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Date: Wed, 13 Nov 2013 13:02:38 -0500
From: Dave Jones <davej@redhat.com>
To: Al Viro <viro@zeniv.linux.org.uk>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: getcwd() rcu locking bug.
Message-ID: <20131113180238.GA6419@redhat.com>
Mail-Followup-To: Dave Jones <davej@redhat.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
References: <20131113174706.GA4541@redhat.com>
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On Wed, Nov 13, 2013 at 12:47:06PM -0500, Dave Jones wrote:
 > My fuzzer just hit this on v3.12-7033-g42a2d923cc34
 > 
 > =====================================
 > [ BUG: bad unlock balance detected! ]
 > 3.12.0+ #2 Not tainted
 > -------------------------------------
 > trinity-child1/11681 is trying to release lock (rcu_read_lock) at:
 > [<ffffffff811d287c>] SyS_getcwd+0x11c/0x300
 > but there are no more locks to release!
 > 
 > other info that might help us debug this:
 > no locks held by trinity-child1/11681.
 > 
 > stack backtrace:
 > CPU: 1 PID: 11681 Comm: trinity-child1 Not tainted 3.12.0+ #2 
 >  ffffffff81c480a0 ffff88009a40fea0 ffffffff8171b3dc ffff8802399b1560
 >  ffff88009a40fec8 ffffffff810d370e ffff8802399b1560 ffffffff81c480a0
 >  ffffffff811d287c ffff88009a40ff00 ffffffff810d80fe ffff88023d2d4600
 > Call Trace:
 >  [<ffffffff8171b3dc>] dump_stack+0x4e/0x7a
 >  [<ffffffff810d370e>] print_unlock_imbalance_bug+0xee/0x100
 >  [<ffffffff811d287c>] ? SyS_getcwd+0x11c/0x300
 >  [<ffffffff810d80fe>] lock_release+0x25e/0x310
 >  [<ffffffff811d2894>] SyS_getcwd+0x134/0x300
 >  [<ffffffff811d2799>] ? SyS_getcwd+0x39/0x300
 >  [<ffffffff8172e064>] tracesys+0xdd/0xe2
 > ------------[ cut here ]------------

adding Linus, as this might be related to 68f0d9d92e54

	Dave