Re: [RFC PATCH v2.2 25/28] mm/damon/sysfs-schemes: move memcg_path_to_id() to sysfs-common

[SeongJae Park <sj@kernel.org>]

On Fri, 15 May 2026 01:24:19 +0000 sashiko-bot@kernel.org wrote:

> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] Undocumented bug fix / behavioral change in a refactoring commit.
> --
> 
> commit e622beadadffa95a924ccd6dd1b387669e2ef39c
> Author: SeongJae Park <sj@kernel.org>
> 
> mm/damon/sysfs-schemes: move memcg_path_to_id() to sysfs-common
> 
> This commit moves memcg_path_to_id() from sysfs-schemes.c to sysfs-common.c
> and makes it non-static so it can be reused by subsequent commits.
> 
> > diff --git a/mm/damon/sysfs-common.c b/mm/damon/sysfs-common.c
> > index 83e24a9b5a0db..bdc6ae2639e4f 100644
> > --- a/mm/damon/sysfs-common.c
> > +++ b/mm/damon/sysfs-common.c
> [ ... ]
> > @@ -104,3 +104,44 @@ const struct kobj_type damon_sysfs_ul_range_ktype = {
> [ ... ]
> > +int damon_sysfs_memcg_path_to_id(char *memcg_path, u64 *id)
> > +{
> [ ... ]
> > +	for (memcg = mem_cgroup_iter(NULL, NULL, NULL); memcg;
> > +			memcg = mem_cgroup_iter(NULL, memcg, NULL)) {
> > +		/* skip offlined memcg */
> > +		if (!mem_cgroup_online(memcg))
> > +			continue;
> > +		if (damon_sysfs_memcg_path_eq(memcg, path, memcg_path)) {
> > +			*id = mem_cgroup_id(memcg);
> > +			found = true;
> > +			mem_cgroup_iter_break(NULL, memcg);
> > +			break;
> > +		}
> > +	}
> 
> This isn't a bug in the new code, but the commit message describes this as a
> pure refactoring change to move the function. However, the newly moved
> version adds a call to mem_cgroup_iter_break() before breaking out of the
> loop, which was missing in the original sysfs-schemes.c implementation.
> 
> While this correctly fixes a pre-existing memcg reference leak, should this
> fix be separated into its own commit? Bundling the functional bug fix with
> the refactoring might cause it to miss backports to stable kernels, since
> there is no Fixes: tag or mention of the fix in the commit message.

Actually the bug fix is in mm-hotfixes branch, while this series is based on
mm-stable, due to Sashiko patch apply failure.  So, this is no problem when the
series is based on mm-unstable or mm-new, which will be when it drops RFC.


Thanks,
SJ

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