From: Lee Jones <lee.jones@linaro.org>
To: Zheng Yejian <zhengyejian1@huawei.com>
Cc: gregkh@linuxfoundation.org, stable@vger.kernel.org,
linux-kernel@vger.kernel.org, judy.chenhui@huawei.com,
zhangjinhao2@huawei.com, tglx@linutronix.de
Subject: Re: [PATCH 4.9.257 1/1] futex: Fix OWNER_DEAD fixup
Date: Mon, 22 Feb 2021 11:54:24 +0000 [thread overview]
Message-ID: <20210222115424.GF376568@dell> (raw)
In-Reply-To: <20210222110542.3531596-2-zhengyejian1@huawei.com>
On Mon, 22 Feb 2021, Zheng Yejian wrote:
> From: Peter Zijlstra <peterz@infradead.org>
>
> 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@linux-m68k.org>
> Reported-by: Dave Jones <davej@codemonkey.org.uk>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Paul E. McKenney <paulmck@us.ibm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
> Link: http://lkml.kernel.org/r/20180122103947.GD2228@hirez.programming.kicks-ass.net
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
> ---
> kernel/futex.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
Reviewed-by: Lee Jones <lee.jones@linaro.org>
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog
next prev parent reply other threads:[~2021-02-22 11:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 11:05 [PATCH 4.9.257 0/1] Bugfix for 781691c797de ("futex: Avoid violating the 10th rule of futex") Zheng Yejian
2021-02-22 11:05 ` [PATCH 4.9.257 1/1] futex: Fix OWNER_DEAD fixup Zheng Yejian
2021-02-22 11:54 ` Lee Jones [this message]
2021-02-22 12:07 ` Greg KH
2021-02-22 12:20 ` Zhengyejian (Zetta)
2021-02-22 12:36 ` Greg KH
2021-02-22 13:11 ` Zhengyejian (Zetta)
2021-02-23 13:00 ` Greg KH
2021-02-23 14:51 ` Zhengyejian (Zetta)
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