==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
BUG: KASAN: null-ptr-deref in atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [inline]
BUG: KASAN: null-ptr-deref in __refcount_add include/linux/refcount.h:193 [inline]
BUG: KASAN: null-ptr-deref in __refcount_inc include/linux/refcount.h:250 [inline]
BUG: KASAN: null-ptr-deref in refcount_inc include/linux/refcount.h:267 [inline]
BUG: KASAN: null-ptr-deref in get_task_struct include/linux/sched/task.h:102 [inline]
BUG: KASAN: null-ptr-deref in kthread_stop+0x2a/0x200 kernel/kthread.c:591
Write of size 4 at addr 0000000000000024 by task kworker/u4:11/15068

CPU: 1 PID: 15068 Comm: kworker/u4:11 Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usbip_event event_handler
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x183/0x22e lib/dump_stack.c:120
 __kasan_report mm/kasan/report.c:400 [inline]
 kasan_report+0x154/0x200 mm/kasan/report.c:413
 check_memory_region_inline mm/kasan/generic.c:134 [inline]
 check_memory_region+0x2b5/0x2f0 mm/kasan/generic.c:185
 instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
 atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [inline]
 __refcount_add include/linux/refcount.h:193 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 get_task_struct include/linux/sched/task.h:102 [inline]
 kthread_stop+0x2a/0x200 kernel/kthread.c:591
 vhci_shutdown_connection+0x16f/0xad0 drivers/usb/usbip/vhci_hcd.c:1023
 event_handler+0x268/0x4d0 drivers/usb/usbip/usbip_event.c:78
 process_one_work+0x833/0x10c0 kernel/workqueue.c:2275
 worker_thread+0xaa4/0x1460 kernel/workqueue.c:2421
 kthread+0x39a/0x3c0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 15068 Comm: kworker/u4:11 Tainted: G    B             5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usbip_event event_handler
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x183/0x22e lib/dump_stack.c:120
 panic+0x2e1/0x850 kernel/panic.c:231
 end_report mm/kasan/report.c:100 [inline]
 __kasan_report mm/kasan/report.c:403 [inline]
 kasan_report+0x1fb/0x200 mm/kasan/report.c:413
 check_memory_region_inline mm/kasan/generic.c:134 [inline]
 check_memory_region+0x2b5/0x2f0 mm/kasan/generic.c:185
 instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
 atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [inline]
 __refcount_add include/linux/refcount.h:193 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 get_task_struct include/linux/sched/task.h:102 [inline]
 kthread_stop+0x2a/0x200 kernel/kthread.c:591
 vhci_shutdown_connection+0x16f/0xad0 drivers/usb/usbip/vhci_hcd.c:1023
 event_handler+0x268/0x4d0 drivers/usb/usbip/usbip_event.c:78
 process_one_work+0x833/0x10c0 kernel/workqueue.c:2275
 worker_thread+0xaa4/0x1460 kernel/workqueue.c:2421
 kthread+0x39a/0x3c0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Kernel Offset: disabled
Rebooting in 86400 seconds..