[Intel-gfx] [PATCH 20/29] zsmalloc: dynamically allocate the mm-zspool shrinker

[Qi Zheng]

In preparation for implementing lockless slab shrink,
we need 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.a...@bytedance.com>
---
 mm/zsmalloc.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 3f057970504e..c03b34ae637e 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;
@@ -2107,8 +2107,7 @@ 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.
@@ -2126,8 +2125,7 @@ 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];
@@ -2142,18 +2140,24 @@ static unsigned long zs_shrinker_count(struct shrinker 
*shrinker,
 
 static void zs_unregister_shrinker(struct zs_pool *pool)
 {
-       unregister_shrinker(&pool->shrinker);
+       unregister_and_free_shrinker(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;
+       int ret;
+
+       pool->shrinker = shrinker_alloc_and_init(zs_shrinker_count,
+                                                zs_shrinker_scan, 0,
+                                                DEFAULT_SEEKS, 0, pool);
+       if (!pool->shrinker)
+               return -ENOMEM;
 
-       return register_shrinker(&pool->shrinker, "mm-zspool:%s",
-                                pool->name);
+       ret = register_shrinker(pool->shrinker, "mm-zspool:%s", pool->name);
+       if (ret)
+               shrinker_free(pool->shrinker);
+
+       return ret;
 }
 
 static int calculate_zspage_chain_size(int class_size)
-- 
2.30.2