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 F32E3420E8A; Thu, 9 Jul 2026 14:06:06 +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=1783605969; cv=none; b=lMqu3HgcjhuXWgnLJHn5pF4IlWzMqS0Sd1AqwbXj6NnWr2sltJumiB3PkrApy+ExYfHU3IZQizyAFxCbyPAaVLsVBJIX3LDbucRKVatB+Cko2nGY+0QHcoUaZRbGNUIv6r6RilWa6M3vvc4kXnohU4WSkcWmE12i2iZgq9M65bE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783605969; c=relaxed/simple; bh=m097nX+o3GUQ1us51vIEofHr/BQDydOSq4G5qjcxZJ8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CL/+15mwO1RI4qeDLM9pvDMR6vfW1v2RkgSeYiujpxm7ITkBmGFRLRdLvEjRQNsM7TzXMeKFNSdtc+f7VRsd+7aoBnPODRc/dO/XIoKvrfAQV56J6CfLg9X9B+CmfWi72Sg9jLo4CkEQ1s+SHr0MIMwPFC3EfzFTjyhfs9bvsJg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=a6W1hRdy; 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="a6W1hRdy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B32401F00A3F; Thu, 9 Jul 2026 14:06:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783605966; bh=J7ZtSpW2RnXSKPujLfG/ONrU6HhGNSKvAXYdnpd8R5s=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=a6W1hRdyqWBuDMlJyNXHSFZ+nwUAdFWZUd8a6SVHWFk5dAvmXelrl0K/7J3L4Uroi aZFvvcmjamabfjrofUoq6Y/tF1TuH6TRbaxuQnt+QtSrh5n5+frsNqhW8M7ng7Gshw RZLyoUHCqdmrcnUwDhwbneAXwOtaJYx5TrarEYkBvYWmMbFL9SKlvT/NUw6L5pbjD+ 46YRdelNH5WVUz6z4qQ3WcwvKhgSj4LO/zE0VFNm1ianeNXAJ5AlAczM6C+QwHHLLT zoR31M5bKPh7CBXJj1vmtznhSgx479gpRDZQ2sV+E5OiWHyYRxYK1WPkADzz10kaK1 7ZlHTq/V9hTsQ== From: SJ Park To: Cc: SJ Park , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v1.2 09/19] mm/damon/core: disallow probe_hits overflow on attrs only monitoring Date: Thu, 9 Jul 2026 07:05:47 -0700 Message-ID: <20260709140600.90950-10-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260709140600.90950-1-sj@kernel.org> References: <20260709140600.90950-1-sj@kernel.org> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When any damon_probe->weight is set, DAMON will do only probe monitoring. probe_hits is 'unsigned char'. It could overflow when the aggregation interval is larger than the sampling interval times 256. damon_as_probe_weights() always return false, so such overflow cannot happen. Even if it happens, it only degrades the monitoring results. That said, the overflow is not intentional. It is better to be prevented as long as the cost is not expensive. Disallow the overflow by adding a validation logic on the core layer parameters validation function. Signed-off-by: SJ Park --- mm/damon/core.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 7d49420ea26c4..4f1425e56950b 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -1332,6 +1332,19 @@ static void damos_set_filters_default_reject(struct damos *s) damos_filters_default_reject(&s->ops_filters); } +static bool damon_valid_probe_params(struct damon_ctx *ctx) +{ + unsigned long sample_interval; + + if (!damon_has_probe_weights(ctx)) + return true; + + sample_interval = ctx->attrs.sample_interval ? : 1; + if (ctx->attrs.aggr_interval / sample_interval > U8_MAX) + return false; + return true; +} + /* * damos_commit_dests() - Copy migration destinations from @src to @dst. * @dst: Destination structure to update. @@ -1736,6 +1749,9 @@ static int __damon_commit_ctx(struct damon_ctx *dst, struct damon_ctx *src) } } + if (!damon_valid_probe_params(src)) + return -EINVAL; + err = damon_commit_schemes(dst, src); if (err) return err; -- 2.47.3