When I offline a memory on linux-3.6-rc5, "possible circular
locking dependency detected" messages are shown.
Are the messages known problem?
[ 201.596363] Offlined Pages 32768
[ 201.596373] remove from free list 140000 1024 148000
[ 201.596493] remove from free list 140400 1024 148000
[ 201.596612] remove from free list 140800 1024 148000
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[ 201.602143]
[ 201.602150] ======================================================
[ 201.602153] [ INFO: possible circular locking dependency detected ]
[ 201.602157] 3.6.0-rc5 #1 Not tainted
[ 201.602159] -------------------------------------------------------
[ 201.602162] bash/2789 is trying to acquire lock:
[ 201.602164] ((memory_chain).rwsem){.+.+.+}, at: [<ffffffff8109fe16>] __blocking_notifier_call_chain+0x66/0xd0
[ 201.602180]
[ 201.602180] but task is already holding lock:
[ 201.602182] (ksm_thread_mutex/1){+.+.+.}, at: [<ffffffff811b41fa>] ksm_memory_callback+0x3a/0xc0
[ 201.602194]
[ 201.602194] which lock already depends on the new lock.
[ 201.602194]
[ 201.602197]
[ 201.602197] the existing dependency chain (in reverse order) is:
[ 201.602200]
[ 201.602200] -> #1 (ksm_thread_mutex/1){+.+.+.}:
[ 201.602208] [<ffffffff810dbee9>] validate_chain+0x6d9/0x7e0
[ 201.602214] [<ffffffff810dc2e6>] __lock_acquire+0x2f6/0x4f0
[ 201.602219] [<ffffffff810dc57d>] lock_acquire+0x9d/0x190
[ 201.602223] [<ffffffff8166b4fc>] __mutex_lock_common+0x5c/0x420
[ 201.602229] [<ffffffff8166ba2a>] mutex_lock_nested+0x4a/0x60
[ 201.602234] [<ffffffff811b41fa>] ksm_memory_callback+0x3a/0xc0
[ 201.602239] [<ffffffff81673447>] notifier_call_chain+0x67/0x150
[ 201.602244] [<ffffffff8109fe2b>] __blocking_notifier_call_chain+0x7b/0xd0
[ 201.602250] [<ffffffff8109fe96>] blocking_notifier_call_chain+0x16/0x20
[ 201.602255] [<ffffffff8144c53b>] memory_notify+0x1b/0x20
[ 201.602261] [<ffffffff81653c51>] offline_pages+0x1b1/0x470
[ 201.602267] [<ffffffff811bfcae>] remove_memory+0x1e/0x20
[ 201.602273] [<ffffffff8144c661>] memory_block_action+0xa1/0x190
[ 201.602278] [<ffffffff8144c7c9>] memory_block_change_state+0x79/0xe0
[ 201.602282] [<ffffffff8144c8f2>] store_mem_state+0xc2/0xd0
[ 201.602287] [<ffffffff81436980>] dev_attr_store+0x20/0x30
[ 201.602293] [<ffffffff812498d3>] sysfs_write_file+0xa3/0x100
[ 201.602299] [<ffffffff811cba80>] vfs_write+0xd0/0x1a0
[ 201.602304] [<ffffffff811cbc54>] sys_write+0x54/0xa0
[ 201.602309] [<ffffffff81678529>] system_call_fastpath+0x16/0x1b
[ 201.602315]
[ 201.602315] -> #0 ((memory_chain).rwsem){.+.+.+}:
[ 201.602322] [<ffffffff810db7e7>] check_prev_add+0x527/0x550
[ 201.602326] [<ffffffff810dbee9>] validate_chain+0x6d9/0x7e0
[ 201.602331] [<ffffffff810dc2e6>] __lock_acquire+0x2f6/0x4f0
[ 201.602335] [<ffffffff810dc57d>] lock_acquire+0x9d/0x190
[ 201.602340] [<ffffffff8166c1a1>] down_read+0x51/0xa0
[ 201.602345] [<ffffffff8109fe16>] __blocking_notifier_call_chain+0x66/0xd0
[ 201.602350] [<ffffffff8109fe96>] blocking_notifier_call_chain+0x16/0x20
[ 201.602355] [<ffffffff8144c53b>] memory_notify+0x1b/0x20
[ 201.602360] [<ffffffff81653e67>] offline_pages+0x3c7/0x470
[ 201.602365] [<ffffffff811bfcae>] remove_memory+0x1e/0x20
[ 201.602370] [<ffffffff8144c661>] memory_block_action+0xa1/0x190
[ 201.602375] [<ffffffff8144c7c9>] memory_block_change_state+0x79/0xe0
[ 201.602379] [<ffffffff8144c8f2>] store_mem_state+0xc2/0xd0
[ 201.602385] [<ffffffff81436980>] dev_attr_store+0x20/0x30
[ 201.602389] [<ffffffff812498d3>] sysfs_write_file+0xa3/0x100
[ 201.602394] [<ffffffff811cba80>] vfs_write+0xd0/0x1a0
[ 201.602398] [<ffffffff811cbc54>] sys_write+0x54/0xa0
[ 201.602403] [<ffffffff81678529>] system_call_fastpath+0x16/0x1b
[ 201.602408]
[ 201.602408] other info that might help us debug this:
[ 201.602408]
[ 201.602412] Possible unsafe locking scenario:
[ 201.602412]
[ 201.602414] CPU0 CPU1
[ 201.602417] ---- ----
[ 201.602419] lock(ksm_thread_mutex/1);
[ 201.602425] lock((memory_chain).rwsem);
[ 201.602430] lock(ksm_thread_mutex/1);
[ 201.602435] lock((memory_chain).rwsem);
[ 201.602440]
[ 201.602440] *** DEADLOCK ***
[ 201.602440]
[ 201.602444] 6 locks held by bash/2789:
[ 201.602446] #0: (&buffer->mutex){+.+.+.}, at: [<ffffffff81249879>] sysfs_write_file+0x49/0x100
[ 201.602456] #1: (s_active#212){.+.+.+}, at: [<ffffffff812498b7>] sysfs_write_file+0x87/0x100
[ 201.602467] #2: (&mem->state_mutex){+.+.+.}, at: [<ffffffff8144c78e>] memory_block_change_state+0x3e/0xe0
[ 201.602477] #3: (mem_hotplug_mutex){+.+.+.}, at: [<ffffffff811bf867>] lock_memory_hotplug+0x17/0x40
[ 201.602487] #4: (pm_mutex){+.+.+.}, at: [<ffffffff811bf885>] lock_memory_hotplug+0x35/0x40
[ 201.602497] #5: (ksm_thread_mutex/1){+.+.+.}, at: [<ffffffff811b41fa>] ksm_memory_callback+0x3a/0xc0
[ 201.602508]
[ 201.602508] stack backtrace:
[ 201.602512] Pid: 2789, comm: bash Not tainted 3.6.0-rc5 #1
[ 201.602515] Call Trace:
[ 201.602522] [<ffffffff810da119>] print_circular_bug+0x109/0x110
[ 201.602527] [<ffffffff810db7e7>] check_prev_add+0x527/0x550
[ 201.602532] [<ffffffff810dbee9>] validate_chain+0x6d9/0x7e0
[ 201.602537] [<ffffffff810dc2e6>] __lock_acquire+0x2f6/0x4f0
[ 201.602543] [<ffffffff8101f7c3>] ? native_sched_clock+0x13/0x80
[ 201.602547] [<ffffffff810dc57d>] lock_acquire+0x9d/0x190
[ 201.602553] [<ffffffff8109fe16>] ? __blocking_notifier_call_chain+0x66/0xd0
[ 201.602558] [<ffffffff8166c1a1>] down_read+0x51/0xa0
[ 201.602563] [<ffffffff8109fe16>] ? __blocking_notifier_call_chain+0x66/0xd0
[ 201.602569] [<ffffffff8109fe16>] __blocking_notifier_call_chain+0x66/0xd0
[ 201.602574] [<ffffffff81186dc6>] ? next_online_pgdat+0x26/0x50
[ 201.602580] [<ffffffff8109fe96>] blocking_notifier_call_chain+0x16/0x20
[ 201.602585] [<ffffffff8144c53b>] memory_notify+0x1b/0x20
[ 201.602590] [<ffffffff81653e67>] offline_pages+0x3c7/0x470
[ 201.602596] [<ffffffff811bfcae>] remove_memory+0x1e/0x20
[ 201.602601] [<ffffffff8144c661>] memory_block_action+0xa1/0x190
[ 201.602606] [<ffffffff8166ba2a>] ? mutex_lock_nested+0x4a/0x60
[ 201.602611] [<ffffffff8144c7c9>] memory_block_change_state+0x79/0xe0
[ 201.602617] [<ffffffff8118f3ec>] ? might_fault+0x5c/0xb0
[ 201.602622] [<ffffffff8144c8f2>] store_mem_state+0xc2/0xd0
[ 201.602627] [<ffffffff812498b7>] ? sysfs_write_file+0x87/0x100
[ 201.602632] [<ffffffff81436980>] dev_attr_store+0x20/0x30
[ 201.602636] [<ffffffff812498d3>] sysfs_write_file+0xa3/0x100
[ 201.602641] [<ffffffff811cba80>] vfs_write+0xd0/0x1a0
[ 201.602646] [<ffffffff811cbc54>] sys_write+0x54/0xa0
[ 201.602652] [<ffffffff81678529>] system_call_fastpath+0x16/0x1b
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