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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 DD387C433DB for ; Tue, 29 Dec 2020 22:24:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 999CF207BC for ; Tue, 29 Dec 2020 22:24:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726209AbgL2WYI (ORCPT ); Tue, 29 Dec 2020 17:24:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46418 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726138AbgL2WYI (ORCPT ); Tue, 29 Dec 2020 17:24:08 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DC562C061574 for ; Tue, 29 Dec 2020 14:23:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=j/bNtqMm2dxQxj54tA+5zXYhll2ElA1bhXS58HU9rB8=; b=HF87GccL7FEt19lB2EOb+Dp1vL pJwxP4UUvqUkpZLrydtqaiJ6BMXK5dYiDyflIsEremMLY1RDv1d5wPWb2uBdcoLg1ahhcREGhwdtq JEYPbVZmI0fo5XY1nBo7Ft677yCx+6f9jGdTDEiuO8agsCmZX2BFdz5kQ7DKDjOzqFhy4qrQJf85i O2w17+RGBkyx1IrrGh+cDLxY7mE4lVQ/MK0z57C8w9M21pmu2PRVGmHO2XLS1TjAdxxp7yOT7CD+w zJKnUoqBj1NaMpWeBeHjSDfIirUbZd9Ohu1xfqJtmEroBAZjp2bhNMnWRU/IfaW7+HnM3ie1mrMaC tD3+xH3w==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1kuNOZ-000H1i-D0; Tue, 29 Dec 2020 22:23:18 +0000 Date: Tue, 29 Dec 2020 22:23:11 +0000 From: Matthew Wilcox To: Randy Dunlap Cc: linux-kernel@vger.kernel.org, Toralf =?iso-8859-1?Q?F=F6rster?= , Andrew Morton , Jens Axboe , linux-mm@kvack.org Subject: Re: [PATCH -mm] mm: readahead: apply a default readahead size Message-ID: <20201229222311.GD28221@casper.infradead.org> References: <20201229212634.31307-1-rdunlap@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201229212634.31307-1-rdunlap@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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