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,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 DB575C433DB for ; Tue, 29 Dec 2020 22:56:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A127D20867 for ; Tue, 29 Dec 2020 22:56:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726203AbgL2W4V (ORCPT ); Tue, 29 Dec 2020 17:56:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51372 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726138AbgL2W4V (ORCPT ); Tue, 29 Dec 2020 17:56:21 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E9F4DC061574 for ; Tue, 29 Dec 2020 14:55:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject:Sender :Reply-To:Content-ID:Content-Description; bh=f+I1LAcrnF7P65uDZQXvWz0UkdO1KBhlZ7poyZtMoZo=; b=etrwlRRw/aXgjwHjIFVxie64ON pYUPeTlAmY8UFf2dp3n3SQLSdIMYANSjSkBhJQtUtzcz95EGB2VH2uPhM//G8jObFRJHoB5n3EcK9 WjACR+EMORE7sFn9rk+8sxw7twupDn34DBdQzjfAKzs9f/dUlCYoief1KPOB58Xz+CaJPlxpEcvIc ZYZplPADW4jF2O8lnXFRWeNxYyMAm7O93t11KpmYNcEIus2XBLR3hhmhypFd+sxbqiGu5i0wbkcH5 bjUmd9bHRppqqslQBz0q//GSbvRq7uYoTiBWo1NQ1S1Lxrtiwd5zOywATEb2rBNJiAQG5A8Qmi8pL r2alw1CA==; Received: from [2601:1c0:6280:3f0::2c43] by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kuNto-0001j6-At; Tue, 29 Dec 2020 22:55:28 +0000 Subject: Re: [PATCH -mm] mm: readahead: apply a default readahead size To: Matthew Wilcox Cc: linux-kernel@vger.kernel.org, =?UTF-8?Q?Toralf_F=c3=b6rster?= , Andrew Morton , Jens Axboe , linux-mm@kvack.org References: <20201229212634.31307-1-rdunlap@infradead.org> <20201229222311.GD28221@casper.infradead.org> From: Randy Dunlap Message-ID: Date: Tue, 29 Dec 2020 14:55:23 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201229222311.GD28221@casper.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/29/20 2:23 PM, Matthew Wilcox wrote: > On Tue, Dec 29, 2020 at 01:26:34PM -0800, Randy Dunlap wrote: >> UBSAN reports an invalid shift size: >> >> mr-fox kernel: UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13 >> mr-fox kernel: shift exponent 64 is too large for 64-bit type 'long unsigned int' >> >> Original report: >> https://lore.kernel.org/lkml/c6e5eb81-680f-dd5c-8a81-62041a5ce50c@gmx.de/ >> >> Follow-up report: >> https://lore.kernel.org/lkml/0c283ea9-b446-0e40-6dc8-e9585ae171b4@gmx.de/T/#m9b604660925f9e8a544f7453130c31d083c1e5bb >> >> >> Willy suggested that get_init_ra_size() was being called with a size of 0, >> which would cause this (instead of some Huge value), so add a check in >> that function for size == 0, and if 0, default it to 32 (pages). > > No, this is wrong. 'size' in this case is the size of the read. > And it's zero. Is this fixed by commit > 3644e2d2dda78e21edd8f5415b6d7ab03f5f54f3 > Toralf, can you test with 5.11-rc1 (or later)? thanks. -- ~Randy