WARNING: CPU: 0 PID: 7645 at kernel/workqueue.c:3018 __flush_work+0x74c/0x8a0 kernel/workqueue.c:3018 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 7645 Comm: kworker/0:5 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: 0018:ffff888057da79a0 EFLAGS: 00010293 RAX: ffff888057d9e4c0 RBX: ffff8880998352b8 RCX: ffffffff814a3dbb RDX: 0000000000000000 RSI: ffffffff814a446c RDI: 0000000000000001 RBP: ffff888057da7b10 R08: ffff888057d9e4c0 R09: ffff888057d9ed88 R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000 R13: ffff888057da7ae8 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..