2016-05-19 23:18 GMT+08:00 Dan Streetman <ddstreet@xxxxxxxx>:
> 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: Dan Streetman <ddstreet@xxxxxxxx>
> Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
> Cc: Dan Streetman <dan.streetman@xxxxxxxxxxxxx>
> Cc: Minchan Kim <minchan@xxxxxxxxxx>
>
> ---
> Changes since v1:
> -add pr_warn to all stat failure cases
> -do not prevent module loading on stat failure
>
Reviewed-by: Ganesh Mahendran <opensource.ganesh@xxxxxxxxx>
> mm/zsmalloc.c | 51 ++++++++++++++++++++++-----------------------------
> 1 file changed, 22 insertions(+), 29 deletions(-)
>
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index aba39a2..b6d4f25 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -45,6 +45,8 @@
> *
> */
>
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> #include <linux/module.h>
> #include <linux/kernel.h>
> #include <linux/sched.h>
> @@ -483,16 +485,16 @@ static inline unsigned long zs_stat_get(struct size_class *class,
>
> #ifdef CONFIG_ZSMALLOC_STAT
>
> -static int __init zs_stat_init(void)
> +static void __init zs_stat_init(void)
> {
> - if (!debugfs_initialized())
> - return -ENODEV;
> + if (!debugfs_initialized()) {
> + pr_warn("debugfs not available, stat dir not created\n");
> + return;
> + }
>
> zs_stat_root = debugfs_create_dir("zsmalloc", NULL);
> if (!zs_stat_root)
> - return -ENOMEM;
> -
> - return 0;
> + pr_warn("debugfs 'zsmalloc' stat dir creation failed\n");
> }
>
> static void __exit zs_stat_exit(void)
> @@ -573,17 +575,19 @@ 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;
> + if (!zs_stat_root) {
> + pr_warn("no root stat dir, not creating <%s> stat dir\n", name);
> + 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 +596,9 @@ 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;
> + debugfs_remove_recursive(pool->stat_dentry);
> + pool->stat_dentry = NULL;
> }
> -
> - return 0;
> }
>
> static void zs_pool_stat_destroy(struct zs_pool *pool)
> @@ -604,18 +607,16 @@ static void zs_pool_stat_destroy(struct zs_pool *pool)
> }
>
> #else /* CONFIG_ZSMALLOC_STAT */
> -static int __init zs_stat_init(void)
> +static void __init zs_stat_init(void)
> {
> - return 0;
> }
>
> 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 +624,6 @@ 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 +1952,8 @@ 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
> @@ -2015,17 +2015,10 @@ static int __init zs_init(void)
> zpool_register_driver(&zs_zpool_driver);
> #endif
>
> - ret = zs_stat_init();
> - if (ret) {
> - pr_err("zs stat initialization failed\n");
> - goto stat_fail;
> - }
> + zs_stat_init();
> +
> return 0;
>
> -stat_fail:
> -#ifdef CONFIG_ZPOOL
> - zpool_unregister_driver(&zs_zpool_driver);
> -#endif
> notifier_fail:
> zs_unregister_cpu_notifier();
>
> --
> 2.7.4
>
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