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 AAE55C25B6F for ; Wed, 25 Oct 2023 23:51:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235051AbjJYXvD (ORCPT ); Wed, 25 Oct 2023 19:51:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234999AbjJYXtd (ORCPT ); Wed, 25 Oct 2023 19:49:33 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E57C1700; Wed, 25 Oct 2023 16:49:14 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 09EB9C433CA; Wed, 25 Oct 2023 23:49:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1698277754; bh=GwYfXA5tzoOCLLpThtBBCoI0RYf7i5nypn0un1JdwVQ=; h=Date:To:From:Subject:From; b=ZKZGevI8yrfkTx88Y7WnC5vBMY4Gdu6nsYTH/ZaEUkVaKfUCbKy1Qvtrvwn74jWsb iUYKpGuzfH633UKjCfiGjikdW6DHVO/cWX308UkPVEomrT3a3UvI/9QqGLAo+gg7lH hzTpooRsYU5I6NTX2CWQbauveNh3cmASHNS2Qn2Y= Date: Wed, 25 Oct 2023 16:49:13 -0700 To: mm-commits@vger.kernel.org, stable@vger.kernel.org, acsjakub@amazon.de, sj@kernel.org, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-damon-implement-a-function-for-max-nr_accesses-safe-calculation.patch removed from -mm tree Message-Id: <20231025234914.09EB9C433CA@smtp.kernel.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The quilt patch titled Subject: mm/damon: implement a function for max nr_accesses safe calculation has been removed from the -mm tree. Its filename was mm-damon-implement-a-function-for-max-nr_accesses-safe-calculation.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: SeongJae Park Subject: mm/damon: implement a function for max nr_accesses safe calculation Date: Thu, 19 Oct 2023 19:49:20 +0000 Patch series "avoid divide-by-zero due to max_nr_accesses overflow". 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. This patch (of 4): 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. Implement a function that handles the corner case. Note that this commit is not fixing the real issue since this is only introducing the safe function that will replaces the problematic divisions. The replacements will be made by followup commits, to make backporting on stable series easier. Link: https://lkml.kernel.org/r/20231019194924.100347-1-sj@kernel.org Link: https://lkml.kernel.org/r/20231019194924.100347-2-sj@kernel.org Fixes: 198f0f4c58b9 ("mm/damon/vaddr,paddr: support pageout prioritization") Signed-off-by: SeongJae Park Reported-by: Jakub Acs Cc: [5.16+] Signed-off-by: Andrew Morton --- include/linux/damon.h | 7 +++++++ 1 file changed, 7 insertions(+) --- a/include/linux/damon.h~mm-damon-implement-a-function-for-max-nr_accesses-safe-calculation +++ a/include/linux/damon.h @@ -681,6 +681,13 @@ static inline bool damon_target_has_pid( return ctx->ops.id == DAMON_OPS_VADDR || ctx->ops.id == DAMON_OPS_FVADDR; } +static inline unsigned int damon_max_nr_accesses(const struct damon_attrs *attrs) +{ + /* {aggr,sample}_interval are unsigned long, hence could overflow */ + return min(attrs->aggr_interval / attrs->sample_interval, + (unsigned long)UINT_MAX); +} + int damon_start(struct damon_ctx **ctxs, int nr_ctxs, bool exclusive); int damon_stop(struct damon_ctx **ctxs, int nr_ctxs); _ Patches currently in -mm which might be from sj@kernel.org are mm-damon-sysfs-remove-requested-targets-when-online-commit-inputs.patch