From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752834AbeDKKc1 (ORCPT ); Wed, 11 Apr 2018 06:32:27 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33824 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752755AbeDKKcX (ORCPT ); Wed, 11 Apr 2018 06:32:23 -0400 Subject: Re: [PATCH v3 2/2] mm: remove odd HAVE_PTE_SPECIAL To: Christophe LEROY , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-doc@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, Jerome Glisse , mhocko@kernel.org, aneesh.kumar@linux.vnet.ibm.com, akpm@linux-foundation.org, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, Jonathan Corbet , Catalin Marinas , Will Deacon , Yoshinori Sato , Rich Felker , "David S . Miller" , Thomas Gleixner , Ingo Molnar , Vineet Gupta , Palmer Dabbelt , Albert Ou , Martin Schwidefsky , Heiko Carstens , David Rientjes , Robin Murphy References: <1523433816-14460-1-git-send-email-ldufour@linux.vnet.ibm.com> <1523433816-14460-3-git-send-email-ldufour@linux.vnet.ibm.com> <93ed4fe4-dd1e-51be-948b-d53b16de21c5@linux.vnet.ibm.com> <278a5212-b962-9a3a-cc86-76cac744afab@c-s.fr> From: Laurent Dufour Date: Wed, 11 Apr 2018 12:32:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <278a5212-b962-9a3a-cc86-76cac744afab@c-s.fr> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 18041110-0044-0000-0000-00000545F5DD X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18041110-0045-0000-0000-000028862A1D Message-Id: <32655c37-91cb-17aa-58e7-74254e2673a0@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-11_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1804110102 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/04/2018 11:09, Christophe LEROY wrote: > > > Le 11/04/2018 à 11:03, Laurent Dufour a écrit : >> >> >> On 11/04/2018 10:58, Christophe LEROY wrote: >>> >>> >>> Le 11/04/2018 à 10:03, Laurent Dufour a écrit : >>>> Remove the additional define HAVE_PTE_SPECIAL and rely directly on >>>> CONFIG_ARCH_HAS_PTE_SPECIAL. >>>> >>>> There is no functional change introduced by this patch >>>> >>>> Signed-off-by: Laurent Dufour >>>> --- >>>>    mm/memory.c | 19 ++++++++----------- >>>>    1 file changed, 8 insertions(+), 11 deletions(-) >>>> >>>> diff --git a/mm/memory.c b/mm/memory.c >>>> index 96910c625daa..7f7dc7b2a341 100644 >>>> --- a/mm/memory.c >>>> +++ b/mm/memory.c >>>> @@ -817,17 +817,12 @@ static void print_bad_pte(struct vm_area_struct *vma, >>>> unsigned long addr, >>>>     * PFNMAP mappings in order to support COWable mappings. >>>>     * >>>>     */ >>>> -#ifdef CONFIG_ARCH_HAS_PTE_SPECIAL >>>> -# define HAVE_PTE_SPECIAL 1 >>>> -#else >>>> -# define HAVE_PTE_SPECIAL 0 >>>> -#endif >>>>    struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long >>>> addr, >>>>                     pte_t pte, bool with_public_device) >>>>    { >>>>        unsigned long pfn = pte_pfn(pte); >>>>    -    if (HAVE_PTE_SPECIAL) { >>>> +    if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) { >>>>            if (likely(!pte_special(pte))) >>>>                goto check_pfn; >>>>            if (vma->vm_ops && vma->vm_ops->find_special_page) >>>> @@ -862,7 +857,7 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, >>>> unsigned long addr, >>>>            return NULL; >>>>        } >>>>    -    /* !HAVE_PTE_SPECIAL case follows: */ >>>> +    /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */ >>>>          if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { >>>>            if (vma->vm_flags & VM_MIXEDMAP) { >>>> @@ -881,7 +876,8 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, >>>> unsigned long addr, >>>>          if (is_zero_pfn(pfn)) >>>>            return NULL; >>>> -check_pfn: >>>> + >>>> +check_pfn: __maybe_unused >>> >>> See below >>> >>>>        if (unlikely(pfn > highest_memmap_pfn)) { >>>>            print_bad_pte(vma, addr, pte, NULL); >>>>            return NULL; >>>> @@ -891,7 +887,7 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, >>>> unsigned long addr, >>>>         * NOTE! We still have PageReserved() pages in the page tables. >>>>         * eg. VDSO mappings can cause them to exist. >>>>         */ >>>> -out: >>>> +out: __maybe_unused >>> >>> Why do you need that change ? >>> >>> There is no reason for the compiler to complain. It would complain if the goto >>> was within a #ifdef, but all the purpose of using IS_ENABLED() is to allow the >>> compiler to properly handle all possible cases. That's all the force of >>> IS_ENABLED() compared to ifdefs, and that the reason why they are plebicited, >>> ref Linux Codying style for a detailed explanation. >> >> Fair enough. >> >> Should I submit a v4 just to remove these so ugly __maybe_unused ? >> > > Most likely, unless the mm maintainer agrees to remove them by himself when > applying your patch ? That was my point. Andrew, should I send a v4 or could you wipe the 2 __maybe_unsued when applying the patch ? Thanks, Laurent.