On Mon, Nov 07, 2022 at 02:41:29PM -0600, Bjorn Helgaas wrote: > On Fri, Nov 04, 2022 at 07:08:34PM -0400, James Puthukattukaran wrote: > > Looking to solve a problem where we have nvme drives that are hung > > in the field and we are not sure of the root cause but the working > > theory is that the controller is "bad" and not responding properly > > to commands. The nvme driver times out on outstanding IO requests > > and as part of recovery, attempts to reset the controller and > > reinitialize the device. The reset controller also hangs like here > > -- > > > > ernel:info: [10419813.132341] Workqueue: nvme-reset-wq nvme_reset_work [nvme] > > kernel:warning: [10419813.132342] Call Trace: > > kernel:warning: [10419813.132345] __schedule+0x2bc/0x89b > > kernel:warning: [10419813.132348] schedule+0x36/0x7c > > kernel:warning: [10419813.132351] blk_mq_freeze_queue_wait+0x4b/0xaa > > kernel:warning: [10419813.132353] ? remove_wait_queue+0x60/0x60 > > kernel:warning: [10419813.132359] nvme_wait_freeze+0x33/0x50 [nvme_core] > > kernel:warning: [10419813.132362] nvme_reset_work+0x802/0xd84 [nvme] > > kernel:warning: [10419813.132364] ? __switch_to_asm+0x40/0x62 > > kernel:warning: [10419813.132365] ? __switch_to_asm+0x34/0x62 > > kernel:warning: [10419813.132367] ? __switch_to+0x9b/0x505 > > kernel:warning: [10419813.132368] ? __switch_to_asm+0x40/0x62 > > kernel:warning: [10419813.132370] ? __switch_to_asm+0x40/0x62 > > kernel:warning: [10419813.132372] process_one_work+0x169/0x399 > > kernel:warning: [10419813.132374] worker_thread+0x4d/0x3e5 > > kernel:warning: [10419813.132377] kthread+0x105/0x138 > > kernel:warning: [10419813.132379] ? rescuer_thread+0x380/0x375 > > kernel:warning: [10419813.132380] ? kthread_bind+0x20/0x15 > > kernel:warning: [10419813.132382] ret_from_fork+0x24/0x49 > > ... > > > > So, I tried to hot power off the device via > > "echo 0 > /sys/bus/pci/slots/X/power" -- the thread also hangs > > waiting for the nvme reset thread to finish (like so) -- > > Looks like this "power" sysfs file could use some documentation. I > couldn't find anything in Documentation/ABI/testing/ that seems to > cover it. That sysfs attribute was introduced in early 2002, I guess we were less diligent with documentation back then: http://git.kernel.org/tglx/history/c/a8a2069f432c (search for power_write_file() in the commit) The problem here is in the NVMe / block layer, not the PCI layer. nvme_wait_freeze() calls blk_mq_freeze_queue_wait(), but obviously it should call blk_mq_freeze_queue_wait_timeout() instead and handle a timeout by retiring any outstanding I/O requests to the drive and marking it as dead. > > kernel:warning: [10419813.158116] __schedule+0x2bc/0x89b > > kernel:warning: [10419813.158119] schedule+0x36/0x7c > > kernel:warning: [10419813.158122] schedule_timeout+0x1f6/0x31f > > kernel:warning: [10419813.158124] ? sched_clock_cpu+0x11/0xa5 > > kernel:warning: [10419813.158126] ? try_to_wake_up+0x59/0x505 > > kernel:warning: [10419813.158130] wait_for_completion+0x12b/0x18a > > kernel:warning: [10419813.158132] ? wake_up_q+0x80/0x73 > > kernel:warning: [10419813.158134] flush_work+0x122/0x1a7 > > kernel:warning: [10419813.158137] ? wake_up_worker+0x30/0x2b > > kernel:warning: [10419813.158141] nvme_remove+0x71/0x100 [nvme] > > kernel:warning: [10419813.158146] pci_device_remove+0x3e/0xb6 > > kernel:warning: [10419813.158149] device_release_driver_internal+0x134/0x1eb > > kernel:warning: [10419813.158151] device_release_driver+0x12/0x14 > > kernel:warning: [10419813.158155] pci_stop_bus_device+0x7c/0x96 > > kernel:warning: [10419813.158158] pci_stop_bus_device+0x39/0x96 > > kernel:warning: [10419813.158164] pci_stop_and_remove_bus_device+0x12/0x1d > > kernel:warning: [10419813.158167] pciehp_unconfigure_device+0x7a/0x1d7 > > kernel:warning: [10419813.158169] pciehp_disable_slot+0x52/0xca > > kernel:warning: [10419813.158171] pciehp_sysfs_disable_slot+0x67/0x112 > > kernel:warning: [10419813.158174] disable_slot+0x12/0x14 > > kernel:warning: [10419813.158175] power_write_file+0x6e/0xf8 > > kernel:warning: [10419813.158179] pci_slot_attr_store+0x24/0x2e > > kernel:warning: [10419813.158180] sysfs_kf_write+0x3f/0x46 > > kernel:warning: [10419813.158182] kernfs_fop_write+0x124/0x1a3 > > kernel:warning: [10419813.158184] __vfs_write+0x3a/0x16d > > kernel:warning: [10419813.158187] ? audit_filter_syscall+0x33/0xce > > kernel:warning: [10419813.158189] vfs_write+0xb2/0x1a1 > > > > Is there a way to force power off the device instead of the > > "graceful" approach? Obviously, we don't want to reset the system > > and don't have physical access to the device. > > > > Would it make sense to create a "force power off" in > > /sys/bus/pci/slots/X which basically The power attribute in sysfs already does what you want, but when unbinding the nvme driver from the device, the flush_work() call waits for nvme_reset_work() to finish. And because that's stuck, unbinding also gets stuck. Again, the solution is a code fix in the NVMe / block layer, so the proper mailing list to ask would be linux-nvme and linux-block. Thanks, Lukas
