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Date:	Tue, 16 Jul 2013 13:44:00 +0300
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Cc:	Michael Wang <wangyun@...ux.vnet.ibm.com>,
	Jiri Kosina <jkosina@...e.cz>, Borislav Petkov <bp@...en8.de>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	linux-kernel@...r.kernel.org, cpufreq@...r.kernel.org,
	linux-pm@...r.kernel.org,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [LOCKDEP] cpufreq: possible circular locking dependency detected

On (07/16/13 14:03), Srivatsa S. Bhat wrote:
> >> So here is the solution:
> >>
> >> On 3.11-rc1, apply these patches in the order mentioned below, and check
> >> whether it fixes _all_ problems (both the warnings about IPI as well as the
> >> lockdep splat).
> >>
> >> 1. Patch given in:  https://lkml.org/lkml/2013/7/11/661
> >>    (Just apply patch 1, not the entire patchset).
> >>
> >> 2. Apply the patch shown below, on top of the above patch:
> >>
> >> ---------------------------------------------------------------------------
> >>
> > 
> > Hello Srivatsa,
> > Thanks, I'll test a bit later -- in the morning. (laptop stopped resuming from
> > suspend, probably radeon dmp).
> > 
> > 
> 
> Sure, thanks!
> 
> > 
> > Shouldn't we also kick the console lock?
> > 
> > 
> >  kernel/printk.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/kernel/printk.c b/kernel/printk.c
> > index d37d45c..3e20233 100644
> > --- a/kernel/printk.c
> > +++ b/kernel/printk.c
> > @@ -1926,8 +1926,11 @@ static int __cpuinit console_cpu_notify(struct notifier_block *self,
> >  {
> >  	switch (action) {
> >  	case CPU_ONLINE:
> > +	case CPU_ONLINE_FROZEN:
> >  	case CPU_DEAD:
> > +	case CPU_DEAD_FROZEN:
> >  	case CPU_DOWN_FAILED:
> > +	case CPU_DOWN_FAILED_FROZEN:
> >  	case CPU_UP_CANCELED:
> >  		console_lock();
> >  		console_unlock();
> > 
> > 
> 
> No need. suspend_console() and resume_console() already handle it
> properly in the suspend/resume case, from what I can see.
>

I've managed to wake up my laptop from suspend, and something's not right.


	# for i in {1..5}; do \
	echo 0 > /sys/devices/system/cpu/cpu3/online; \
	echo 0 > /sys/devices/system/cpu/cpu2/online; \
	echo 1 > /sys/devices/system/cpu/cpu3/online; \
	echo 0 > /sys/devices/system/cpu/cpu1/online; \
	echo 1 > /sys/devices/system/cpu/cpu1/online; \
	echo 1 > /sys/devices/system/cpu/cpu2/online; \
	done
	# systemctl suspend
	->	resume


[  227.329656] ACPI: Preparing to enter system sleep state S3
[  227.353334] PM: Saving platform NVS memory

[  227.355403] ======================================================
[  227.355404] [ INFO: possible circular locking dependency detected ]
[  227.355407] 3.11.0-rc1-dbg-01398-gf537e41-dirty #1838 Not tainted
[  227.355408] -------------------------------------------------------
[  227.355411] systemd-sleep/2280 is trying to acquire lock:
[  227.355426]  (cpu_add_remove_lock){+.+.+.}, at: [<ffffffff8104dab4>]
disable_nonboot_cpus+0x24/0x120
[  227.355427] 
but task is already holding lock:
[  227.355434]  (console_lock){+.+.+.}, at: [<ffffffff8104c956>]
suspend_console+0x26/0x40
[  227.355435] 
which lock already depends on the new lock.

[  227.355436] 
the existing dependency chain (in reverse order) is:
[  227.355441] 
-> #2 (console_lock){+.+.+.}:
[  227.355448]        [<ffffffff810b8fb4>] lock_acquire+0xa4/0x200
[  227.355452]        [<ffffffff8104b197>] console_lock+0x77/0x80
[  227.355456]        [<ffffffff8104cf91>] console_cpu_notify+0x31/0x40
[  227.355462]        [<ffffffff8107cd6d>] notifier_call_chain+0x5d/0x110
[  227.355466]        [<ffffffff8107ce2e>] __raw_notifier_call_chain+0xe/0x10
[  227.355469]        [<ffffffff8104d5a3>] cpu_notify+0x23/0x50
[  227.355473]        [<ffffffff8104d5de>] cpu_notify_nofail+0xe/0x20
[  227.355482]        [<ffffffff815fafad>] _cpu_down+0x1ad/0x330
[  227.355486]        [<ffffffff815fb166>] cpu_down+0x36/0x50
[  227.355493]        [<ffffffff814ad8cd>] cpu_subsys_offline+0x1d/0x30
[  227.355498]        [<ffffffff814a8de5>] device_offline+0x95/0xc0
[  227.355502]        [<ffffffff814a8ee2>] store_online+0x42/0x90
[  227.355506]        [<ffffffff814a64f8>] dev_attr_store+0x18/0x30
[  227.355513]        [<ffffffff811ec71b>] sysfs_write_file+0xdb/0x150
[  227.355517]        [<ffffffff8117a68d>] vfs_write+0xbd/0x1e0
[  227.355522]        [<ffffffff8117ad7c>] SyS_write+0x4c/0xa0
[  227.355527]        [<ffffffff8160cbfe>] tracesys+0xd0/0xd5
[  227.355531] 
-> #1 (cpu_hotplug.lock){+.+.+.}:
[  227.355535]        [<ffffffff810b8fb4>] lock_acquire+0xa4/0x200
[  227.355541]        [<ffffffff81605b47>] mutex_lock_nested+0x67/0x410
[  227.355545]        [<ffffffff8104d54b>] cpu_hotplug_begin+0x2b/0x60
[  227.355549]        [<ffffffff8104d61a>] _cpu_up+0x2a/0x170
[  227.355552]        [<ffffffff8104d7b9>] cpu_up+0x59/0x80
[  227.355558]        [<ffffffff81cf51b6>] smp_init+0x64/0x95
[  227.355566]        [<ffffffff81cdaf21>] kernel_init_freeable+0x84/0x191
[  227.355570]        [<ffffffff815fa34e>] kernel_init+0xe/0x180
[  227.355574]        [<ffffffff8160c9ac>] ret_from_fork+0x7c/0xb0
[  227.355578] 
-> #0 (cpu_add_remove_lock){+.+.+.}:
[  227.355582]        [<ffffffff810b8106>] __lock_acquire+0x1766/0x1d30
[  227.355586]        [<ffffffff810b8fb4>] lock_acquire+0xa4/0x200
[  227.355590]        [<ffffffff81605b47>] mutex_lock_nested+0x67/0x410
[  227.355594]        [<ffffffff8104dab4>] disable_nonboot_cpus+0x24/0x120
[  227.355601]        [<ffffffff810a0973>] suspend_devices_and_enter+0x1f3/0x680
[  227.355605]        [<ffffffff810a0fd2>] pm_suspend+0x1d2/0x240
[  227.355609]        [<ffffffff8109fa19>] state_store+0x79/0xf0
[  227.355614]        [<ffffffff81312dbf>] kobj_attr_store+0xf/0x20
[  227.355618]        [<ffffffff811ec71b>] sysfs_write_file+0xdb/0x150
[  227.355621]        [<ffffffff8117a68d>] vfs_write+0xbd/0x1e0
[  227.355624]        [<ffffffff8117ad7c>] SyS_write+0x4c/0xa0
[  227.355628]        [<ffffffff8160cbfe>] tracesys+0xd0/0xd5
[  227.355629] 
other info that might help us debug this:

[  227.355635] Chain exists of:
  cpu_add_remove_lock --> cpu_hotplug.lock --> console_lock

  [  227.355637]  Possible unsafe locking scenario:

  [  227.355638]        CPU0                    CPU1
  [  227.355639]        ----                    ----
  [  227.355642]   lock(console_lock);
  [  227.355644]                                lock(cpu_hotplug.lock);
  [  227.355647]                                lock(console_lock);
  [  227.355650]   lock(cpu_add_remove_lock);
  [  227.355651] 
   *** DEADLOCK ***

   [  227.355653] 5 locks held by systemd-sleep/2280:
   [  227.355661]  #0:  (sb_writers#6){.+.+.+}, at: [<ffffffff8117a78b>]   vfs_write+0x1bb/0x1e0
   [  227.355668]  #1:  (&buffer->mutex){+.+.+.}, at:   [<ffffffff811ec67c>] sysfs_write_file+0x3c/0x150
   [  227.355676]  #2:  (s_active#110){.+.+.+}, at: [<ffffffff811ec703>]   sysfs_write_file+0xc3/0x150
   [  227.355683]  #3:  (pm_mutex){+.+.+.}, at: [<ffffffff810a0e32>]   pm_suspend+0x32/0x240
   [  227.355690]  #4:  (console_lock){+.+.+.}, at: [<ffffffff8104c956>]   suspend_console+0x26/0x40
   [  227.355691] 
   stack backtrace:
   [  227.355695] CPU: 0 PID: 2280 Comm: systemd-sleep Not tainted   3.11.0-rc1-dbg-01398-gf537e41-dirty #1838
   [  227.355697] Hardware name: Acer             Aspire 5741G   /Aspire 5741G    , BIOS V1.20 02/08/2011
   [  227.355703]  ffffffff82208680 ffff88015151bbc8 ffffffff81603038   ffffffff822073f0
   [  227.355707]  ffff88015151bc08 ffffffff815ffdaa ffff880153389fa0   ffff88015338a788
   [  227.355712]  1d81e4832c04c441 ffff88015338a760 ffff88015338a788   ffff880153389fa0
   [  227.355713] Call Trace:
   [  227.355719]  [<ffffffff81603038>] dump_stack+0x4e/0x82
   [  227.355723]  [<ffffffff815ffdaa>] print_circular_bug+0x2b6/0x2c5
   [  227.355727]  [<ffffffff810b8106>] __lock_acquire+0x1766/0x1d30
   [  227.355733]  [<ffffffff81054aec>] ?   walk_system_ram_range+0x5c/0x140
   [  227.355737]  [<ffffffff810b63f4>] ? mark_held_locks+0x94/0x140
   [  227.355741]  [<ffffffff810b8fb4>] lock_acquire+0xa4/0x200
   [  227.355745]  [<ffffffff8104dab4>] ?   disable_nonboot_cpus+0x24/0x120
   [  227.355749]  [<ffffffff8104dab4>] ?   disable_nonboot_cpus+0x24/0x120
   [  227.355753]  [<ffffffff81605b47>] mutex_lock_nested+0x67/0x410
   [  227.355757]  [<ffffffff8104dab4>] ?   disable_nonboot_cpus+0x24/0x120
   [  227.355761]  [<ffffffff81607e9e>] ? mutex_unlock+0xe/0x10
   [  227.355768]  [<ffffffff8135bd2f>] ? acpi_os_get_iomem+0x4c/0x54
   [  227.355772]  [<ffffffff8104dab4>] disable_nonboot_cpus+0x24/0x120
   [  227.355777]  [<ffffffff810a0973>]   suspend_devices_and_enter+0x1f3/0x680
   [  227.355780]  [<ffffffff815fefc6>] ? printk+0x67/0x69
   [  227.355785]  [<ffffffff810a0fd2>] pm_suspend+0x1d2/0x240
   [  227.355789]  [<ffffffff8109fa19>] state_store+0x79/0xf0
   [  227.355792]  [<ffffffff81312dbf>] kobj_attr_store+0xf/0x20
   [  227.355796]  [<ffffffff811ec71b>] sysfs_write_file+0xdb/0x150
   [  227.355799]  [<ffffffff8117a68d>] vfs_write+0xbd/0x1e0
   [  227.355804]  [<ffffffff81198490>] ? fget_light+0x320/0x4b0
   [  227.355808]  [<ffffffff8117ad7c>] SyS_write+0x4c/0xa0
   [  227.355811]  [<ffffffff8160cbfe>] tracesys+0xd0/0xd5
   [  227.355814] Disabling non-boot CPUs ...
   [  227.357731] smpboot: CPU 1 is now offline
   [  227.461072] smpboot: CPU 2 is now offline
   [  227.565119] smpboot: CPU 3 is now offline



Just to make sure I didn't miss anything:

git diff -u -p drivers/cpufreq/

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 0937b8d..7dcfa68 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1942,13 +1942,15 @@ static int __cpuinit cpufreq_cpu_callback(struct notifier_block *nfb,
        if (dev) {
                switch (action) {
                case CPU_ONLINE:
+               case CPU_ONLINE_FROZEN:
                        cpufreq_add_dev(dev, NULL);
                        break;
                case CPU_DOWN_PREPARE:
-               case CPU_UP_CANCELED_FROZEN:
+               case CPU_DOWN_PREPARE_FROZEN:
                        __cpufreq_remove_dev(dev, NULL);
                        break;
                case CPU_DOWN_FAILED:
+               case CPU_DOWN_FAILED_FROZEN:
                        cpufreq_add_dev(dev, NULL);
                        break;
                }
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 4645876..7b839a8 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -25,7 +25,6 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/workqueue.h>
-#include <linux/cpu.h>
 
 #include "cpufreq_governor.h"
 
@@ -137,10 +136,8 @@ void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy,
        if (!all_cpus) {
                __gov_queue_work(smp_processor_id(), dbs_data, delay);
        } else {
-               get_online_cpus();
                for_each_cpu(i, policy->cpus)
                        __gov_queue_work(i, dbs_data, delay);
-               put_online_cpus();
        }
 }
 EXPORT_SYMBOL_GPL(gov_queue_work);
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index cd9e817..12225d1 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -353,13 +353,11 @@ static int __cpuinit cpufreq_stat_cpu_callback(struct notifier_block *nfb,
                cpufreq_update_policy(cpu);
                break;
        case CPU_DOWN_PREPARE:
+       case CPU_DOWN_PREPARE_FROZEN:
                cpufreq_stats_free_sysfs(cpu);
                break;
        case CPU_DEAD:
-               cpufreq_stats_free_table(cpu);
-               break;
-       case CPU_UP_CANCELED_FROZEN:
-               cpufreq_stats_free_sysfs(cpu);
+       case CPU_DEAD_FROZEN:
                cpufreq_stats_free_table(cpu);
                break;
        }


	-ss
--
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