Hello! During debugging of pci-aardvark.c driver I got following synchronous external abort 96000210 which I can reproduce with VIA XHCI controller when PCIe hot plug support is enabled in kernel and PCIe Root Bridge triggers link down event via PCIe hot plug interrupt. [ 71.773033] pcieport 0000:00:00.0: pciehp: Slot(0): Link Down [ 71.779120] xhci_hcd 0000:01:00.0: remove, state 4 [ 71.784113] usb usb5: USB disconnect, device number 1 [ 71.790398] xhci_hcd 0000:01:00.0: USB bus 5 deregistered [ 72.511899] Internal error: synchronous external abort: 96000210 [#1] SMP [ 72.518918] Modules linked in: [ 72.522074] CPU: 1 PID: 988 Comm: irq/53-pciehp Not tainted 5.12.0-dirty #949 [ 72.536983] pstate: 60000085 (nZCv daIf -PAN -UAO -TCO BTYPE=--) [ 72.543182] pc : xhci_irq+0x70/0x17b8 [ 72.546972] lr : xhci_irq+0x28/0x17b8 [ 72.550752] sp : ffffffc012b8bab0 [ 72.554167] x29: ffffffc012b8bab0 x28: 00000000000000a0 [ 72.559652] x27: 0000000000000060 x26: ffffff8000af2250 [ 72.565135] x25: ffffffc0100b0d48 x24: ffffffc0100b0be0 [ 72.570620] x23: ffffff80003be028 x22: ffffff8000af229c [ 72.576104] x21: 0000000000000080 x20: ffffff8000af2000 [ 72.581587] x19: ffffff8000af2000 x18: 0000000000000004 [ 72.587071] x17: 0000000000000000 x16: 0000000000000000 [ 72.592553] x15: ffffffc01154cc70 x14: ffffff8001751df8 [ 72.598037] x13: 0000000000000000 x12: 0000000000000000 [ 72.603519] x11: ffffff8001751da8 x10: ffffffc01154cc78 [ 72.609001] x9 : ffffffc01087c238 x8 : 0000000000000000 [ 72.614485] x7 : ffffffc01162c4e0 x6 : 0000000000000000 [ 72.619967] x5 : fffffffe00085000 x4 : fffffffe00085000 [ 72.625451] x3 : 0000000000000000 x2 : 0000000000000001 [ 72.630933] x1 : ffffffc0118bd024 x0 : 0000000000000000 [ 72.636415] Call trace: [ 72.638936] xhci_irq+0x70/0x17b8 [ 72.642360] usb_hcd_irq+0x34/0x50 [ 72.645876] usb_hcd_pci_remove+0x78/0x138 [ 72.650106] xhci_pci_remove+0x6c/0xa8 [ 72.653978] pci_device_remove+0x44/0x108 [ 72.658122] device_release_driver_internal+0x110/0x1e0 [ 72.663521] device_release_driver+0x1c/0x28 [ 72.667931] pci_stop_bus_device+0x84/0xc0 [ 72.672162] pci_stop_and_remove_bus_device+0x1c/0x30 [ 72.677373] pciehp_unconfigure_device+0x98/0xf8 [ 72.682138] pciehp_disable_slot+0x60/0x118 [ 72.686457] pciehp_handle_presence_or_link_change+0xec/0x3b0 [ 72.692386] pciehp_ist+0x170/0x1a0 [ 72.695984] irq_thread_fn+0x30/0x90 [ 72.699674] irq_thread+0x13c/0x200 [ 72.703271] kthread+0x12c/0x130 [ 72.706603] ret_from_fork+0x10/0x1c [ 72.710299] Code: 35ffff83 35002741 f9400f41 91001021 (b9400021) [ 72.716586] ---[ end trace 20ce3e30ff292c93 ]--- [ 72.721453] genirq: exiting task "irq/53-pciehp" (988) is an active IRQ thread (irq 53) [ 72.730068] sched: RT throttling activated And after that kernel is in some semi-broken state. Some functionality works, but some other (like reboot) does not. I can reproduce it also when I manually inject/fake this link down PCIe hot plug interrupt with setting corresponding bits in PCIe Root Status registers, so pciehp driver thinks that link down even occurred. I suspect that issue is in usb_hcd_pci_remove() function which calls local_irq_disable()+usb_hcd_irq()+local_irq_enable() functions but do not take into care that whole usb_hcd_pci_remove() function may be called from interrupt context. Can you look at this issue if it is really safe to call usb_hcd_irq() from interrupt context? Or rather if it is safe to call functions like pciehp_disable_slot() or device_release_driver() from interrupt context like it can be seen in call trace?
