mm/zsmalloc: don't fail if can't create debugfs info

Change the return type of zs_pool_stat_create() to void, and remove the
logic to abort pool creation if the stat debugfs dir/file could not be
created.

The debugfs stat file is for debugging/information only, and doesn't
affect operation of zsmalloc; there is no reason to abort creating the
pool if the stat file can't be created.  This was seen with zswap, which
used the same name for all pool creations, which caused zsmalloc to fail
to create a second pool for zswap if CONFIG_ZSMALLOC_STAT was enabled.
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Reviewed-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Dan Streetman <dan.streetman@canonical.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/zsmalloc.c

@@ -573,17 +573,17 @@ static const struct file_operations zs_stat_size_ops = {
 	.release        = single_release,
 };
 
-static int zs_pool_stat_create(struct zs_pool *pool, const char *name)
+static void zs_pool_stat_create(struct zs_pool *pool, const char *name)
 {
 	struct dentry *entry;
 
 	if (!zs_stat_root)
-		return -ENODEV;
+		return;
 
 	entry = debugfs_create_dir(name, zs_stat_root);
 	if (!entry) {
 		pr_warn("debugfs dir <%s> creation failed\n", name);
-		return -ENOMEM;
+		return;
 	}
 	pool->stat_dentry = entry;
 
@@ -592,10 +592,8 @@ static int zs_pool_stat_create(struct zs_pool *pool, const char *name)
 	if (!entry) {
 		pr_warn("%s: debugfs file entry <%s> creation failed\n",
 				name, "classes");
-		return -ENOMEM;
+		return;
 	}
-
-	return 0;
 }
 
 static void zs_pool_stat_destroy(struct zs_pool *pool)
@@ -613,9 +611,8 @@ static void __exit zs_stat_exit(void)
 {
 }
 
-static inline int zs_pool_stat_create(struct zs_pool *pool, const char *name)
+static inline void zs_pool_stat_create(struct zs_pool *pool, const char *name)
 {
-	return 0;
 }
 
 static inline void zs_pool_stat_destroy(struct zs_pool *pool)
@@ -623,7 +620,6 @@ static inline void zs_pool_stat_destroy(struct zs_pool *pool)
 }
 #endif
 
-
 /*
  * For each size class, zspages are divided into different groups
  * depending on how "full" they are. This was done so that we could
@@ -1952,8 +1948,8 @@ struct zs_pool *zs_create_pool(const char *name)
 		prev_class = class;
 	}
 
-	if (zs_pool_stat_create(pool, name))
-		goto err;
+	/* debug only, don't abort if it fails */
+	zs_pool_stat_create(pool, name);
 
 	/*
 	 * Not critical, we still can use the pool