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Message-ID: <87zjne7f75.fsf@nemi.mork.no>
Date: Thu, 02 Jan 2014 13:15:10 +0100
From: Bjørn Mork <bjorn@...k.no>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Viresh Kumar <viresh.kumar@...aro.org>,
linaro-kernel@...ts.linaro.org, patches@...aro.org,
cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] cpufreq: try to resume policies which failed on last resume
"Rafael J. Wysocki" <rjw@...ysocki.net> writes:
> On Tuesday, December 24, 2013 07:11:00 AM Viresh Kumar wrote:
>> __cpufreq_add_dev() can fail sometimes while we are resuming our system.
>> Currently we are clearing all sysfs nodes for cpufreq's failed policy as that
>> could make userspace unstable. But if we suspend/resume again, we should atleast
>> try to bring back those policies.
>>
>> This patch fixes this issue by clearing fallback data on failure and trying to
>> allocate a new struct cpufreq_policy on second resume.
>>
>> Reported-and-tested-by: Bjørn Mork <bjorn@...k.no>
>> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
>
> Well, while I appreciate the work done here, I don't like the changelog,
> I don't really like the way the code is written and I don't like the comments.
> Sorry about that.
>
> Bjorn, can you please test the patch below instead along with the [2/2]
> from this series (on top of linux-pm.git/pm-cpufreq)?
I tested this series with your modified 1/2 today, but on top of a
current mainline (commit 9a0bb2966ef) instead of linux-pm.git/pm-cpufreq.
Shouldn't make much difference since Linus already has pulled your
'pm+acpi-3.13-rc6' tag, which included that pm-cpufreq branch.
This series fixes the reported bug for me.
But I observed this, most likely unrelated, splat during the test:
ACPI Exception: AE_BAD_PARAMETER, Returned by Handler for [EmbeddedControl] (20131115/evregion-282)
ACPI Error: Method parse/execution failed [\_SB_.PCI0.LPC_.EC__.LPMD] (Node ffff880232499c18), AE_BAD_PARAMETER (20131115/psparse-536)
ACPI Error: Method parse/execution failed [\_PR_.CPU0._PPC] (Node ffff8802326f93d0), AE_BAD_PARAMETER (20131115/psparse-536)
ACPI Error: Method parse/execution failed [\_PR_.CPU1._PPC] (Node ffff8802326f9268), AE_BAD_PARAMETER (20131115/psparse-536)
ACPI Exception: AE_BAD_PARAMETER, Evaluating _PPC (20131115/processor_perflib-140)
======================================================
[ INFO: possible circular locking dependency detected ]
3.13.0-rc6+ #181 Not tainted
-------------------------------------------------------
s2disk/5651 is trying to acquire lock:
(s_active#170){++++.+}, at: [<ffffffff8118b9d7>] sysfs_addrm_finish+0x28/0x46
but task is already holding lock:
(cpu_hotplug.lock){+.+.+.}, at: [<ffffffff81039ff5>] cpu_hotplug_begin+0x28/0x50
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (cpu_hotplug.lock){+.+.+.}:
[<ffffffff81075027>] lock_acquire+0xfb/0x144
[<ffffffff8139d4d2>] mutex_lock_nested+0x6c/0x397
[<ffffffff81039f4a>] get_online_cpus+0x3c/0x50
[<ffffffff812a6974>] store+0x20/0xad
[<ffffffff8118a9a1>] sysfs_write_file+0x138/0x18b
[<ffffffff8112a428>] vfs_write+0x9c/0x102
[<ffffffff8112a716>] SyS_write+0x50/0x85
[<ffffffff813a57a2>] system_call_fastpath+0x16/0x1b
-> #0 (s_active#170){++++.+}:
[<ffffffff81074760>] __lock_acquire+0xae3/0xe68
[<ffffffff81075027>] lock_acquire+0xfb/0x144
[<ffffffff8118b027>] sysfs_deactivate+0xa5/0x108
[<ffffffff8118b9d7>] sysfs_addrm_finish+0x28/0x46
[<ffffffff8118bd3f>] sysfs_remove+0x2a/0x31
[<ffffffff8118be2f>] sysfs_remove_dir+0x66/0x6b
[<ffffffff811d5d11>] kobject_del+0x18/0x42
[<ffffffff811d5e1c>] kobject_cleanup+0xe1/0x14f
[<ffffffff811d5ede>] kobject_put+0x45/0x49
[<ffffffff812a6e85>] cpufreq_policy_put_kobj+0x37/0x83
[<ffffffff812a8bab>] __cpufreq_add_dev.isra.18+0x75e/0x78c
[<ffffffff812a8c39>] cpufreq_cpu_callback+0x53/0x88
[<ffffffff813a314c>] notifier_call_chain+0x67/0x92
[<ffffffff8105bce4>] __raw_notifier_call_chain+0x9/0xb
[<ffffffff81039e7c>] __cpu_notify+0x1b/0x32
[<ffffffff81039ea1>] cpu_notify+0xe/0x10
[<ffffffff8103a12b>] _cpu_up+0xf1/0x124
[<ffffffff8138ee7d>] enable_nonboot_cpus+0x52/0xbf
[<ffffffff8107a2a3>] hibernation_snapshot+0x1be/0x2ed
[<ffffffff8107eb84>] snapshot_ioctl+0x1e5/0x431
[<ffffffff81139080>] do_vfs_ioctl+0x45e/0x4a8
[<ffffffff8113911c>] SyS_ioctl+0x52/0x82
[<ffffffff813a57a2>] system_call_fastpath+0x16/0x1b
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(cpu_hotplug.lock);
lock(s_active#170);
lock(cpu_hotplug.lock);
lock(s_active#170);
*** DEADLOCK ***
7 locks held by s2disk/5651:
#0: (pm_mutex){+.+.+.}, at: [<ffffffff8107e9ea>] snapshot_ioctl+0x4b/0x431
#1: (device_hotplug_lock){+.+.+.}, at: [<ffffffff81283730>] lock_device_hotplug+0x12/0x14
#2: (acpi_scan_lock){+.+.+.}, at: [<ffffffff8122c657>] acpi_scan_lock_acquire+0x12/0x14
#3: (console_lock){+.+.+.}, at: [<ffffffff810817f2>] suspend_console+0x20/0x38
#4: (cpu_add_remove_lock){+.+.+.}, at: [<ffffffff81039fb9>] cpu_maps_update_begin+0x12/0x14
#5: (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff81039ff5>] cpu_hotplug_begin+0x28/0x50
#6: (cpufreq_rwsem){.+.+.+}, at: [<ffffffff812a84cc>] __cpufreq_add_dev.isra.18+0x7f/0x78c
stack backtrace:
CPU: 0 PID: 5651 Comm: s2disk Not tainted 3.13.0-rc6+ #181
Hardware name: LENOVO 2776LEG/2776LEG, BIOS 6EET55WW (3.15 ) 12/19/2011
ffffffff81d3edf0 ffff8802174898f8 ffffffff81399cac 0000000000004549
ffffffff81d3edf0 ffff880217489948 ffffffff81397dc5 ffff880217489928
ffff88023198ea50 0000000000000006 ffff88023198f1d8 0000000000000006
Call Trace:
[<ffffffff81399cac>] dump_stack+0x4e/0x68
[<ffffffff81397dc5>] print_circular_bug+0x1f8/0x209
[<ffffffff81074760>] __lock_acquire+0xae3/0xe68
[<ffffffff8107565d>] ? debug_check_no_locks_freed+0x12c/0x143
[<ffffffff81075027>] lock_acquire+0xfb/0x144
[<ffffffff8118b9d7>] ? sysfs_addrm_finish+0x28/0x46
[<ffffffff81072201>] ? lockdep_init_map+0x14e/0x160
[<ffffffff8118b027>] sysfs_deactivate+0xa5/0x108
[<ffffffff8118b9d7>] ? sysfs_addrm_finish+0x28/0x46
[<ffffffff8118b9d7>] sysfs_addrm_finish+0x28/0x46
[<ffffffff8118bd3f>] sysfs_remove+0x2a/0x31
[<ffffffff8118be2f>] sysfs_remove_dir+0x66/0x6b
[<ffffffff811d5d11>] kobject_del+0x18/0x42
[<ffffffff811d5e1c>] kobject_cleanup+0xe1/0x14f
[<ffffffff811d5ede>] kobject_put+0x45/0x49
[<ffffffff812a6e85>] cpufreq_policy_put_kobj+0x37/0x83
[<ffffffff812a8bab>] __cpufreq_add_dev.isra.18+0x75e/0x78c
[<ffffffff81071b04>] ? __lock_is_held+0x32/0x54
[<ffffffff812a8c39>] cpufreq_cpu_callback+0x53/0x88
[<ffffffff813a314c>] notifier_call_chain+0x67/0x92
[<ffffffff8105bce4>] __raw_notifier_call_chain+0x9/0xb
[<ffffffff81039e7c>] __cpu_notify+0x1b/0x32
[<ffffffff81039ea1>] cpu_notify+0xe/0x10
[<ffffffff8103a12b>] _cpu_up+0xf1/0x124
[<ffffffff8138ee7d>] enable_nonboot_cpus+0x52/0xbf
[<ffffffff8107a2a3>] hibernation_snapshot+0x1be/0x2ed
[<ffffffff8107eb84>] snapshot_ioctl+0x1e5/0x431
[<ffffffff81139080>] do_vfs_ioctl+0x45e/0x4a8
[<ffffffff811414c8>] ? fcheck_files+0xa1/0xe4
[<ffffffff81141a67>] ? fget_light+0x33/0x9a
[<ffffffff8113911c>] SyS_ioctl+0x52/0x82
[<ffffffff811df4ce>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff813a57a2>] system_call_fastpath+0x16/0x1b
CPU1 is up
ACPI: Waking up from system sleep state S4
PM: noirq thaw of devices complete after 2.727 msecs
PM: early thaw of devices complete after 1.137 msecs
This warning appeared when I tried cancelling hibernation, which is
known to fail when using the acpi-cpufreq driver. The point of the test
was to verify that such failures still produce the expected result:
- all stale sysfs files are cleaned up and removed
- later suspend/resume actions will restore (or actually reinitiate)
the cpufreq driver for the non-boot CPUs
Which was successful, except that it produced the above lockdep warning.
I have not verified that this is a new warning (which means that it most
likely is not). And I expect the whole acpi-cpufreq problem, including
that warning, to go away when you eventually push
http://www.spinics.net/lists/cpufreq/msg08714.html with your improved
changelog (thanks for doing that BTW). So I don't worry too much about
it. Just wanted to let you know.
Bjørn
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