From mboxrd@z Thu Jan  1 00:00:00 1970
From: Edward Napierala <trasz@freebsd.org>
Subject: Re: [PATCH v2 0/2] mm: introduce MAP_FIXED_SAFE
Date: Thu, 14 Dec 2017 12:44:17 +0000
Message-ID: <CAFLM3-oANXKEU=tuurSJx9rdzfWGfym-0FUEWnfBq8mOaVMzOA@mail.gmail.com>
References: <20171213092550.2774-1-mhocko@kernel.org> <20171213163210.6a16ccf8753b74a6982ef5b6@linux-foundation.org>
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Cc: Michal Hocko <mhocko@kernel.org>, linux-api@vger.kernel.org, Khalid Aziz <khalid.aziz@oracle.com>, Michael Ellerman <mpe@ellerman.id.au>, Russell King - ARM Linux <linux@armlinux.org.uk>, Andrea Arcangeli <aarcange@redhat.com>, linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>, linux-arch@vger.kernel.org, Florian Weimer <fweimer@redhat.com>, John Hubbard <jhubbard@nvidia.com>, Matthew Wilcox <willy@infradead.org>, Abdul Haleem <abdhalee@linux.vnet.ibm.com>, Joel Stanley <joel@jms.id.au>, Kees Cook <keescook@chromium.org>, Michal Hocko <mhocko@suse.com>, jasone@google.com, davidtgoldblatt@gmail.com
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Regarding the name - how about adopting MAP_EXCL?  It was introduced in
FreeBSD,
and seems to do exactly this; quoting mmap(2):

MAP_FIXED    Do not permit the system to select a different address
                        than the one specified.  If the specified address
                        cannot be used, mmap() will fail.  If MAP_FIXED is
                        specified, addr must be a multiple of the page size.
                        If MAP_EXCL is not specified, a successful MAP_FIXED
                        request replaces any previous mappings for the
                        process' pages in the range from addr to addr + len.
                        In contrast, if MAP_EXCL is specified, the request
                        will fail if a mapping already exists within the
                        range.

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