
+        printk(KERN_INFO
+                "swap_cgroup: uses %ld bytes of vmalloc for pointer array space"
+                " and %ld bytes to hold mem_cgroup pointers on swap\n",
+                array_size, length * PAGE_SIZE);
+        printk(KERN_INFO
+        "swap_cgroup can be disabled by noswapaccount boot option.\n");
+
+        return 0;
+nomem:
+        printk(KERN_INFO "couldn't allocate enough memory for swap_cgroup.\n");
+        printk(KERN_INFO
+                "swap_cgroup can be disabled by noswapaccount boot option\n");
+        return -ENOMEM;
+}
+
+void swap_cgroup_swapoff(int type)
+{
+        int i;
+        struct swap_cgroup_ctrl *ctrl;
+
+        if (!do_swap_account)
+                return;
+
+        mutex_lock(&swap_cgroup_mutex);
+        ctrl = &swap_cgroup_ctrl[type];
+        if (ctrl->map) {
+                for (i = 0; i < ctrl->length; i++) {
+                        struct page *page = ctrl->map[i];
+                        if (page)
+                                __free_page(page);
+                }
+                vfree(ctrl->map);
+                ctrl->map = NULL;
+                ctrl->length = 0;
+        }
+        mutex_unlock(&swap_cgroup_mutex);
+}
+
+#endif