From: Andrew Morton <akpm@osdl.org>
To: Jamie Lokier <jamie@shareable.org>
Cc: linux-kernel@vger.kernel.org, rusty@rustcorp.com.au,
mingo@elte.hu, seto.hidetoshi@jp.fujitsu.com, ahu@ds9a.nl
Subject: Re: Futex queue_me/get_user ordering (was: 2.6.10-rc1-mm5 [u])
Date: Sun, 14 Nov 2004 01:09:43 -0800 [thread overview]
Message-ID: <20041114010943.3d56985a.akpm@osdl.org> (raw)
In-Reply-To: <20041114090023.GA478@mail.shareable.org>
Emergency Services Jamie Lokier <jamie@shareable.org> wrote:
>
> Revert the patch which moves queue_me(); it's buggy. It is a bug to
> move queue_me() after get_user().
yup.
> It fully explains the blocking threads in Apache and Evolution.
>
> Even if it worked, the patch wouldn't have saved any time, as it's a
> rare condition if the caller is using futex properly.
The patch wasn't supposed to optimise anything. It fixed a bug which was
causing hangs. See
ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.10-rc1/2.6.10-rc1-mm5/broken-out/futex_wait-fix.patch
Or are you saying that userspace is buggy??
next prev parent reply other threads:[~2004-11-14 9:09 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20041113164048.2f31a8dd.akpm@osdl.org>
2004-11-14 9:00 ` Emergency Services Jamie Lokier
2004-11-14 9:09 ` Andrew Morton [this message]
2004-11-14 9:23 ` Jamie Lokier
2004-11-14 9:50 ` bert hubert
2004-11-15 14:12 ` Jamie Lokier
2004-11-16 8:30 ` Futex queue_me/get_user ordering Hidetoshi Seto
2004-11-16 14:58 ` Jamie Lokier
2004-11-18 1:29 ` Hidetoshi Seto
2004-11-15 0:58 ` Hidetoshi Seto
2004-11-15 2:01 ` Jamie Lokier
2004-11-15 3:06 ` Hidetoshi Seto
2004-11-15 13:22 ` Jamie Lokier
2004-11-17 8:47 ` Jakub Jelinek
2004-11-18 2:10 ` Hidetoshi Seto
2004-11-18 7:20 ` Jamie Lokier
2004-11-18 19:47 ` Jakub Jelinek
2005-03-17 10:26 ` Jakub Jelinek
2005-03-17 15:20 ` Jamie Lokier
2005-03-17 15:55 ` Jakub Jelinek
2005-03-18 17:00 ` Ingo Molnar
2005-03-21 2:55 ` Jamie Lokier
2005-03-18 16:53 ` Jakub Jelinek
2004-11-26 17:06 ` Jamie Lokier
2004-11-28 17:36 ` Joe Seigh
2004-11-29 11:24 ` Jakub Jelinek
2004-11-29 21:50 ` Jamie Lokier
2004-11-15 4:24 Futex queue_me/get_user ordering (was: 2.6.10-rc1-mm5 [u]) Chuck Ebbert
2004-11-15 8:08 ` Jamie Lokier
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