Hi Forks, On the kernel version 5.2.37 or a bit earlier, running pressure testing with module insert & remove, actually the inserted module is not special and could be anyone. After dozens of testing, there will be throw below call trace and the system hung. Testing script for insert & remove module like below: for each in {1..100} ; do echo "$each" ; insmod openvswitch.ko ; rmmod openvswitch.ko ; usleep 100000 ; done The target machine is: arm64, cortex a53. Disassembled the line " __wake_up_common_lock+0x98/0xe0 ", it located the code "include/linux/spinlock.h" , it should be using the NULL pointer "lock->rlock " static __always_inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags) { raw_spin_unlock_irqrestore(&lock->rlock, flags); Did you ever see this issue or have a fix for this based on kernel 5.2.37 version? Call trace: openvswitch: Open vSwitch switching datapath Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 Mem abort info: ESR = 0x86000005 Exception class = IABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 user pgtable: 4k pages, 39-bit VAs, pgdp=00000008f2ea9000 [0000000000000000] pgd=0000000000000000, pud=0000000000000000 Internal error: Oops: 86000005 [#1] PREEMPT SMP Modules linked in: openvswitch hse sch_fq_codel nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 [last unloaded: openvswitch] CPU: 2 PID: 209 Comm: kworker/u9:3 Not tainted 5.2.37-yocto-standard #1 Hardware name: Freescale S32G275 (DT) Workqueue: xprtiod xs_stream_data_receive_workfn pstate: 80000085 (Nzcv daIf -PAN -UAO) pc : 0x0 lr : __wake_up_common+0x90/0x150 sp : ffffff801146ba60 x29: ffffff801146ba60 x28: ffffff8010d36000 x27: ffffff801146bb90 x26: 0000000000000000 x25: 0000000000000003 x24: 0000000000000000 x23: 0000000000000001 x22: ffffff801146bb00 x21: ffffff8010d351e8 x20: 0000000000000000 x19: ffffff80112c37a0 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: 0000003002000000 x12: 0000902802000000 x11: 0000000000000000 x10: 000001000000ed01 x9 : 0000010000000000 x8 : 9b5e0000000048a6 x7 : 0000000000000068 x6 : ffffff80112c37a0 x5 : 0000000000000000 x4 : ffffff801146bb90 x3 : ffffff801146bb90 x2 : 0000000000000000 x1 : 0000000000000003 x0 : ffffff80112c37a0 Call trace: 0x0 __wake_up_common_lock+0x98/0xe0 __wake_up+0x40/0x50 wake_up_bit+0x8c/0xb8 rpc_make_runnable+0xc8/0xd0 rpc_wake_up_task_on_wq_queue_action_locked+0x110/0x278 rpc_wake_up_queued_task.part.0+0x40/0x58 rpc_wake_up_queued_task+0x38/0x48 xprt_complete_rqst+0x68/0x128 xs_read_stream.constprop.0+0x2ec/0x3d0 xs_stream_data_receive_workfn+0x60/0x190 process_one_work+0x1bc/0x440 worker_thread+0x50/0x408 kthread+0x104/0x130 ret_from_fork+0x10/0x1c Code: bad PC value Kernel panic - not syncing: Fatal exception in interrupt SMP: stopping secondary CPUs Kernel Offset: disabled CPU features: 0x0002,2000200c Memory Limit: none Thanks Xulin