Memory controller: add per cgroup LRU and reclaim

Add the page_cgroup to the per cgroup LRU.  The reclaim algorithm has
been modified to make the isolate_lru_pages() as a pluggable component.  The
scan_control data structure now accepts the cgroup on behalf of which
reclaims are carried out.  try_to_free_pages() has been extended to become
cgroup aware.

[akpm@linux-foundation.org: fix warning]
[Lee.Schermerhorn@hp.com: initialize all scan_control's isolate_pages member]
[bunk@kernel.org: make do_try_to_free_pages() static]
[hugh@veritas.com: memcgroup: fix try_to_free order]
[kamezawa.hiroyu@jp.fujitsu.com: this unlock_page_cgroup() is unnecessary]
Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: David Rientjes <rientjes@google.com>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-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>

3 files changed, 248 insertions, 30 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b25df2a9d024..9e9ff914c0f1 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -22,10 +22,15 @@
 #include <linux/cgroup.h>
 #include <linux/mm.h>
 #include <linux/page-flags.h>
+#include <linux/backing-dev.h>
 #include <linux/bit_spinlock.h>
 #include <linux/rcupdate.h>
+#include <linux/swap.h>
+#include <linux/spinlock.h>
+#include <linux/fs.h>
 
 struct cgroup_subsys mem_cgroup_subsys;
+static const int MEM_CGROUP_RECLAIM_RETRIES = 5;
 
 /*
  * The memory controller data structure. The memory controller controls both
@@ -51,6 +56,10 @@ struct mem_cgroup {
          */
         struct list_head active_list;
         struct list_head inactive_list;
+        /*
+         * spin_lock to protect the per cgroup LRU
+         */
+        spinlock_t lru_lock;
 };
 
 /*
@@ -141,6 +150,94 @@ void __always_inline unlock_page_cgroup(struct page *page)
         bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
 }
 
+void __mem_cgroup_move_lists(struct page_cgroup *pc, bool active)
+{
+        if (active)
+                list_move(&pc->lru, &pc->mem_cgroup->active_list);
+        else
+                list_move(&pc->lru, &pc->mem_cgroup->inactive_list);
+}
+
+/*
+ * This routine assumes that the appropriate zone's lru lock is already held
+ */
+void mem_cgroup_move_lists(struct page_cgroup *pc, bool active)
+{
+        struct mem_cgroup *mem;
+        if (!pc)
+                return;
+
+        mem = pc->mem_cgroup;
+
+        spin_lock(&mem->lru_lock);
+        __mem_cgroup_move_lists(pc, active);
+        spin_unlock(&mem->lru_lock);
+}
+
+unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
+                                        struct list_head *dst,
+                                        unsigned long *scanned, int order,
+                                        int mode, struct zone *z,
+                                        struct mem_cgroup *mem_cont,
+                                        int active)
+{
+        unsigned long nr_taken = 0;
+        struct page *page;
+        unsigned long scan;
+        LIST_HEAD(pc_list);
+        struct list_head *src;
+        struct page_cgroup *pc;
+
+        if (active)
+                src = &mem_cont->active_list;
+        else
+                src = &mem_cont->inactive_list;
+
+        spin_lock(&mem_cont->lru_lock);
+        for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
+                pc = list_entry(src->prev, struct page_cgroup, lru);
+                page = pc->page;
+                VM_BUG_ON(!pc);
+
+                if (PageActive(page) && !active) {
+                        __mem_cgroup_move_lists(pc, true);
+                        scan--;
+                        continue;
+                }
+                if (!PageActive(page) && active) {
+                        __mem_cgroup_move_lists(pc, false);
+                        scan--;
+                        continue;
+                }
+
+                /*
+                 * Reclaim, per zone
+                 * TODO: make the active/inactive lists per zone
+                 */
+                if (page_zone(page) != z)
+                        continue;
+
+                /*
+                 * Check if the meta page went away from under us
+                 */
+                if (!list_empty(&pc->lru))
+                        list_move(&pc->lru, &pc_list);
+                else
+                        continue;
+
+                if (__isolate_lru_page(page, mode) == 0) {
+                        list_move(&page->lru, dst);
+                        nr_taken++;
+                }
+        }
+
+        list_splice(&pc_list, src);
+        spin_unlock(&mem_cont->lru_lock);
+
+        *scanned = scan;
+        return nr_taken;
+}
+
 /*
  * Charge the memory controller for page usage.
  * Return
@@ -151,6 +248,8 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm)
 {
         struct mem_cgroup *mem;
         struct page_cgroup *pc, *race_pc;
+        unsigned long flags;
+        unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
 
         /*
          * Should page_cgroup's go to their own slab?
@@ -159,14 +258,20 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm)
          * to see if the cgroup page already has a page_cgroup associated
          * with it
          */
+retry:
         lock_page_cgroup(page);
         pc = page_get_page_cgroup(page);
         /*
          * The page_cgroup exists and the page has already been accounted
          */
         if (pc) {
-                atomic_inc(&pc->ref_cnt);
-                goto done;
+                if (unlikely(!atomic_inc_not_zero(&pc->ref_cnt))) {
+                        /* this page is under being uncharged ? */
+                        unlock_page_cgroup(page);
+                        cpu_relax();
+                        goto retry;
+                } else
+                        goto done;
         }
 
         unlock_page_cgroup(page);
@@ -197,7 +302,32 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm)
          * If we created the page_cgroup, we should free it on exceeding
          * the cgroup limit.
          */
-        if (res_counter_charge(&mem->res, 1)) {
+        while (res_counter_charge(&mem->res, 1)) {
+                if (try_to_free_mem_cgroup_pages(mem))
+                        continue;
+
+                /*
+                 * try_to_free_mem_cgroup_pages() might not give us a full
+                 * picture of reclaim. Some pages are reclaimed and might be
+                 * moved to swap cache or just unmapped from the cgroup.
+                 * Check the limit again to see if the reclaim reduced the
+                 * current usage of the cgroup before giving up
+                 */
+                if (res_counter_check_under_limit(&mem->res))
+                        continue;
+                        /*
+                         * Since we control both RSS and cache, we end up with a
+                         * very interesting scenario where we end up reclaiming
+                         * memory (essentially RSS), since the memory is pushed
+                         * to swap cache, we eventually end up adding those
+                         * pages back to our list. Hence we give ourselves a
+                         * few chances before we fail
+                         */
+                else if (nr_retries--) {
+                        congestion_wait(WRITE, HZ/10);
+                        continue;
+                }
+
                 css_put(&mem->css);
                 goto free_pc;
         }
@@ -221,14 +351,16 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm)
         pc->page = page;
         page_assign_page_cgroup(page, pc);
 
+        spin_lock_irqsave(&mem->lru_lock, flags);
+        list_add(&pc->lru, &mem->active_list);
+        spin_unlock_irqrestore(&mem->lru_lock, flags);
+
 done:
         unlock_page_cgroup(page);
         return 0;
 free_pc:
         kfree(pc);
-        return -ENOMEM;
 err:
-        unlock_page_cgroup(page);
         return -ENOMEM;
 }
 
@@ -240,6 +372,7 @@ void mem_cgroup_uncharge(struct page_cgroup *pc)
 {
         struct mem_cgroup *mem;
         struct page *page;
+        unsigned long flags;
 
         if (!pc)
                 return;
@@ -252,6 +385,10 @@ void mem_cgroup_uncharge(struct page_cgroup *pc)
                 page_assign_page_cgroup(page, NULL);
                 unlock_page_cgroup(page);
                 res_counter_uncharge(&mem->res, 1);
+
+                spin_lock_irqsave(&mem->lru_lock, flags);
+                list_del_init(&pc->lru);
+                spin_unlock_irqrestore(&mem->lru_lock, flags);
                 kfree(pc);
         }
 }
@@ -310,6 +447,7 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
         res_counter_init(&mem->res);
         INIT_LIST_HEAD(&mem->active_list);
         INIT_LIST_HEAD(&mem->inactive_list);
+        spin_lock_init(&mem->lru_lock);
         return &mem->css;
 }
 
diff --git a/mm/swap.c b/mm/swap.c
index 57b7e25a939c..710a20bb9749 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -29,6 +29,7 @@
 #include <linux/cpu.h>
 #include <linux/notifier.h>
 #include <linux/backing-dev.h>
+#include <linux/memcontrol.h>
 
 /* How many pages do we try to swap or page in/out together? */
 int page_cluster;
@@ -175,6 +176,7 @@ void activate_page(struct page *page)
                 SetPageActive(page);
                 add_page_to_active_list(zone, page);
                 __count_vm_event(PGACTIVATE);
+                mem_cgroup_move_lists(page_get_page_cgroup(page), true);
         }
         spin_unlock_irq(&zone->lru_lock);
 }
diff --git a/mm/vmscan.c b/mm/vmscan.c
index e5a9597e3bbc..7408a8a7d882 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -37,6 +37,7 @@
 #include <linux/delay.h>
 #include <linux/kthread.h>
 #include <linux/freezer.h>
+#include <linux/memcontrol.h>
 
 #include <asm/tlbflush.h>
 #include <asm/div64.h>
@@ -68,6 +69,15 @@ struct scan_control {
         int all_unreclaimable;
 
         int order;
+
+        /* Which cgroup do we reclaim from */
+        struct mem_cgroup *mem_cgroup;
+
+        /* Pluggable isolate pages callback */
+        unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst,
+                        unsigned long *scanned, int order, int mode,
+                        struct zone *z, struct mem_cgroup *mem_cont,
+                        int active);
 };
 
 #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
@@ -626,7 +636,7 @@ keep:
  *
  * returns 0 on success, -ve errno on failure.
  */
-static int __isolate_lru_page(struct page *page, int mode)
+int __isolate_lru_page(struct page *page, int mode)
 {
         int ret = -EINVAL;
 
@@ -760,6 +770,21 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
         return nr_taken;
 }
 
+static unsigned long isolate_pages_global(unsigned long nr,
+                                        struct list_head *dst,
+                                        unsigned long *scanned, int order,
+                                        int mode, struct zone *z,
+                                        struct mem_cgroup *mem_cont,
+                                        int active)
+{
+        if (active)
+                return isolate_lru_pages(nr, &z->active_list, dst,
+                                                scanned, order, mode);
+        else
+                return isolate_lru_pages(nr, &z->inactive_list, dst,
+                                                scanned, order, mode);
+}
+
 /*
  * clear_active_flags() is a helper for shrink_active_list(), clearing
  * any active bits from the pages in the list.
@@ -801,11 +826,11 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
                 unsigned long nr_freed;
                 unsigned long nr_active;
 
-                nr_taken = isolate_lru_pages(sc->swap_cluster_max,
-                             &zone->inactive_list,
+                nr_taken = sc->isolate_pages(sc->swap_cluster_max,
                              &page_list, &nr_scan, sc->order,
                              (sc->order > PAGE_ALLOC_COSTLY_ORDER)?
-                                             ISOLATE_BOTH : ISOLATE_INACTIVE);
+                                             ISOLATE_BOTH : ISOLATE_INACTIVE,
+                                zone, sc->mem_cgroup, 0);
                 nr_active = clear_active_flags(&page_list);
                 __count_vm_events(PGDEACTIVATE, nr_active);
 
@@ -1018,8 +1043,9 @@ force_reclaim_mapped:
 
         lru_add_drain();
         spin_lock_irq(&zone->lru_lock);
-        pgmoved = isolate_lru_pages(nr_pages, &zone->active_list,
-                            &l_hold, &pgscanned, sc->order, ISOLATE_ACTIVE);
+        pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order,
+                                        ISOLATE_ACTIVE, zone,
+                                        sc->mem_cgroup, 1);
         zone->pages_scanned += pgscanned;
         __mod_zone_page_state(zone, NR_ACTIVE, -pgmoved);
         spin_unlock_irq(&zone->lru_lock);
@@ -1051,6 +1077,7 @@ force_reclaim_mapped:
                 ClearPageActive(page);
 
                 list_move(&page->lru, &zone->inactive_list);
+                mem_cgroup_move_lists(page_get_page_cgroup(page), false);
                 pgmoved++;
                 if (!pagevec_add(&pvec, page)) {
                         __mod_zone_page_state(zone, NR_INACTIVE, pgmoved);
@@ -1079,6 +1106,7 @@ force_reclaim_mapped:
                 SetPageLRU(page);
                 VM_BUG_ON(!PageActive(page));
                 list_move(&page->lru, &zone->active_list);
+                mem_cgroup_move_lists(page_get_page_cgroup(page), true);
                 pgmoved++;
                 if (!pagevec_add(&pvec, page)) {
                         __mod_zone_page_state(zone, NR_ACTIVE, pgmoved);
@@ -1206,7 +1234,8 @@ static unsigned long shrink_zones(int priority, struct zone **zones,
  * holds filesystem locks which prevent writeout this might not work, and the
  * allocation attempt will fail.
  */
-unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask)
+static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
+                                          struct scan_control *sc)
 {
         int priority;
         int ret = 0;
@@ -1215,14 +1244,6 @@ unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask)
         struct reclaim_state *reclaim_state = current->reclaim_state;
         unsigned long lru_pages = 0;
         int i;
-        struct scan_control sc = {
-                .gfp_mask = gfp_mask,
-                .may_writepage = !laptop_mode,
-                .swap_cluster_max = SWAP_CLUSTER_MAX,
-                .may_swap = 1,
-                .swappiness = vm_swappiness,
-                .order = order,
-        };
 
         count_vm_event(ALLOCSTALL);
 
@@ -1237,17 +1258,22 @@ unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask)
         }
 
         for (priority = DEF_PRIORITY; priority >= 0; priority--) {
-                sc.nr_scanned = 0;
+                sc->nr_scanned = 0;
                 if (!priority)
                         disable_swap_token();
-                nr_reclaimed += shrink_zones(priority, zones, &sc);
-                shrink_slab(sc.nr_scanned, gfp_mask, lru_pages);
+                nr_reclaimed += shrink_zones(priority, zones, sc);
+                /*
+                 * Don't shrink slabs when reclaiming memory from
+                 * over limit cgroups
+                 */
+                if (sc->mem_cgroup == NULL)
+                        shrink_slab(sc->nr_scanned, gfp_mask, lru_pages);
                 if (reclaim_state) {
                         nr_reclaimed += reclaim_state->reclaimed_slab;
                         reclaim_state->reclaimed_slab = 0;
                 }
-                total_scanned += sc.nr_scanned;
-                if (nr_reclaimed >= sc.swap_cluster_max) {
+                total_scanned += sc->nr_scanned;
+                if (nr_reclaimed >= sc->swap_cluster_max) {
                         ret = 1;
                         goto out;
                 }
@@ -1259,18 +1285,18 @@ unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask)
                  * that's undesirable in laptop mode, where we *want* lumpy
                  * writeout.  So in laptop mode, write out the whole world.
                  */
-                if (total_scanned > sc.swap_cluster_max +
-                                        sc.swap_cluster_max / 2) {
+                if (total_scanned > sc->swap_cluster_max +
+                                        sc->swap_cluster_max / 2) {
                         wakeup_pdflush(laptop_mode ? 0 : total_scanned);
-                        sc.may_writepage = 1;
+                        sc->may_writepage = 1;
                 }
 
                 /* Take a nap, wait for some writeback to complete */
-                if (sc.nr_scanned && priority < DEF_PRIORITY - 2)
+                if (sc->nr_scanned && priority < DEF_PRIORITY - 2)
                         congestion_wait(WRITE, HZ/10);
         }
         /* top priority shrink_caches still had more to do? don't OOM, then */
-        if (!sc.all_unreclaimable)
+        if (!sc->all_unreclaimable && sc->mem_cgroup == NULL)
                 ret = 1;
 out:
         /*
@@ -1293,6 +1319,54 @@ out:
         return ret;
 }
 
+unsigned long try_to_free_pages(struct zone **zones, int order, gfp_t gfp_mask)
+{
+        struct scan_control sc = {
+                .gfp_mask = gfp_mask,
+                .may_writepage = !laptop_mode,
+                .swap_cluster_max = SWAP_CLUSTER_MAX,
+                .may_swap = 1,
+                .swappiness = vm_swappiness,
+                .order = order,
+                .mem_cgroup = NULL,
+                .isolate_pages = isolate_pages_global,
+        };
+
+        return do_try_to_free_pages(zones, gfp_mask, &sc);
+}
+
+#ifdef CONFIG_CGROUP_MEM_CONT
+
+#ifdef CONFIG_HIGHMEM
+#define ZONE_USERPAGES ZONE_HIGHMEM
+#else
+#define ZONE_USERPAGES ZONE_NORMAL
+#endif
+
+unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont)
+{
+        struct scan_control sc = {
+                .gfp_mask = GFP_KERNEL,
+                .may_writepage = !laptop_mode,
+                .may_swap = 1,
+                .swap_cluster_max = SWAP_CLUSTER_MAX,
+                .swappiness = vm_swappiness,
+                .order = 0,
+                .mem_cgroup = mem_cont,
+                .isolate_pages = mem_cgroup_isolate_pages,
+        };
+        int node;
+        struct zone **zones;
+
+        for_each_online_node(node) {
+                zones = NODE_DATA(node)->node_zonelists[ZONE_USERPAGES].zones;
+                if (do_try_to_free_pages(zones, sc.gfp_mask, &sc))
+                        return 1;
+        }
+        return 0;
+}
+#endif
+
 /*
  * For kswapd, balance_pgdat() will work across all this node's zones until
  * they are all at pages_high.
@@ -1328,6 +1402,8 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
                 .swap_cluster_max = SWAP_CLUSTER_MAX,
                 .swappiness = vm_swappiness,
                 .order = order,
+                .mem_cgroup = NULL,
+                .isolate_pages = isolate_pages_global,
         };
         /*
          * temp_priority is used to remember the scanning priority at which
@@ -1649,6 +1725,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
                 .swap_cluster_max = nr_pages,
                 .may_writepage = 1,
                 .swappiness = vm_swappiness,
+                .isolate_pages = isolate_pages_global,
         };
 
         current->reclaim_state = &reclaim_state;
@@ -1834,6 +1911,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
                                         SWAP_CLUSTER_MAX),
                 .gfp_mask = gfp_mask,
                 .swappiness = vm_swappiness,
+                .isolate_pages = isolate_pages_global,
         };
         unsigned long slab_reclaimable;