From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
To: Mike Kravetz <mike.kravetz@oracle.com>,
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: Sun, 9 Jul 2017 12:53:30 +0530 [thread overview]
Message-ID: <37f275bb-57c2-1485-02f2-dc71021f612a@linux.vnet.ibm.com> (raw)
In-Reply-To: <3a43d5fa-223d-1315-513b-85d3a09a07b6@oracle.com>
On 07/07/2017 10:44 PM, Mike Kravetz wrote:
> 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.
That would be redundant. Mirroring will just happen because old_size is
0 whether we mention the MREMAP_MIRROR flag or not. IMHO it should just
mirror if the flag is specified irrespective of the old_size value.
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next prev parent reply other threads:[~2017-07-09 7:23 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
2017-07-09 7:23 ` Anshuman Khandual [this message]
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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