WARNING: CPU: 0 PID: 14 at kernel/workqueue.c:2911 __flush_work+0x740/0x880 kernel/workqueue.c:2911
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 14 Comm: kworker/0:1 Not tainted 4.19.40 #8
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: md_misc mddev_delayed_delete
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 panic+0x263/0x51d kernel/panic.c:185
 __warn.cold+0x20/0x54 kernel/panic.c:540
 report_bug+0x263/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 fixup_bug arch/x86/kernel/traps.c:173 [inline]
 do_error_trap+0x204/0x360 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:997
RIP: 0010:__flush_work+0x740/0x880 kernel/workqueue.c:2911
Code: 74 58 e8 63 59 25 00 fb 66 0f 1f 44 00 00 45 31 e4 e9 86 fd ff ff e8 4f 59 25 00 0f 0b 45 31 e4 e9 77 fd ff ff e8 40 59 25 00 <0f> 0b 45 31 e4 e9 68 fd ff ff e8 31 59 25 00 4c 89 ff 45 31 e4 e8
RSP: 0018:ffff8880aa26f990 EFLAGS: 00010293
RAX: ffff8880aa25e380 RBX: dffffc0000000000 RCX: ffffffff814620bb
RDX: 0000000000000000 RSI: ffffffff81462760 RDI: 0000000000000001
RBP: ffff8880aa26faf8 R08: ffff8880aa25e380 R09: ffff8880aa25ec48
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809aec4690
R13: ffff8880aa26fad0 R14: 0000000000000001 R15: 0000000000000001
 __cancel_work_timer+0x3bf/0x520 kernel/workqueue.c:3007
 cancel_work_sync+0x18/0x20 kernel/workqueue.c:3043
 blk_sync_queue+0x33/0x1c0 block/blk-core.c:408
 blk_cleanup_queue+0x404/0x720 block/blk-core.c:807
 md_free+0xcb/0x1b0 drivers/md/md.c:5223
 kobject_cleanup lib/kobject.c:662 [inline]
 kobject_release lib/kobject.c:691 [inline]
 kref_put include/linux/kref.h:70 [inline]
 kobject_put.cold+0x28f/0x2ec lib/kobject.c:708
 mddev_delayed_delete+0x34/0x40 drivers/md/md.c:5251
 process_one_work+0x98e/0x1760 kernel/workqueue.c:2153
 worker_thread+0x98/0xe40 kernel/workqueue.c:2296
 kthread+0x357/0x430 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
Kernel Offset: disabled
Rebooting in 86400 seconds..