From: Paolo Bonzini <pbonzini@redhat.com>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
qemu-devel@nongnu.org, KVM list <kvm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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Andres Lagar-Cavilla <andreslc@google.com>,
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Mel Gorman <mgorman@suse.de>,
Andy Lutomirski <luto@amacapital.net>,
Andrew Morton <akpm@linux-foundation.org>,
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Christopher Covington <cov@codeaurora.org>,
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"Huangpeng (Peter)" <peter.huangpeng@huawei.com>,
Isaku Yamahata <yamahata@valinux.co.jp>,
Anthony Liguori <anthony@codemonkey.ws>,
Stefan Hajnoczi <stefanha@gmail.com>,
Wenchao Xia <wenchaoqemu@gmail.com>,
Andrew Jones <drjones@redhat.com>,
Juan Quintela <quintela@redhat.com>
Subject: Re: [PATCH 10/17] mm: rmap preparation for remap_anon_pages
Date: Tue, 07 Oct 2014 19:14:31 +0200 [thread overview]
Message-ID: <54341F77.6060400@redhat.com> (raw)
In-Reply-To: <20141007170731.GO2404@work-vm>
Il 07/10/2014 19:07, Dr. David Alan Gilbert ha scritto:
>> >
>> > So I'd *much* rather have a "write()" style interface (ie _copying_
>> > bytes from user space into a newly allocated page that gets mapped)
>> > than a "remap page" style interface
> Something like that might work for the postcopy case; it doesn't work
> for some of the other uses that need to stop a page being changed by the
> guest, but then need to somehow get a copy of that page internally to QEMU,
> and perhaps provide it back later.
I cannot parse this. Which uses do you have in mind? Is it for
QEMU-specific or is it for other applications of userfaults?
As long as the page is atomically mapped, I'm not sure what the
difference from remap_anon_pages are (as far as the destination page is
concerned). Are you thinking of having userfaults enabled on the source
as well?
Paolo
> remap_anon_pages worked for those cases
> as well; I can't think of another current way of doing it in userspace.
next prev parent reply other threads:[~2014-10-07 17:15 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-03 17:07 [PATCH 00/17] RFC: userfault v2 Andrea Arcangeli
2014-10-03 17:07 ` [PATCH 01/17] mm: gup: add FOLL_TRIED Andrea Arcangeli
2014-10-03 18:15 ` Linus Torvalds
2014-10-03 20:55 ` Paolo Bonzini
2014-10-03 17:07 ` [PATCH 02/17] mm: gup: add get_user_pages_locked and get_user_pages_unlocked Andrea Arcangeli
2014-10-03 17:07 ` [PATCH 03/17] mm: gup: use get_user_pages_unlocked within get_user_pages_fast Andrea Arcangeli
2014-10-03 17:07 ` [PATCH 04/17] mm: gup: make get_user_pages_fast and __get_user_pages_fast latency conscious Andrea Arcangeli
2014-10-03 18:23 ` Linus Torvalds
2014-10-06 14:14 ` Andrea Arcangeli
2014-10-03 17:07 ` [PATCH 05/17] mm: gup: use get_user_pages_fast and get_user_pages_unlocked Andrea Arcangeli
2014-10-03 17:07 ` [PATCH 06/17] kvm: Faults which trigger IO release the mmap_sem Andrea Arcangeli
2014-10-03 17:07 ` [PATCH 07/17] mm: madvise MADV_USERFAULT: prepare vm_flags to allow more than 32bits Andrea Arcangeli
2014-10-07 9:03 ` Kirill A. Shutemov
2014-11-06 20:08 ` Konstantin Khlebnikov
2014-10-03 17:07 ` [PATCH 08/17] mm: madvise MADV_USERFAULT Andrea Arcangeli
2014-10-03 23:13 ` Mike Hommey
2014-10-06 17:24 ` Andrea Arcangeli
2014-10-07 10:36 ` Kirill A. Shutemov
2014-10-07 10:46 ` Dr. David Alan Gilbert
2014-10-07 10:52 ` [Qemu-devel] " Kirill A. Shutemov
2014-10-07 11:01 ` Dr. David Alan Gilbert
2014-10-07 11:30 ` Kirill A. Shutemov
2014-10-07 13:24 ` Andrea Arcangeli
2014-10-07 15:21 ` Kirill A. Shutemov
2014-10-03 17:07 ` [PATCH 09/17] mm: PT lock: export double_pt_lock/unlock Andrea Arcangeli
2014-10-03 17:08 ` [PATCH 10/17] mm: rmap preparation for remap_anon_pages Andrea Arcangeli
2014-10-03 18:31 ` Linus Torvalds
2014-10-06 8:55 ` Dr. David Alan Gilbert
2014-10-06 16:41 ` Andrea Arcangeli
2014-10-07 12:47 ` Linus Torvalds
2014-10-07 14:19 ` Andrea Arcangeli
2014-10-07 15:52 ` Andrea Arcangeli
2014-10-07 15:54 ` Andy Lutomirski
2014-10-07 16:13 ` Peter Feiner
2014-10-07 16:56 ` Linus Torvalds
2014-10-07 17:07 ` Dr. David Alan Gilbert
2014-10-07 17:14 ` Paolo Bonzini [this message]
2014-10-07 17:25 ` Dr. David Alan Gilbert
2014-10-07 11:10 ` [Qemu-devel] " Kirill A. Shutemov
2014-10-07 13:37 ` Andrea Arcangeli
2014-10-03 17:08 ` [PATCH 11/17] mm: swp_entry_swapcount Andrea Arcangeli
2014-10-03 17:08 ` [PATCH 12/17] mm: sys_remap_anon_pages Andrea Arcangeli
2014-10-04 13:13 ` Andi Kleen
2014-10-06 17:00 ` Andrea Arcangeli
2014-10-03 17:08 ` [PATCH 13/17] waitqueue: add nr wake parameter to __wake_up_locked_key Andrea Arcangeli
2014-10-03 17:08 ` [PATCH 14/17] userfaultfd: add new syscall to provide memory externalization Andrea Arcangeli
2014-10-03 17:08 ` [PATCH 15/17] userfaultfd: make userfaultfd_write non blocking Andrea Arcangeli
2014-10-03 17:08 ` [PATCH 16/17] powerpc: add remap_anon_pages and userfaultfd Andrea Arcangeli
2014-10-03 17:08 ` [PATCH 17/17] userfaultfd: implement USERFAULTFD_RANGE_REGISTER|UNREGISTER Andrea Arcangeli
2014-10-27 9:32 ` [PATCH 00/17] RFC: userfault v2 zhanghailiang
2014-10-29 17:46 ` Andrea Arcangeli
2014-10-29 17:56 ` [Qemu-devel] " Peter Maydell
2014-11-21 20:14 ` Andrea Arcangeli
2014-11-21 23:05 ` Peter Maydell
2014-11-25 19:45 ` Andrea Arcangeli
2014-10-30 11:31 ` zhanghailiang
2014-10-30 12:49 ` Dr. David Alan Gilbert
2014-10-31 1:26 ` zhanghailiang
2014-11-19 18:49 ` Andrea Arcangeli
2014-11-20 2:54 ` zhanghailiang
2014-11-20 17:38 ` Andrea Arcangeli
2014-11-21 7:19 ` zhanghailiang
2014-10-31 2:23 ` Peter Feiner
2014-10-31 3:29 ` zhanghailiang
2014-10-31 4:38 ` zhanghailiang
2014-10-31 5:17 ` Andres Lagar-Cavilla
2014-10-31 8:11 ` zhanghailiang
2014-10-31 19:39 ` Peter Feiner
2014-11-01 8:48 ` zhanghailiang
2014-11-20 17:29 ` Andrea Arcangeli
2014-11-12 7:18 ` zhanghailiang
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