From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-rt-users <linux-rt-users@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
rostedt@goodmis.org, John Kacur <jkacur@redhat.com>
Subject: Re: [ANNOUNCE] 3.14-rt1
Date: Sat, 26 Apr 2014 10:38:11 +0200 [thread overview]
Message-ID: <1398501491.12941.5.camel@marge.simpson.net> (raw)
In-Reply-To: <1398411635.11930.45.camel@marge.simpson.net>
On Fri, 2014-04-25 at 09:40 +0200, Mike Galbraith wrote:
> Hotplug can still deadlock in rt trees too, and will if you beat it
> hard.
Box actually deadlocks like so.
CPU3 boot.kdump
sys_wait4
do_wait
read_lock(&tasklist_lock)
rt_read_lock
__rt_spin_lock(lock)
migrate_disable()
pin_current_cpu()
if (hp->grab_lock) {
preempt_enable(); <== hmm
hotplug_lock(hp);
hp = &__get_cpu_var(hotplug_pcp); <== hmm
struct hotplug_pcp {
unplug = 0xffff8800b7d0e540,
sync_tsk = 0x0,
refcount = 0, <== hmm
grab_lock = 1,
...
lock = {
...
owner = 0xffff8802039f0001,
stress-cpu-hotplug_stress.sh?!?
<=== he's way over yonder.
Yo, dude, would you please NOT
take percpu locks with you?
CPU0 stress-cpu-hotplug_stress.sh
sysfs_write_file
dev_attr_store
online_store
device_offline
cpu_subsys_offline
cpu_down
_cpu_down
cpu_hotplug_begin
mutex_lock(&cpu_hotplug.lock);
...
check_for_tasks
write_lock_irq(&tasklist_lock);
held by CPU3 boot.kdump over there ===>
CPU0 kworker/0:0
cpuset_hotplug_workfn+0x23e/0x380
rebuild_sched_domains+0x15/0x30
rebuild_sched_domains_locked+0x17/0x80
get_online_cpus+0x35/0x50
mutex_lock(&cpu_hotplug.lock);
held by stress-cpu-hotplug_stress.sh
twiddle twiddle twiddle...
INFO: task kworker/0:0:4 blocked for more than 120 seconds.
next prev parent reply other threads:[~2014-04-26 8:38 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-11 18:57 Sebastian Andrzej Siewior
2014-04-11 19:34 ` Pavel Vasilyev
2014-04-19 14:46 ` Mike Galbraith
2014-04-21 3:31 ` Mike Galbraith
2014-05-02 10:16 ` Sebastian Andrzej Siewior
2014-04-25 7:40 ` Mike Galbraith
2014-04-26 8:38 ` Mike Galbraith [this message]
2014-04-26 13:58 ` Mike Galbraith
2014-04-28 5:09 ` Mike Galbraith
2014-04-28 9:09 ` Mike Galbraith
2014-04-28 14:18 ` Steven Rostedt
2014-04-28 14:37 ` Mike Galbraith
2014-04-28 14:43 ` Mike Galbraith
2014-04-29 5:21 ` Mike Galbraith
2014-04-30 0:13 ` Steven Rostedt
2014-04-30 7:43 ` Mike Galbraith
2014-04-30 13:06 ` Mike Galbraith
2014-04-30 13:15 ` Steven Rostedt
2014-04-30 14:00 ` Mike Galbraith
2014-04-30 14:19 ` Steven Rostedt
2014-04-30 14:33 ` Steven Rostedt
2014-04-30 14:54 ` Mike Galbraith
2014-04-30 15:11 ` Steven Rostedt
2014-04-30 15:15 ` Mike Galbraith
2014-04-30 15:48 ` Steven Rostedt
2014-04-30 15:56 ` Mike Galbraith
2014-05-01 17:36 ` Mike Galbraith
2014-05-01 18:42 ` Steven Rostedt
2014-05-02 1:45 ` Mike Galbraith
2014-04-30 15:21 ` Mike Galbraith
2014-04-30 14:45 ` Mike Galbraith
2014-05-02 10:09 ` Sebastian Andrzej Siewior
2014-05-02 11:16 ` Mike Galbraith
2014-04-23 10:37 ` Mike Galbraith
2014-04-23 12:19 ` Steven Rostedt
2014-04-24 4:06 ` Mike Galbraith
2014-04-24 7:12 ` Sebastian Andrzej Siewior
2014-04-24 7:26 ` Mike Galbraith
2014-04-26 18:29 ` Fernando Lopez-Lezcano
2014-05-02 11:37 ` Sebastian Andrzej Siewior
2014-05-15 17:51 ` Fernando Lopez-Lezcano
2014-05-15 20:09 ` Fernando Lopez-Lezcano
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