From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12F19C001DF for ; Fri, 20 Oct 2023 17:20:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229614AbjJTRUN (ORCPT ); Fri, 20 Oct 2023 13:20:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45564 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229928AbjJTRUM (ORCPT ); Fri, 20 Oct 2023 13:20:12 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C91411B for ; Fri, 20 Oct 2023 10:20:10 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9CBC6C433C8; Fri, 20 Oct 2023 17:20:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1697822409; bh=0Jl5TG7tOzbMBGPygq3s9lxzCb8SDE2g8mqcax8QtI0=; h=Date:To:From:Subject:From; b=cp0Z5XdYClMeXVRdV5As6UlveIbyIOFOMFhMWWIcDwpgAknTz9u5iNrC8GyHaDqC4 n8yQlcSxFtzXYQhbUsp66H4AMC8pfQ5bZ4vt8hvHvrvP716Bu2S1sKMOP2c6cEOeDu vk3lj6mfkYIIMmpQbb+REgI5uL/2O9XRqMCU6Fx0= Date: Fri, 20 Oct 2023 10:20:09 -0700 To: mm-commits@vger.kernel.org, sj@kernel.org, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-damon-core-avoid-divide-by-zero-from-pseudo-moving-window-length-calculation.patch added to mm-unstable branch Message-Id: <20231020172009.9CBC6C433C8@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm/damon/core: avoid divide-by-zero from pseudo-moving window length calculation has been added to the -mm mm-unstable branch. Its filename is mm-damon-core-avoid-divide-by-zero-from-pseudo-moving-window-length-calculation.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-core-avoid-divide-by-zero-from-pseudo-moving-window-length-calculation.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: SeongJae Park Subject: mm/damon/core: avoid divide-by-zero from pseudo-moving window length calculation Date: Thu, 19 Oct 2023 19:49:24 +0000 When calculating the pseudo-moving access rate, DAMON divides some values by the maximum nr_accesses. However, due to the type of the related variables, simple division-based calculation of the divisor can return zero. As a result, divide-by-zero is possible. Fix it by using damon_max_nr_accesses(), which handles the case. Note that this is a fix for a commit that not in the mainline but mm tree. Link: https://lkml.kernel.org/r/20231019194924.100347-6-sj@kernel.org Fixes: ace30fb21af5 ("mm/damon/core: use pseudo-moving sum for nr_accesses_bp") Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton --- mm/damon/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/damon/core.c~mm-damon-core-avoid-divide-by-zero-from-pseudo-moving-window-length-calculation +++ a/mm/damon/core.c @@ -1665,7 +1665,7 @@ void damon_update_region_access_rate(str * aggr_interval, owing to validation of damon_set_attrs(). */ if (attrs->sample_interval) - len_window = attrs->aggr_interval / attrs->sample_interval; + len_window = damon_max_nr_accesses(attrs); r->nr_accesses_bp = damon_moving_sum(r->nr_accesses_bp, r->last_nr_accesses * 10000, len_window, accessed ? 10000 : 0); _ Patches currently in -mm which might be from sj@kernel.org are mm-damon-implement-a-function-for-max-nr_accesses-safe-calculation.patch mm-damon-core-avoid-divide-by-zero-during-monitoring-results-update.patch mm-damon-ops-common-avoid-divide-by-zero-during-region-hotness-calculation.patch mm-damon-lru_sort-avoid-divide-by-zero-in-hot-threshold-calculation.patch mm-damon-core-avoid-divide-by-zero-from-pseudo-moving-window-length-calculation.patch