Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932289AbbDMNV3 (ORCPT ); Mon, 13 Apr 2015 09:21:29 -0400 Received: from e06smtp10.uk.ibm.com ([195.75.94.106]:37910 "EHLO e06smtp10.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932085AbbDMNVZ (ORCPT ); Mon, 13 Apr 2015 09:21:25 -0400 Message-ID: <552BC2CA.80309@linux.vnet.ibm.com> Date: Mon, 13 Apr 2015 15:21:14 +0200 From: Laurent Dufour User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: "Kirill A. Shutemov" CC: Andrew Morton , "Kirill A. Shutemov" , Hugh Dickins , Rik van Riel , Mel Gorman , Pavel Emelyanov , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Ingo Molnar , linuxppc-dev@lists.ozlabs.org, cov@codeaurora.org, criu@openvz.org Subject: Re: [RESEND PATCH v3 1/2] mm: Introducing arch_remap hook References: <9d827fc618a718830b2c47aa87e8be546914c897.1428916945.git.ldufour@linux.vnet.ibm.com> <20150413115811.GA12354@node.dhcp.inet.fi> <552BB972.3010704@linux.vnet.ibm.com> <20150413131357.GC12354@node.dhcp.inet.fi> In-Reply-To: <20150413131357.GC12354@node.dhcp.inet.fi> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15041313-0041-0000-0000-000003E5EDF0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3701 Lines: 97 On 13/04/2015 15:13, Kirill A. Shutemov wrote: > On Mon, Apr 13, 2015 at 02:41:22PM +0200, Laurent Dufour wrote: >> On 13/04/2015 13:58, Kirill A. Shutemov wrote: >>> On Mon, Apr 13, 2015 at 11:56:27AM +0200, Laurent Dufour wrote: >>>> Some architecture would like to be triggered when a memory area is moved >>>> through the mremap system call. >>>> >>>> This patch is introducing a new arch_remap mm hook which is placed in the >>>> path of mremap, and is called before the old area is unmapped (and the >>>> arch_unmap hook is called). >>>> >>>> The architectures which need to call this hook should define >>>> __HAVE_ARCH_REMAP in their asm/mmu_context.h and provide the arch_remap >>>> service with the following prototype: >>>> void arch_remap(struct mm_struct *mm, >>>> unsigned long old_start, unsigned long old_end, >>>> unsigned long new_start, unsigned long new_end); >>>> >>>> Signed-off-by: Laurent Dufour >>>> Reviewed-by: Ingo Molnar >>>> --- >>>> mm/mremap.c | 19 +++++++++++++------ >>>> 1 file changed, 13 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/mm/mremap.c b/mm/mremap.c >>>> index 2dc44b1cb1df..009db5565893 100644 >>>> --- a/mm/mremap.c >>>> +++ b/mm/mremap.c >>>> @@ -25,6 +25,7 @@ >>>> >>>> #include >>>> #include >>>> +#include >>>> >>>> #include "internal.h" >>>> >>>> @@ -286,13 +287,19 @@ static unsigned long move_vma(struct vm_area_struct *vma, >>>> old_len = new_len; >>>> old_addr = new_addr; >>>> new_addr = -ENOMEM; >>>> - } else if (vma->vm_file && vma->vm_file->f_op->mremap) { >>>> - err = vma->vm_file->f_op->mremap(vma->vm_file, new_vma); >>>> - if (err < 0) { >>>> - move_page_tables(new_vma, new_addr, vma, old_addr, >>>> - moved_len, true); >>>> - return err; >>>> + } else { >>>> + if (vma->vm_file && vma->vm_file->f_op->mremap) { >>>> + err = vma->vm_file->f_op->mremap(vma->vm_file, new_vma); >>>> + if (err < 0) { >>>> + move_page_tables(new_vma, new_addr, vma, >>>> + old_addr, moved_len, true); >>>> + return err; >>>> + } >>>> } >>>> +#ifdef __HAVE_ARCH_REMAP >>> >>> It would be cleaner to provide dummy arch_remap() for !__HAVE_ARCH_REMAP >>> in some generic header. >> >> The idea was to not impact all the architectures as arch_unmap(), >> arch_dup_mmap() or arch_exit_mmap() implies. >> >> I look at the headers where such a dummy arch_remap could be put but I >> can't figure out one which will not impact all the architecture. >> What about defining a dummy service earlier in mm/remap.c in the case >> __HAVE_ARCH_REMAP is not defined ? >> Something like : >> #ifndef __HAVE_ARCH_REMAP >> static inline void void arch_remap(struct mm_struct *mm, >> unsigned long old_start, >> unsigned long old_end, >> unsigned long new_start, >> unsigned long new_end) >> { >> } >> #endif > > Or just #define arch_remap(...) do { } while (0) > I guessed you wanted the arch_remap() prototype to be exposed somewhere in the code. To be honest, I can't find the benefit of defining a dummy arch_remap() in mm/remap.c if __HAVE_ARCH_REMAP is not defined instead of calling it in move_vma if __HAVE_ARCH_REMAP is defined. Is it really what you want ? Thanks, Laurent. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/