From: SJ Park <sj@kernel.org>
To: Kunwu Chan <kunwu.chan@gmail.com>
Cc: SJ Park <sj@kernel.org>, Kunwu Chan <kunwu.chan@linux.dev>,
Andrew Morton <akpm@linux-foundation.org>,
damon@lists.linux.dev, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH 05/12] mm/damon/sysfs: remove probes number validation
Date: Wed, 2 Sep 2026 07:37:06 -0700 [thread overview]
Message-ID: <20260902143706.88115-1-sj@kernel.org> (raw)
In-Reply-To: <20260902140714.4023700-1-kunwu.chan@linux.dev>
On Wed, 2 Sep 2026 22:07:13 +0800 Kunwu Chan <kunwu.chan@gmail.com> wrote:
> On Tue, 1 Sep 2026 22:47:38 -0700 SJ Park <sj@kernel.org> wrote:
[...]
> I was wondering whether DAMON_MAX_PROBES is purely a core invariant
> or also an interface constraint.
Thank you for reviewing my patch and raising this question!
>
> With this change, sysfs allows nr_probes larger than
> DAMON_MAX_PROBES and damon_sysfs_probes_add_dirs() will start creating
> probe objects before the configuration is later rejected by
> damon_valid_probe_params().
>
> Since nr_probes directly controls the number of sysfs objects created,
> do we still want to keep an early check here?
>
> I agree that the core validation is required for non-sysfs callers,
> but I am not sure whether this particular limit should be duplicated
> at the sysfs layer.
I agree the user experience may be not that good.
In my humble opinion, however, keeping code simplicity is more important than
the user experience here. After all, DAMON_SYSFS is recommended to be used by
another high level tools like DAMON user-space tool (damo) rather than human
fingers. The user-space tools like damo can do the early check.
Please feel free to let me know if you have any other opinions or questions.
Thanks,
SJ
[...]
next prev parent reply other threads:[~2026-09-02 14:37 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-02 5:47 [PATCH 00/12] mm/damon: cleanup code, add test cases, and update guidances in docs SJ Park
2026-09-02 5:47 ` [PATCH 01/12] mm/damon/core: use damon_nr_samples_per_aggr() for max merge threshold SJ Park
2026-09-02 5:53 ` sashiko-bot
2026-09-03 2:00 ` Kunwu Chan
2026-09-02 5:47 ` [PATCH 02/12] mm/damon/core: remove debug messages SJ Park
2026-09-02 5:52 ` sashiko-bot
2026-09-02 6:11 ` SJ Park
2026-09-02 6:14 ` SJ Park
2026-09-02 5:47 ` [PATCH 03/12] mm/damon/vaddr: remove a debug message SJ Park
2026-09-02 5:50 ` sashiko-bot
2026-09-03 2:24 ` Kunwu Chan
2026-09-02 5:47 ` [PATCH 04/12] mm/damon/core: validate number of probes in valid_probe_params() SJ Park
2026-09-02 6:02 ` sashiko-bot
2026-09-02 15:32 ` Kunwu Chan
2026-09-02 5:47 ` [PATCH 05/12] mm/damon/sysfs: remove probes number validation SJ Park
2026-09-02 5:59 ` sashiko-bot
2026-09-02 14:07 ` Kunwu Chan
2026-09-02 14:37 ` SJ Park [this message]
2026-09-02 15:33 ` Kunwu Chan
2026-09-02 5:47 ` [PATCH 06/12] mm/damon/tests/core-kunit: extend set_regions() test for error case SJ Park
2026-09-02 5:56 ` sashiko-bot
2026-09-02 5:47 ` [PATCH 07/12] mm/damon/tests/core-kunit: test <=0 size damon_set_regions() inputs SJ Park
2026-09-02 5:52 ` sashiko-bot
2026-09-02 5:47 ` [PATCH 08/12] mm/damon/tests/core-kunit: test overlapping ranges for set_regions() SJ Park
2026-09-02 5:56 ` sashiko-bot
2026-09-03 3:04 ` Kunwu Chan
2026-09-02 5:47 ` [PATCH 09/12] mm/damon/tests/core-kunit: test damon_nr_samples_per_aggr() SJ Park
2026-09-02 5:54 ` sashiko-bot
2026-09-02 15:08 ` Kunwu Chan
2026-09-02 15:19 ` SJ Park
2026-09-02 15:49 ` Kunwu Chan
2026-09-03 0:22 ` SJ Park
2026-09-02 5:47 ` [PATCH 10/12] selftests/damon/sysfs.sh: test hugepage_mem_bp quota goal SJ Park
2026-09-02 5:54 ` sashiko-bot
2026-09-03 3:06 ` Kunwu Chan
2026-09-02 5:47 ` [PATCH 11/12] Docs/mm/damon/maintainer-profile: update AI review for Sashiko replies SJ Park
2026-09-02 5:54 ` sashiko-bot
2026-09-02 5:47 ` [PATCH 12/12] Docs/ABI/damon: recommend subsystem doc instead of admin-guide SJ Park
2026-09-02 5:55 ` sashiko-bot
2026-09-03 3:09 ` Kunwu Chan
2026-09-02 6:16 ` [PATCH 00/12] mm/damon: cleanup code, add test cases, and update guidances in docs SJ Park
2026-09-02 22:42 ` Andrew Morton
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