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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 995F2C001DF for ; Fri, 20 Oct 2023 17:30:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 19BF18D01D2; Fri, 20 Oct 2023 13:30:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 14AAF8D0003; Fri, 20 Oct 2023 13:30:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F2E3D8D01D2; Fri, 20 Oct 2023 13:30:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id DDF748D0003 for ; Fri, 20 Oct 2023 13:30:40 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id B2811120877 for ; Fri, 20 Oct 2023 17:30:40 +0000 (UTC) X-FDA: 81366529440.10.76578B8 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf26.hostedemail.com (Postfix) with ESMTP id F17AC140022 for ; Fri, 20 Oct 2023 17:30:38 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=XIbOXKyk; spf=pass (imf26.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1697823039; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=gwvaW3hsBR/7IbhnzI54lXvXXpGp8ZhSO23TYLxUMB0=; b=bGsPzzvlncN8NabsYveJIaSCz+h6NBjfTS8zFfLSDhD8ngE2BiHQhgRWHPiuHtctmhlqhU vnyfKME4mhDa1loefsDnczb4YJkbzaxcWPJ1G/B5GiFI0Y79b3jGCvUgTc1t2R2CJj38Kl loUIdVT4dInRekJfkfcfhTrNDtsLUfk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1697823039; a=rsa-sha256; cv=none; b=WmASBLeg3HpHd9I5J+X46ihXSATChMNX3MZV+Nf04c7Vr1LmZHZ7kYUQxOv64TXkkGE7V4 RodwWj7vDrq5YMVv7JrG+SY9d6BHJXS+XXGdtu/DIftyUiY78S2DYxfyXy8tUuKvS2gpX9 AoJkaSBcPBLVZRbCqT/Vdzl3uUldYpU= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=XIbOXKyk; spf=pass (imf26.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 11E666227A; Fri, 20 Oct 2023 17:30:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83D8BC433C7; Fri, 20 Oct 2023 17:30:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1697823037; bh=cJeCmKC38qm90zyfdcG4SUKfILLYa+5rU2Q+LCqJ8lM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=XIbOXKykVs348OUb2DLZnFwaZAO6yQOODMlyMioGr7OgM6CvBy+LNZcvXM0I9N1U1 9N94CneC/tHv2yls/XwFziprrJXA1NQGwu7D3VG75vhzQMvmrGovs7eabtAjPKjT/x ncOf/qPcc1NjxqBFZynMjaCLtE3pn3839yr3DUfw= Date: Fri, 20 Oct 2023 10:30:36 -0700 From: Andrew Morton To: SeongJae Park Cc: damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, acsjakub@amazon.de Subject: Re: [PATCH 0/5] avoid divide-by-zero due to max_nr_accesses overflow Message-Id: <20231020103036.027282d16aaf56498230cc12@linux-foundation.org> In-Reply-To: <20231020171901.63994-1-sj@kernel.org> References: <20231019194924.100347-1-sj@kernel.org> <20231020171901.63994-1-sj@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: F17AC140022 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: c1suxs1k3fwatrqngsbj4f9ykkxqcp8s X-HE-Tag: 1697823038-609290 X-HE-Meta: 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 fcXyHgtT qSXwtDo3sOlEar1RL6TIX4GvZ6UKZ9AC2JaH1FQ55Y0ofMu30Z2AA5uzJ7qPHJORU07NxAtx4m9/rkDo+GWnkHa8Yn6bhA3IsxNOw6TI2yDdvSCYI2F87z7uZdQD/MCIREi/5dRqf1t7VzrMBU3KJ/Wk9DvfuiYGedM1RgoxIK+ixfh2hIsBaaGcIWfME5RHlFeHWqa9sRfBWS2DUzdDBF8OiIwEXz+RPj+Nsxjaym0tbh/b2p0ZYOTcTB2DSMB71CzGTZI78mLCoeylhiNuTVHjCy8TSehcs1yr7yyZbJ1UGE8iJrqqrfZkT7GVlh+nbbKbcAy27kt1NM6w= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 20 Oct 2023 17:19:01 +0000 SeongJae Park wrote: > On Thu, 19 Oct 2023 19:49:19 +0000 SeongJae Park wrote: > > > 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. > > Actually, the issue was reported by Jakub, and I didn't add 'Reported-by:' tags > for him. I sure Andrew could add that on his own, but I want to minimize > Andrew's load, so will send v2 of this patchset. Andrew, please let me know if > that doesn't help but only increasing your load. Editing the changelogs is far quicker than updating a patch series ;) btw, it's now conventional to add a link to the reporter's report. The new "Closes:" tag, immediately after the Reported-by:. But it's not a big deal.