From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E0D1326B0A9 for ; Tue, 16 Jun 2026 15:24:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781623453; cv=none; b=SVm/Iht/MhuSBZUKVizfWI/O/NejbRtlLz1LE2jujuEei0X6sWkdmZ5pOIngPJThLOcdqK9ALjw1lk4T5Wy3UaFpoX5VXuHDb1IwnKSebrScARFInfzizaMOi0sBcq5vuCoSk+fmUgAktevymnN6rmt8jTOcoCCKaKlHxWTioSY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781623453; c=relaxed/simple; bh=zR00yLDCx3Zpw+MXabJHUhTy77xG9STeMAFJqva1brM=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=r7nLyBakdPoCGe9IDDM+Pgxzm0ChTYA/KpeXFsNvz4+u7wpTYzu9sZC/w6kfvIjb8GswjJuftn+fnNySwQgQlBu1Pv5pSlMN+Mfui2oy1dAOzBAjLn6xbsC3yMVwfSidHLV6LotVCe+FlmUrqxMfXCFOAF0iAvNSC0hjMI7NeB4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DkvZXDIN; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DkvZXDIN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD0241F000E9; Tue, 16 Jun 2026 15:24:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781623452; bh=1Nvs5Z4hIjaBsS6AOcI8tjpH3s+Y9DlpGYKNzqYIW48=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=DkvZXDINCKhxJj5qnglPjv1NakoYWH5ylA2wAuZ2/U1n3Wqver6C9y7dSn8yz0IsK eIxqy8IitFknNdJVvrr4Awa8HTWMr2MmCSF8H6pPCCtlHgwZv+S8Hkq6cPkEMjf5Wv fIuKe2Nd7WP6HTsqRofyASYsrHP3Sm7gkg8Z9NTEz8VHkZ7JSnkLD7HuFvky6a0dby YEXvFt71GvsPDT1XZeWbF8QFYm9Eh2O6ORrn/kb7NwH9/daqViFUngO3whX0257t9j qIYHdy8GQyx3PkfzdtQVXWyM0fWizTZH67tJ0o3tfm9ptxZQOO4sdfIVCrogdLBkEc 8oGzIxnskP9bA== From: sashiko-bot@kernel.org Subject: Re: [RFC PATCH 9/9] mm/damon/sysfs: kobject_del() probe dirs Reply-To: sashiko-reviews@lists.linux.dev To: "SeongJae Park" Cc: damon@lists.linux.dev In-Reply-To: <20260616150844.88305-10-sj@kernel.org> References: <20260616150844.88305-10-sj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 16 Jun 2026 15:24:11 +0000 Message-Id: <20260616152411.AD0241F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: Pre-existing issues: - [Medium] The patch adds `kobject_del()` to `damon_sysfs_probes_rm_dirs()`= to fix sysfs name collisions caused by delayed kobject releases, but misse= s the exact same flaw on the error paths of `damon_sysfs_probes_add_dirs()`= and multiple other array-building functions. This leaves the system vulner= able to `-EEXIST` failures upon retry after an error. -- commit 4a5efc2733f009261a15fd64a4d901ca19499bb5 Author: SeongJae Park mm/damon/sysfs: kobject_del() probe dirs This commit fixes a directory creation failure caused by name conflicts when CONFIG_DEBUG_KOBJECT_RELEASE is enabled. It adds missing kobject_del() calls during the removal of probe directories. > diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c > index 04725ff3d9f3c..04ca0a34e1206 100644 > --- a/mm/damon/sysfs.c > +++ b/mm/damon/sysfs.c > @@ -1139,6 +1139,7 @@ static void damon_sysfs_probes_rm_dirs( > =20 > for (i =3D 0; i < probes->nr; i++) { > damon_sysfs_probe_rm_dirs(probes_arr[i]); > + kobject_del(&probes_arr[i]->kobj); [Severity: Medium] This is a pre-existing issue, but it looks like the same lack of kobject_del() on error paths could cause name collisions upon retry. For example, if damon_sysfs_probe_add_dirs() fails inside damon_sysfs_probes_add_dirs(), the error path drops the probe by calling kobject_put() without kobject_del(): mm/damon/sysfs.c:damon_sysfs_probes_add_dirs() { ... err =3D damon_sysfs_probe_add_dirs(probe); if (err) { kobject_put(&probe->kobj); damon_sysfs_probes_rm_dirs(probes); return err; } ... } Under CONFIG_DEBUG_KOBJECT_RELEASE, if userspace immediately retries the operation after an error, won't kobject_init_and_add() fail with -EEXIST due to a name collision with the lingering directory? Should we also add synchronous sysfs deletion via kobject_del() to these similar error paths? - mm/damon/sysfs.c:damon_sysfs_targets_add_dirs() - mm/damon/sysfs.c:damon_sysfs_contexts_add_dirs() - mm/damon/sysfs.c:damon_sysfs_kdamonds_add_dirs() - mm/damon/sysfs-schemes.c:damon_sysfs_schemes_add_dirs() > kobject_put(&probes_arr[i]->kobj); > } > probes->nr =3D 0; --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260616150844.8830= 5-1-sj@kernel.org?part=3D9