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 4A971C77B7C for ; Fri, 26 May 2023 19:35:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AA322900004; Fri, 26 May 2023 15:35:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A53A1900002; Fri, 26 May 2023 15:35:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 91AFC900004; Fri, 26 May 2023 15:35:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 81EFC900002 for ; Fri, 26 May 2023 15:35:27 -0400 (EDT) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 347FCAED32 for ; Fri, 26 May 2023 19:35:27 +0000 (UTC) X-FDA: 80833410294.22.44493CF Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf03.hostedemail.com (Postfix) with ESMTP id 70F2620009 for ; Fri, 26 May 2023 19:35:25 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=Mw2R36mU; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf03.hostedemail.com: domain of sj@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=sj@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1685129725; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=8romIX85D4OBHtWltWUODAU2SRYOjVW+fjymVe7tBqw=; b=rbEcgTmWgKOw3STZq2G/B9GeeeYkVSCzUPpgTMLhVd5ZeS7ulXziUD6LYqIbxIFFfCctEY JOyymmraW8NS5uWfB7DCxYWX65lZlQB7oC3VdxCJNrIQ8Lf+Xko8YF3bFCotgHufCwBooK qqeQtkWmwwNnFmSIhoKJYD0NzM2QeBY= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=Mw2R36mU; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf03.hostedemail.com: domain of sj@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=sj@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1685129725; a=rsa-sha256; cv=none; b=tSKE6jo4ED2ToOLNgw72szYXcal1fB6ip1zIT+q8Alr5z2RsJYwfHtGFr9aeqBeF3Vnk/V MuI8vWrYNAKQef7DabXcrDloc0XW2wyL6nA6cF0FFFF/AQ//izUSYpY4O9RvQ/RC+fa3bI JNzl11Z76LGJhhgxWcSN2zKYfmkYRNY= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6530765310; Fri, 26 May 2023 19:35:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 21280C433D2; Fri, 26 May 2023 19:35:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1685129723; bh=hrXnPJh/IHKl7DDBAAfTeqFjAiG1/nHeuB1mCrXtIxc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Mw2R36mU/rvchgfsAwGQYlRZa8+xIa3vvVi9pcrJ8B0+yKO7PcH8+WFZDFc52UCWd CPriTpOkoyx/RKHKD9TI6fubLQK5kngHwkKitATbfmUTZokHjsDmDYMYBD9z8FvOyy /mUN87nG9OjpksX8kRieuRsfJp2Jy+olXVFOJoVXq200WQk923ycsVTe8LwSTiAp9j Zmz5Th4Qw42sYKzNnPBWoFN7DlX6ukrhPHwkj6Dfg0FXgo7+Q34xPTc9KICMSH3CXu 4hr+I+dXx11QU0gDut72zqPcNGpd2ZdvexAB1z4zhP4L1V7zhN/9K7IRcZXdLJ5e2t llEtA/HWdqjTQ== From: SeongJae Park To: SeongJae Park Cc: Kefeng Wang , syzbot , akpm@linux-foundation.org, damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [damon?] divide error in damon_set_attrs Date: Fri, 26 May 2023 19:35:21 +0000 Message-Id: <20230526193521.162787-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230526185409.92039-1-sj@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 70F2620009 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 6mq8n68tiro6j9haeqeqwph1qjwa4fr5 X-HE-Tag: 1685129725-85587 X-HE-Meta: U2FsdGVkX18vYaJ5mWRFF02LcC/Bmuv5N5AqVgzHq0bIPZsKQFQ6OVStrjmFgEXiCr9tM7Q33YRTFEsrPq75yE8SWgYdRqfuAqWdo7/ACR3xnk7q8q7JVFyz9oqJ3fxy2aHShwmP/fgEYKQdWUCo0gfsqA+3s6HXcKlc0w91CwkgxjsZcycbM+x7W+m22r07vXZFzZbSED41SdOqHJ2LnmRCeBVdFL64Wbzv64NJ6T/+NUfz4Sf4OHx5d1WuvtLztRlr2V+Kqf4uSjYa38zjZVCu4CUb6BaLoZNON5ov3v03koAf7vv9NYKUe6sacitdv8VBVSJBl2nJS7uLsqp17+4gkFY7S22gALf6Br3HNu1M5P8mQPlSzftllfUVFBRmCvZJc8oPOBsjHUkZcNKLHZ43iZzH5vxZ3esgDWOyBKJAg99D1G9E+cP5AtUrzcTia0TU+gNlhZpMl5VOLXEOpNEKsj4xlMDQomJNjS1RjLUe2ESfAEUzRNOhj4oOiX3+++nYiAEIqBHP1dR56YlXQIUkpDS3Dmpw6c0zelj/MrLl2mHE+2GZrAIF3kBM0/Eovrb4iAx3i24L1CRSUmhSJu6hSOCPLB4Ffw6MBslcJXR88DUAsmGv9xnxy1+Gm3fXTbChBbhUxxsADQUZfaqgn7qVu423rrgR0qCxzFO9uhJYd9XtHympzwWG2vnxpruMbNJ5yE/QGOnzoDBUtWLy5tbxx8HvXm8RoErtOB7Nu4+1GFN04I180+JNzgJbyWT/HMwKNQT+Cr0ffZaBbimibq3X4xRSTRXnQPzujy4YAMT98WDvRlJz+Jfv71sQpvNqXe7Sqny7qlIsWPJFkOBdlqzdMd7akKRytKwd3bLFz1qhjr/mzgtrfDFvFjmOPvJ0Xz3/GTB4Xov2IwJg5j7g6/txqnOW4OqbGk0ZcU1nDr/0TdVzjEESoSlKZyI9/yo1MZZmKvcaplSSJr12DVr h2TI/31U 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 26 May 2023 18:54:09 +0000 SeongJae Park wrote: [...] > > > > > > divide error: 0000 [#1] PREEMPT SMP KASAN > > > CPU: 1 PID: 13527 Comm: syz-executor.1 Not tainted 6.4.0-rc3-syzkaller #0 > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023 > > > RIP: 0010:damon_nr_accesses_to_accesses_bp mm/damon/core.c:491 [inline] > > > RIP: 0010:damon_nr_accesses_for_new_attrs mm/damon/core.c:497 [inline] > > > RIP: 0010:damon_update_monitoring_result mm/damon/core.c:506 [inline] > > > RIP: 0010:damon_update_monitoring_results mm/damon/core.c:534 [inline] > > > RIP: 0010:damon_set_attrs+0x224/0x460 mm/damon/core.c:555 > > Thank you for finding and reporting this bug! > > The code of the problem is as below: > > /* convert nr_accesses to access ratio in bp (per 10,000) */ > static unsigned int damon_nr_accesses_to_accesses_bp( > unsigned int nr_accesses, struct damon_attrs *attrs) > { > unsigned int max_nr_accesses = > attrs->aggr_interval / attrs->sample_interval; > > return nr_accesses * 10000 / max_nr_accesses; > } > > The problem can happen when 'aggr_interval' is smaller than 'sample_interval', > because 'max_nr_accesses' becomes zero in the case, and resulting in divide by > zero. > > Same problem is in damon_accesses_bp_to_nr_accesses(). This is not true, because the function doesn't divide something by 'max_nr_acceses'. I was confused, sorry. Thanks, SJ [...]