The patch introduces shrinker::id number, which is used to enumerate
memcg-aware shrinkers. The number start from 0, and the code tries
to maintain it as small as possible.
This will be used as to represent a memcg-aware shrinkers in memcg
shrinkers map.
Since all memcg-aware shrinkers are based on list_lru, which is per-memcg
in case of !CONFIG_MEMCG_KMEM only, the new functionality will be under
this config option.
Signed-off-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
---
include/linux/shrinker.h | 4 +++
mm/vmscan.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+)
diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 6794490f25b2..7ca9c18cf130 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -66,6 +66,10 @@ struct shrinker {
/* These are for internal use */
struct list_head list;
+#ifdef CONFIG_MEMCG_KMEM
+ /* ID in shrinker_idr */
+ int id;
+#endif
/* objs pending delete, per node */
atomic_long_t *nr_deferred;
};
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 50055d72f294..3de12a9bdf85 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -169,6 +169,48 @@ unsigned long vm_total_pages;
static LIST_HEAD(shrinker_list);
static DECLARE_RWSEM(shrinker_rwsem);
+#ifdef CONFIG_MEMCG_KMEM
+static DEFINE_IDR(shrinker_idr);
+
+static int prealloc_memcg_shrinker(struct shrinker *shrinker)
+{
+ int id, ret;
+
+ shrinker->id = -1;
+ down_write(&shrinker_rwsem);
+ ret = id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);
+ if (ret < 0)
+ goto unlock;
+ shrinker->id = id;
+ ret = 0;
+unlock:
+ up_write(&shrinker_rwsem);
+ return ret;
+}
+
+static void unregister_memcg_shrinker(struct shrinker *shrinker)
+{
+ int id = shrinker->id;
+
+ if (id < 0)
+ return;
+
+ down_write(&shrinker_rwsem);
+ idr_remove(&shrinker_idr, id);
+ up_write(&shrinker_rwsem);
+ shrinker->id = -1;
+}
+#else /* CONFIG_MEMCG_KMEM */
+static int prealloc_memcg_shrinker(struct shrinker *shrinker)
+{
+ return 0;
+}
+
+static void unregister_memcg_shrinker(struct shrinker *shrinker)
+{
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
#ifdef CONFIG_MEMCG
static bool global_reclaim(struct scan_control *sc)
{
@@ -306,6 +348,7 @@ unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone
int prealloc_shrinker(struct shrinker *shrinker)
{
size_t size = sizeof(*shrinker->nr_deferred);
+ int ret;
if (shrinker->flags & SHRINKER_NUMA_AWARE)
size *= nr_node_ids;
@@ -313,11 +356,26 @@ int prealloc_shrinker(struct shrinker *shrinker)
shrinker->nr_deferred = kzalloc(size, GFP_KERNEL);
if (!shrinker->nr_deferred)
return -ENOMEM;
+
+ if (shrinker->flags & SHRINKER_MEMCG_AWARE) {
+ ret = prealloc_memcg_shrinker(shrinker);
+ if (ret)
+ goto free_deferred;
+ }
+
return 0;
+
+free_deferred:
+ kfree(shrinker->nr_deferred);
+ shrinker->nr_deferred = NULL;
+ return -ENOMEM;
}
void free_prealloced_shrinker(struct shrinker *shrinker)
{
+ if (shrinker->flags & SHRINKER_MEMCG_AWARE)
+ unregister_memcg_shrinker(shrinker);
+
kfree(shrinker->nr_deferred);
shrinker->nr_deferred = NULL;
}
@@ -347,6 +405,8 @@ void unregister_shrinker(struct shrinker *shrinker)
{
if (!shrinker->nr_deferred)
return;
+ if (shrinker->flags & SHRINKER_MEMCG_AWARE)
+ unregister_memcg_shrinker(shrinker);
down_write(&shrinker_rwsem);
list_del(&shrinker->list);
up_write(&shrinker_rwsem);
