diff mbox series

[v8,11/13] mm: vmscan: don't need allocate shrinker->nr_deferred for memcg aware shrinkers

Message ID 20210217001322.2226796-12-shy828301@gmail.com (mailing list archive)
State New
Headers show
Series Make shrinker's nr_deferred memcg aware | expand

Commit Message

Yang Shi Feb. 17, 2021, 12:13 a.m. UTC
Now nr_deferred is available on per memcg level for memcg aware shrinkers, so don't need
allocate shrinker->nr_deferred for such shrinkers anymore.

The prealloc_memcg_shrinker() would return -ENOSYS if !CONFIG_MEMCG or memcg is disabled
by kernel command line, then shrinker's SHRINKER_MEMCG_AWARE flag would be cleared.
This makes the implementation of this patch simpler.

Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Yang Shi <shy828301@gmail.com>
---
 mm/vmscan.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

Comments

Shakeel Butt March 8, 2021, 9:57 p.m. UTC | #1
On Tue, Feb 16, 2021 at 4:13 PM Yang Shi <shy828301@gmail.com> wrote:
>
> Now nr_deferred is available on per memcg level for memcg aware shrinkers, so don't need
> allocate shrinker->nr_deferred for such shrinkers anymore.
>
> The prealloc_memcg_shrinker() would return -ENOSYS if !CONFIG_MEMCG or memcg is disabled
> by kernel command line, then shrinker's SHRINKER_MEMCG_AWARE flag would be cleared.
> This makes the implementation of this patch simpler.
>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
> Acked-by: Roman Gushchin <guro@fb.com>
> Signed-off-by: Yang Shi <shy828301@gmail.com>

Reviewed-by: Shakeel Butt <shakeelb@google.com>
diff mbox series

Patch

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 57cbc6bc8a49..d8800e4da67d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -344,6 +344,9 @@  static int prealloc_memcg_shrinker(struct shrinker *shrinker)
 {
 	int id, ret = -ENOMEM;
 
+	if (mem_cgroup_disabled())
+		return -ENOSYS;
+
 	down_write(&shrinker_rwsem);
 	/* This may call shrinker, so it must use down_read_trylock() */
 	id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);
@@ -423,7 +426,7 @@  static bool writeback_throttling_sane(struct scan_control *sc)
 #else
 static int prealloc_memcg_shrinker(struct shrinker *shrinker)
 {
-	return 0;
+	return -ENOSYS;
 }
 
 static void unregister_memcg_shrinker(struct shrinker *shrinker)
@@ -534,8 +537,18 @@  unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone
  */
 int prealloc_shrinker(struct shrinker *shrinker)
 {
-	unsigned int size = sizeof(*shrinker->nr_deferred);
+	unsigned int size;
+	int err;
+
+	if (shrinker->flags & SHRINKER_MEMCG_AWARE) {
+		err = prealloc_memcg_shrinker(shrinker);
+		if (err != -ENOSYS)
+			return err;
 
+		shrinker->flags &= ~SHRINKER_MEMCG_AWARE;
+	}
+
+	size = sizeof(*shrinker->nr_deferred);
 	if (shrinker->flags & SHRINKER_NUMA_AWARE)
 		size *= nr_node_ids;
 
@@ -543,28 +556,16 @@  int prealloc_shrinker(struct shrinker *shrinker)
 	if (!shrinker->nr_deferred)
 		return -ENOMEM;
 
-	if (shrinker->flags & SHRINKER_MEMCG_AWARE) {
-		if (prealloc_memcg_shrinker(shrinker))
-			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->nr_deferred)
-		return;
-
 	if (shrinker->flags & SHRINKER_MEMCG_AWARE) {
 		down_write(&shrinker_rwsem);
 		unregister_memcg_shrinker(shrinker);
 		up_write(&shrinker_rwsem);
+		return;
 	}
 
 	kfree(shrinker->nr_deferred);