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-rw-r--r--Documentation/cgroups/memory.txt4
-rw-r--r--mm/memcontrol.c21
2 files changed, 19 insertions, 6 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index c07f7b4fb88d..71c4da413444 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -466,6 +466,10 @@ Note:
5.3 swappiness
Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.
+Please note that unlike the global swappiness, memcg knob set to 0
+really prevents from any swapping even if there is a swap storage
+available. This might lead to memcg OOM killer if there are no file
+pages to reclaim.
Following cgroups' swappiness can't be changed.
- root cgroup (uses /proc/sys/vm/swappiness).
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7acf43bf04a2..93a7e36ded89 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1452,17 +1452,26 @@ static int mem_cgroup_count_children(struct mem_cgroup *memcg)
static u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
{
u64 limit;
- u64 memsw;
limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
- limit += total_swap_pages << PAGE_SHIFT;
- memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
/*
- * If memsw is finite and limits the amount of swap space available
- * to this memcg, return that limit.
+ * Do not consider swap space if we cannot swap due to swappiness
*/
- return min(limit, memsw);
+ if (mem_cgroup_swappiness(memcg)) {
+ u64 memsw;
+
+ limit += total_swap_pages << PAGE_SHIFT;
+ memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
+
+ /*
+ * If memsw is finite and limits the amount of swap space
+ * available to this memcg, return that limit.
+ */
+ limit = min(limit, memsw);
+ }
+
+ return limit;
}
void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,