memcg: limit change shrink usage

Shrinking memory usage at limit change.

[akpm@linux-foundation.org: coding-style fixes]
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/controllers/memory.txt b/Documentation/controllers/memory.txt
index 866b9cd9a9590d6b6b8c3d577038e8d51234082b..9b53d5827361fd647f3388212e648f502defc698 100644 (file)
--- a/Documentation/controllers/memory.txt
+++ b/Documentation/controllers/memory.txt
@@ -242,8 +242,7 @@ rmdir() if there are no tasks.
 1. Add support for accounting huge pages (as a separate controller)
 2. Make per-cgroup scanner reclaim not-shared pages first
 3. Teach controller to account for shared-pages
-4. Start reclamation when the limit is lowered
-5. Start reclamation in the background when the limit is
+4. Start reclamation in the background when the limit is
    not yet hit but the usage is getting closer
 
 Summary

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0c035647d36abb6e9dba83544620f613cd2148e8..fba566c513220dcf8c30133a617e5d27328a23f2 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -812,6 +812,30 @@ int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
        return 0;
 }
 
+int mem_cgroup_resize_limit(struct mem_cgroup *memcg, unsigned long long val)
+{
+
+       int retry_count = MEM_CGROUP_RECLAIM_RETRIES;
+       int progress;
+       int ret = 0;
+
+       while (res_counter_set_limit(&memcg->res, val)) {
+               if (signal_pending(current)) {
+                       ret = -EINTR;
+                       break;
+               }
+               if (!retry_count) {
+                       ret = -EBUSY;
+                       break;
+               }
+               progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL);
+               if (!progress)
+                       retry_count--;
+       }
+       return ret;
+}
+
+
 /*
  * This routine traverse page_cgroup in given list and drop them all.
  * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
@@ -896,13 +920,29 @@ static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
        return res_counter_read_u64(&mem_cgroup_from_cont(cont)->res,
                                    cft->private);
 }
-
+/*
+ * The user of this function is...
+ * RES_LIMIT.
+ */
 static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
                            const char *buffer)
 {
-       return res_counter_write(&mem_cgroup_from_cont(cont)->res,
-                                cft->private, buffer,
-                                res_counter_memparse_write_strategy);
+       struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+       unsigned long long val;
+       int ret;
+
+       switch (cft->private) {
+       case RES_LIMIT:
+               /* This function does all necessary parse...reuse it */
+               ret = res_counter_memparse_write_strategy(buffer, &val);
+               if (!ret)
+                       ret = mem_cgroup_resize_limit(memcg, val);
+               break;
+       default:
+               ret = -EINVAL; /* should be BUG() ? */
+               break;
+       }
+       return ret;
 }
 
 static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)