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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 D4AE1CA9EA0 for ; Fri, 25 Oct 2019 07:11:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A7E00222BE for ; Fri, 25 Oct 2019 07:11:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="JS6Rw9Wo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406542AbfJYHLS (ORCPT ); Fri, 25 Oct 2019 03:11:18 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:1146 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406166AbfJYHLR (ORCPT ); Fri, 25 Oct 2019 03:11:17 -0400 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 46zwJL1km6z9txyl; Fri, 25 Oct 2019 09:11:14 +0200 (CEST) Authentication-Results: localhost; dkim=pass reason="1024-bit key; insecure key" header.d=c-s.fr header.i=@c-s.fr header.b=JS6Rw9Wo; dkim-adsp=pass; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id IEyuu55Vu2Vj; Fri, 25 Oct 2019 09:11:14 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 46zwJL044Jz9txyd; Fri, 25 Oct 2019 09:11:14 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=c-s.fr; s=mail; t=1571987474; bh=sSY9vZFiyvVRvxrTbg3cBY9vh4bHCPcOU8OggoNJn50=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=JS6Rw9Woz5UGQqHdTS6uzWgmc4CU/P/yOx+M2iQQgUsIUyeQU6CEy1rN1WbGM/gMX jg5kH3n063w2jEkgx41+z8O5phWdZyM3jwWcRyaHHpi22TkWJphSF18ZBHt9X26ALg 0sa7mSxQ44NMG02wKJaVu3L7vo7n7mt0UVXaQK8I= Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id DF5238B7C7; Fri, 25 Oct 2019 09:11:14 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id NUWV8rK7Wu_n; Fri, 25 Oct 2019 09:11:14 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id D5FF28B7BE; Fri, 25 Oct 2019 09:11:12 +0200 (CEST) Subject: Re: [PATCH V7] mm/debug: Add tests validating architecture page table helpers To: Qian Cai , Anshuman Khandual Cc: linux-mm@kvack.org, Andrew Morton , Vlastimil Babka , Greg Kroah-Hartman , Thomas Gleixner , Mike Rapoport , Jason Gunthorpe , Dan Williams , Peter Zijlstra , Michal Hocko , Mark Rutland , Mark Brown , Steven Price , Ard Biesheuvel , Masahiro Yamada , Kees Cook , Tetsuo Handa , Matthew Wilcox , Sri Krishna chowdary , Dave Hansen , Russell King - ARM Linux , Michael Ellerman , Paul Mackerras , Martin Schwidefsky , Heiko Carstens , "David S. Miller" , Vineet Gupta , James Hogan , Paul Burton , Ralf Baechle , "Kirill A . Shutemov" , Gerald Schaefer , Mike Kravetz , Ingo Molnar , linux-snps-arc@lists.infradead.org, linux-mips@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org References: <69256008-2235-4AF1-A3BA-0146C82CCB93@lca.pw> From: Christophe Leroy Message-ID: <3cfec421-4006-4159-ca32-313ff5196ff9@c-s.fr> Date: Fri, 25 Oct 2019 09:11:12 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <69256008-2235-4AF1-A3BA-0146C82CCB93@lca.pw> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 25/10/2019 à 07:52, Qian Cai a écrit : > > >> On Oct 24, 2019, at 11:45 PM, Anshuman Khandual wrote: >> >> Nothing specific. But just tested this with x86 defconfig with relevant configs >> which are required for this test. Not sure if it involved W=1. > > No, it will not. It needs to run like, > > make W=1 -j 64 2>/tmp/warns > Are we talking about this peace of code ? +static unsigned long __init get_random_vaddr(void) +{ + unsigned long random_vaddr, random_pages, total_user_pages; + + total_user_pages = (TASK_SIZE - FIRST_USER_ADDRESS) / PAGE_SIZE; + + random_pages = get_random_long() % total_user_pages; + random_vaddr = FIRST_USER_ADDRESS + random_pages * PAGE_SIZE; + + WARN_ON((random_vaddr > TASK_SIZE) || + (random_vaddr < FIRST_USER_ADDRESS)); + return random_vaddr; +} + ramdom_vaddr is unsigned, random_pages is unsigned and lower than total_user_pages So the max value random_vaddr can get is FIRST_USER_ADDRESS + ((TASK_SIZE - FIRST_USER_ADDRESS - 1) / PAGE_SIZE) * PAGE_SIZE = TASK_SIZE - 1 And the min value random_vaddr can get is FIRST_USER_ADDRESS (that's when random_pages = 0) So the WARN_ON() is just unneeded, isn't it ? Christophe