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From: Andrew Morton <>
To: Miklos Szeredi <>
Subject: Re: [patch 2/3] only allow nonlinear vmas for ram backed filesystems
Date: Sun, 25 Mar 2007 16:00:50 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Sat, 24 Mar 2007 23:09:19 +0100 Miklos Szeredi <> wrote:

> Dirty page accounting/limiting doesn't work for nonlinear mappings,

Doesn't it?  iirc the problem is that we don't correctly re-clean the ptes
while starting writeout.  And the dirty-page accounting is in fact correct
(it'd darn well better be).

> so
> for non-ram backed filesystems emulate with linear mappings.  This
> retains ABI compatibility with previous kernels at minimal code cost.
> All known users of nonlinear mappings actually use tmpfs, so this
> shouldn't have any negative effect.

Unless someone is using remap_file_pages() against an ext3 file, in which
case their application stops working?

That would be a problem.  These guys:, for example, will be in
for a little surprise.

  parent reply	other threads:[~2007-03-26  0:01 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-24 22:07 [patch 1/3] split mmap Miklos Szeredi
2007-03-24 22:09 ` [patch 2/3] only allow nonlinear vmas for ram backed filesystems Miklos Szeredi
2007-03-25 12:12   ` Peter Zijlstra
2007-03-25 15:51     ` Matt Mackall
2007-03-27  0:02       ` William Lee Irwin III
2007-03-26  0:00   ` Andrew Morton [this message]
2007-03-26  6:57     ` Peter Zijlstra
2007-03-24 22:11 ` [patch 3/3] update ctime and mtime for mmaped write Miklos Szeredi
2007-03-25 12:12   ` Peter Zijlstra
2007-03-25 21:08     ` Miklos Szeredi
2007-03-25 12:12 ` [patch 1/3] split mmap Peter Zijlstra

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