From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id 9CF9E6B000C for ; Wed, 11 Apr 2018 05:09:11 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id z83so790253wmc.2 for ; Wed, 11 Apr 2018 02:09:11 -0700 (PDT) Received: from pegase1.c-s.fr (pegase1.c-s.fr. [93.17.236.30]) by mx.google.com with ESMTPS id j14si615133wme.149.2018.04.11.02.09.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 Apr 2018 02:09:09 -0700 (PDT) Subject: Re: [PATCH v3 2/2] mm: remove odd HAVE_PTE_SPECIAL 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> From: Christophe LEROY Message-ID: <278a5212-b962-9a3a-cc86-76cac744afab@c-s.fr> Date: Wed, 11 Apr 2018 11:09:05 +0200 MIME-Version: 1.0 In-Reply-To: <93ed4fe4-dd1e-51be-948b-d53b16de21c5@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Laurent Dufour , 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 Le 11/04/2018 A 11:03, Laurent Dufour a A(C)critA : > > > On 11/04/2018 10:58, Christophe LEROY wrote: >> >> >> Le 11/04/2018 A 10:03, Laurent Dufour a A(C)critA : >>> 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 >>> --- >>> A mm/memory.c | 19 ++++++++----------- >>> A 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, >>> A A * PFNMAP mappings in order to support COWable mappings. >>> A A * >>> A A */ >>> -#ifdef CONFIG_ARCH_HAS_PTE_SPECIAL >>> -# define HAVE_PTE_SPECIAL 1 >>> -#else >>> -# define HAVE_PTE_SPECIAL 0 >>> -#endif >>> A struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr, >>> A A A A A A A A A A A A A A A A A A pte_t pte, bool with_public_device) >>> A { >>> A A A A A unsigned long pfn = pte_pfn(pte); >>> A -A A A if (HAVE_PTE_SPECIAL) { >>> +A A A if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) { >>> A A A A A A A A A if (likely(!pte_special(pte))) >>> A A A A A A A A A A A A A goto check_pfn; >>> A A A A A A A A A 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, >>> A A A A A A A A A return NULL; >>> A A A A A } >>> A -A A A /* !HAVE_PTE_SPECIAL case follows: */ >>> +A A A /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */ >>> A A A A A A if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { >>> A A A A A A A A A if (vma->vm_flags & VM_MIXEDMAP) { >>> @@ -881,7 +876,8 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, >>> unsigned long addr, >>> A A A A A A if (is_zero_pfn(pfn)) >>> A A A A A A A A A return NULL; >>> -check_pfn: >>> + >>> +check_pfn: __maybe_unused >> >> See below >> >>> A A A A A if (unlikely(pfn > highest_memmap_pfn)) { >>> A A A A A A A A A print_bad_pte(vma, addr, pte, NULL); >>> A A A A A A A A A return NULL; >>> @@ -891,7 +887,7 @@ struct page *_vm_normal_page(struct vm_area_struct *vma, >>> unsigned long addr, >>> A A A A A A * NOTE! We still have PageReserved() pages in the page tables. >>> A A A A A A * eg. VDSO mappings can cause them to exist. >>> A A A A A A */ >>> -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 ? Christophe