Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933987AbeAKNGL (ORCPT + 1 other); Thu, 11 Jan 2018 08:06:11 -0500 Received: from relay5-d.mail.gandi.net ([217.70.183.197]:42630 "EHLO relay5-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932665AbeAKNGK (ORCPT ); Thu, 11 Jan 2018 08:06:10 -0500 X-Originating-IP: 92.154.27.243 Subject: Re: [PATCH] mm, THP: vmf_insert_pfn_pud depends on CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD To: Michal Hocko Cc: linux-mm@kvack.org, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, dan.j.williams@intel.com, zi.yan@cs.rutgers.edu, gregkh@linuxfoundation.org, n-horiguchi@ah.jp.nec.com, willy@linux.intel.com, mark.rutland@arm.com, linux-kernel@vger.kernel.org References: <1515660811-12293-1-git-send-email-aghiti@upmem.com> <20180111100620.GY1732@dhcp22.suse.cz> From: Alexandre Ghiti Message-ID: <71853228-0beb-1e69-df47-59fa1bc5bd2f@upmem.com> Date: Thu, 11 Jan 2018 14:05:34 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <20180111100620.GY1732@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 11/01/2018 11:06, Michal Hocko wrote: > On Thu 11-01-18 09:53:31, Alexandre Ghiti wrote: >> The only definition of vmf_insert_pfn_pud depends on >> CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD being defined. Then its declaration in >> include/linux/huge_mm.h should have the same restriction so that we do >> not expose this function if CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD is >> not defined. > Why is this a problem? Compiler should simply throw away any > declarations which are not used? It is not a big problem but surrounding the declaration with the #ifdef makes the compilation of external modules fail with an "error: implicit declaration of function vmf_insert_pfn_pud" if CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD is not defined. I think it is cleaner than generating a .ko which would not load anyway. > >> Signed-off-by: Alexandre Ghiti >> --- >> include/linux/huge_mm.h | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h >> index a8a1262..11794f6a 100644 >> --- a/include/linux/huge_mm.h >> +++ b/include/linux/huge_mm.h >> @@ -48,8 +48,10 @@ extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, >> int prot_numa); >> int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, >> pmd_t *pmd, pfn_t pfn, bool write); >> +#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD >> int vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, >> pud_t *pud, pfn_t pfn, bool write); >> +#endif >> enum transparent_hugepage_flag { >> TRANSPARENT_HUGEPAGE_FLAG, >> TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, >> -- >> 2.1.4 >>