linux-kernel - Re: [PATCH] futex: move debug_rt_mutex_free

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Message-ID: <20170308153731.z3vjtb24h75eyv4u@linutronix.de>
Date:   Wed, 8 Mar 2017 16:37:32 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     tglx@...utronix.de, mingo@...nel.org, juri.lelli@....com,
        rostedt@...dmis.org, xlpang@...hat.com,
        linux-kernel@...r.kernel.org, mathieu.desnoyers@...icios.com,
        jdesfossez@...icios.com, bristot@...hat.com, dvhart@...radead.org
Subject: Re: [PATCH] futex: move debug_rt_mutex_free_waiter() further down

On 2017-03-08 16:29:02 [+0100], To Peter Zijlstra wrote:
> Without this, futex_requeue_pi_signal_restart will trigger
> 
> |kernel BUG at locking/rtmutex_common.h:55!
> |Call Trace:
> | rt_mutex_cleanup_proxy_lock+0x54/0x90
> | futex_wait_requeue_pi.constprop.21+0x387/0x4d0
> | do_futex+0x289/0xbf0
> |RIP: remove_waiter+0x157/0x170 RSP: ffffc90000e0fbe0
> 
> with BUG 2222222222222222 != pointer once this patch is applied.

My wording is wrong. This BUG_ON() statement described here in this
patch (together with the test case mentioned) will trigger once

 "[PATCH -v5 12/14] futex,rt_mutex: Restructure rt_mutex_finish_proxy_lock()"

is applied.

Sebastian