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From: David Miller <davem@davemloft.net>
To: hugh.dickins@tiscali.co.uk
Cc: viro@ZenIV.linux.org.uk, viro@ftp.linux.org.uk,
	linux-arch@vger.kernel.org, torvalds@linux-foundation.org,
	akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCHSET] mremap/mmap mess
Date: Tue, 08 Dec 2009 13:08:02 -0800 (PST)	[thread overview]
Message-ID: <20091208.130802.25121122.davem@davemloft.net> (raw)
In-Reply-To: <Pine.LNX.4.64.0912081254500.3365@sister.anvils>

From: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Date: Tue, 8 Dec 2009 13:03:30 +0000 (GMT)

> That would impose some (unacceptable?) limits, and require some funny
> code to migrate the pages over to the new mm later (instead of
> relocating within the new mm as we do now).

I think this approach would create new failure cases that don't exist
now.  Whether that's acceptable or not is another issue.

The forced page table move, and TLB+cache flush that goes along with
that, for every single compat task we get now on the other hand is not
acceptable :-)

I also think this page table move overhead is worse than the
non-swapability added by Al's approach.

  reply	other threads:[~2009-12-08 21:07 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-05 19:08 [RFC][PATCHSET] mremap/mmap mess Al Viro
2009-12-05 19:08 ` Al Viro
2009-12-05 20:44 ` Linus Torvalds
2009-12-05 23:01 ` Al Viro
2009-12-05 23:58 ` Russell King
2009-12-06 17:22 ` Hugh Dickins
2009-12-06 18:00   ` Linus Torvalds
2009-12-07  3:58 ` Al Viro
2009-12-07 18:58   ` Hugh Dickins
2009-12-07 18:58     ` Hugh Dickins
2009-12-07 19:30     ` Al Viro
2009-12-07 20:05       ` Hugh Dickins
2009-12-07 20:05         ` Hugh Dickins
2009-12-08  6:07         ` Al Viro
2009-12-08 11:42           ` Hugh Dickins
2009-12-08 13:03             ` Hugh Dickins
2009-12-08 21:08               ` David Miller [this message]
2009-12-08 22:06                 ` Al Viro
2009-12-09 11:43                   ` Hugh Dickins
2009-12-09 12:21                     ` Peter Zijlstra
2009-12-09 12:21                       ` Peter Zijlstra
2009-12-09 13:12                       ` Hugh Dickins
2009-12-09 13:37                         ` Peter Zijlstra
2009-12-09 13:24                       ` Al Viro
2009-12-09 13:39                         ` Peter Zijlstra
2009-12-09 13:46                     ` Al Viro
2009-12-09 14:36                       ` Hugh Dickins
2009-12-09 15:12                     ` Linus Torvalds

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