The patch titled Subject: mm/damon/sysfs: cleanup intervals subdirs on attrs dir setup failure has been added to the -mm mm-new branch. Its filename is mm-damon-sysfs-cleanup-intervals-subdirs-on-attrs-dir-setup-failure.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new.
The mm-new branch of mm.git is not included in linux-next
Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days
------------------------------------------------------ From: SeongJae Park sj@kernel.org Subject: mm/damon/sysfs: cleanup intervals subdirs on attrs dir setup failure Date: Wed, 24 Dec 2025 18:30:34 -0800
Patch series "mm/damon/sysfs: free setup failures generated zombie sub-sub dirs".
Some DAMON sysfs directory setup functions generates its sub and sub-sub directories. For example, 'monitoring_attrs/' directory setup creates 'intervals/' and 'intervals/intervals_goal/' directories under 'monitoring_attrs/' directory. When such sub-sub directories are successfully made but followup setup is failed, the setup function should recursively clean up the subdirectories.
However, such setup functions are only dereferencing sub directory reference counters. As a result, under certain setup failures, the sub-sub directories keep having non-zero reference counters. It means the directories cannot be removed like zombies, and the memory for the directories cannot be freed.
The user impact of this issue is limited due to the following reasons.
When the issue happens, the zombie directories are still taking the path. Hence attempts to generate the directories again will fail, without additional memory leak. This means the upper bound memory leak is limited. Nonetheless this also implies controlling DAMON with a feature that requires the setup-failed sysfs files will be impossible until the system reboots.
Also, the setup operations are quite simple. The certain failures would hence only rarely happen, and are difficult to artificially trigger.
This patch (of 4):
When attrs/ DAMON sysfs directory setup is failed after setup of intervals/ directory, intervals/intervals_goal/ directory is not cleaned up. As a result, DAMON sysfs interface is nearly broken until the system reboots, and the memory for the unremoved directory is leaked.
Cleanup the directory under such failures.
Link: https://lkml.kernel.org/r/20251225023043.18579-1-sj@kernel.org Link: https://lkml.kernel.org/r/20251225023043.18579-2-sj@kernel.org Fixes: 8fbbcbeaafeb ("mm/damon/sysfs: implement intervals tuning goal directory") Signed-off-by: SeongJae Park sj@kernel.org Cc: chongjiapeng jiapeng.chong@linux.alibaba.com Cc: stable@vger.kernel.org # 6.15.x Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
mm/damon/sysfs.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/mm/damon/sysfs.c~mm-damon-sysfs-cleanup-intervals-subdirs-on-attrs-dir-setup-failure +++ a/mm/damon/sysfs.c @@ -792,7 +792,7 @@ static int damon_sysfs_attrs_add_dirs(st nr_regions_range = damon_sysfs_ul_range_alloc(10, 1000); if (!nr_regions_range) { err = -ENOMEM; - goto put_intervals_out; + goto rmdir_put_intervals_out; }
err = kobject_init_and_add(&nr_regions_range->kobj, @@ -806,6 +806,8 @@ static int damon_sysfs_attrs_add_dirs(st put_nr_regions_intervals_out: kobject_put(&nr_regions_range->kobj); attrs->nr_regions_range = NULL; +rmdir_put_intervals_out: + damon_sysfs_intervals_rm_dirs(intervals); put_intervals_out: kobject_put(&intervals->kobj); attrs->intervals = NULL; _
Patches currently in -mm which might be from sj@kernel.org are
mm-damon-core-remove-call_control-in-inactive-contexts.patch mm-damon-core-introduce-nr_snapshots-damos-stat.patch mm-damon-sysfs-schemes-introduce-nr_snapshots-damos-stat-file.patch docs-mm-damon-design-update-for-nr_snapshots-damos-stat.patch docs-admin-guide-mm-damon-usage-update-for-nr_snapshots-damos-stat.patch docs-abi-damon-update-for-nr_snapshots-damos-stat.patch mm-damon-update-damos-kerneldoc-for-stat-field.patch mm-damon-core-implement-max_nr_snapshots.patch mm-damon-sysfs-schemes-implement-max_nr_snapshots-file.patch docs-mm-damon-design-update-for-max_nr_snapshots.patch docs-admin-guide-mm-damon-usage-update-for-max_nr_snapshots.patch docs-abi-damon-update-for-max_nr_snapshots.patch mm-damon-core-add-trace-point-for-damos-stat-per-apply-interval.patch mm-damon-sysfs-cleanup-intervals-subdirs-on-attrs-dir-setup-failure.patch mm-damon-sysfs-cleanup-attrs-subdirs-on-context-dir-setup-failure.patch mm-damon-sysfs-scheme-cleanup-quotas-subdirs-on-scheme-dir-setup-failure.patch mm-damon-sysfs-scheme-cleanup-access_pattern-subdirs-on-scheme-dir-setup-failure.patch