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 X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2A3F7C433E0 for ; Tue, 29 Dec 2020 18:02:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id AEAB52222A for ; Tue, 29 Dec 2020 18:02:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AEAB52222A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmx.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id B2BDF6B00DE; Tue, 29 Dec 2020 13:02:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id ADA4A6B00DF; Tue, 29 Dec 2020 13:02:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9C9B28D002C; Tue, 29 Dec 2020 13:02:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0245.hostedemail.com [216.40.44.245]) by kanga.kvack.org (Postfix) with ESMTP id 86D636B00DE for ; Tue, 29 Dec 2020 13:02:02 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 459638249980 for ; Tue, 29 Dec 2020 18:02:02 +0000 (UTC) X-FDA: 77647088484.30.money99_24102e02749e Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin30.hostedemail.com (Postfix) with ESMTP id 17766180B3C83 for ; Tue, 29 Dec 2020 18:02:02 +0000 (UTC) X-HE-Tag: money99_24102e02749e X-Filterd-Recvd-Size: 3974 Received: from mout.gmx.net (mout.gmx.net [212.227.15.19]) by imf11.hostedemail.com (Postfix) with ESMTP for ; Tue, 29 Dec 2020 18:02:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1609264916; bh=SK8QITzCfWoZ/op3YpTUgnGR0uIsWk1XBJ/06nVaCnw=; h=X-UI-Sender-Class:Subject:To:Cc:References:From:Date:In-Reply-To; b=FO1EJ9ABcWzp/xDi9Q3yWXhGcFk1S6PgHUJDWsfYHxIbLaB6PG2wIM+WrXsG0kAU7 Hci5v/2hSHbHvvCsxKcCQVSBqRbUu72vZ+N7wfCxp/MPq5bSJx+dZJan6XYP1VXBFe 1damZl+J9t1OkdaGuCK67muinFVaFHLchgpHrKM4= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [192.168.178.23] ([77.6.105.225]) by mail.gmx.com (mrgmx005 [212.227.17.190]) with ESMTPSA (Nemesis) id 1M8ykW-1kzGrK1aha-0065Jm; Tue, 29 Dec 2020 19:01:56 +0100 Subject: Re: [RFC PATCH 2/2] mm: readahead: handle LARGE input to get_init_ra_size() To: Randy Dunlap , Andrew Morton Cc: linux-kernel@vger.kernel.org, Jens Axboe , linux-mm@kvack.org References: <20201220211051.1416-1-rdunlap@infradead.org> <20201222173533.c9e28416835d7487b0e28cda@linux-foundation.org> <6a595671-20a8-e63f-f3ea-f4749a574efa@infradead.org> From: =?UTF-8?Q?Toralf_F=c3=b6rster?= Message-ID: Date: Tue, 29 Dec 2020 19:01:55 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <6a595671-20a8-e63f-f3ea-f4749a574efa@infradead.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:O57Jbv6kXlXZvbyRWDd9xH2aYHMSjIDdEK/JCXmJADBX42EyMzX LL0jUj6u14qy4yJtCdb9NXZ9AWB0HNGF1Qmwg9rGBeDpz1JNW1ZZDB36zzC7zDxa20/UopD Lf273dw33OevxfFGr2xnPrsrLUswP1LZeWcn8TkZ6OL60VzyMYt7oqyuUvKoEIH77h2HV5u KrZrJkW2VK6DgBIeZ3B3Q== X-UI-Out-Filterresults: notjunk:1;V03:K0:VnL47sgNejg=:X0iVsPMBWnbU304MgmUW73 fAzlnctILy1ZoCB96gR15CzJC+aEMQyRspayN670fgaqvFHSEnqdDP4uoT+t8Y4lgif3+hyVa CJkLd7AVQvDH6EFe1BlILTs5hrj5eriFx7i2rGrNkEQ+nZKuepkhgoa/R7oDTNNzAIk/Nd/4l EhjofJhRUgzC60zgmGuprnroaUuo0uXF38+28yvqQ3GquNvz/CJRbWjI7r6qSnRC2Sl6B49Fr etc2gMTstE/Le74dgtCsK/VIebV/QpG///NhASwklRxIv0RxhU5UMDAMMlqUC5okgWfX0f44q oKqwq2dRIgIaGuSrT/PxbBEWuYXfxFQnkKZpTmRqGbwGSZmherqRHimRgWLSytVTrnHrMlvYK vZ548K2NSXMm0z1RGmlWzU8btBhgZhndMzWCQloROb1SD3zz6IMtRfejxPrKCtXI86IgQisZs zWNRsWWYrYNsYHyNXhtIINjShVnlpjiLZh48JyEguttyHUPctu+3DpSOJLiqER/x5nLsYPkre MhNnuwa9IkKsWJt+gz1UbRv2Iejvb20GfHWVIWwUbq+FY2+dFt6RHkF8Z2ctlZu8dJHPoVItT N7Nc2+n5B/VZJxMjX+whj0yuXpVcpg//01zb/PrLBhRj9R7WGHPElSD3pGZ6pd0FTgUP2dn25 Qo8XOEBaCJlwa3w4lZxLdZRNAx+Rk/SE8biaOS2+CFMsEyEk8DihpX5a5jh6KCDyepuJ7A8K2 XbaNHK81vvaLBJAoTYwLal/eyZna3R9aDzgEcXU/N3zlZZNYFFWOLhypXdhwoH2vXZHQCoruh QDI6LAgGct51MmEgJGjdc3v54Lf90rWQPdaeFZsfytxbq1BWfrrzJmZ98yNgVIgnWaJONQp/H urG2BJj5XFik0T7SKadg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 12/23/20 2:50 AM, Randy Dunlap wrote: >> What motivates this change? Is there any reason to think this can >> happen? > Spotted in the wild: I run 2 hardened Gentoo systems, a server and a desktop. I patched the server with this: mr-fox ~ # cat ubsan.patch =2D-- linux-5.10.1.orig/mm/readahead.c +++ linux-5.10.1/mm/readahead.c @@ -310,7 +310,11 @@ void force_page_cache_ra(struct readahea */ static unsigned long get_init_ra_size(unsigned long size, unsigned long max) { - unsigned long newsize =3D roundup_pow_of_two(size); + unsigned long newsize; + + if (!size) + size =3D 32; + newsize =3D roundup_pow_of_two(size); if (newsize <=3D max / 32) newsize =3D newsize * 4; and the issue did no longer occurred at the server (5.10.2). I did not patched the desktop system and the issue occurred still 3 times since 21th of december (5.10.2/3) =2D- Toralf