mm/zsmalloc: simplify shrinker init/destroy

Structure zs_pool has special flag to indicate success of shrinker
initialization.  unregister_shrinker() has improved and can detect by
itself whether actual deinitialization should be performed or not, so
extra flag becomes redundant.

[akpm@linux-foundation.org: update comment (Aliaksei), remove unneeded cast]
Link: http://lkml.kernel.org/r/1513680552-9798-1-git-send-email-akaraliou.dev@gmail.com
Signed-off-by: Aliaksei Karaliou <akaraliou.dev@gmail.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 683c0651098c719ab25c5b48789262e541a13362..e136a8e72c4842ae0036f2287620448fc9d3e703 100644 (file)
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -46,6 +46,7 @@
 #include <linux/vmalloc.h>
 #include <linux/preempt.h>
 #include <linux/spinlock.h>
+#include <linux/shrinker.h>
 #include <linux/types.h>
 #include <linux/debugfs.h>
 #include <linux/zsmalloc.h>
@@ -257,11 +258,7 @@ struct zs_pool {
 
        /* Compact classes */
        struct shrinker shrinker;
-       /*
-        * To signify that register_shrinker() was successful
-        * and unregister_shrinker() will not Oops.
-        */
-       bool shrinker_enabled;
+
 #ifdef CONFIG_ZSMALLOC_STAT
        struct dentry *stat_dentry;
 #endif
@@ -2324,10 +2321,7 @@ static unsigned long zs_shrinker_count(struct shrinker *shrinker,
 
 static void zs_unregister_shrinker(struct zs_pool *pool)
 {
-       if (pool->shrinker_enabled) {
-               unregister_shrinker(&pool->shrinker);
-               pool->shrinker_enabled = false;
-       }
+       unregister_shrinker(&pool->shrinker);
 }
 
 static int zs_register_shrinker(struct zs_pool *pool)
@@ -2426,11 +2420,13 @@ struct zs_pool *zs_create_pool(const char *name)
                goto err;
 
        /*
-        * Not critical, we still can use the pool
-        * and user can trigger compaction manually.
+        * Not critical since shrinker is only used to trigger internal
+        * defragmentation of the pool which is pretty optional thing.  If
+        * registration fails we still can use the pool normally and user can
+        * trigger compaction manually. Thus, ignore return code.
         */
-       if (zs_register_shrinker(pool) == 0)
-               pool->shrinker_enabled = true;
+       zs_register_shrinker(pool);
+
        return pool;
 
 err: