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Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages |
Date: |
Mon, 6 Oct 2014 09:55:41 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
* Linus Torvalds (address@hidden) wrote:
> On Fri, Oct 3, 2014 at 10:08 AM, Andrea Arcangeli <address@hidden> wrote:
> >
> > Overall this looks a fairly small change to the rmap code, notably
> > less intrusive than the nonlinear vmas created by remap_file_pages.
>
> Considering that remap_file_pages() was an unmitigated disaster, and
> -mm has a patch to remove it entirely, I'm not at all convinced this
> is a good argument.
>
> We thought remap_file_pages() was a good idea, and it really really
> really wasn't. Almost nobody used it, why would the anonymous page
> case be any different?
I've posted code that uses this interface to qemu-devel and it works nicely;
so chalk up at least one user.
For the postcopy case I'm using it for, we need to place a page, atomically
some thread might try and access it, and must either
1) get caught by userfault etc or
2) must succeed in it's access
and we'll have that happening somewhere between thousands and millions of times
to pages in no particular order, so we need to avoid creating millions of
mappings.
Dave
>
> Linus
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [PATCH 04/17] mm: gup: make get_user_pages_fast and __get_user_pages_fast latency conscious, (continued)
- [Qemu-devel] [PATCH 11/17] mm: swp_entry_swapcount, Andrea Arcangeli, 2014/10/03
- [Qemu-devel] [PATCH 15/17] userfaultfd: make userfaultfd_write non blocking, Andrea Arcangeli, 2014/10/03
- [Qemu-devel] [PATCH 13/17] waitqueue: add nr wake parameter to __wake_up_locked_key, Andrea Arcangeli, 2014/10/03
- [Qemu-devel] [PATCH 09/17] mm: PT lock: export double_pt_lock/unlock, Andrea Arcangeli, 2014/10/03
- [Qemu-devel] [PATCH 07/17] mm: madvise MADV_USERFAULT: prepare vm_flags to allow more than 32bits, Andrea Arcangeli, 2014/10/03
- [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Andrea Arcangeli, 2014/10/03
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Linus Torvalds, 2014/10/03
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages,
Dr. David Alan Gilbert <=
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Andrea Arcangeli, 2014/10/06
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Linus Torvalds, 2014/10/07
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Andrea Arcangeli, 2014/10/07
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Andrea Arcangeli, 2014/10/07
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Andy Lutomirski, 2014/10/07
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Peter Feiner, 2014/10/07
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Linus Torvalds, 2014/10/07
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Dr. David Alan Gilbert, 2014/10/07
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Paolo Bonzini, 2014/10/07
- Re: [Qemu-devel] [PATCH 10/17] mm: rmap preparation for remap_anon_pages, Dr. David Alan Gilbert, 2014/10/07