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Date: Thu, 4 Feb 2016 05:01:03 +0530
From: Shilpa Bhat <shilpabhatppc@...il.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
Juri Lelli <juri.lelli@....com>
Cc: Viresh Kumar <viresh.kumar@...aro.org>,
Rafael Wysocki <rjw@...ysocki.net>,
Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
Saravana Kannan <skannan@...eaurora.org>,
Peter Zijlstra <peterz@...radead.org>,
Michael Turquette <mturquette@...libre.com>,
Steve Muckle <steve.muckle@...aro.org>,
Vincent Guittot <vincent.guittot@...aro.org>,
Morten Rasmussen <morten.rasmussen@....com>,
dietmar.eggemann@....com,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 0/7] cpufreq: governors: Fix ABBA lockups
Hi,
On 02/03/2016 10:50 PM, Rafael J. Wysocki wrote:
> On Wed, Feb 3, 2016 at 6:20 PM, Juri Lelli <juri.lelli@....com> wrote:
>> On 03/02/16 21:40, Viresh Kumar wrote:
>>> On 03-02-16, 15:54, Juri Lelli wrote:
>>>> Ouch, I've just got this executing -f basic on Juno. :(
>>>> It happens with the hotplug_1_by_1 test.
>>>>
>>
>> [...]
>>
>>>
>>> Urg..
>>>
>>> I failed to understand it for now though. Please test only the first 4
>>> patches and leave the bottom three. AFAICT, this is caused by the 6th
>>> patch.
>>>
>>> The first 4 are important for 4.5 and must be tested soonish.
>>>
>>
>> First 4 look ok from a testing viewpoint.
>
> Good, thanks for the confirmation!
>
> I'm going to apply them and they will go to Linus next week.
>
> Thanks,
> Rafael
Sorry for the delayed report. But I see the below backtrace on Power8 box. It
has 4 chips with 128 cpus.
I see the below trace with the first four patches on running tests
from Viresh's testcase.
'./runme.sh -f basic'
hit this trace at 'shuffle_governors_for_all_cpus' test.
[ 906.762045] ======================================================
[ 906.762114] [ INFO: possible circular locking dependency detected ]
[ 906.762172] 4.5.0-rc2-sgb+ #96 Not tainted
[ 906.762207] -------------------------------------------------------
[ 906.762263] runme.sh/2840 is trying to acquire lock:
[ 906.762309] (s_active#91){++++.+}, at: [<c000000000407db8>]
kernfs_remove+0x48/0x70
[ 906.762419]
but task is already holding lock:
[ 906.762476] (od_dbs_cdata.mutex){+.+.+.}, at: [<c000000000ad7594>]
cpufreq_governor_dbs+0x64/0x7e0
[ 906.762592]
which lock already depends on the new lock.
[ 906.762659]
the existing dependency chain (in reverse order) is:
[ 906.762727]
-> #2 (od_dbs_cdata.mutex){+.+.+.}:
[ 906.762807] [<c000000000d485b0>] mutex_lock_nested+0x90/0x590
[ 906.762877] [<c000000000ad57f8>] update_sampling_rate+0x88/0x1c0
[ 906.762946] [<c000000000ad5990>] store_sampling_rate+0x60/0xa0
[ 906.763013] [<c000000000ad6af0>] governor_store+0x80/0xc0
[ 906.763070] [<c00000000040a8a4>] sysfs_kf_write+0x94/0xc0
[ 906.763128] [<c0000000004094a8>] kernfs_fop_write+0x188/0x1f0
[ 906.763196] [<c000000000347b8c>] __vfs_write+0x6c/0x180
[ 906.763254] [<c0000000003490a0>] vfs_write+0xc0/0x200
[ 906.763311] [<c00000000034a3cc>] SyS_write+0x6c/0x110
[ 906.763369] [<c00000000000926c>] system_call+0x38/0xd0
[ 906.763427]
-> #1 (&dbs_data->mutex){+.+...}:
[ 906.763495] [<c000000000d485b0>] mutex_lock_nested+0x90/0x590
[ 906.763563] [<c000000000ad6ac0>] governor_store+0x50/0xc0
[ 906.763620] [<c00000000040a8a4>] sysfs_kf_write+0x94/0xc0
[ 906.763677] [<c0000000004094a8>] kernfs_fop_write+0x188/0x1f0
[ 906.763745] [<c000000000347b8c>] __vfs_write+0x6c/0x180
[ 906.763801] [<c0000000003490a0>] vfs_write+0xc0/0x200
[ 906.763859] [<c00000000034a3cc>] SyS_write+0x6c/0x110
[ 906.763916] [<c00000000000926c>] system_call+0x38/0xd0
[ 906.763973]
-> #0 (s_active#91){++++.+}:
[ 906.764052] [<c00000000015f318>] lock_acquire+0xd8/0x1a0
[ 906.764111] [<c0000000004065f4>] __kernfs_remove+0x344/0x410
[ 906.764179] [<c000000000407db8>] kernfs_remove+0x48/0x70
[ 906.764236] [<c00000000040b868>] sysfs_remove_dir+0x78/0xd0
[ 906.764304] [<c0000000005eccec>] kobject_del+0x2c/0x80
[ 906.764362] [<c0000000005ec9e8>] kobject_release+0xa8/0x250
[ 906.764430] [<c000000000ad7c28>] cpufreq_governor_dbs+0x6f8/0x7e0
[ 906.764497] [<c000000000ad4bdc>] od_cpufreq_governor_dbs+0x3c/0x60
[ 906.764567] [<c000000000acf830>] __cpufreq_governor+0x1d0/0x390
[ 906.764634] [<c000000000ad0750>] cpufreq_set_policy+0x3b0/0x450
[ 906.764703] [<c000000000ad12cc>] store_scaling_governor+0x8c/0xf0
[ 906.764771] [<c000000000aced34>] store+0xb4/0x110
[ 906.764828] [<c00000000040a8a4>] sysfs_kf_write+0x94/0xc0
[ 906.764885] [<c0000000004094a8>] kernfs_fop_write+0x188/0x1f0
[ 906.764952] [<c000000000347b8c>] __vfs_write+0x6c/0x180
[ 906.765048] [<c0000000003490a0>] vfs_write+0xc0/0x200
[ 906.765160] [<c00000000034a3cc>] SyS_write+0x6c/0x110
[ 906.765272] [<c00000000000926c>] system_call+0x38/0xd0
[ 906.765384]
other info that might help us debug this:
[ 906.765522] Chain exists of:
s_active#91 --> &dbs_data->mutex --> od_dbs_cdata.mutex
[ 906.765768] Possible unsafe locking scenario:
[ 906.765880] CPU0 CPU1
[ 906.765969] ---- ----
[ 906.766058] lock(od_dbs_cdata.mutex);
[ 906.766170] lock(&dbs_data->mutex);
[ 906.766304] lock(od_dbs_cdata.mutex);
[ 906.766461] lock(s_active#91);
[ 906.766572]
*** DEADLOCK ***
[ 906.766686] 6 locks held by runme.sh/2840:
[ 906.766756] #0: (sb_writers#6){.+.+.+}, at: [<c00000000034cf10>]
__sb_start_write+0x120/0x150
[ 906.767002] #1: (&of->mutex){+.+.+.}, at: [<c00000000040939c>]
kernfs_fop_write+0x7c/0x1f0
[ 906.767225] #2: (s_active#82){.+.+.+}, at: [<c0000000004093a8>]
kernfs_fop_write+0x88/0x1f0
[ 906.767471] #3: (cpu_hotplug.lock){++++++}, at: [<c0000000000e06d8>]
get_online_cpus+0x48/0xc0
[ 906.767676] #4: (&policy->rwsem){+++++.}, at: [<c000000000aced04>]
store+0x84/0x110
[ 906.767878] #5: (od_dbs_cdata.mutex){+.+.+.}, at: [<c000000000ad7594>]
cpufreq_governor_dbs+0x64/0x7e0
[ 906.768124]
stack backtrace:
[ 906.768215] CPU: 0 PID: 2840 Comm: runme.sh Not tainted 4.5.0-rc2-sgb+ #96
[ 906.768329] Call Trace:
[ 906.768375] [c000007fe3126ec0] [c000000000d56530] dump_stack+0x90/0xbc
(unreliable)
[ 906.768536] [c000007fe3126ef0] [c00000000015884c]
print_circular_bug+0x28c/0x3e0
[ 906.768696] [c000007fe3126f90] [c00000000015ed88]
__lock_acquire+0x2278/0x22d0
[ 906.768853] [c000007fe3127120] [c00000000015f318] lock_acquire+0xd8/0x1a0
[ 906.768987] [c000007fe31271e0] [c0000000004065f4] __kernfs_remove+0x344/0x410
[ 906.769121] [c000007fe31272e0] [c000000000407db8] kernfs_remove+0x48/0x70
[ 906.769256] [c000007fe3127310] [c00000000040b868] sysfs_remove_dir+0x78/0xd0
[ 906.769394] [c000007fe3127350] [c0000000005eccec] kobject_del+0x2c/0x80
[ 906.769528] [c000007fe3127380] [c0000000005ec9e8] kobject_release+0xa8/0x250
[ 906.769607] [c000007fe3127410] [c000000000ad7c28]
cpufreq_governor_dbs+0x6f8/0x7e0
[ 906.769687] [c000007fe31274c0] [c000000000ad4bdc]
od_cpufreq_governor_dbs+0x3c/0x60
[ 906.769766] [c000007fe3127500] [c000000000acf830]
__cpufreq_governor+0x1d0/0x390
[ 906.769845] [c000007fe3127580] [c000000000ad0750]
cpufreq_set_policy+0x3b0/0x450
[ 906.769924] [c000007fe3127610] [c000000000ad12cc]
store_scaling_governor+0x8c/0xf0
[ 906.770003] [c000007fe3127c10] [c000000000aced34] store+0xb4/0x110
[ 906.770071] [c000007fe3127c60] [c00000000040a8a4] sysfs_kf_write+0x94/0xc0
[ 906.770139] [c000007fe3127ca0] [c0000000004094a8]
kernfs_fop_write+0x188/0x1f0
[ 906.770221] [c000007fe3127cf0] [c000000000347b8c] __vfs_write+0x6c/0x180
[ 906.770290] [c000007fe3127d90] [c0000000003490a0] vfs_write+0xc0/0x200
[ 906.770358] [c000007fe3127de0] [c00000000034a3cc] SyS_write+0x6c/0x110
[ 906.770426] [c000007fe3127e30] [c00000000000926c] system_call+0x38/0xd0
Thanks and Regards,
Shilpa
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