From: Hugh Dickins <hughd@google.com>
To: Kenny Simpson <theonetruekenny@gmail.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Michal Hocko <mhocko@suse.cz>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Dave Jones <davej@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Armin Rigo <arigo@tunes.org>
Subject: Re: remap_file_pages() use
Date: Tue, 20 May 2014 21:32:47 -0700 (PDT) [thread overview]
Message-ID: <alpine.LSU.2.11.1405202112520.5142@eggly.anvils> (raw)
In-Reply-To: <CALN0BAvfgby97e69mMd+94pcn6AOPL=VPNesfu_W4_9rhkHZxw@mail.gmail.com>
On Tue, 20 May 2014, Kenny Simpson wrote:
> I might need a gentle nudge with a clue stick...
> checking against latest git tree it looks as though most common
> filesystem types do support remap_file_pages.
>
> I just wrote a simple test case and it worked on my 3.13-based ubuntu
> 14.04 system on an ext4 filesystem.
It is all very confusing, yes.
When Kirill said disk-backed files don't support remap_file_pages since
commit 3ee6dafc677a, he was meaning that that they do not support it
with a special nonlinear vma; but the remap_file_pages syscall emulates
the layout for them with separate linear vmas instead.
Confusingly, these filesystems opt in to this emulation by pointing
their remap_pages method to generic_file_remap_pages - code which is
then never used for them! tmpfs is the only filesystem (having no
page_mkwrite) which actually passes through that code.
You can understand why there's some enthusiasm for cleaning this up :)
Hugh
prev parent reply other threads:[~2014-05-21 4:34 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-18 4:03 Kenny Simpson
2014-05-19 13:01 ` Michal Hocko
2014-05-19 14:35 ` Kirill A. Shutemov
2014-05-19 14:38 ` Christoph Hellwig
2014-05-19 15:02 ` Kirill A. Shutemov
2014-05-19 15:11 ` Christoph Hellwig
2014-05-19 15:17 ` Kirill A. Shutemov
2014-05-19 15:42 ` Armin Rigo
2014-05-19 15:53 ` Kirill A. Shutemov
2014-05-19 16:42 ` Armin Rigo
2014-05-19 17:50 ` Dave Hansen
2014-05-19 22:05 ` Armin Rigo
2014-05-19 16:56 ` Christoph Hellwig
2014-05-19 19:14 ` Richard Weinberger
2014-05-26 0:19 ` Jeff Smith
2014-05-26 9:42 ` Kirill A. Shutemov
2014-05-26 13:24 ` Jeff Smith
2014-05-26 13:35 ` Paolo Bonzini
2014-05-26 13:38 ` Jeff Smith
2014-05-26 13:47 ` Kirill A. Shutemov
2014-05-26 13:52 ` Jeff Smith
2014-05-26 14:16 ` Kirill A. Shutemov
2014-05-26 13:37 ` Kirill A. Shutemov
2014-05-19 17:34 ` Kenny Simpson
2014-05-19 21:24 ` Kirill A. Shutemov
2014-05-21 1:53 ` Kenny Simpson
2014-05-21 3:56 ` Kenny Simpson
2014-05-21 4:32 ` Hugh Dickins [this message]
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