Hi, I am not sure when this started happening but at least 5.6, 5.7 and 5.8-rc6 all exhibit this problem. Please note that the this is happining on a laptop which is not completely healthy. The BIOS complains that the Battery cannot be charged because the power supply cannot be recognized. This is somehting I have for a longer time without noticing the kworker/0:3+pm problem so I do not think they are related but who knows. Anyway, kworker/0:3+pm is hogging CPU. /proc/<pid>/0:3+pm is very often empty so I suspect it just schedules very often and performs only small amount of work. Here are few backtraces I've managed to catch [<0>] preempt_schedule_thunk+0x16/0x18 [<0>] usb_hcd_submit_urb+0x686/0x773 [<0>] usb_start_wait_urb+0x59/0xc8 [<0>] usb_control_msg+0xd4/0x10d [<0>] get_port_status+0x51/0x6f [<0>] hub_port_status+0x41/0xa3 [<0>] hub_activate+0x230/0x4ee [<0>] hub_resume+0x20/0x9a [<0>] usb_resume_interface.isra.0+0xb0/0xd0 [<0>] usb_suspend_both+0xf6/0x20c [<0>] usb_runtime_suspend+0x32/0x62 [<0>] __rpm_callback+0x70/0xd4 [<0>] rpm_callback+0x55/0x6b [<0>] rpm_suspend+0x2af/0x440 [<0>] __pm_runtime_suspend+0x48/0x62 [<0>] usb_runtime_idle+0x26/0x2d [<0>] __rpm_callback+0x70/0xd4 [<0>] rpm_idle+0x179/0x1df [<0>] pm_runtime_work+0x6b/0x81 [<0>] process_one_work+0x1bd/0x2c6 [<0>] worker_thread+0x19c/0x240 [<0>] kthread+0x11b/0x123 [<0>] ret_from_fork+0x22/0x30 [<0>] slab_pre_alloc_hook+0x15/0x46 [<0>] __kmalloc+0x148/0x15a [<0>] usb_hcd_submit_urb+0x5c6/0x773 [<0>] usb_start_wait_urb+0x59/0xc8 [<0>] usb_control_msg+0xd4/0x10d [<0>] get_port_status+0x51/0x6f [<0>] hub_port_status+0x41/0xa3 [<0>] hub_activate+0x230/0x4ee [<0>] hub_resume+0x20/0x9a [<0>] usb_resume_interface.isra.0+0xb0/0xd0 [<0>] usb_suspend_both+0xf6/0x20c [<0>] slab_pre_alloc_hook+0x15/0x46 [<0>] __kmalloc+0x148/0x15a [<0>] usb_hcd_submit_urb+0x5c6/0x773 [<0>] usb_start_wait_urb+0x59/0xc8 [<0>] usb_control_msg+0xd4/0x10d [<0>] set_port_feature+0x33/0x38 [<0>] hub_suspend+0x15c/0x16a [<0>] usb_suspend_both+0x91/0x20c [<0>] usb_runtime_suspend+0x32/0x62 [<0>] __rpm_callback+0x70/0xd4 [<0>] rpm_callback+0x55/0x6b [<0>] rpm_suspend+0x2af/0x440 [<0>] __pm_runtime_suspend+0x48/0x62 [<0>] usb_runtime_idle+0x26/0x2d [<0>] __rpm_callback+0x70/0xd4 [<0>] rpm_idle+0x179/0x1df [<0>] pm_runtime_work+0x6b/0x81 [<0>] process_one_work+0x1bd/0x2c6 [<0>] worker_thread+0x19c/0x240 [<0>] kthread+0x11b/0x123 [<0>] ret_from_fork+0x22/0x30 Is this something known or something I can give more information about? >From a very quick look into the code it sounds as if the system wanted to suspend an USB device/controller but that keeps failing again and again. -- Michal Hocko SUSE Labs
