WARNING: CPU: 1 PID: 7943 at kernel/workqueue.c:3018 __flush_work+0x74c/0x8a0 kernel/workqueue.c:3018
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 7943 Comm: kworker/1:3 Not tainted 5.0.0-rc4-next-20190201 #25
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+0x2cb/0x65c kernel/panic.c:214
 __warn.cold+0x20/0x45 kernel/panic.c:571
 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+0x11b/0x200 arch/x86/kernel/traps.c:271
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:290
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:973
RIP: 0010:__flush_work+0x74c/0x8a0 kernel/workqueue.c:3018
Code: 74 58 e8 47 b7 25 00 fb 66 0f 1f 44 00 00 45 31 e4 e9 86 fd ff ff e8 33 b7 25 00 0f 0b 45 31 e4 e9 77 fd ff ff e8 24 b7 25 00 <0f> 0b 45 31 e4 e9 68 fd ff ff e8 15 b7 25 00 4c 89 ff 45 31 e4 e8
RSP: 0000:ffff8880888879a0 EFLAGS: 00010293
RAX: ffff88808bd7e0c0 RBX: ffff8880a049c468 RCX: ffffffff814a3dbb
RDX: 0000000000000000 RSI: ffffffff814a446c RDI: 0000000000000001
RBP: ffff888088887b10 R08: ffff88808bd7e0c0 R09: ffff88808bd7e988
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff888088887ae8 R14: 0000000000000001 R15: 0000000000000001
 __cancel_work_timer+0x3bf/0x520 kernel/workqueue.c:3114
 cancel_work_sync+0x18/0x20 kernel/workqueue.c:3150
 blk_sync_queue+0x33/0x190 block/blk-core.c:234
 blk_cleanup_queue+0x100/0x200 block/blk-core.c:367
 md_free+0xcb/0x1b0 drivers/md/md.c:5215
 kobject_cleanup lib/kobject.c:662 [inline]
 kobject_release lib/kobject.c:691 [inline]
 kref_put include/linux/kref.h:67 [inline]
 kobject_put.cold+0x28f/0x2ec lib/kobject.c:708
 mddev_delayed_delete+0x34/0x40 drivers/md/md.c:5243
 process_one_work+0x98e/0x1790 kernel/workqueue.c:2257
 worker_thread+0x98/0xe40 kernel/workqueue.c:2403
 kthread+0x357/0x430 kernel/kthread.c:247
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..