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From: Florian Weimer <fweimer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Brian Geffon <bgeffon-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	"Michael S . Tsirkin"
	<mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>,
	LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	linux-mm <linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>,
	linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>,
	Andrea Arcangeli
	<aarcange-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Sonny Rao <sonnyrao-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Minchan Kim <minchan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Joel Fernandes
	<joel-QYYGw3jwrUn5owFQY34kdNi2O/JbrIOy@public.gmane.org>,
	Yu Zhao <yuzhao-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Jesse Barnes <jsbarnes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH v2] mm: Add MREMAP_DONTUNMAP to mremap().
Date: Thu, 30 Jan 2020 13:19:39 +0100	[thread overview]
Message-ID: <87eevh3zms.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <CADyq12xCpTzLpYC16FjnM60tHhCfnccNfg6JJuqcBd_6ACDGcQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> (Brian Geffon's message of "Mon, 27 Jan 2020 14:33:44 -0800")

* Brian Geffon:

> Hi Florian,
> copy_vma will make a copy of the existing VMA leaving the old VMA
> unchanged, so the source keeps its existing protections, this is what
> makes it very useful along with userfaultfd.

I see.  On the other hand, it's impossible to get the PROT_NONE behavior
by a subsequent mprotect call because the mremap has to fail in some
cases in vm.overcommit_memory=2 mode.  But maybe that other behavior can
be provided with a different flag if it turns out to be useful in the
future.

Thanks,
Florian

WARNING: multiple messages have this Message-ID (diff)
From: Florian Weimer <fweimer@redhat.com>
To: Brian Geffon <bgeffon@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	 "Michael S . Tsirkin" <mst@redhat.com>,
	 Arnd Bergmann <arnd@arndb.de>,
	 LKML <linux-kernel@vger.kernel.org>,
	 linux-mm <linux-mm@kvack.org>,
	 linux-api@vger.kernel.org,
	 Andy Lutomirski <luto@amacapital.net>,
	 Andrea Arcangeli <aarcange@redhat.com>,
	 Sonny Rao <sonnyrao@google.com>,
	 Minchan Kim <minchan@kernel.org>,
	 Joel Fernandes <joel@joelfernandes.org>,
	 Yu Zhao <yuzhao@google.com>,  Jesse Barnes <jsbarnes@google.com>
Subject: Re: [PATCH v2] mm: Add MREMAP_DONTUNMAP to mremap().
Date: Thu, 30 Jan 2020 13:19:39 +0100	[thread overview]
Message-ID: <87eevh3zms.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <CADyq12xCpTzLpYC16FjnM60tHhCfnccNfg6JJuqcBd_6ACDGcQ@mail.gmail.com> (Brian Geffon's message of "Mon, 27 Jan 2020 14:33:44 -0800")

* Brian Geffon:

> Hi Florian,
> copy_vma will make a copy of the existing VMA leaving the old VMA
> unchanged, so the source keeps its existing protections, this is what
> makes it very useful along with userfaultfd.

I see.  On the other hand, it's impossible to get the PROT_NONE behavior
by a subsequent mprotect call because the mremap has to fail in some
cases in vm.overcommit_memory=2 mode.  But maybe that other behavior can
be provided with a different flag if it turns out to be useful in the
future.

Thanks,
Florian



  parent reply	other threads:[~2020-01-30 12:19 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-23  1:46 [PATCH] mm: Add MREMAP_DONTUNMAP to mremap() Brian Geffon
2020-01-23  1:46 ` Brian Geffon
2020-01-27  4:46 ` Dan Carpenter
2020-01-27  4:46   ` Dan Carpenter
2020-01-27  4:46   ` Dan Carpenter
2020-01-27  4:46   ` Dan Carpenter
     [not found] ` <20200123014627.71720-1-bgeffon-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2020-01-23  3:02   ` Andy Lutomirski
2020-01-23  3:02     ` Andy Lutomirski
2020-01-23 18:47     ` Lokesh Gidra
2020-01-23 19:02     ` Brian Geffon
2020-01-23 19:03     ` Brian Geffon
2020-01-24 19:06   ` [PATCH v2] " Brian Geffon
2020-01-24 19:06     ` Brian Geffon
     [not found]     ` <20200124190625.257659-1-bgeffon-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2020-01-26  5:16       ` Nathan Chancellor
2020-01-26  5:16         ` Nathan Chancellor
2020-01-27  2:21         ` Brian Geffon
2020-01-27  2:21           ` Brian Geffon
2020-01-26 22:06       ` Kirill A. Shutemov
2020-01-26 22:06         ` Kirill A. Shutemov
2020-01-28  1:35         ` Brian Geffon
     [not found]           ` <CADyq12xCK_3MhGi88Am5P6DVZvrW8vqtyJMHO0zjNhvhYegm1w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2020-01-29 10:46             ` Kirill A. Shutemov
2020-01-29 10:46               ` Kirill A. Shutemov
2020-02-01 21:03               ` Brian Geffon
2020-02-01 21:03                 ` Brian Geffon
2020-02-02  4:17               ` Brian Geffon
2020-02-03 13:09                 ` Kirill A. Shutemov
2020-02-07 20:42                   ` Brian Geffon
     [not found]                     ` <CADyq12x98QspiWSqNui1OH8+FEUzVyJwxia+ho00S2+Q+PmTjw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2020-02-10 10:35                       ` Kirill A. Shutemov
2020-02-10 10:35                         ` Kirill A. Shutemov
2020-01-27 10:13       ` Florian Weimer
2020-01-27 10:13         ` Florian Weimer
     [not found]         ` <87imkxxl5d.fsf-fjB847h8rq1N9UpBYOmNkhcY2uh10dtjAL8bYrjMMd8@public.gmane.org>
2020-01-27 22:33           ` Brian Geffon
2020-01-27 22:33             ` Brian Geffon
     [not found]             ` <CADyq12xCpTzLpYC16FjnM60tHhCfnccNfg6JJuqcBd_6ACDGcQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2020-01-30 12:19               ` Florian Weimer [this message]
2020-01-30 12:19                 ` Florian Weimer
2020-01-27  5:30   ` [PATCH v3] " Brian Geffon
2020-01-27  5:30     ` Brian Geffon
     [not found]     ` <20200127053056.213679-1-bgeffon-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2020-01-28 15:26       ` Will Deacon
2020-01-28 15:26         ` Will Deacon
2020-01-30 10:12         ` Will Deacon
2020-01-30 10:12           ` Will Deacon

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