From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f48.google.com (mail-wg0-f48.google.com [74.125.82.48]) by kanga.kvack.org (Postfix) with ESMTP id 211986B0038 for ; Mon, 13 Apr 2015 10:11:27 -0400 (EDT) Received: by wgyo15 with SMTP id o15so82369487wgy.2 for ; Mon, 13 Apr 2015 07:11:26 -0700 (PDT) Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com. [195.75.94.110]) by mx.google.com with ESMTPS id n9si14179600wie.84.2015.04.13.07.11.24 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 13 Apr 2015 07:11:25 -0700 (PDT) Received: from /spool/local by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 13 Apr 2015 15:11:24 +0100 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 509FA2190063 for ; Mon, 13 Apr 2015 15:11:08 +0100 (BST) Received: from d06av06.portsmouth.uk.ibm.com (d06av06.portsmouth.uk.ibm.com [9.149.37.217]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t3DEBM1O13041852 for ; Mon, 13 Apr 2015 14:11:22 GMT Received: from d06av06.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av06.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t3D95p4p006371 for ; Mon, 13 Apr 2015 05:05:52 -0400 Message-ID: <552BCE87.8040103@linux.vnet.ibm.com> Date: Mon, 13 Apr 2015 16:11:19 +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> <552BC2CA.80309@linux.vnet.ibm.com> <552BC619.9080603@parallels.com> <20150413140219.GA14480@node.dhcp.inet.fi> In-Reply-To: <20150413140219.GA14480@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" , Pavel Emelyanov Cc: Andrew Morton , "Kirill A. Shutemov" , Hugh Dickins , Rik van Riel , Mel Gorman , 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 16:02, Kirill A. Shutemov wrote: > On Mon, Apr 13, 2015 at 04:35:21PM +0300, Pavel Emelyanov wrote: >> On 04/13/2015 04:21 PM, Laurent Dufour wrote: >>> 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 ? >> >> I think Kirill meant something like e.g. the arch_enter_lazy_mmu_mode() >> is implemented and called in mm/mremap.c -- the "generic" part is in the >> include/asm-generic/pgtable.h and those architectures willing to have >> their own implementation are in arch/$arch/... >> >> Kirill, if I'm right with it, can you suggest the header where to put >> the "generic" mremap hook's (empty) body? > > I initially thought it would be enough to put it into > , expecting it works as > . But that's not the case. > > It probably worth at some point rework all to include > at the end as we do for . > But that's outside the scope of the patchset, I guess. > > I don't see any better candidate for such dummy header. :-/ Clearly, I'm not confortable with a rewrite of :( So what about this patch, is this v3 acceptable ? Cheers, 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