Re: [PATCH 4.9.y 1/1] futex: Fix OWNER_DEAD fixup

[Greg KH]

On Tue, Feb 23, 2021 at 10:41:51PM +0800, Zheng Yejian wrote:
> From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> 
> commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 upstream.
> 
> Both Geert and DaveJ reported that the recent futex commit:
> 
>   c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
> 
> introduced a problem with setting OWNER_DEAD. We set the bit on an
> uninitialized variable and then entirely optimize it away as a
> dead-store.
> 
> Move the setting of the bit to where it is more useful.
> 
> Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Reported-by: Dave Jones <davej@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
> Link: http://lkml.kernel.org/r/20180122103947.GD2228@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> Signed-off-by: Zheng Yejian <zhengyejian1@xxxxxxxxxx>
> ---
>  kernel/futex.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

Now queued up, thanks.

greg k-h