On 07/16/2013 10:41 PM, Srivatsa S. Bhat wrote: > Hi, > > I have been seeing this warning every time during boot. I haven't > spent time digging through it though... Please let me know if > any machine-specific info is needed. > > Regards, > Srivatsa S. Bhat > > > ---------------------------------------------------- > > ============================================= > [ INFO: possible recursive locking detected ] > 3.11.0-rc1-lockdep-fix-a #6 Not tainted > --------------------------------------------- > kworker/0:1/142 is trying to acquire lock: > ((&wfc.work)){+.+.+.}, at: [<ffffffff81077100>] flush_work+0x0/0xb0 > > but task is already holding lock: > ((&wfc.work)){+.+.+.}, at: [<ffffffff81075dd9>] process_one_work+0x169/0x610 > > other info that might help us debug this: > Possible unsafe locking scenario: > > CPU0 > ---- > lock((&wfc.work)); > lock((&wfc.work));
Hi, Srivatsa This is false negative, the two "wfc"s are different, they are both on stack. flush_work() can't be deadlock in such case: void foo(void *) { ... if (xxx) work_on_cpu(..., foo, ...); ... } bar() { work_on_cpu(..., foo, ...); } The complaint is caused by "work_on_cpu() uses a static lock_class_key". we should fix work_on_cpu(). (but the caller should also be careful, the foo()/local_pci_probe() is re-entering) But I can't find an elegant fix. long work_on_cpu(int cpu, long (*fn)(void *), void *arg) { struct work_for_cpu wfc = { .fn = fn, .arg = arg }; +#ifdef CONFIG_LOCKDEP + static struct lock_class_key __key; + INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); + lockdep_init_map(&wfc.work.lockdep_map, &wfc.work, &__key, 0); +#else INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); +#endif schedule_work_on(cpu, &wfc.work); flush_work(&wfc.work); return wfc.ret; } Any think? Tejun? thanks, Lai > > *** DEADLOCK *** > > May be due to missing lock nesting notation > > 3 locks held by kworker/0:1/142: > #0: (events){.+.+.+}, at: [<ffffffff81075dd9>] process_one_work+0x169/0x610 > #1: ((&wfc.work)){+.+.+.}, at: [<ffffffff81075dd9>] > process_one_work+0x169/0x610 > #2: (&__lockdep_no_validate__){......}, at: [<ffffffff8139a3ba>] > device_attach+0x2a/0xc0 > > stack backtrace: > CPU: 0 PID: 142 Comm: kworker/0:1 Not tainted 3.11.0-rc1-lockdep-fix-a #6 > Hardware name: IBM -[8737R2A]-/00Y2738, BIOS -[B2E120RUS-1.20]- 11/30/2012 > Workqueue: events work_for_cpu_fn > ffff881036fecd88 ffff881036fef678 ffffffff8161a919 0000000000000003 > ffff881036fec400 ffff881036fef6a8 ffffffff810c2234 ffff881036fec400 > ffff881036fecd88 ffff881036fec400 0000000000000000 ffff881036fef708 > Call Trace: > [<ffffffff8161a919>] dump_stack+0x59/0x80 > [<ffffffff810c2234>] print_deadlock_bug+0xf4/0x100 > [<ffffffff810c3d14>] validate_chain+0x504/0x750 > [<ffffffff810c426d>] __lock_acquire+0x30d/0x580 > [<ffffffff810c4577>] lock_acquire+0x97/0x170 > [<ffffffff81077100>] ? start_flush_work+0x220/0x220 > [<ffffffff81077148>] flush_work+0x48/0xb0 > [<ffffffff81077100>] ? start_flush_work+0x220/0x220 > [<ffffffff810c2c10>] ? mark_held_locks+0x80/0x130 > [<ffffffff81074cfb>] ? queue_work_on+0x4b/0xa0 > [<ffffffff810c2f85>] ? trace_hardirqs_on_caller+0x105/0x1d0 > [<ffffffff810c305d>] ? trace_hardirqs_on+0xd/0x10 > [<ffffffff81077320>] work_on_cpu+0x80/0x90 > [<ffffffff8106f950>] ? wqattrs_hash+0x190/0x190 > [<ffffffff812d37b0>] ? pci_pm_prepare+0x60/0x60 > [<ffffffff812a0059>] ? cpumask_next_and+0x29/0x50 > [<ffffffff812d38da>] __pci_device_probe+0x9a/0xe0 > [<ffffffff81620850>] ? _raw_spin_unlock_irq+0x30/0x50 > [<ffffffff812d4be2>] ? pci_dev_get+0x22/0x30 > [<ffffffff812d4c2a>] pci_device_probe+0x3a/0x60 > [<ffffffff81620850>] ? _raw_spin_unlock_irq+0x30/0x50 > [<ffffffff8139a4bc>] really_probe+0x6c/0x320 > [<ffffffff8139a7b7>] driver_probe_device+0x47/0xa0 > [<ffffffff8139a8c0>] ? __driver_attach+0xb0/0xb0 > [<ffffffff8139a913>] __device_attach+0x53/0x60 > [<ffffffff81398404>] bus_for_each_drv+0x74/0xa0 > [<ffffffff8139a430>] device_attach+0xa0/0xc0 > [<ffffffff812cb2d9>] pci_bus_add_device+0x39/0x60 > [<ffffffff812eec21>] virtfn_add+0x251/0x3e0 > [<ffffffff810c305d>] ? trace_hardirqs_on+0xd/0x10 > [<ffffffff812ef29f>] sriov_enable+0x22f/0x3d0 > [<ffffffff812ef48d>] pci_enable_sriov+0x4d/0x60 > [<ffffffffa0143045>] be_vf_setup+0x175/0x410 [be2net] > [<ffffffffa01493ca>] be_setup+0x37a/0x4b0 [be2net] > [<ffffffffa0149ac0>] be_probe+0x5c0/0x820 [be2net] > [<ffffffff812d37fe>] local_pci_probe+0x4e/0x90 > [<ffffffff8106f968>] work_for_cpu_fn+0x18/0x30 > [<ffffffff81075e4a>] process_one_work+0x1da/0x610 > [<ffffffff81075dd9>] ? process_one_work+0x169/0x610 > [<ffffffff8107650c>] worker_thread+0x28c/0x3a0 > [<ffffffff81076280>] ? process_one_work+0x610/0x610 > [<ffffffff8107da3e>] kthread+0xee/0x100 > [<ffffffff8107d950>] ? __init_kthread_worker+0x70/0x70 > [<ffffffff8162a71c>] ret_from_fork+0x7c/0xb0 > [<ffffffff8107d950>] ? __init_kthread_worker+0x70/0x70 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/