linux-kernel - Re: [PATCH 5/5] cpufreq: use correct values of cpus in __cpufreq_remove_dev

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Date:	Thu, 12 Sep 2013 12:08:04 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
CC:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
	Patch Tracking <patches@...aro.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/5] cpufreq: use correct values of cpus in __cpufreq_remove_dev_finish()

On 09/12/2013 03:21 AM, Viresh Kumar wrote:
> On 12 September 2013 12:46, Srivatsa S. Bhat
> <srivatsa.bhat@...ux.vnet.ibm.com> wrote:
>> That sounds good! Even the naming is much better, it conveys the intent
>> clearly.
> 
> Folded below change in my patch (attached):
...

For the record, the patch which was attached to Viresh's email solves
the hangs I was getting in next-20130912 during (the second?) CPU
hotplug and resume. So,

Tested-by: Stephen Warren <swarren@...dia.com>

Without this, I saw:

> root@...alhost:~# ./cpuonline.py 
> echo 0 > /sys/devices/system/cpu/cpu1/online
> [   24.049729] CPU1: shutdown
> echo 1 > /sys/devices/system/cpu/cpu1/online
> [   26.090439] CPU1: Booted secondary processor
> root@...alhost:~# ./cpuonline.py 
> echo 0 > /sys/devices/system/cpu/cpu1/online
> [   29.003016] CPU1: shutdown
> echo 1 > /sys/devices/system/cpu/cpu1/online
> [   31.032562] CPU1: Booted secondary processor
[hung]
> [  240.300393] INFO: task ondemand:678 blocked for more than 120 seconds.
> [  240.312842] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [  240.326658] ondemand        D c050f6cc     0   678      1 0x00000000
> [  240.339062] [<c050f6cc>] (__schedule+0x330/0x6d0) from [<c050fe50>] (schedule_preempt_disabled+0x24/0x34)
> [  240.354904] [<c050fe50>] (schedule_preempt_disabled+0x24/0x34) from [<c050e810>] (__mutex_lock_slowpath+0x178/0x370)
> [  240.371767] [<c050e810>] (__mutex_lock_slowpath+0x178/0x370) from [<c050ea14>] (mutex_lock+0xc/0x24)
> [  240.387363] [<c050ea14>] (mutex_lock+0xc/0x24) from [<c00245e8>] (get_online_cpus+0x2c/0x48)
> [  240.402273] [<c00245e8>] (get_online_cpus+0x2c/0x48) from [<c0342c0c>] (store+0x18/0xbc)
> [  240.417688] [<c0342c0c>] (store+0x18/0xbc) from [<c011d598>] (sysfs_write_file+0x168/0x198)
> [  240.432687] [<c011d598>] (sysfs_write_file+0x168/0x198) from [<c00cbf98>] (vfs_write+0xb0/0x188)
> [  240.448185] [<c00cbf98>] (vfs_write+0xb0/0x188) from [<c00cc348>] (SyS_write+0x3c/0x70)
> [  240.462964] [<c00cc348>] (SyS_write+0x3c/0x70) from [<c000e540>] (ret_fast_syscall+0x0/0x30)
> [  240.478239] INFO: task sh:827 blocked for more than 120 seconds.
> [  240.491027] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [  240.505795] sh              D c050f6cc     0   827    825 0x00000001
> [  240.519169] [<c050f6cc>] (__schedule+0x330/0x6d0) from [<c0510660>] (__down_write_nested+0x78/0xcc)
> [  240.535666] [<c0510660>] (__down_write_nested+0x78/0xcc) from [<c0342ae0>] (lock_policy_rwsem_write+0x34/0x48)
> [  240.552950] [<c0342ae0>] (lock_policy_rwsem_write+0x34/0x48) from [<c0343a04>] (cpufreq_update_policy+0x20/0xec)
> [  240.570631] [<c0343a04>] (cpufreq_update_policy+0x20/0xec) from [<c0344410>] (cpufreq_cpu_callback+0x78/0x8c)
> [  240.588051] [<c0344410>] (cpufreq_cpu_callback+0x78/0x8c) from [<c0042f44>] (notifier_call_chain+0x44/0x84)
> [  240.605401] [<c0042f44>] (notifier_call_chain+0x44/0x84) from [<c0024594>] (__cpu_notify+0x28/0x44)
> [  240.622085] [<c0024594>] (__cpu_notify+0x28/0x44) from [<c00247fc>] (_cpu_up+0x100/0x154)
> [  240.638006] [<c00247fc>] (_cpu_up+0x100/0x154) from [<c00248c4>] (cpu_up+0x5c/0x84)
> [  240.653405] [<c00248c4>] (cpu_up+0x5c/0x84) from [<c028a2a8>] (device_online+0x64/0x88)
> [  240.669263] [<c028a2a8>] (device_online+0x64/0x88) from [<c028a328>] (store_online+0x5c/0x64)
> [  240.685683] [<c028a328>] (store_online+0x5c/0x64) from [<c028816c>] (dev_attr_store+0x18/0x24)
> [  240.702337] [<c028816c>] (dev_attr_store+0x18/0x24) from [<c011d598>] (sysfs_write_file+0x168/0x198)
> [  240.719520] [<c011d598>] (sysfs_write_file+0x168/0x198) from [<c00cbf98>] (vfs_write+0xb0/0x188)
> [  240.736614] [<c00cbf98>] (vfs_write+0xb0/0x188) from [<c00cc348>] (SyS_write+0x3c/0x70)
> [  240.752799] [<c00cc348>] (SyS_write+0x3c/0x70) from [<c000e540>] (ret_fast_syscall+0x0/0x30)

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