linux-kernel - Re: [patch v2] mremap.2: Add description of old

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Message-ID: <20170925123621.35godwzhvw4wbisc@dhcp22.suse.cz>
Date:   Mon, 25 Sep 2017 14:36:21 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
Cc:     Mike Kravetz <mike.kravetz@...cle.com>, linux-man@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-api@...r.kernel.org, Jann Horn <jannh@...gle.com>,
        Florian Weimer <fweimer@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>
Subject: Re: [patch v2] mremap.2: Add description of old_size == 0
 functionality

On Wed 20-09-17 09:25:42, Michael Kerrisk wrote:
[...]
>     BUGS
>        Before Linux 4.14, if old_size was zero and the  mapping  referred
>        to  by  old_address  was  a private mapping (mmap(2) MAP_PRIVATE),
>        mremap() created a new private mapping unrelated to  the  original
>        mapping.   This behavior was unintended and probably unexpected in
>        user-space applications (since the intention  of  mremap()  is  to
>        create  a new mapping based on the original mapping).  Since Linux
>        4.14, mremap() fails with the error EINVAL in this scenario.
> 
> Does that seem okay?

sorry to be late but yes this wording makes perfect sense to me.
-- 
Michal Hocko
SUSE Labs