From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f180.google.com (mail-wi0-f180.google.com [209.85.212.180]) by kanga.kvack.org (Postfix) with ESMTP id AD7126B006C for ; Mon, 13 Apr 2015 09:21:24 -0400 (EDT) Received: by widdi4 with SMTP id di4so51363519wid.0 for ; Mon, 13 Apr 2015 06:21:24 -0700 (PDT) Received: from e06smtp10.uk.ibm.com (e06smtp10.uk.ibm.com. [195.75.94.106]) by mx.google.com with ESMTPS id p3si13974186wia.63.2015.04.13.06.21.22 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 13 Apr 2015 06:21:23 -0700 (PDT) Received: from /spool/local by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 13 Apr 2015 14:21:21 +0100 Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 969E2219004D for ; Mon, 13 Apr 2015 14:21:03 +0100 (BST) Received: from d06av07.portsmouth.uk.ibm.com (d06av07.portsmouth.uk.ibm.com [9.149.37.248]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t3DDLI1Y9241054 for ; Mon, 13 Apr 2015 13:21:18 GMT Received: from d06av07.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av07.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t3DDLHbe018143 for ; Mon, 13 Apr 2015 09:21:17 -0400 Message-ID: <552BC2CA.80309@linux.vnet.ibm.com> Date: Mon, 13 Apr 2015 15:21:14 +0200 From: Laurent Dufour MIME-Version: 1.0 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 Sender: owner-linux-mm@kvack.org List-ID: 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 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org