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SubjectRe: sched: circular dependency between sched_domains_mutex and oom_notify_list
On 02/17/2013 01:42 PM, Sasha Levin wrote:
> Hi all,
>
> I was fuzzing with trinity inside a KVM tools guest, with today's -next kernel
> when I've hit the following spew.
>
> I suspect it's the result of adding the new rcu_oom_notify, but that happened
> about half a year ago so I'm not sure why this showed up only now.

Hi, Sasha

This is a rarely one, isn't it? require 2 conditions:
1. system is oom.
2. rebooting.

The possible dead lock related to oom_notify_list I suppose is:

CONTEXT A CONTEXT B

1 oom reboot

2 LOCK oom_notify_list cpu_down()

3 rcu_oom_notify() LOCK cpu_hotplug.lock

4 get_online_cpus() partition_sched_domains()

5 LOCK cpu_hotplug.lock __sdt_alloc()

6 oom

7 LOCK oom_notify_list

DEAD LOCK

So rcu_oom_notify() trying to lock cpu_hotplug.lock with oom_notify_list
locked, and __sdt_alloc() trying to lock oom_notify_list with
cpu_hotplug.lock locked, a circular locking case.

But I'm not sure why the log show the "sched_domains_mutex" as a target,
so is your system really dead lock or it's just a fake report?

Regards,
Michael Wang

>
> [ 1039.634183] ======================================================
> [ 1039.635717] [ INFO: possible circular locking dependency detected ]
> [ 1039.637255] 3.8.0-rc7-next-20130215-sasha-00003-gea816fa #286 Tainted: G W
> [ 1039.639104] -------------------------------------------------------
> [ 1039.640579] init/1 is trying to acquire lock:
> [ 1039.641224] ((oom_notify_list).rwsem){.+.+..}, at: [<ffffffff81141c8f>] __blocking_notifier_call_chain+0x7f/0xc0
> [ 1039.641224]
> [ 1039.641224] but task is already holding lock:
> [ 1039.641224] (sched_domains_mutex){+.+.+.}, at: [<ffffffff811522d8>] partition_sched_domains+0x28/0x3f0
> [ 1039.641224]
> [ 1039.641224] which lock already depends on the new lock.
> [ 1039.641224]
> [ 1039.641224]
> [ 1039.641224] the existing dependency chain (in reverse order) is:
> [ 1039.641224]
> -> #2 (sched_domains_mutex){+.+.+.}:
> [ 1039.641224] [<ffffffff8118013a>] check_prevs_add+0xba/0x1a0
> [ 1039.641224] [<ffffffff811808c0>] validate_chain.isra.21+0x6a0/0x7b0
> [ 1039.641224] [<ffffffff81183b43>] __lock_acquire+0xa13/0xb00
> [ 1039.641224] [<ffffffff8118451a>] lock_acquire+0x1ca/0x270
> [ 1039.641224] [<ffffffff83d8a19a>] __mutex_lock_common+0x5a/0x560
> [ 1039.641224] [<ffffffff83d8a7cf>] mutex_lock_nested+0x3f/0x50
> [ 1039.641224] [<ffffffff811522d8>] partition_sched_domains+0x28/0x3f0
> [ 1039.641224] [<ffffffff8115274b>] cpuset_cpu_inactive+0x3b/0x50
> [ 1039.641224] [<ffffffff83d9174e>] notifier_call_chain+0xee/0x130
> [ 1039.641224] [<ffffffff81141b09>] __raw_notifier_call_chain+0x9/0x10
> [ 1039.641224] [<ffffffff8110dd1b>] __cpu_notify+0x1b/0x30
> [ 1039.641224] [<ffffffff83ce34ef>] _cpu_down+0xaf/0x350
> [ 1039.641224] [<ffffffff8110e164>] disable_nonboot_cpus+0x84/0x1c0
> [ 1039.641224] [<ffffffff811288f6>] kernel_restart+0x16/0x60
> [ 1039.641224] [<ffffffff81128ab1>] sys_reboot+0x161/0x2b0
> [ 1039.641224] [<ffffffff83d96198>] tracesys+0xe1/0xe6
> [ 1039.641224]
> -> #1 (cpu_hotplug.lock){+.+.+.}:
> [ 1039.641224] [<ffffffff8118013a>] check_prevs_add+0xba/0x1a0
> [ 1039.641224] [<ffffffff811808c0>] validate_chain.isra.21+0x6a0/0x7b0
> [ 1039.641224] [<ffffffff81183b43>] __lock_acquire+0xa13/0xb00
> [ 1039.641224] [<ffffffff8118451a>] lock_acquire+0x1ca/0x270
> [ 1039.641224] [<ffffffff83d8a19a>] __mutex_lock_common+0x5a/0x560
> [ 1039.641224] [<ffffffff83d8a7cf>] mutex_lock_nested+0x3f/0x50
> [ 1039.641224] [<ffffffff8110de77>] get_online_cpus+0x37/0x50
> [ 1039.641224] [<ffffffff811d01b4>] rcu_oom_notify+0x94/0x150
> [ 1039.641224] [<ffffffff83d9174e>] notifier_call_chain+0xee/0x130
> [ 1039.641224] [<ffffffff81141ca8>] __blocking_notifier_call_chain+0x98/0xc0
> [ 1039.641224] [<ffffffff81141ce1>] blocking_notifier_call_chain+0x11/0x20
> [ 1039.641224] [<ffffffff81212155>] out_of_memory+0x45/0x1f0
> [ 1039.641224] [<ffffffff812184dd>] __alloc_pages_nodemask+0x83d/0xbf0
> [ 1039.641224] [<ffffffff8125d6ac>] alloc_pages_vma+0xfc/0x150
> [ 1039.641224] [<ffffffff812509f0>] read_swap_cache_async+0x90/0x220
> [ 1039.641224] [<ffffffff81250c1e>] swapin_readahead+0x9e/0xf0
> [ 1039.641224] [<ffffffff8123af57>] do_swap_page.isra.41+0x107/0x5a0
> [ 1039.641224] [<ffffffff8123d056>] handle_pte_fault+0x126/0x200
> [ 1039.641224] [<ffffffff8123e4a7>] handle_mm_fault+0x397/0x3e0
> [ 1039.641224] [<ffffffff8123e9d8>] __get_user_pages+0x418/0x5f0
> [ 1039.641224] [<ffffffff81240563>] __mlock_vma_pages_range+0xb3/0xc0
> [ 1039.641224] [<ffffffff81240a74>] __mm_populate+0xf4/0x170
> [ 1039.641224] [<ffffffff81240e10>] sys_mlockall+0x160/0x1a0
> [ 1039.641224] [<ffffffff83d96198>] tracesys+0xe1/0xe6
> [ 1039.641224]
> -> #0 ((oom_notify_list).rwsem){.+.+..}:
> [ 1039.641224] [<ffffffff8117fb55>] check_prev_add+0x115/0x640
> [ 1039.641224] [<ffffffff8118013a>] check_prevs_add+0xba/0x1a0
> [ 1039.641224] [<ffffffff811808c0>] validate_chain.isra.21+0x6a0/0x7b0
> [ 1039.641224] [<ffffffff81183b43>] __lock_acquire+0xa13/0xb00
> [ 1039.641224] [<ffffffff8118451a>] lock_acquire+0x1ca/0x270
> [ 1039.641224] [<ffffffff83d8adb7>] down_read+0x47/0x8e
> [ 1039.641224] [<ffffffff81141c8f>] __blocking_notifier_call_chain+0x7f/0xc0
> [ 1039.641224] [<ffffffff81141ce1>] blocking_notifier_call_chain+0x11/0x20
> [ 1039.641224] [<ffffffff81212155>] out_of_memory+0x45/0x1f0
> [ 1039.641224] [<ffffffff812184dd>] __alloc_pages_nodemask+0x83d/0xbf0
> [ 1039.641224] [<ffffffff8126629a>] allocate_slab+0x13a/0x1f0
> [ 1039.641224] [<ffffffff8126637b>] new_slab+0x2b/0x1b0
> [ 1039.641224] [<ffffffff83d030e1>] __slab_alloc.isra.34+0x1c5/0x31f
> [ 1039.641224] [<ffffffff81268e14>] kmem_cache_alloc_node_trace+0x114/0x390
> [ 1039.641224] [<ffffffff8114b567>] __sdt_alloc+0x137/0x1f0
> [ 1039.641224] [<ffffffff81151d2c>] build_sched_domains+0x2c/0x4e0
> [ 1039.641224] [<ffffffff81152603>] partition_sched_domains+0x353/0x3f0
> [ 1039.641224] [<ffffffff8115274b>] cpuset_cpu_inactive+0x3b/0x50
> [ 1039.641224] [<ffffffff83d9174e>] notifier_call_chain+0xee/0x130
> [ 1039.641224] [<ffffffff81141b09>] __raw_notifier_call_chain+0x9/0x10
> [ 1039.641224] [<ffffffff8110dd1b>] __cpu_notify+0x1b/0x30
> [ 1039.641224] [<ffffffff83ce34ef>] _cpu_down+0xaf/0x350
> [ 1039.641224] [<ffffffff8110e164>] disable_nonboot_cpus+0x84/0x1c0
> [ 1039.641224] [<ffffffff811288f6>] kernel_restart+0x16/0x60
> [ 1039.641224] [<ffffffff81128ab1>] sys_reboot+0x161/0x2b0
> [ 1039.641224] [<ffffffff83d96198>] tracesys+0xe1/0xe6
> [ 1039.641224]
> [ 1039.641224] other info that might help us debug this:
> [ 1039.641224]
> [ 1039.641224] Chain exists of:
> (oom_notify_list).rwsem --> cpu_hotplug.lock --> sched_domains_mutex
>
> [ 1039.641224] Possible unsafe locking scenario:
> [ 1039.641224]
> [ 1039.641224] CPU0 CPU1
> [ 1039.641224] ---- ----
> [ 1039.641224] lock(sched_domains_mutex);
> [ 1039.641224] lock(cpu_hotplug.lock);
> [ 1039.641224] lock(sched_domains_mutex);
> [ 1039.641224] lock((oom_notify_list).rwsem);
> [ 1039.641224]
> [ 1039.641224] *** DEADLOCK ***
> [ 1039.641224]
> [ 1039.641224] 4 locks held by init/1:
> [ 1039.641224] #0: (reboot_mutex){+.+.+.}, at: [<ffffffff81128a2e>] sys_reboot+0xde/0x2b0
> [ 1039.641224] #1: (cpu_add_remove_lock){+.+.+.}, at: [<ffffffff8110dea2>] cpu_maps_update_begin+0x12/0x20
> [ 1039.641224] #2: (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff8110dd87>] cpu_hotplug_begin+0x27/0x60
> [ 1039.641224] #3: (sched_domains_mutex){+.+.+.}, at: [<ffffffff811522d8>] partition_sched_domains+0x28/0x3f0
> [ 1039.641224]
> [ 1039.641224] stack backtrace:
> [ 1039.641224] Pid: 1, comm: init Tainted: G W 3.8.0-rc7-next-20130215-sasha-00003-gea816fa #286
> [ 1039.641224] Call Trace:
> [ 1039.641224] [<ffffffff83cff50f>] print_circular_bug+0xd3/0xe4
> [ 1039.641224] [<ffffffff8117fb55>] check_prev_add+0x115/0x640
> [ 1039.641224] [<ffffffff8118013a>] check_prevs_add+0xba/0x1a0
> [ 1039.641224] [<ffffffff81074ef5>] ? sched_clock+0x15/0x20
> [ 1039.641224] [<ffffffff811808c0>] validate_chain.isra.21+0x6a0/0x7b0
> [ 1039.641224] [<ffffffff81183b43>] __lock_acquire+0xa13/0xb00
> [ 1039.641224] [<ffffffff81074ef5>] ? sched_clock+0x15/0x20
> [ 1039.641224] [<ffffffff810a1258>] ? kvm_clock_read+0x38/0x70
> [ 1039.641224] [<ffffffff8118451a>] lock_acquire+0x1ca/0x270
> [ 1039.641224] [<ffffffff81141c8f>] ? __blocking_notifier_call_chain+0x7f/0xc0
> [ 1039.641224] [<ffffffff83d8adb7>] down_read+0x47/0x8e
> [ 1039.641224] [<ffffffff81141c8f>] ? __blocking_notifier_call_chain+0x7f/0xc0
> [ 1039.641224] [<ffffffff81141c8f>] __blocking_notifier_call_chain+0x7f/0xc0
> [ 1039.641224] [<ffffffff81141ce1>] blocking_notifier_call_chain+0x11/0x20
> [ 1039.641224] [<ffffffff81212155>] out_of_memory+0x45/0x1f0
> [ 1039.641224] [<ffffffff812184dd>] __alloc_pages_nodemask+0x83d/0xbf0
> [ 1039.641224] [<ffffffff8126629a>] allocate_slab+0x13a/0x1f0
> [ 1039.641224] [<ffffffff8126637b>] new_slab+0x2b/0x1b0
> [ 1039.641224] [<ffffffff83d030e1>] __slab_alloc.isra.34+0x1c5/0x31f
> [ 1039.641224] [<ffffffff81182492>] ? __lock_is_held+0x52/0x80
> [ 1039.641224] [<ffffffff8114b567>] ? __sdt_alloc+0x137/0x1f0
> [ 1039.641224] [<ffffffff81268e14>] kmem_cache_alloc_node_trace+0x114/0x390
> [ 1039.641224] [<ffffffff8123349b>] ? pcpu_alloc+0x32b/0x3e0
> [ 1039.641224] [<ffffffff8114b52b>] ? __sdt_alloc+0xfb/0x1f0
> [ 1039.641224] [<ffffffff8114b567>] ? __sdt_alloc+0x137/0x1f0
> [ 1039.641224] [<ffffffff8114b567>] __sdt_alloc+0x137/0x1f0
> [ 1039.641224] [<ffffffff811524d0>] ? partition_sched_domains+0x220/0x3f0
> [ 1039.641224] [<ffffffff81151d2c>] build_sched_domains+0x2c/0x4e0
> [ 1039.641224] [<ffffffff81152603>] partition_sched_domains+0x353/0x3f0
> [ 1039.641224] [<ffffffff81152397>] ? partition_sched_domains+0xe7/0x3f0
> [ 1039.641224] [<ffffffff8115274b>] cpuset_cpu_inactive+0x3b/0x50
> [ 1039.641224] [<ffffffff83d9174e>] notifier_call_chain+0xee/0x130
> [ 1039.641224] [<ffffffff81141b09>] __raw_notifier_call_chain+0x9/0x10
> [ 1039.641224] [<ffffffff8110dd1b>] __cpu_notify+0x1b/0x30
> [ 1039.641224] [<ffffffff83ce34ef>] _cpu_down+0xaf/0x350
> [ 1039.641224] [<ffffffff83cfd6b8>] ? printk+0x5c/0x5e
> [ 1039.641224] [<ffffffff8110e164>] disable_nonboot_cpus+0x84/0x1c0
> [ 1039.641224] [<ffffffff811288f6>] kernel_restart+0x16/0x60
> [ 1039.641224] [<ffffffff81128ab1>] sys_reboot+0x161/0x2b0
> [ 1039.641224] [<ffffffff811d5dc4>] ? rcu_eqs_exit_common+0x64/0x340
> [ 1039.641224] [<ffffffff811d7146>] ? rcu_eqs_enter_common+0x306/0x3a0
> [ 1039.641224] [<ffffffff8120cac5>] ? user_exit+0xa5/0xd0
> [ 1039.641224] [<ffffffff811813e8>] ? trace_hardirqs_on_caller+0x128/0x160
> [ 1039.641224] [<ffffffff8118142d>] ? trace_hardirqs_on+0xd/0x10
> [ 1039.641224] [<ffffffff8107ad34>] ? syscall_trace_enter+0x24/0x2e0
> [ 1039.641224] [<ffffffff811813e8>] ? trace_hardirqs_on_caller+0x128/0x160
> [ 1039.641224] [<ffffffff83d96198>] tracesys+0xe1/0xe6
>
>
> Thanks,
> Sasha
> --
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