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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 646D0FA372A for ; Wed, 16 Oct 2019 09:54:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 243EE21848 for ; Wed, 16 Oct 2019 09:54:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 243EE21848 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BDBA58E0006; Wed, 16 Oct 2019 05:54:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B8C158E0001; Wed, 16 Oct 2019 05:54:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A7A9D8E0006; Wed, 16 Oct 2019 05:54:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0167.hostedemail.com [216.40.44.167]) by kanga.kvack.org (Postfix) with ESMTP id 865688E0001 for ; Wed, 16 Oct 2019 05:54:16 -0400 (EDT) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 1BD11183A352A for ; Wed, 16 Oct 2019 09:54:16 +0000 (UTC) X-FDA: 76049187312.09.jeans90_5f255e92d691f X-HE-Tag: jeans90_5f255e92d691f X-Filterd-Recvd-Size: 4682 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Wed, 16 Oct 2019 09:54:13 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A6076142F; Wed, 16 Oct 2019 02:54:11 -0700 (PDT) Received: from [10.163.1.216] (unknown [10.163.1.216]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DD8023F6C4; Wed, 16 Oct 2019 02:53:56 -0700 (PDT) Subject: Re: [PATCH V6 2/2] mm/debug: Add tests validating architecture page table helpers To: Qian Cai , linux-mm@kvack.org Cc: 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 , Christophe Leroy , 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: <1571131302-32290-1-git-send-email-anshuman.khandual@arm.com> <1571131302-32290-3-git-send-email-anshuman.khandual@arm.com> <1571162982.5937.42.camel@lca.pw> From: Anshuman Khandual Message-ID: <7cd03155-6713-3116-1e88-f81f84dd794f@arm.com> Date: Wed, 16 Oct 2019 15:24:23 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1571162982.5937.42.camel@lca.pw> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 10/15/2019 11:39 PM, Qian Cai wrote: > On Tue, 2019-10-15 at 14:51 +0530, Anshuman Khandual wrote: >> +static unsigned long __init get_random_vaddr(void) >> +{ >> + unsigned long random_vaddr, random_pages, total_user_pages; >> + >> + total_user_pages =3D (TASK_SIZE - FIRST_USER_ADDRESS) / PAGE_SIZE; >> + >> + random_pages =3D get_random_long() % total_user_pages; >> + random_vaddr =3D FIRST_USER_ADDRESS + random_pages * PAGE_SIZE; >> + >> + WARN_ON(random_vaddr > TASK_SIZE); >> + WARN_ON(random_vaddr < FIRST_USER_ADDRESS); >=20 > It would be nice if this patch does not introduce a new W=3D1 GCC warni= ng here on > x86 because FIRST_USER_ADDRESS is 0, and GCC think the code is dumb bec= ause > "random_vaddr" is unsigned, >=20 > In file included from ./arch/x86/include/asm/bug.h:83, > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0from ./include/linux/bug.h:5, > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0from ./include/linux/mmdebug.h:5, > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0from ./include/linux/gfp.h:5, > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0from mm/debug_vm_pgtable.c:13: > mm/debug_vm_pgtable.c: In function =E2=80=98get_random_vaddr=E2=80=99: > mm/debug_vm_pgtable.c:359:23: warning: comparison of unsigned expressio= n < 0 is > always false [-Wtype-limits] > =C2=A0 WARN_ON(random_vaddr < FIRST_USER_ADDRESS); > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0^ > ./include/asm-generic/bug.h:113:25: note: in definition of macro =E2=80= =98WARN_ON=E2=80=99 > =C2=A0 int __ret_warn_on =3D !!(condition);=C2=A0=C2=A0=C2=A0=C2=A0\ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0^~~~~~~~~ The test checks against an erroneous unsigned long overflow when FIRST_USER_ADDRESS is not 0 but a positive number. Wondering if the compiler will still complain if we merge both the WARN_ON() checks as || on a single statement.