Re: Futex queue_me/get_user ordering (was: 2.6.10-rc1-mm5 [u])

[Andrew Morton]

Emergency Services Jamie Lokier <jamie@xxxxxxxxxxxxx> 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??
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