[PATCH v4 40/48] zsmalloc: dynamically allocate the mm-zspool shrinker

Qi Zheng
2023-08-07T11:22:44Z

In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the mm-zspool shrinker, so that it can be freed
asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU
read-side critical section when releasing the struct zs_pool.

Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
---
mm/zsmalloc.c | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index b58f957429f0..1909234bb345 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -229,7 +229,7 @@ struct zs_pool {
struct zs_pool_stats stats;

/* Compact classes */
- struct shrinker shrinker;
+ struct shrinker *shrinker;

#ifdef CONFIG_ZSMALLOC_STAT
struct dentry *stat_dentry;
@@ -2086,8 +2086,7 @@ static unsigned long zs_shrinker_scan(struct shrinker *shrinker,
struct shrink_control *sc)
{
unsigned long pages_freed;
- struct zs_pool *pool = container_of(shrinker, struct zs_pool,
- shrinker);
+ struct zs_pool *pool = shrinker->private_data;

/*
* Compact classes and calculate compaction delta.
@@ -2105,8 +2104,7 @@ static unsigned long zs_shrinker_count(struct shrinker *shrinker,
int i;
struct size_class *class;
unsigned long pages_to_free = 0;
- struct zs_pool *pool = container_of(shrinker, struct zs_pool,
- shrinker);
+ struct zs_pool *pool = shrinker->private_data;

for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
class = pool->size_class[i];
@@ -2121,18 +2119,24 @@ static unsigned long zs_shrinker_count(struct shrinker *shrinker,

static void zs_unregister_shrinker(struct zs_pool *pool)
{
- unregister_shrinker(&pool->shrinker);
+ shrinker_free(pool->shrinker);
}

static int zs_register_shrinker(struct zs_pool *pool)
{
- pool->shrinker.scan_objects = zs_shrinker_scan;
- pool->shrinker.count_objects = zs_shrinker_count;
- pool->shrinker.batch = 0;
- pool->shrinker.seeks = DEFAULT_SEEKS;
+ pool->shrinker = shrinker_alloc(0, "mm-zspool:%s", pool->name);
+ if (!pool->shrinker)
+ return -ENOMEM;
+
+ pool->shrinker->scan_objects = zs_shrinker_scan;
+ pool->shrinker->count_objects = zs_shrinker_count;
+ pool->shrinker->batch = 0;
+ pool->shrinker->seeks = DEFAULT_SEEKS;
+ pool->shrinker->private_data = pool;

- return register_shrinker(&pool->shrinker, "mm-zspool:%s",
- pool->name);
+ shrinker_register(pool->shrinker);
+
+ return 0;
}

static int calculate_zspage_chain_size(int class_size)
--
2.30.2