From: Peter Zijlstra <peterz@infradead.org>
To: Fengguang Wu <fengguang.wu@intel.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
David Howells <dhowells@redhat.com>,
Miklos Szeredi <mszeredi@suse.cz>,
lkp@01.org, Sasha Levin <alexander.levin@verizon.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Byungchul Park <byungchul.park@lge.com>,
Paul McKenney <paulmck@linux.vnet.ibm.com>
Subject: Re: [d_alloc_parallel] WARNING: bad unlock balance detected!
Date: Tue, 7 Nov 2017 09:51:07 +0100 [thread overview]
Message-ID: <20171107085107.GH3326@worktop> (raw)
In-Reply-To: <20171107040329.yftf6ceduet4zaph@wfg-t540p.sh.intel.com>
On Tue, Nov 07, 2017 at 12:03:29PM +0800, Fengguang Wu wrote:
> >>[ 428.512005] e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
> >>LKP: HOSTNAME vm-lkp-wsx03-openwrt-i386-8, MAC , kernel 4.14.0-rc8 158, serial console /dev/ttyS0
> >>[ 429.798345] Kernel tests: Boot OK!
> >>[ 430.761760] [ 430.766166] =====================================
> >>[ 430.775297] WARNING: bad unlock balance detected!
> >>[ 430.784342] 4.14.0-rc8 #158 Not tainted
> >>[ 430.792153] -------------------------------------
> >>[ 430.801319] pidof/1024 is trying to release lock (rcu_preempt_state) at:
> >>[ 430.813514] [<c10e4348>] rcu_read_unlock_special+0x5f8/0x620
> >>[ 430.824041] but there are no more locks to release!
> >
> >Er... yes? What of that? Since when is rcu_read_lock() not allowed to
> >be used under an rwsem?
That's not what it says, it is.. The warning is about trying to release
a lock that's not held. And its right, RCU was doing that. It would
acquire a lock without lockdep knowing about it and then telling lockdep
about freeing it.
This is fixed by commit:
02a7c234e540 ("rcu: Suppress lockdep false-positive ->boost_mtx complaints")
The problem is that RCU boosting was mixing futex and !futex rt_mutex
ops.
prev parent reply other threads:[~2017-11-07 8:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-07 2:01 [d_alloc_parallel] WARNING: bad unlock balance detected! Fengguang Wu
2017-11-07 2:33 ` Al Viro
2017-11-07 4:03 ` Fengguang Wu
2017-11-07 8:51 ` Peter Zijlstra [this message]
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