"Rafael J. Wysocki" rjw@rjwysocki.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@mork.no Signed-off-by: Viresh Kumar viresh.kumar@linaro.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