From: Mike Kravetz <mike.kravetz@oracle.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org, Linux API <linux-api@vger.kernel.org>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Aaron Lu <aaron.lu@intel.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Vlastimil Babka <vbabka@suse.cz>,
Anshuman Khandual <khandual@linux.vnet.ibm.com>
Subject: Re: [PATCH v2] mm/mremap: Fail map duplication attempts for private mappings
Date: Fri, 21 Jul 2017 14:18:31 -0700 [thread overview]
Message-ID: <cb9d9f6a-7095-582f-15a5-62643d65c736@oracle.com> (raw)
In-Reply-To: <20170721143644.GC5944@dhcp22.suse.cz>
On 07/21/2017 07:36 AM, Michal Hocko wrote:
> On Thu 20-07-17 13:37:59, Mike Kravetz wrote:
>> mremap will create a 'duplicate' mapping if old_size == 0 is
>> specified. Such duplicate mappings make no sense for private
>> mappings.
>
> sorry for the nit picking but this is not true strictly speaking.
> It makes some sense, arguably (e.g. take an atomic snapshot of the
> mapping). It doesn't make any sense with the _current_ implementation.
>
>> If duplication is attempted for a private mapping,
>> mremap creates a separate private mapping unrelated to the
>> original mapping and makes no modifications to the original.
>> This is contrary to the purpose of mremap which should return
>> a mapping which is in some way related to the original.
>>
>> Therefore, return EINVAL in the case where if an attempt is
>> made to duplicate a private mapping. Also, print a warning
>> message (once) if such an attempt is made.
>>
>> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
>
> I do not insist on the comment update suggested
> http://lkml.kernel.org/r/20170720082058.GF9058@dhcp22.suse.cz
> but I would appreciate it...
>
> Other than that looks reasonably to me
>
> Acked-by: Michal Hocko <mhocko@suse.com>
My apologies. I overlooked your comment about the comment when
creating the patch. Below is the patch with commit message and
comment updated.
next prev parent reply other threads:[~2017-07-21 21:18 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-13 15:58 [PATCH] mm/mremap: Fail map duplication attempts for private mappings Mike Kravetz
2017-07-13 19:11 ` Vlastimil Babka
2017-07-13 22:33 ` Mike Kravetz
2017-07-14 4:51 ` Anshuman Khandual
2017-07-14 8:26 ` Michal Hocko
2017-07-14 17:29 ` Mike Kravetz
2017-07-17 6:44 ` Michal Hocko
2017-07-19 16:39 ` Mike Kravetz
2017-07-20 8:20 ` Michal Hocko
2017-07-20 20:37 ` [PATCH v2] " Mike Kravetz
2017-07-21 14:36 ` Michal Hocko
2017-07-21 21:18 ` Mike Kravetz [this message]
2017-07-24 8:50 ` Michal Hocko
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