linux-kernel - Re: PI futexes + lock stealing woes

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Message-ID: <20171206234622.GZ3326@worktop>
Date:   Thu, 7 Dec 2017 00:46:22 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Julia Cartwright <julia@...com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Gratian Crisan <gratian.crisan@...com>,
        linux-kernel@...r.kernel.org, Darren Hart <dvhart@...radead.org>,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: PI futexes + lock stealing woes

On Wed, Nov 29, 2017 at 11:56:05AM -0600, Julia Cartwright wrote:

> fixup_owner() used to have additional seemingly relevant checks in place
> that were removed 73d786bd043eb ("futex: Rework inconsistent
> rt_mutex/futex_q state").

*groan*... yes. I completely missed that extra case also applied to
requeue_pi (requeue always did hurt my brain).

I got as far as actually understanding the problem; but its near 1am and
I desperately need a sleep, I'll see if I can come up with a solution
tomorrow. I just wanted to let you know I finally got around to looking
at this..