From: Dave Jones <davej@redhat.com>
To: Linux Kernel <linux-kernel@vger.kernel.org>
Cc: davidel@xmailserver.org
Subject: recursive locking: epoll.
Date: Fri, 15 Jul 2011 17:04:20 -0400 [thread overview]
Message-ID: <20110715210420.GA22551@redhat.com> (raw)
In-Reply-To: <4E1FF63F.4040704@gmail.com>
We just had a Fedora user report this lockdep trace.
=============================================
[ INFO: possible recursive locking detected ]
3.0-0.rc7.git0.1.fc16.i686 #1
---------------------------------------------
systemd-logind/651 is trying to acquire lock:
(&ep->mtx){+.+.+.}, at: [<c05285f1>] ep_scan_ready_list+0x32/0x154
but task is already holding lock:
(&ep->mtx){+.+.+.}, at: [<c0528a90>] sys_epoll_ctl+0x103/0x481
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&ep->mtx);
lock(&ep->mtx);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by systemd-logind/651:
#0: (epmutex){+.+.+.}, at: [<c0528a4b>] sys_epoll_ctl+0xbe/0x481
#1: (&ep->mtx){+.+.+.}, at: [<c0528a90>] sys_epoll_ctl+0x103/0x481
stack backtrace:
Pid: 651, comm: systemd-logind Not tainted 3.0-0.rc7.git0.1.fc16.i686 #1
Call Trace:
[<c08490fe>] ? printk+0x2d/0x2f
[<c046b2ef>] __lock_acquire+0x811/0xb63
[<c0407c77>] ? sched_clock+0x8/0xb
[<c045d190>] ? sched_clock_local+0x10/0x18b
[<c05285f1>] ? ep_scan_ready_list+0x32/0x154
[<c046ba5e>] lock_acquire+0xad/0xe4
[<c05285f1>] ? ep_scan_ready_list+0x32/0x154
[<c08506bd>] __mutex_lock_common+0x49/0x2ee
[<c05285f1>] ? ep_scan_ready_list+0x32/0x154
[<c04332e6>] ? __might_sleep+0x29/0xfb
[<c046a912>] ? mark_lock+0x26/0x1f2
[<c0850a7c>] mutex_lock_nested+0x43/0x49
[<c05285f1>] ? ep_scan_ready_list+0x32/0x154
[<c05285f1>] ep_scan_ready_list+0x32/0x154
[<c05281cb>] ? ep_remove+0x9b/0x9b
[<c0528727>] ep_poll_readyevents_proc+0x14/0x16
[<c05283d6>] ep_call_nested.constprop.2+0x6d/0x9a
[<c0528713>] ? ep_scan_ready_list+0x154/0x154
[<c05284d2>] ep_eventpoll_poll+0x45/0x55
[<c0528b8c>] sys_epoll_ctl+0x1ff/0x481
[<c05282fb>] ? ep_send_events_proc+0xd5/0xd5
[<c08521ac>] syscall_call+0x7/0xb
next parent reply other threads:[~2011-07-15 21:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4E1FF63F.4040704@gmail.com>
2011-07-15 21:04 ` Dave Jones [this message]
2011-07-20 8:05 ` recursive locking: epoll Paul Bolle
2011-07-21 11:55 ` Paul Bolle
2011-07-29 18:50 ` Paul Bolle
2011-07-30 18:26 ` Nelson Elhage
2011-07-30 21:25 ` Nelson Elhage
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