mm: vmscan: pass root_mem_cgroup instead of NULL to memcg aware shrinker
It's just convenient to implement a memcg aware shrinker when you know
that shrink_control->memcg != NULL unless memcg_kmem_enabled() returns
false.
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f87cfaa..b41b82d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -382,9 +382,8 @@
*
* @memcg specifies the memory cgroup to target. If it is not NULL,
* only shrinkers with SHRINKER_MEMCG_AWARE set will be called to scan
- * objects from the memory cgroup specified. Otherwise all shrinkers
- * are called, and memcg aware shrinkers are supposed to scan the
- * global list then.
+ * objects from the memory cgroup specified. Otherwise, only unaware
+ * shrinkers are called.
*
* @nr_scanned and @nr_eligible form a ratio that indicate how much of
* the available objects should be scanned. Page reclaim for example
@@ -404,7 +403,7 @@
struct shrinker *shrinker;
unsigned long freed = 0;
- if (memcg && !memcg_kmem_online(memcg))
+ if (memcg && (!memcg_kmem_enabled() || !mem_cgroup_online(memcg)))
return 0;
if (nr_scanned == 0)
@@ -428,7 +427,13 @@
.memcg = memcg,
};
- if (memcg && !(shrinker->flags & SHRINKER_MEMCG_AWARE))
+ /*
+ * If kernel memory accounting is disabled, we ignore
+ * SHRINKER_MEMCG_AWARE flag and call all shrinkers
+ * passing NULL for memcg.
+ */
+ if (memcg_kmem_enabled() &&
+ !!memcg != !!(shrinker->flags & SHRINKER_MEMCG_AWARE))
continue;
if (!(shrinker->flags & SHRINKER_NUMA_AWARE))