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Wed, 02 Sep 2026 08:32:23 -0700 (PDT) From: Kunwu Chan X-Google-Original-From: Kunwu Chan To: SJ Park Cc: Kunwu Chan , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kunwu Chan Subject: Re: [PATCH 04/12] mm/damon/core: validate number of probes in valid_probe_params() Date: Wed, 2 Sep 2026 23:32:15 +0800 Message-ID: <20260902153216.4034305-1-kunwu.chan@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260902054747.99370-5-sj@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 28AEF1C0013 X-Stat-Signature: wiapae6ji9smwma9kxz85nngcw4643dr X-Rspam-User: X-HE-Tag: 1788363146-193948 X-HE-Meta: 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 SSoL8xkI 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 1 Sep 2026 22:47:37 -0700 SJ Park wrote: > Each DAMON context is allowed to have only up to DAMON_MAX_PROBES > probes. The central place for validating DAMON probe parameters, > damon_valid_probe_params(), is not validating the upper limit, though. > Do the validation. > > Signed-off-by: SJ Park > --- > mm/damon/core.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/mm/damon/core.c b/mm/damon/core.c > index 4d28eb033fc4a..c010f686d033e 100644 > --- a/mm/damon/core.c > +++ b/mm/damon/core.c > @@ -1420,6 +1420,13 @@ static bool damon_valid_probe_params(struct damon_ctx *ctx) > unsigned char max_probe_hits; > struct damon_probe *probe; > unsigned int wsum, wsum_to_add; > + int nr_probes; > + > + nr_probes = 0; > + damon_for_each_probe(probe, ctx) > + nr_probes++; > + if (nr_probes > DAMON_MAX_PROBES) > + return false; Hi SJ, Thanks for the explanation. I agree that `DAMON_MAX_PROBES` is better enforced in the core layer, so that all callers share the same validation path without duplicating the limit in the sysfs layer. Reviewed-by: Kunwu Chan Thanks, Kunwu > > if (!damon_has_probe_weights(ctx)) > return true; > -- > 2.47.3 > Sent using hkml (https://github.com/sjp38/hackermail)