[Let's CC Ingo and Peter]
On Tue 12-03-13 11:15:55, Michal Hocko wrote:
> On Tue 12-03-13 14:36:46, Li Zefan wrote:
> > Seems a new bug in 3.9 kernel?
> >
> >
> > [ 207.271924] ======================================================
> > [ 207.271932] [ INFO: possible circular locking dependency detected ]
> > [ 207.271942] 3.9.0-rc1-0.7-default+ #34 Not tainted
> > [ 207.271948] -------------------------------------------------------
>
> 1) load_module -> subsys_interface_register -> mc_deveice_add (*) -> subsys->p->mutex -> link_path_walk -> lookup_slow -> i_mutex
> 2) sys_write -> _cpu_down -> cpu_hotplug_begin -> cpu_hotplug.lock -> mce_cpu_callback -> mce_device_remove(**) -> device_unregister -> bus_remove_device -> subsys mutex
> 3) vfs_readdir -> i_mutex -> filldir64 -> might_fault -> might_lock_read(mmap_sem) -> page_fault -> mmap_sem -> drain_all_stock -> cpu_hotplug.lock
>
> 1) takes cpu_subsys subsys (*) but 2) takes mce_device subsys (**) so
> the deadlock is not possible AFAICS.
>
> I am not familiar with lockdep to propose anything useful though.
>
> > [ 207.271957] bash/10493 is trying to acquire lock:
> > [ 207.271963] (subsys mutex){+.+.+.}, at: [<ffffffff8134af27>] bus_remove_device+0x37/0x1c0
> > [ 207.271987]
> > [ 207.271987] but task is already holding lock:
> > [ 207.271995] (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff81046ccf>] cpu_hotplug_begin+0x2f/0x60
> > [ 207.272012]
> > [ 207.272012] which lock already depends on the new lock.
> > [ 207.272012]
> > [ 207.272023]
> > [ 207.272023] the existing dependency chain (in reverse order) is:
> > [ 207.272033]
> > [ 207.272033] -> #4 (cpu_hotplug.lock){+.+.+.}:
> > [ 207.272044] [<ffffffff810ae329>] lock_acquire+0xe9/0x120
> > [ 207.272056] [<ffffffff814ad807>] mutex_lock_nested+0x37/0x360
> > [ 207.272069] [<ffffffff81046ba9>] get_online_cpus+0x29/0x40
> > [ 207.272082] [<ffffffff81185210>] drain_all_stock+0x30/0x150
> > [ 207.272094] [<ffffffff811853da>] mem_cgroup_reclaim+0xaa/0xe0
> > [ 207.272104] [<ffffffff8118775e>] __mem_cgroup_try_charge+0x51e/0xcf0
> > [ 207.272114] [<ffffffff81188486>] mem_cgroup_charge_common+0x36/0x60
> > [ 207.272125] [<ffffffff811884da>] mem_cgroup_newpage_charge+0x2a/0x30
> > [ 207.272135] [<ffffffff81150531>] do_wp_page+0x231/0x830
> > [ 207.272147] [<ffffffff8115151e>] handle_pte_fault+0x19e/0x8d0
> > [ 207.272157] [<ffffffff81151da8>] handle_mm_fault+0x158/0x1e0
> > [ 207.272166] [<ffffffff814b6153>] do_page_fault+0x2a3/0x4e0
> > [ 207.272178] [<ffffffff814b2578>] page_fault+0x28/0x30
> > [ 207.272189]
> > [ 207.272189] -> #3 (&mm->mmap_sem){++++++}:
> > [ 207.272199] [<ffffffff810ae329>] lock_acquire+0xe9/0x120
> > [ 207.272208] [<ffffffff8114c5ad>] might_fault+0x6d/0x90
> > [ 207.272218] [<ffffffff811a11e3>] filldir64+0xb3/0x120
> > [ 207.272229] [<ffffffffa013fc19>] call_filldir+0x89/0x130 [ext3]
> > [ 207.272248] [<ffffffffa0140377>] ext3_readdir+0x6b7/0x7e0 [ext3]
> > [ 207.272263] [<ffffffff811a1519>] vfs_readdir+0xa9/0xc0
> > [ 207.272273] [<ffffffff811a15cb>] sys_getdents64+0x9b/0x110
> > [ 207.272284] [<ffffffff814bb599>] system_call_fastpath+0x16/0x1b
> > [ 207.272296]
> > [ 207.272296] -> #2 (&type->i_mutex_dir_key#3){+.+.+.}:
> > [ 207.272309] [<ffffffff810ae329>] lock_acquire+0xe9/0x120
> > [ 207.272319] [<ffffffff814ad807>] mutex_lock_nested+0x37/0x360
> > [ 207.272329] [<ffffffff8119c254>] link_path_walk+0x6f4/0x9a0
> > [ 207.272339] [<ffffffff8119e7fa>] path_openat+0xba/0x470
> > [ 207.272349] [<ffffffff8119ecf8>] do_filp_open+0x48/0xa0
> > [ 207.272358] [<ffffffff8118d81c>] file_open_name+0xdc/0x110
> > [ 207.272369] [<ffffffff8118d885>] filp_open+0x35/0x40
> > [ 207.272378] [<ffffffff8135c76e>] _request_firmware+0x52e/0xb20
> > [ 207.272389] [<ffffffff8135cdd6>] request_firmware+0x16/0x20
> > [ 207.272399] [<ffffffffa03bdb91>] request_microcode_fw+0x61/0xd0 [microcode]
> > [ 207.272416] [<ffffffffa03bd554>] microcode_init_cpu+0x104/0x150 [microcode]
> > [ 207.272431] [<ffffffffa03bd61c>] mc_device_add+0x7c/0xb0 [microcode]
> > [ 207.272444] [<ffffffff8134a419>] subsys_interface_register+0xc9/0x100
> > [ 207.272457] [<ffffffffa04fc0f4>] 0xffffffffa04fc0f4
> > [ 207.272472] [<ffffffff81000202>] do_one_initcall+0x42/0x180
> > [ 207.272485] [<ffffffff810bbeff>] load_module+0x19df/0x1b70
> > [ 207.272499] [<ffffffff810bc376>] sys_init_module+0xe6/0x130
> > [ 207.272511] [<ffffffff814bb599>] system_call_fastpath+0x16/0x1b
> > [ 207.272523]
> > [ 207.272523] -> #1 (umhelper_sem){++++.+}:
> > [ 207.272537] [<ffffffff810ae329>] lock_acquire+0xe9/0x120
> > [ 207.272548] [<ffffffff814ae9c4>] down_read+0x34/0x50
> > [ 207.272559] [<ffffffff81062bff>] usermodehelper_read_trylock+0x4f/0x100
> > [ 207.272575] [<ffffffff8135c7dd>] _request_firmware+0x59d/0xb20
> > [ 207.272587] [<ffffffff8135cdd6>] request_firmware+0x16/0x20
> > [ 207.272599] [<ffffffffa03bdb91>] request_microcode_fw+0x61/0xd0 [microcode]
> > [ 207.272613] [<ffffffffa03bd554>] microcode_init_cpu+0x104/0x150 [microcode]
> > [ 207.272627] [<ffffffffa03bd61c>] mc_device_add+0x7c/0xb0 [microcode]
> > [ 207.272641] [<ffffffff8134a419>] subsys_interface_register+0xc9/0x100
> > [ 207.272654] [<ffffffffa04fc0f4>] 0xffffffffa04fc0f4
> > [ 207.272666] [<ffffffff81000202>] do_one_initcall+0x42/0x180
> > [ 207.272678] [<ffffffff810bbeff>] load_module+0x19df/0x1b70
> > [ 207.272690] [<ffffffff810bc376>] sys_init_module+0xe6/0x130
> > [ 207.272702] [<ffffffff814bb599>] system_call_fastpath+0x16/0x1b
> > [ 207.272715]
> > [ 207.272715] -> #0 (subsys mutex){+.+.+.}:
> > [ 207.272729] [<ffffffff810ae002>] __lock_acquire+0x13b2/0x15f0
> > [ 207.272740] [<ffffffff810ae329>] lock_acquire+0xe9/0x120
> > [ 207.272751] [<ffffffff814ad807>] mutex_lock_nested+0x37/0x360
> > [ 207.272763] [<ffffffff8134af27>] bus_remove_device+0x37/0x1c0
> > [ 207.272775] [<ffffffff81349114>] device_del+0x134/0x1f0
> > [ 207.272786] [<ffffffff813491f2>] device_unregister+0x22/0x60
> > [ 207.272798] [<ffffffff814a24ea>] mce_cpu_callback+0x15e/0x1ad
> > [ 207.272812] [<ffffffff814b6402>] notifier_call_chain+0x72/0x130
> > [ 207.272824] [<ffffffff81073d6e>] __raw_notifier_call_chain+0xe/0x10
> > [ 207.272839] [<ffffffff81498f76>] _cpu_down+0x1d6/0x350
> > [ 207.272851] [<ffffffff81499130>] cpu_down+0x40/0x60
> > [ 207.272862] [<ffffffff8149cc55>] store_online+0x75/0xe0
> > [ 207.272874] [<ffffffff813474a0>] dev_attr_store+0x20/0x30
> > [ 207.272886] [<ffffffff812090d9>] sysfs_write_file+0xd9/0x150
> > [ 207.272900] [<ffffffff8118e10b>] vfs_write+0xcb/0x130
> > [ 207.272911] [<ffffffff8118e924>] sys_write+0x64/0xa0
> > [ 207.272923] [<ffffffff814bb599>] system_call_fastpath+0x16/0x1b
> > [ 207.272936]
> > [ 207.272936] other info that might help us debug this:
> > [ 207.272936]
> > [ 207.272952] Chain exists of:
> > [ 207.272952] subsys mutex --> &mm->mmap_sem --> cpu_hotplug.lock
> > [ 207.272952]
> > [ 207.272973] Possible unsafe locking scenario:
> > [ 207.272973]
> > [ 207.272984] CPU0 CPU1
> > [ 207.272992] ---- ----
> > [ 207.273000] lock(cpu_hotplug.lock);
> > [ 207.273009] lock(&mm->mmap_sem);
> > [ 207.273020] lock(cpu_hotplug.lock);
> > [ 207.273031] lock(subsys mutex);
> > [ 207.273040]
> > [ 207.273040] *** DEADLOCK ***
> > [ 207.273040]
> > [ 207.273055] 5 locks held by bash/10493:
> > [ 207.273062] #0: (&buffer->mutex){+.+.+.}, at: [<ffffffff81209049>] sysfs_write_file+0x49/0x150
> > [ 207.273080] #1: (s_active#150){.+.+.+}, at: [<ffffffff812090c2>] sysfs_write_file+0xc2/0x150
> > [ 207.273099] #2: (x86_cpu_hotplug_driver_mutex){+.+.+.}, at: [<ffffffff81027557>] cpu_hotplug_driver_lock+0x17/0x20
> > [ 207.273121] #3: (cpu_add_remove_lock){+.+.+.}, at: [<ffffffff8149911c>] cpu_down+0x2c/0x60
> > [ 207.273140] #4: (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff81046ccf>] cpu_hotplug_begin+0x2f/0x60
> > [ 207.273158]
> > [ 207.273158] stack backtrace:
> > [ 207.273170] Pid: 10493, comm: bash Not tainted 3.9.0-rc1-0.7-default+ #34
> > [ 207.273180] Call Trace:
> > [ 207.273192] [<ffffffff810ab373>] print_circular_bug+0x223/0x310
> > [ 207.273204] [<ffffffff810ae002>] __lock_acquire+0x13b2/0x15f0
> > [ 207.273216] [<ffffffff812086b0>] ? sysfs_hash_and_remove+0x60/0xc0
> > [ 207.273227] [<ffffffff810ae329>] lock_acquire+0xe9/0x120
> > [ 207.273239] [<ffffffff8134af27>] ? bus_remove_device+0x37/0x1c0
> > [ 207.273251] [<ffffffff814ad807>] mutex_lock_nested+0x37/0x360
> > [ 207.273263] [<ffffffff8134af27>] ? bus_remove_device+0x37/0x1c0
> > [ 207.273274] [<ffffffff812086b0>] ? sysfs_hash_and_remove+0x60/0xc0
> > [ 207.273286] [<ffffffff8134af27>] bus_remove_device+0x37/0x1c0
> > [ 207.273298] [<ffffffff81349114>] device_del+0x134/0x1f0
> > [ 207.273309] [<ffffffff813491f2>] device_unregister+0x22/0x60
> > [ 207.273321] [<ffffffff814a24ea>] mce_cpu_callback+0x15e/0x1ad
> > [ 207.273332] [<ffffffff814b6402>] notifier_call_chain+0x72/0x130
> > [ 207.273344] [<ffffffff81073d6e>] __raw_notifier_call_chain+0xe/0x10
> > [ 207.273356] [<ffffffff81498f76>] _cpu_down+0x1d6/0x350
> > [ 207.273368] [<ffffffff81027557>] ? cpu_hotplug_driver_lock+0x17/0x20
> > [ 207.273380] [<ffffffff81499130>] cpu_down+0x40/0x60
> > [ 207.273391] [<ffffffff8149cc55>] store_online+0x75/0xe0
> > [ 207.273402] [<ffffffff813474a0>] dev_attr_store+0x20/0x30
> > [ 207.273413] [<ffffffff812090d9>] sysfs_write_file+0xd9/0x150
> > [ 207.273425] [<ffffffff8118e10b>] vfs_write+0xcb/0x130
> > [ 207.273436] [<ffffffff8118e924>] sys_write+0x64/0xa0
> > [ 207.273447] [<ffffffff814bb599>] system_call_fastpath+0x16/0x1b
> > --
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>
> --
> Michal Hocko
> SUSE Labs
>
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--
Michal Hocko
SUSE Labs
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