After calling debugfs_change_name function, the return value should be
checked and the old name restored. If debugfs_change_name fails, the new
name memory should be freed.

Signed-off-by: Liu Ye <liuye@kylinos.cn>
---
 mm/shrinker_debug.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c
index 794bd433cce0..20eaee3e97f7 100644
--- a/mm/shrinker_debug.c
+++ b/mm/shrinker_debug.c
@@ -214,10 +214,14 @@ int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...)
 	ret = debugfs_change_name(shrinker->debugfs_entry, "%s-%d",
 			shrinker->name, shrinker->debugfs_id);
 
+	if (ret) {
+		shrinker->name = old;
+		kfree_const(new);
+	} else {
+		kfree_const(old);
+	}
 	mutex_unlock(&shrinker_mutex);
 
-	kfree_const(old);
-
 	return ret;
 }
 EXPORT_SYMBOL(shrinker_debugfs_rename);
-- 
2.25.1

> On Mar 5, 2025, at 10:01, Liu Ye <liuye@kylinos.cn> wrote:
> 
> After calling debugfs_change_name function, the return value should be
> checked and the old name restored. If debugfs_change_name fails, the new
> name memory should be freed.

Seems it is not a big problem, no memory leak at least. The effect is that
the shrinker->name is not consistent with the name displayed in debugfs.
Right? But the improvement LGTM. So:

Reviewed-by: Muchun Song <muchun.song@linux.dev>

Thanks.

> 
> Signed-off-by: Liu Ye <liuye@kylinos.cn>
> ---
> mm/shrinker_debug.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c
> index 794bd433cce0..20eaee3e97f7 100644
> --- a/mm/shrinker_debug.c
> +++ b/mm/shrinker_debug.c
> @@ -214,10 +214,14 @@ int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...)
> ret = debugfs_change_name(shrinker->debugfs_entry, "%s-%d",
> shrinker->name, shrinker->debugfs_id);
> 
> + 	if (ret) {
> + 		shrinker->name = old;
> + 		kfree_const(new);
> + 	} else {
> + 		kfree_const(old);
> + 	}
> 	mutex_unlock(&shrinker_mutex);
> 
> - 	kfree_const(old);
> -
> 	return ret;
> }
> EXPORT_SYMBOL(shrinker_debugfs_rename);
> -- 
> 2.25.1
> 

On 3/5/25 11:17 AM, Muchun Song wrote:
> 
> 
>> On Mar 5, 2025, at 10:01, Liu Ye <liuye@kylinos.cn> wrote:
>>
>> After calling debugfs_change_name function, the return value should be
>> checked and the old name restored. If debugfs_change_name fails, the new
>> name memory should be freed.
> 
> Seems it is not a big problem, no memory leak at least. The effect is that
> the shrinker->name is not consistent with the name displayed in debugfs.
> Right? But the improvement LGTM. So:

Right, so the subject needs to be changed.

Maybe:

mm: shrinker: fix name consistency issue in shrinker_debugfs_rename()

?

BTW, it seems that the callers of shrinker_debugfs_rename() did not
process the return value of the function?

> 
> Reviewed-by: Muchun Song <muchun.song@linux.dev>
> 
> Thanks.
> 
>>
>> Signed-off-by: Liu Ye <liuye@kylinos.cn>
>> ---
>> mm/shrinker_debug.c | 8 ++++++--
>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c
>> index 794bd433cce0..20eaee3e97f7 100644
>> --- a/mm/shrinker_debug.c
>> +++ b/mm/shrinker_debug.c
>> @@ -214,10 +214,14 @@ int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...)
>> ret = debugfs_change_name(shrinker->debugfs_entry, "%s-%d",
>> shrinker->name, shrinker->debugfs_id);
>>
>> + 	if (ret) {
>> + 		shrinker->name = old;
>> + 		kfree_const(new);
>> + 	} else {
>> + 		kfree_const(old);
>> + 	}
>> 	mutex_unlock(&shrinker_mutex);
>>
>> - 	kfree_const(old);
>> -
>> 	return ret;
>> }
>> EXPORT_SYMBOL(shrinker_debugfs_rename);
>> -- 
>> 2.25.1
>>
>