From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793633493; b=iCp+mi0nsnnTjVnO0/4LF0jGT2illZN6gdDP2Ejr0+fYigxySxUugvMIQ2MvPlKsMmON SSOSyyh8OwK9hyDDKpSqzUhcAk4wexDXcK30MHSQb1flHrK8DhBqAf+oLtpd5xIQ+St4d feLRjUni3Wh5hBucSlPJ0WCzABuLrZ7fmQZUFFiyn8KaZ+D21e/vb0pQ4WQ8vlZl7pv6r tm839sO7eenE8opYPGMVf7KVhM4IC8sKbzGk3CG0nYC1WbazsZekjS92a10NNMkRlMhJN Sp1x4OpYFKfnGzi1LUKsiRmrctl25pEDIdRcID5L5N++uyBc0W2kPJwnHpXeL1h4qVA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793633493; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=L32s6S0vUKZsiYS7pN7hr8gAcikEUWWmZIDjAqEYZW0=; b=TVbfRUGL9pfKrfTWghIwHIPDetszkWg0Ah+3YbcVITASXOjr8qlWODdBMvTC2Yxyhplo 7oHFek1/QdlzkabH848pf/ltdAdWnPYKyUbmEZr6rsTNBlQc9SFFHCQu0LdkshSkNAfqx +KbhOebP/klHy+s954bUBXkOX95JafyaoS3PZXQGEtkkh8MHpG8lTi2nId5kMrFUbAM/E xqNNwAeUPa4WoRO76P8SvM3VdL+l1lEEr0yIn9CFeRHycucdLM5GPN955iAWImjC8wIJD P+/Y/QlVLUzH3AqUuX0uvq8ggeIBrQ3yabrPKj6scIuGRgmUvsMseuPNdbH3JHg+PVg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=nvG5R6ZD; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C5E9A60D5454 for ; Mon, 2 Nov 2026 15:31:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=nvG5R6ZD Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83D761F00A17; Mon, 2 Nov 2026 15:31:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793633492; bh=L32s6S0vUKZsiYS7pN7hr8gAcikEUWWmZIDjAqEYZW0=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=nvG5R6ZDPMwH2wVjQZpK8fjdI+B78aM7qYpf3uOVesGkjiUqzQDil9G+KKVzhB+Yo qgUeqGrwGDLMB6vqLqxuS2Z4R5K95GqhS8vkCFNHUKEqa258MgsZO5vRNxMHSzksPE zH6GkJCIEI/uHliUGY7EAcJ13CQ0NxQ6dWDolULPrpVsEVfaXZdIzQDDXTdoMkVsRw 3Yyk0qQhHvm2n4nzYJzFdCscRGdKzy0iqOm7y4tEijtb96vQLDyBOlm+P3/vT1BAh9 cbbEKvaRS50j1d91g9ebAHecDQR2S1B220pvl5TNVlye+tXY41yZt/sgtItDJuUC2k diA2ZhC2c6r5g== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH 4/9] mm/damon/stat: avoid 32-bit overflow in idle percentiles Reply-To: sashiko-reviews@lists.linux.dev To: "SJ Park" Cc: damon@lists.linux.dev In-Reply-To: <20261102150757.93058-5-sj@kernel.org> References: <20261102150757.93058-1-sj@kernel.org> <20261102150757.93058-5-sj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 02 Nov 2026 15:31:32 +0000 X-Mailing-List: damon@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > From: Aveline Noir >=20 > On 32-bit, accounted_bytes * 100 can wrap before division by total_sz. > Some entries in memory_idle_ms_percentiles then keep their old values > instead of being updated. >=20 > For example, a 256 MiB i386 QEMU guest reported p0=3D19200 ms, but p50 and > p100 were both zero. The issue was also shared with another mail [1]. >=20 > Cast accounted_bytes to u64 before multiplying and use div64_ul() for > the division. Compute the percentage once per region. >=20 > Link: https://lore.kernel.org/r/CANOyQmHad1vamnZT12M5yPrJ69=3D=3DPt1U0+MG= w6u0MuNtr-DRCw@mail.gmail.com [1] > Link: https://lore.kernel.org/179207592479.3.11595453180868898703@gmail.c= om > Cc: Andrew Morton > Signed-off-by: Aveline Noir > Reviewed-by: SJ Park > Signed-off-by: SJ Park Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261102150757.9305= 8-1-sj@kernel.org?part=3D4