linux-kernel - Re: [3.15-rc3] rtmutex-debug assertion.

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Message-ID: <20140430034023.GA12319@redhat.com>
Date:	Tue, 29 Apr 2014 23:40:23 -0400
From:	Dave Jones <davej@...hat.com>
To:	Davidlohr Bueso <davidlohr@...com>
Cc:	Linux Kernel <linux-kernel@...r.kernel.org>, peterz@...radead.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	tglx@...utronix.de
Subject: Re: [3.15-rc3] rtmutex-debug assertion.

On Tue, Apr 29, 2014 at 07:24:30PM -0700, Davidlohr Bueso wrote:

 > > futex(uaddr=0x7f55ff8c4000, op=0x6, val=0x200000006223800b, utime=0x7f55ff8c4000, uaddr2=0x7f55ff8c4000, val3=-123)
 > 
 > Perhaps because of chance. Even for pi futexes, if the lock is
 > uncontended, the kernel will never take part.

Ok, once more..

futex(uaddr=0x25fe000[page_rand], op=0x6, val=0xffff4e2644b3dfcb, utime=0x25fe004[page_rand], uaddr2=0x25fe008[page_rand], val3=0xffffffff440fcd80)

FUTEX_LOCK_PI again.

 > Would reverting commit c365c292d059 (sched: Consider pi boosting in
 > setscheduler()) fix this?

I'll try and write a standalone reproducer in the morning.
Then I'll be able to tell you for sure if that commit is good/bad.

	Dave

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