Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932655AbbDMODp (ORCPT ); Mon, 13 Apr 2015 10:03:45 -0400 Received: from mta-out1.inet.fi ([62.71.2.195]:39805 "EHLO jenni1.inet.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754209AbbDMODk (ORCPT ); Mon, 13 Apr 2015 10:03:40 -0400 Date: Mon, 13 Apr 2015 17:02:19 +0300 From: "Kirill A. Shutemov" To: Pavel Emelyanov Cc: Laurent Dufour , 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 Subject: Re: [RESEND PATCH v3 1/2] mm: Introducing arch_remap hook Message-ID: <20150413140219.GA14480@node.dhcp.inet.fi> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <552BC619.9080603@parallels.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4899 Lines: 116 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. :-/ -- Kirill A. Shutemov -- 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/