Re: [RFC PATCH v1.2 11/11] mm/damon/sysfs-schemes: kobject_del() region for populate_region error

[sashiko-bot@kernel.org]

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

Pre-existing issues:
- [High] Memory leak in the error path of damon_sysfs_scheme_add_dirs() due to skipped cleanup of the 'stats' kobject.
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commit 73251d9a8366deae80fbc88ff7d3d42f79676704
Author: SeongJae Park <sj@kernel.org>

mm/damon/sysfs-schemes: kobject_del() region for populate_region error

This patch fixes directory creation failures due to name conflicts when
CONFIG_DEBUG_KOBJECT_RELEASE is enabled. It adds a missing kobject_del()
call to properly clean up tried region directories in the error path of
damos_sysfs_populate_region_dir().

> diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
> index ebc692682481d..0b8a6f1f6b9fc 100644
> --- a/mm/damon/sysfs-schemes.c
> +++ b/mm/damon/sysfs-schemes.c
[ ... ]

[Severity: High]
This isn't a bug introduced by this patch, but while reviewing the kobject
cleanup in this file, I noticed a memory leak in the error path of
damon_sysfs_scheme_add_dirs():

mm/damon/sysfs-schemes.c:damon_sysfs_scheme_add_dirs() {
    ...
	err = damon_sysfs_scheme_set_stats(scheme);
	if (err)
		goto put_filters_watermarks_quotas_access_pattern_out;
	err = damon_sysfs_scheme_set_tried_regions(scheme);
	if (err)
		goto put_tried_regions_out;
	return 0;

put_tried_regions_out:
	kobject_put(&scheme->tried_regions->kobj);
	scheme->tried_regions = NULL;
put_filters_watermarks_quotas_access_pattern_out:
	kobject_put(&scheme->ops_filters->kobj);
    ...
}

If damon_sysfs_scheme_set_tried_regions() fails, it jumps to
put_tried_regions_out. This attempts to clean up the failed tried_regions
allocation, but then falls through to the next label.

Does this completely skip cleaning up the successfully allocated
scheme->stats->kobj? Missing a call to kobject_put(&scheme->stats->kobj)
here appears to permanently leak the stats kobject and its associated
sysfs state.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260618151517.5366-1-sj@kernel.org?part=11