vmscan: Convert shrinker_idr to XArray

Signed-off-by: Matthew Wilcox <willy@infradead.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index dbdc46a84f63089de614a2807ef62a70f7c14968..83d1d33a60dc9f716add07e40663fc2e7cf760d0 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -192,29 +192,29 @@ static DECLARE_RWSEM(shrinker_rwsem);
  */
 #define SHRINKER_REGISTERING ((struct shrinker *)~0UL)
 
-static DEFINE_IDR(shrinker_idr);
+static DEFINE_XARRAY_ALLOC(memcg_shrinkers);
 static int shrinker_nr_max;
 
 static int prealloc_memcg_shrinker(struct shrinker *shrinker)
 {
-       int id, ret = -ENOMEM;
+       int ret;
 
        down_write(&shrinker_rwsem);
        /* This may call shrinker, so it must use down_read_trylock() */
-       id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL);
-       if (id < 0)
+       ret = xa_alloc(&memcg_shrinkers, &shrinker->id, SHRINKER_REGISTERING,
+                       xa_limit_31b, GFP_KERNEL);
+       if (ret < 0)
                goto unlock;
 
-       if (id >= shrinker_nr_max) {
-               if (memcg_expand_shrinker_maps(id)) {
-                       idr_remove(&shrinker_idr, id);
+       if (shrinker->id >= shrinker_nr_max) {
+               if (memcg_expand_shrinker_maps(shrinker->id)) {
+                       xa_erase(&memcg_shrinkers, shrinker->id);
+                       ret = -ENOMEM;
                        goto unlock;
                }
 
-               shrinker_nr_max = id + 1;
+               shrinker_nr_max = shrinker->id + 1;
        }
-       shrinker->id = id;
-       ret = 0;
 unlock:
        up_write(&shrinker_rwsem);
        return ret;
@@ -226,9 +226,7 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
 
        BUG_ON(id < 0);
 
-       down_write(&shrinker_rwsem);
-       idr_remove(&shrinker_idr, id);
-       up_write(&shrinker_rwsem);
+       xa_erase(&memcg_shrinkers, id);
 }
 #else /* CONFIG_MEMCG_KMEM */
 static int prealloc_memcg_shrinker(struct shrinker *shrinker)
@@ -429,7 +427,7 @@ void register_shrinker_prepared(struct shrinker *shrinker)
        list_add_tail(&shrinker->list, &shrinker_list);
 #ifdef CONFIG_MEMCG_KMEM
        if (shrinker->flags & SHRINKER_MEMCG_AWARE)
-               idr_replace(&shrinker_idr, shrinker, shrinker->id);
+               xa_store(&memcg_shrinkers, shrinker->id, shrinker, GFP_KERNEL);
 #endif
        up_write(&shrinker_rwsem);
 }
@@ -621,7 +619,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
                };
                struct shrinker *shrinker;
 
-               shrinker = idr_find(&shrinker_idr, i);
+               shrinker = xa_load(&memcg_shrinkers, i);
                if (unlikely(!shrinker || shrinker == SHRINKER_REGISTERING)) {
                        if (!shrinker)
                                clear_bit(i, map->map);