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>

1 files changed, 143 insertions, 5 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;
 }