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From: Mike Kravetz <mike.kravetz@oracle.com>
To: Anshuman Khandual <khandual@linux.vnet.ibm.com>,
	linux-mm@kvack.org, linux-api@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Michal Hocko <mhocko@suse.com>, Aaron Lu <aaron.lu@intel.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [RFC PATCH 1/1] mm/mremap: add MREMAP_MIRROR flag for existing mirroring functionality
Date: Fri, 7 Jul 2017 10:14:53 -0700	[thread overview]
Message-ID: <3a43d5fa-223d-1315-513b-85d3a09a07b6@oracle.com> (raw)
In-Reply-To: <ea962c4b-3d47-2a95-7697-2efb4e8cd2f0@linux.vnet.ibm.com>

On 07/07/2017 01:45 AM, Anshuman Khandual wrote:
> On 07/06/2017 09:47 PM, Mike Kravetz wrote:
>> The mremap system call has the ability to 'mirror' parts of an existing
>> mapping.  To do so, it creates a new mapping that maps the same pages as
>> the original mapping, just at a different virtual address.  This
>> functionality has existed since at least the 2.6 kernel.
>>
>> This patch simply adds a new flag to mremap which will make this
>> functionality part of the API.  It maintains backward compatibility with
>> the existing way of requesting mirroring (old_size == 0).
>>
>> If this new MREMAP_MIRROR flag is specified, then new_size must equal
>> old_size.  In addition, the MREMAP_MAYMOVE flag must be specified.
> 
> Yeah it all looks good. But why is this requirement that if
> MREMAP_MAYMOVE is specified then old_size and new_size must
> be equal.

No real reason.  I just wanted to clearly separate the new interface from
the old.  On second thought, it would be better to require old_size == 0
as in the legacy interface.

-- 
Mike Kravetz

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  reply	other threads:[~2017-07-07 17:14 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-06 16:17 [RFC PATCH 0/1] mm/mremap: add MREMAP_MIRROR flag Mike Kravetz
2017-07-06 16:17 ` [RFC PATCH 1/1] mm/mremap: add MREMAP_MIRROR flag for existing mirroring functionality Mike Kravetz
2017-07-07  8:45   ` Anshuman Khandual
2017-07-07 17:14     ` Mike Kravetz [this message]
2017-07-09  7:23       ` Anshuman Khandual
2017-07-07 10:23   ` Kirill A. Shutemov
2017-07-07 17:29     ` Mike Kravetz
2017-07-07 17:45       ` Kirill A. Shutemov
2017-07-07 18:09         ` Mike Kravetz
2017-07-09  7:32           ` Anshuman Khandual
2017-07-10 16:22             ` Vlastimil Babka
2017-07-10 17:22               ` Mike Kravetz
2017-07-11 12:36   ` Michal Hocko
2017-07-11 18:23     ` Mike Kravetz
2017-07-11 21:02       ` Andrea Arcangeli
2017-07-11 21:57         ` Mike Kravetz
     [not found]           ` <fcfa8403-3151-41eb-4ac4-bbac55705626-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2017-07-11 23:31             ` Andrea Arcangeli
     [not found]       ` <7f14334f-81d1-7698-d694-37278f05a78e-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2017-07-12 11:46         ` Michal Hocko
2017-07-12 16:55           ` Mike Kravetz
2017-07-13  6:16             ` Michal Hocko
2017-07-13 16:01               ` Mike Kravetz
2017-07-13 16:30                 ` Andrea Arcangeli
2017-07-13 18:11                   ` Mike Kravetz
     [not found]                     ` <28a8da13-bdc2-3f23-dee9-607377ac1cc3-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2017-07-13 20:33                       ` Andrea Arcangeli
2017-07-07  8:19 ` [RFC PATCH 0/1] mm/mremap: add MREMAP_MIRROR flag Anshuman Khandual
2017-07-07 17:04   ` Mike Kravetz
     [not found] ` <1499357846-7481-1-git-send-email-mike.kravetz-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2017-07-07 11:03   ` Anshuman Khandual
2017-07-07 17:12     ` Mike Kravetz

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