Re: [RFC PATCH v1.1 08/11] mm/damon/sysfs: kobject_del() probe dirs

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [Medium] Missing `kobject_del()` in the error path of `damon_sysfs_schemes_add_dirs()` leads to deferred sysfs deletion and potential name conflicts.
--

commit 59e78cde42822b1eaae59f38d966ef1a15a1a9b6
Author: SeongJae Park <sj@kernel.org>

mm/damon/sysfs: kobject_del() probe dirs
    
This commit adds missing kobject_del() calls in the cleanup path for data
attribute probe directories. It prevents directory creation failures caused
by name conflicts when CONFIG_DEBUG_KOBJECT_RELEASE is enabled.

> diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
> index 3c349f0fe80f0..5ca45654cdd39 100644
> --- a/mm/damon/sysfs.c
> +++ b/mm/damon/sysfs.c
> @@ -1139,6 +1139,7 @@ static void damon_sysfs_probes_rm_dirs(
>  
>  	for (i = 0; i < probes->nr; i++) {
>  		damon_sysfs_probe_rm_dirs(probes_arr[i]);
> +		kobject_del(&probes_arr[i]->kobj);
>  		kobject_put(&probes_arr[i]->kobj);

[Severity: Medium]
This is a pre-existing issue, but does damon_sysfs_schemes_add_dirs()
in mm/damon/sysfs-schemes.c need a similar fix?

If kobject_init_and_add(&scheme->kobj) succeeds but the subsequent
damon_sysfs_scheme_add_dirs(scheme) fails, the error path drops the
reference without synchronously unregistering the kobject:

mm/damon/sysfs-schemes.c:damon_sysfs_schemes_add_dirs() {
        ...
out:
        damon_sysfs_schemes_rm_dirs(schemes);
        kobject_put(&scheme->kobj);
        return err;
}

Without an explicit kobject_del() here, the cleanup is deferred. If
CONFIG_DEBUG_KOBJECT_RELEASE is enabled, could retrying the operation
fail with -EEXIST due to a name collision?

>  	}
>  	probes->nr = 0;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260617144807.91441-1-sj@kernel.org?part=8