From nobody Thu Apr 9 16:24:11 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 91B5633C198; Sat, 7 Mar 2026 19:54:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772913247; cv=none; b=pZbD+f+UU0EdrI4pseqH/7SPrY0hhs2xf81txGVnF7FG1QktAN8UIMNUtP2ZJxI2apynC+TJBXG7UJmmiW8QNOKNkuodWAhtjn+4+QmMWaCIvrQCY1RKcJ4TT5u/bIFaCrpnkd0Huc+rwdHPeqAkd5RCJRxYRT0gSfeQ97S1BjU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772913247; c=relaxed/simple; bh=JAJpE6K1OeR9GVQIfwKv0nXxU/6wR4CIuDdh8NIuA0g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=f5+WwECWcVhWkqtWedoSyhXQutOUW/9hjftjNSiML4TUH4hH9mcOy1a2NlERGsnvbGzL4SWzhEVcv6SxsUMTXhDmFOAZSW5rifRi2IHiDW0t9P4oE09nb/wpYgPI+eA9G+x0A70BzkdWoceNAImhk6EmViZfqMZPSjlgBgX6Luw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KvI/3slL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KvI/3slL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42748C2BCB2; Sat, 7 Mar 2026 19:54:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772913247; bh=JAJpE6K1OeR9GVQIfwKv0nXxU/6wR4CIuDdh8NIuA0g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KvI/3slLTixTWJPuy8wRgOO7cNbeRJ12UJMkkQu4o6PX9jqH5pgpLj1u5hXria7XV HA16d7/8v+ycDnzUleKLRhdztkVi/mjdmyPnLBmjWEi9T71/8P7MsOb1KqA5fxX3jF 9ec4n7LyCq2DJI882zt8zstCfyRmShCocp7SmfjWy0DGW6OALxOqk3gE7Gu5dUlLyF wVLV2AAlFe39YCEm+TfNs8eK9QrS3DTNi7tkoPoy0yJYvUdjyoX1qjL+m9kubIV5Dw Fd4kfCQ7zKWBNMvGhR4a7tuGEhVi8occ9UK4G4IKK+7sYwmE9EgQSowLHpSXTvxC0V H9FLAC4L+lVrQ== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 1/7] mm/damon/core: use mult_frac() Date: Sat, 7 Mar 2026 11:53:49 -0800 Message-ID: <20260307195356.203753-2-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260307195356.203753-1-sj@kernel.org> References: <20260307195356.203753-1-sj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" There are multiple places in core code that do open-code rate calculations. Use mult_frac(), which is developed for doing that in a way more safe from overflow and precision loss. Signed-off-by: SeongJae Park --- mm/damon/core.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/mm/damon/core.c b/mm/damon/core.c index cd2d7a8e3fe92..4e931f7380477 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -665,7 +665,7 @@ static unsigned int damon_accesses_bp_to_nr_accesses( static unsigned int damon_nr_accesses_to_accesses_bp( unsigned int nr_accesses, struct damon_attrs *attrs) { - return nr_accesses * 10000 / damon_max_nr_accesses(attrs); + return mult_frac(nr_accesses, 10000, damon_max_nr_accesses(attrs)); } =20 static unsigned int damon_nr_accesses_for_new_attrs(unsigned int nr_access= es, @@ -1722,7 +1722,7 @@ static unsigned long damon_get_intervals_score(struct= damon_ctx *c) } target_access_events =3D max_access_events * goal_bp / 10000; target_access_events =3D target_access_events ? : 1; - return access_events * 10000 / target_access_events; + return mult_frac(access_events, 10000, target_access_events); } =20 static unsigned long damon_feed_loop_next_input(unsigned long last_input, @@ -2202,7 +2202,7 @@ static __kernel_ulong_t damos_get_node_mem_bp( numerator =3D i.totalram - i.freeram; else /* DAMOS_QUOTA_NODE_MEM_FREE_BP */ numerator =3D i.freeram; - return numerator * 10000 / i.totalram; + return mult_frac(numerator, 10000, i.totalram); } =20 static unsigned long damos_get_node_memcg_used_bp( @@ -2235,7 +2235,7 @@ static unsigned long damos_get_node_memcg_used_bp( numerator =3D used_pages; else /* DAMOS_QUOTA_NODE_MEMCG_FREE_BP */ numerator =3D i.totalram - used_pages; - return numerator * 10000 / i.totalram; + return mult_frac(numerator, 10000, i.totalram); } #else static __kernel_ulong_t damos_get_node_mem_bp( @@ -2265,8 +2265,8 @@ static unsigned int damos_get_in_active_mem_bp(bool a= ctive_ratio) global_node_page_state(NR_LRU_BASE + LRU_INACTIVE_FILE); total =3D active + inactive; if (active_ratio) - return active * 10000 / total; - return inactive * 10000 / total; + return mult_frac(active, 10000, total); + return mult_frac(inactive, 10000, total); } =20 static void damos_set_quota_goal_current_value(struct damos_quota_goal *go= al) @@ -2309,8 +2309,8 @@ static unsigned long damos_quota_score(struct damos_q= uota *quota) damos_for_each_quota_goal(goal, quota) { damos_set_quota_goal_current_value(goal); highest_score =3D max(highest_score, - goal->current_value * 10000 / - goal->target_value); + mult_frac(goal->current_value, 10000, + goal->target_value)); } =20 return highest_score; @@ -2340,8 +2340,8 @@ static void damos_set_effective_quota(struct damos_qu= ota *quota) =20 if (quota->ms) { if (quota->total_charged_ns) - throughput =3D mult_frac(quota->total_charged_sz, 1000000, - quota->total_charged_ns); + throughput =3D mult_frac(quota->total_charged_sz, + 1000000, quota->total_charged_ns); else throughput =3D PAGE_SIZE * 1024; esz =3D min(throughput * quota->ms, esz); --=20 2.47.3