Hi, On 11/24/21 05:13, Lukas Wunner wrote: > On Mon, Nov 22, 2021 at 03:29:43PM -0600, Bjorn Helgaas wrote: >> On Mon, Nov 22, 2021 at 05:45:32PM +0100, Hans de Goede wrote: >>> With 5.16-rc2 I'm getting the following lockdep warning when unplugging >>> a Lenovo X1C8 from a Lenovo 2nd gen TB3 dock: > > Thanks for the report. I'm aware of this issue, it's still on my todo > list. Theodore already came across it a while ago: > > https://lore.kernel.org/linux-pci/20190402021933.GA2966@xxxxxxx/ > > It's a false positive, we need to use a separate lockdep class either > for each hotplug port or for each level in the PCI hierarchy. Can we easily determine what the level in the PCI hierarchy is ? If yes; and if having a separate lock class per level is enough, then the code could simply switch to down_read_nested (and other xxx_nested) functions passing the level as "subclass" parameter. If no, maybe we should add an "int level" member to struct controller ? And then make the switch to the foo_nested locking functions based on that ? Regards, Hans >>> [ 28.583853] pcieport 0000:06:01.0: pciehp: Slot(1): Link Down >>> [ 28.583891] pcieport 0000:06:01.0: pciehp: Slot(1): Card not present >>> [ 28.583995] pcieport 0000:09:04.0: can't change power state from D3cold to D0 (config space inaccessible) >>> >>> [ 28.584849] ============================================ >>> [ 28.584854] WARNING: possible recursive locking detected >>> [ 28.584858] 5.16.0-rc2+ #621 Not tainted >>> [ 28.584864] -------------------------------------------- >>> [ 28.584867] irq/124-pciehp/86 is trying to acquire lock: >>> [ 28.584873] ffff8e5ac4299ef8 (&ctrl->reset_lock){.+.+}-{3:3}, at: pciehp_check_presence+0x23/0x80 >>> [ 28.584904] >>> but task is already holding lock: >>> [ 28.584908] ffff8e5ac4298af8 (&ctrl->reset_lock){.+.+}-{3:3}, at: pciehp_ist+0xf3/0x180 >>> [ 28.584929] >>> other info that might help us debug this: >>> [ 28.584933] Possible unsafe locking scenario: >>> >>> [ 28.584936] CPU0 >>> [ 28.584939] ---- >>> [ 28.584942] lock(&ctrl->reset_lock); >>> [ 28.584949] lock(&ctrl->reset_lock); >>> [ 28.584955] >>> *** DEADLOCK *** >>> >>> [ 28.584959] May be due to missing lock nesting notation >>> >>> [ 28.584963] 3 locks held by irq/124-pciehp/86: >>> [ 28.584970] #0: ffff8e5ac4298af8 (&ctrl->reset_lock){.+.+}-{3:3}, at: pciehp_ist+0xf3/0x180 >>> [ 28.584991] #1: ffffffffa3b024e8 (pci_rescan_remove_lock){+.+.}-{3:3}, at: pciehp_unconfigure_device+0x31/0x110 >>> [ 28.585012] #2: ffff8e5ac1ee2248 (&dev->mutex){....}-{3:3}, at: device_release_driver+0x1c/0x40 >>> [ 28.585037] >>> stack backtrace: >>> [ 28.585042] CPU: 4 PID: 86 Comm: irq/124-pciehp Not tainted 5.16.0-rc2+ #621 >>> [ 28.585052] Hardware name: LENOVO 20U90SIT19/20U90SIT19, BIOS N2WET30W (1.20 ) 08/26/2021 >>> [ 28.585059] Call Trace: >>> [ 28.585064] <TASK> >>> [ 28.585073] dump_stack_lvl+0x59/0x73 >>> [ 28.585087] __lock_acquire.cold+0xc5/0x2c6 >>> [ 28.585106] ? find_held_lock+0x2b/0x80 >>> [ 28.585124] lock_acquire+0xb5/0x2b0 >>> [ 28.585132] ? pciehp_check_presence+0x23/0x80 >>> [ 28.585144] ? lock_is_held_type+0xa8/0x120 >>> [ 28.585161] down_read+0x3e/0x50 >>> [ 28.585172] ? pciehp_check_presence+0x23/0x80 >>> [ 28.585183] pciehp_check_presence+0x23/0x80 >>> [ 28.585194] pciehp_runtime_resume+0x5c/0xa0 >>> [ 28.585206] ? pci_msix_init+0x60/0x60 >>> [ 28.585214] device_for_each_child+0x45/0x70 >>> [ 28.585227] pcie_port_device_runtime_resume+0x20/0x30 >>> [ 28.585236] pci_pm_runtime_resume+0xa7/0xc0 >>> [ 28.585246] ? pci_pm_freeze_noirq+0x100/0x100 >>> [ 28.585257] __rpm_callback+0x41/0x110 >>> [ 28.585271] ? pci_pm_freeze_noirq+0x100/0x100 >>> [ 28.585281] rpm_callback+0x59/0x70 >>> [ 28.585293] rpm_resume+0x512/0x7b0 >>> [ 28.585309] __pm_runtime_resume+0x4a/0x90 >>> [ 28.585322] __device_release_driver+0x28/0x240 >>> [ 28.585338] device_release_driver+0x26/0x40 >>> [ 28.585351] pci_stop_bus_device+0x68/0x90 >>> [ 28.585363] pci_stop_bus_device+0x2c/0x90 >>> [ 28.585373] pci_stop_and_remove_bus_device+0xe/0x20 >>> [ 28.585384] pciehp_unconfigure_device+0x6c/0x110 >>> [ 28.585396] ? __pm_runtime_resume+0x58/0x90 >>> [ 28.585409] pciehp_disable_slot+0x5b/0xe0 >>> [ 28.585421] pciehp_handle_presence_or_link_change+0xc3/0x2f0 >>> [ 28.585436] pciehp_ist+0x179/0x180 >>> [ 28.585449] ? disable_irq_nosync+0x10/0x10 >>> [ 28.585460] irq_thread_fn+0x1d/0x60 >>> [ 28.585470] ? irq_thread+0x81/0x1a0 >>> [ 28.585480] irq_thread+0xcb/0x1a0 >>> [ 28.585491] ? irq_thread_fn+0x60/0x60 >>> [ 28.585502] ? irq_thread_check_affinity+0xb0/0xb0 >>> [ 28.585514] kthread+0x165/0x190 >>> [ 28.585522] ? set_kthread_struct+0x40/0x40 >>> [ 28.585531] ret_from_fork+0x1f/0x30 >>> [ 28.585554] </TASK> >
