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Date: Thu, 20 Dec 2012 14:26:23 -0500
From: Dave Jones <davej@...hat.com>
To: Linux Kernel <linux-kernel@...r.kernel.org>
Subject: CPU hotplug lockdep trace during offline.
>From Linus' tree as of a half hour ago.
echo 0 > /sys/devices/system/cpu/cpu1/online
[ 67.675171] ======================================================
[ 67.676121] [ INFO: possible circular locking dependency detected ]
[ 67.677084] 3.7.0+ #34 Not tainted
[ 67.677641] -------------------------------------------------------
[ 67.678614] bash/604 is trying to acquire lock:
[ 67.679326] blocked: (cgroup_mutex){+.+.+.}, instance: ffffffff81c38278, at: [<ffffffff810cef77>] cgroup_lock+0x17/0x20
[ 67.681220]
but task is already holding lock:
[ 67.682115] held: (cpu_hotplug.lock){+.+.+.}, instance: ffffffff81c1f700, at: [<ffffffff81049ddf>] cpu_hotplug_begin+0x2f/0x60
[ 67.684087]
which lock already depends on the new lock.
[ 67.685316]
the existing dependency chain (in reverse order) is:
[ 67.686450]
-> #2 (cpu_hotplug.lock){+.+.+.}:
[ 67.687183] [<ffffffff810b84e2>] lock_acquire+0x92/0x1d0
[ 67.688165] [<ffffffff816a7713>] mutex_lock_nested+0x73/0x3b0
[ 67.689186] [<ffffffff81049ddf>] cpu_hotplug_begin+0x2f/0x60
[ 67.690217] [<ffffffff816986df>] _cpu_up+0x29/0x14b
[ 67.691134] [<ffffffff8169884f>] cpu_up+0x4e/0x5e
[ 67.692025] [<ffffffff81edf551>] smp_init+0x82/0xa3
[ 67.692950] [<ffffffff8168d214>] kernel_init+0xd4/0x2d0
[ 67.693924] [<ffffffff816b2b5c>] ret_from_fork+0x7c/0xb0
[ 67.694921]
-> #1 (cpu_add_remove_lock){+.+.+.}:
[ 67.695791] [<ffffffff810b84e2>] lock_acquire+0x92/0x1d0
[ 67.696770] [<ffffffff816a7713>] mutex_lock_nested+0x73/0x3b0
[ 67.697814] [<ffffffff81049f47>] cpu_maps_update_begin+0x17/0x20
[ 67.698897] [<ffffffff8168e406>] register_cpu_notifier+0x16/0x40
[ 67.699973] [<ffffffff8168f450>] mem_cgroup_css_alloc+0x450/0x6a0
[ 67.701071] [<ffffffff81edfde7>] cgroup_init_subsys+0x5e/0xf8
[ 67.702112] [<ffffffff81ee00ad>] cgroup_init+0x46/0x129
[ 67.703076] [<ffffffff81ec8bd9>] start_kernel+0x3cb/0x413
[ 67.704071] [<ffffffff81ec832d>] x86_64_start_reservations+0x131/0x135
[ 67.705206] [<ffffffff81ec8409>] x86_64_start_kernel+0xd8/0xdc
[ 67.706266]
-> #0 (cgroup_mutex){+.+.+.}:
[ 67.707091] [<ffffffff810b7daf>] __lock_acquire+0x1a7f/0x1b30
[ 67.708133] [<ffffffff810b84e2>] lock_acquire+0x92/0x1d0
[ 67.709111] [<ffffffff816a7713>] mutex_lock_nested+0x73/0x3b0
[ 67.710129] [<ffffffff810cef77>] cgroup_lock+0x17/0x20
[ 67.711081] [<ffffffff810d9599>] cpuset_update_active_cpus+0x19/0x160
[ 67.712225] [<ffffffff810891e7>] cpuset_cpu_inactive+0x47/0x50
[ 67.713286] [<ffffffff816ae6d6>] notifier_call_chain+0x66/0x150
[ 67.714358] [<ffffffff81078a2e>] __raw_notifier_call_chain+0xe/0x10
[ 67.715425] [<ffffffff81049d70>] __cpu_notify+0x20/0x40
[ 67.716389] [<ffffffff8168e0bd>] _cpu_down+0x8d/0x330
[ 67.717306] [<ffffffff8168e396>] cpu_down+0x36/0x50
[ 67.718230] [<ffffffff81691b1d>] store_online+0x5d/0xd0
[ 67.719194] [<ffffffff8143b1b8>] dev_attr_store+0x18/0x30
[ 67.720186] [<ffffffff81238440>] sysfs_write_file+0xe0/0x150
[ 67.721224] [<ffffffff811b8fef>] vfs_write+0xaf/0x180
[ 67.722163] [<ffffffff811b9335>] sys_write+0x55/0xa0
[ 67.723095] [<ffffffff816b2c02>] system_call_fastpath+0x16/0x1b
[ 67.724142]
other info that might help us debug this:
[ 67.725345] Chain exists of:
cgroup_mutex --> cpu_add_remove_lock --> cpu_hotplug.lock
[ 67.745352] Possible unsafe locking scenario:
[ 67.758710] CPU0 CPU1
[ 67.765527] ---- ----
[ 67.772259] lock(cpu_hotplug.lock);
[ 67.778901] lock(cpu_add_remove_lock);
[ 67.785983] lock(cpu_hotplug.lock);
[ 67.792943] lock(cgroup_mutex);
[ 67.799358]
*** DEADLOCK ***
[ 67.816718] 5 locks on stack by bash/604:
[ 67.822496] #0: held: (&buffer->mutex){+.+.+.}, instance: ffff880108886518, at: [<ffffffff812383a7>] sysfs_write_file+0x47/0x150
[ 67.829905] #1: blocked: (s_active#69){.+.+.+}, instance: ffff88012ce6cd60, at: [<ffffffff81238428>] sysfs_write_file+0xc8/0x150
[ 67.837370] #2: held: (x86_cpu_hotplug_driver_mutex){+.+.+.}, instance: ffffffff81c1aef8, at: [<ffffffff8101e4b7>] cpu_hotplug_driver_lock+0x17/0x20
[ 67.845512] #3: held: (cpu_add_remove_lock){+.+.+.}, instance: ffffffff81c1f638, at: [<ffffffff81049f47>] cpu_maps_update_begin+0x17/0x20
[ 67.853640] #4: held: (cpu_hotplug.lock){+.+.+.}, instance: ffffffff81c1f700, at: [<ffffffff81049ddf>] cpu_hotplug_begin+0x2f/0x60
[ 67.861874]
stack backtrace:
[ 67.874926] Pid: 604, comm: bash Not tainted 3.7.0+ #34
[ 67.881886] Call Trace:
[ 67.888481] [<ffffffff8169f49d>] print_circular_bug+0x1fe/0x20f
[ 67.895623] [<ffffffff810b7daf>] __lock_acquire+0x1a7f/0x1b30
[ 67.902779] [<ffffffff810b8e6e>] ? mark_held_locks+0xae/0x110
[ 67.909957] [<ffffffff810b2ffe>] ? put_lock_stats.isra.23+0xe/0x40
[ 67.917206] [<ffffffff816aacb5>] ? _raw_spin_unlock_irqrestore+0x65/0x80
[ 67.924565] [<ffffffff810b84e2>] lock_acquire+0x92/0x1d0
[ 67.931733] [<ffffffff810cef77>] ? cgroup_lock+0x17/0x20
[ 67.938894] [<ffffffff816a7713>] mutex_lock_nested+0x73/0x3b0
[ 67.946061] [<ffffffff810cef77>] ? cgroup_lock+0x17/0x20
[ 67.953171] [<ffffffff810b907d>] ? trace_hardirqs_on+0xd/0x10
[ 67.960330] [<ffffffff810cef77>] ? cgroup_lock+0x17/0x20
[ 67.967439] [<ffffffff8101df26>] ? native_send_call_func_single_ipi+0x36/0x40
[ 67.974840] [<ffffffff810c04c1>] ? generic_exec_single+0xb1/0xc0
[ 67.982097] [<ffffffff810cef77>] cgroup_lock+0x17/0x20
[ 67.989262] [<ffffffff810d9599>] cpuset_update_active_cpus+0x19/0x160
[ 67.996640] [<ffffffff810c3ff2>] ? __module_address+0xf2/0x130
[ 68.003933] [<ffffffff810b394e>] ? __lock_is_held+0x5e/0x90
[ 68.011206] [<ffffffff810891e7>] cpuset_cpu_inactive+0x47/0x50
[ 68.018485] [<ffffffff816ae6d6>] notifier_call_chain+0x66/0x150
[ 68.025765] [<ffffffff81078a2e>] __raw_notifier_call_chain+0xe/0x10
[ 68.033047] [<ffffffff81049d70>] __cpu_notify+0x20/0x40
[ 68.040181] [<ffffffff8168e0bd>] _cpu_down+0x8d/0x330
[ 68.047281] [<ffffffff8168e396>] cpu_down+0x36/0x50
[ 68.054328] [<ffffffff81691b1d>] store_online+0x5d/0xd0
[ 68.061400] [<ffffffff8143b1b8>] dev_attr_store+0x18/0x30
[ 68.068489] [<ffffffff81238440>] sysfs_write_file+0xe0/0x150
[ 68.075618] [<ffffffff811b8fef>] vfs_write+0xaf/0x180
[ 68.082647] [<ffffffff811b9335>] sys_write+0x55/0xa0
[ 68.089623] [<ffffffff816b2c02>] system_call_fastpath+0x16/0x1b
--
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