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SubjectRe: v4.11.12-rt10 - hotplug lockdep splat
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Date
On Thu, 2017-08-31 at 18:18 +0200, Sebastian Andrzej Siewior wrote:
> On 2017-08-23 11:53:44 [+0200], Mike Galbraith wrote:
> > virt box reminded me this morning to report this gripe.
>
> if you can reproduce it, then this should make it go away:

Bug yawns, stretches: "Huh? Make what go away?" ;-)

[ 186.049162] ======================================================
[ 186.049163] [ INFO: possible circular locking dependency detected ]
[ 186.049164] 4.11.12-rt11-virgin #47 Tainted: G E
[ 186.049164] -------------------------------------------------------
[ 186.049165] stress-cpu-hotp/3338 is trying to acquire lock:
[ 186.049165] (&p->pi_lock){-...-.}, at: [<ffffffff810b3eed>] try_to_wake_up+0x2d/0x970
[ 186.049179]
[ 186.049179] but task is already holding lock:
[ 186.049179] (hrtimer_bases.lock/1){......}, at: [<ffffffff8111cb6d>] hrtimers_dead_cpu+0x7d/0x390
[ 186.049186]
[ 186.049186] which lock already depends on the new lock.
[ 186.049186]
[ 186.049186]
[ 186.049186] the existing dependency chain (in reverse order) is:
[ 186.049186]
[ 186.049186] -> #4 (hrtimer_bases.lock/1){......}:
[ 186.049189] lock_acquire+0xbd/0x250
[ 186.049194] _raw_spin_lock_nested+0x41/0x60
[ 186.049195] hrtimers_dead_cpu+0x7d/0x390
[ 186.049196] cpuhp_invoke_callback+0x248/0x9d0
[ 186.049197] cpuhp_down_callbacks+0x42/0x80
[ 186.049198] _cpu_down+0xc5/0x100
[ 186.049199] do_cpu_down+0x3c/0x60
[ 186.049199] cpu_down+0x10/0x20
[ 186.049203] cpu_subsys_offline+0x14/0x20
[ 186.049204] device_offline+0x8a/0xb0
[ 186.049205] online_store+0x40/0x80
[ 186.049209] dev_attr_store+0x18/0x30
[ 186.049213] sysfs_kf_write+0x44/0x60
[ 186.049214] kernfs_fop_write+0x13c/0x1d0
[ 186.049217] __vfs_write+0x28/0x140
[ 186.049218] vfs_write+0xc7/0x1f0
[ 186.049219] SyS_write+0x49/0xa0
[ 186.049221] entry_SYSCALL_64_fastpath+0x1f/0xc2
[ 186.049221]
[ 186.049221] -> #3 (hrtimer_bases.lock){-.....}:
[ 186.049226] lock_acquire+0xbd/0x250
[ 186.049226] _raw_spin_lock_irqsave+0x53/0x70
[ 186.049227] lock_hrtimer_base.isra.27+0x29/0x50
[ 186.049228] hrtimer_start_range_ns+0x2f/0x410
[ 186.049229] enqueue_task_rt+0x325/0x360
[ 186.049232] __sched_setscheduler+0x2d5/0xb60
[ 186.049233] _sched_setscheduler+0x68/0x70
[ 186.049234] sched_setscheduler+0x13/0x20
[ 186.049235] ktimer_softirqd_set_sched_params+0x2a/0x60
[ 186.049236] smpboot_thread_fn+0x131/0x320
[ 186.049238] kthread+0x114/0x150
[ 186.049239] ret_from_fork+0x2a/0x40
[ 186.049239]
[ 186.049239] -> #2 (&rt_b->rt_runtime_lock){-.....}:
[ 186.049241] lock_acquire+0xbd/0x250
[ 186.049242] _raw_spin_lock+0x3b/0x50
[ 186.049242] enqueue_task_rt+0x1d8/0x360
[ 186.049243] __sched_setscheduler+0x2d5/0xb60
[ 186.049244] _sched_setscheduler+0x68/0x70
[ 186.049245] sched_setscheduler+0x13/0x20
[ 186.049246] ktimer_softirqd_set_sched_params+0x2a/0x60
[ 186.049247] smpboot_thread_fn+0x131/0x320
[ 186.049248] kthread+0x114/0x150
[ 186.049248] ret_from_fork+0x2a/0x40
[ 186.049248]
[ 186.049248] -> #1 (&rq->lock){-...-.}:
[ 186.049250] lock_acquire+0xbd/0x250
[ 186.049250] _raw_spin_lock+0x3b/0x50
[ 186.049251] task_fork_fair+0x3a/0x100
[ 186.049252] sched_fork+0x10d/0x2f0
[ 186.049255] copy_process.part.32+0x747/0x20a0
[ 186.049256] _do_fork+0xe4/0x710
[ 186.049257] kernel_thread+0x29/0x30
[ 186.049258] rest_init+0x22/0xe0
[ 186.049266] start_kernel+0x489/0x496
[ 186.049268] x86_64_start_reservations+0x2a/0x2c
[ 186.049269] x86_64_start_kernel+0x13d/0x14c
[ 186.049271] verify_cpu+0x0/0xfc
[ 186.049271]
[ 186.049271] -> #0 (&p->pi_lock){-...-.}:
[ 186.049272] __lock_acquire+0x1527/0x1560
[ 186.049273] lock_acquire+0xbd/0x250
[ 186.049273] _raw_spin_lock_irqsave+0x53/0x70
[ 186.049274] try_to_wake_up+0x2d/0x970
[ 186.049274] wake_up_process+0x15/0x20
[ 186.049275] wakeup_timer_softirqd+0x32/0x40
[ 186.049276] wakeup_proper_softirq+0x25/0x30
[ 186.049277] raise_softirq_irqoff+0x3c/0x50
[ 186.049278] hrtimers_dead_cpu+0x289/0x390
[ 186.049278] cpuhp_invoke_callback+0x248/0x9d0
[ 186.049279] cpuhp_down_callbacks+0x42/0x80
[ 186.049279] _cpu_down+0xc5/0x100
[ 186.049280] do_cpu_down+0x3c/0x60
[ 186.049280] cpu_down+0x10/0x20
[ 186.049281] cpu_subsys_offline+0x14/0x20
[ 186.049282] device_offline+0x8a/0xb0
[ 186.049283] online_store+0x40/0x80
[ 186.049284] dev_attr_store+0x18/0x30
[ 186.049284] sysfs_kf_write+0x44/0x60
[ 186.049285] kernfs_fop_write+0x13c/0x1d0
[ 186.049285] __vfs_write+0x28/0x140
[ 186.049286] vfs_write+0xc7/0x1f0
[ 186.049287] SyS_write+0x49/0xa0
[ 186.049287] entry_SYSCALL_64_fastpath+0x1f/0xc2
[ 186.049288]
[ 186.049288] other info that might help us debug this:
[ 186.049288]
[ 186.049288] Chain exists of:
[ 186.049288] &p->pi_lock --> hrtimer_bases.lock --> hrtimer_bases.lock/1
[ 186.049288]
[ 186.049289] Possible unsafe locking scenario:
[ 186.049289]
[ 186.049289] CPU0 CPU1
[ 186.049290] ---- ----
[ 186.049290] lock(hrtimer_bases.lock/1);
[ 186.049290] lock(hrtimer_bases.lock);
[ 186.049291] lock(hrtimer_bases.lock/1);
[ 186.049291] lock(&p->pi_lock);
[ 186.049292]
[ 186.049292] *** DEADLOCK ***
[ 186.049292]
[ 186.049292] 9 locks held by stress-cpu-hotp/3338:
[ 186.049292] #0: (sb_writers#3){.+.+.+}, at: [<ffffffff8127f746>] vfs_write+0x196/0x1f0
[ 186.049294] #1: (&of->mutex){+.+.+.}, at: [<ffffffff813187cc>] kernfs_fop_write+0x10c/0x1d0
[ 186.049295] #2: (s_active#139){.+.+.+}, at: [<ffffffff813187d4>] kernfs_fop_write+0x114/0x1d0
[ 186.049296] #3: (device_hotplug_lock){+.+.+.}, at: [<ffffffff81553e95>] lock_device_hotplug_sysfs+0x15/0x40
[ 186.049297] #4: (&dev->mutex){......}, at: [<ffffffff81555718>] device_offline+0x48/0xb0
[ 186.049299] #5: (cpu_add_remove_lock){+.+.+.}, at: [<ffffffff8107e295>] do_cpu_down+0x25/0x60
[ 186.049300] #6: (cpu_hotplug_lock.rw_sem){++++++}, at: [<ffffffff810de1e6>] percpu_down_write+0x26/0x120
[ 186.049301] #7: (hrtimer_bases.lock){-.....}, at: [<ffffffff8111cb60>] hrtimers_dead_cpu+0x70/0x390
[ 186.049303] #8: (hrtimer_bases.lock/1){......}, at: [<ffffffff8111cb6d>] hrtimers_dead_cpu+0x7d/0x390
[ 186.049304]
[ 186.049304] stack backtrace:
[ 186.049305] CPU: 0 PID: 3338 Comm: stress-cpu-hotp Tainted: G E 4.11.12-rt11-virgin #47
[ 186.049306] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
[ 186.049306] Call Trace:
[ 186.049312] dump_stack+0x85/0xc8
[ 186.049317] print_circular_bug+0x1f9/0x207
[ 186.049318] __lock_acquire+0x1527/0x1560
[ 186.049320] lock_acquire+0xbd/0x250
[ 186.049321] ? try_to_wake_up+0x2d/0x970
[ 186.049322] _raw_spin_lock_irqsave+0x53/0x70
[ 186.049322] ? try_to_wake_up+0x2d/0x970
[ 186.049323] try_to_wake_up+0x2d/0x970
[ 186.049324] wake_up_process+0x15/0x20
[ 186.049325] wakeup_timer_softirqd+0x32/0x40
[ 186.049326] wakeup_proper_softirq+0x25/0x30
[ 186.049327] raise_softirq_irqoff+0x3c/0x50
[ 186.049328] hrtimers_dead_cpu+0x289/0x390
[ 186.049329] ? hrtimers_prepare_cpu+0x90/0x90
[ 186.049330] cpuhp_invoke_callback+0x248/0x9d0
[ 186.049335] ? flow_cache_lookup+0x430/0x430
[ 186.049336] cpuhp_down_callbacks+0x42/0x80
[ 186.049337] _cpu_down+0xc5/0x100
[ 186.049338] do_cpu_down+0x3c/0x60
[ 186.049339] cpu_down+0x10/0x20
[ 186.049340] cpu_subsys_offline+0x14/0x20
[ 186.049341] device_offline+0x8a/0xb0
[ 186.049341] online_store+0x40/0x80
[ 186.049343] dev_attr_store+0x18/0x30
[ 186.049343] sysfs_kf_write+0x44/0x60
[ 186.049344] kernfs_fop_write+0x13c/0x1d0
[ 186.049345] __vfs_write+0x28/0x140
[ 186.049346] ? rcu_read_lock_sched_held+0x98/0xa0
[ 186.049347] ? rcu_sync_lockdep_assert+0x32/0x60
[ 186.049348] ? __sb_start_write+0x1d2/0x290
[ 186.049349] ? vfs_write+0x196/0x1f0
[ 186.049352] ? security_file_permission+0x3b/0xc0
[ 186.049353] vfs_write+0xc7/0x1f0
[ 186.049354] ? trace_hardirqs_on_caller+0xf9/0x1c0
[ 186.049355] SyS_write+0x49/0xa0
[ 186.049356] entry_SYSCALL_64_fastpath+0x1f/0xc2
[ 186.049357] RIP: 0033:0x7fde821d0d10
[ 186.049358] RSP: 002b:00007ffc2ee807e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 186.049359] RAX: ffffffffffffffda RBX: 0000000001fae090 RCX: 00007fde821d0d10
[ 186.049360] RDX: 0000000000000002 RSI: 00007fde82d3e000 RDI: 0000000000000001
[ 186.049360] RBP: 00007ffc2ee80800 R08: 000000000000000a R09: 00007fde82cf8700
[ 186.049360] R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000000007
[ 186.049361] R13: 0000000000000001 R14: 0000000000000009 R15: 000000000000000a

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