From patchwork Fri Oct 20 17:23:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 15695 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:612c:2010:b0:403:3b70:6f57 with SMTP id fe16csp1213095vqb; Fri, 20 Oct 2023 10:23:26 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGnivJElwaNk3WfJAiIxQGTtMgwCwA/76mYXaolk3XOn0jPviDisKQKEIvXaSnmdOlftZ4b X-Received: by 2002:a05:6e02:150:b0:352:a1c8:6e99 with SMTP id j16-20020a056e02015000b00352a1c86e99mr2635105ilr.6.1697822606674; Fri, 20 Oct 2023 10:23:26 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1697822606; cv=none; d=google.com; s=arc-20160816; b=sFwnaUR/VBlL+ZyrMSaixqHSGTL4xYd9ITUTUYoV5LKRL8sSNo+LYcyxAF2lGuckRa ajyFDhflrL1I4Q/0B2VR+4Ir6j8mwjCYcT3gj5dTuikjxW4A8U5S7wTqknHDm/Cjz5X2 lvQb7mkBaMgMMPJJiSMZd5SMsBhDVLqToV0OIXcbu4OgALZwm/Cam/OJQxTNRS0fiajy UyHDPJMPhKDXhfaFqLumq7E4hWF1i4InOnkKtfkE+KbDu3PcSlpl0pM07uk5tLwC8n+0 s+d48gHy7xA9xF9VnVQz9KRJkWwjNShR8b05Wbt165c0RkosNKvK89OqJkjP0mTH6Crh P8Eg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from:dkim-signature; bh=9mRENkl4NOUx3H36jA8HkUdIKz6si0TG43C56zhZjxQ=; fh=vI/GIqgT+uqXYq4/+/dxLb8ThG7wUii5FmQCc4qJiNw=; b=km9uysgGdgeKW+qP2sjvHUGUZ1GXnMQeAWkONd20Ifqd8Jdax0wNjWjz4r4nM0x+PT Yc88GcOi/FLs7uIF/ghMxdCAGm9aXcy95yJpWT7FPIjH3LMrH+tLnAlCX9NsX9vQzNrY wMzU9hWG41Yhf4GBmeW026UoEqfLNCd/KQ0KenikCZ5rU1fvKJPw8xG9/2pxyR0Kd4mj ZNjg6oFsg8AF0CZXzAkQTDi9ryTvFdLF2mi5MdBSTNvOeypMrAeOSxvX8jv+6Ib1SRgs VbI0IhUFXObyJvb0ddNX+SFE7tjqObU2//vTAob8ntT9NHnhUAX2aKhVryeEthJOpMFh xL+Q== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=UQhrh7+6; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from snail.vger.email (snail.vger.email. [2620:137:e000::3:7]) by mx.google.com with ESMTPS id i190-20020a6387c7000000b0057c2f614756si2257395pge.212.2023.10.20.10.23.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Oct 2023 10:23:26 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=UQhrh7+6; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by snail.vger.email (Postfix) with ESMTP id 0416F830C309; Fri, 20 Oct 2023 10:23:26 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at snail.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377891AbjJTRXX (ORCPT + 26 others); Fri, 20 Oct 2023 13:23:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44324 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229614AbjJTRXW (ORCPT ); Fri, 20 Oct 2023 13:23:22 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BA8A41A3 for ; Fri, 20 Oct 2023 10:23:20 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6732C433C7; Fri, 20 Oct 2023 17:23:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697822600; bh=9DTH2ejZ6gRx9v5Kr+Y3Lfgwo0SmTNuA/A5IR8D58/Y=; h=From:To:Cc:Subject:Date:From; b=UQhrh7+6S/MSu4IcYRnXuy7EYcConABwkV5hydTwSyGaPGdbM+HMqPvgfmUEdx3Q2 2pBWW6qmhoe340ImjiAKa6WW0FD71QgmiHBHceMfRdW4VLA1W3NQyHUjHIXN+eXJP/ VlBL0uJMjRaOjf/o5PY5oVU6dzu7hzgNv6yKwCT7zH+CxhfMgHie2tydm/d+/n7S+N CZNwWgm3CF7e66+DDpUriULU2laVgMqusZkUK7RZkGYU/tb698rfmgSsfILGziBHQE brznPtN20sErmnwVXeT5lynnssIpxOJhevA05ao1A4x8QeQG4b4ek2Ioxqg1VwmSzs OZcVn5GEq5lGA== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , Jakub Acs , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 0/5] avoid divide-by-zero due to max_nr_accesses overflow Date: Fri, 20 Oct 2023 17:23:12 +0000 Message-Id: <20231020172317.64192-1-sj@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Fri, 20 Oct 2023 10:23:26 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1780214648704515170 X-GMAIL-MSGID: 1780296037639447523 Changes from v1 (https://lore.kernel.org/damon/20231019194924.100347-1-sj@kernel.org/) - Add Reported-by: Jakub Acs The maximum nr_accesses of given DAMON context can be calculated by dividing the aggregation interval by the sampling interval. Some logics in DAMON uses the maximum nr_accesses as a divisor. Hence, the value shouldn't be zero. Such case is avoided since DAMON avoids setting the agregation interval as samller than the sampling interval. However, since nr_accesses is unsigned int while the intervals are unsigned long, the maximum nr_accesses could be zero while casting. Avoid the divide-by-zero by implementing a function that handles the corner case (first patch), and replaces the vulnerable direct max nr_accesses calculations (remaining patches). Note that the patches for the replacements are divided for broken commits, to make backporting on required tres easier. Especially, the last patch is for a patch that not yet merged into the mainline but in mm tree. SeongJae Park (5): mm/damon: implement a function for max nr_accesses safe calculation mm/damon/core: avoid divide-by-zero during monitoring results update mm/damon/ops-common: avoid divide-by-zero during region hotness calculation mm/damon/lru_sort: avoid divide-by-zero in hot threshold calculation mm/damon/core: avoid divide-by-zero from pseudo-moving window length calculation include/linux/damon.h | 7 +++++++ mm/damon/core.c | 12 +++--------- mm/damon/lru_sort.c | 4 +--- mm/damon/ops-common.c | 5 ++--- 4 files changed, 13 insertions(+), 15 deletions(-) base-commit: e845524c56a529768a8793e96304db09134eafdf