INFO: task kworker/u4:11:11619 blocked for more than 143 seconds. Not tainted 5.15.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u4:11 state:D stack:23888 pid:11619 ppid: 2 flags:0x00004000 Workqueue: nbd-del nbd_dev_remove_work Call Trace: context_switch kernel/sched/core.c:4969 [inline] __schedule+0xa9a/0x4940 kernel/sched/core.c:6250 schedule+0xd2/0x260 kernel/sched/core.c:6323 blk_mq_freeze_queue_wait+0x112/0x160 block/blk-mq.c:178 del_gendisk+0x598/0x860 block/genhd.c:623 nbd_dev_remove+0x3c/0xf0 drivers/block/nbd.c:252 process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298 worker_thread+0x658/0x11f0 kernel/workqueue.c:2445 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Showing all locks held in the system: 1 lock held by khungtaskd/27: #0: ffffffff8bb83b60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6458 1 lock held by in:imklog/6214: 2 locks held by agetty/6440: #0: ffff8880139ac098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:252 #1: ffffc90002afc2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xcf0/0x1230 drivers/tty/n_tty.c:2113 2 locks held by agetty/6441: #0: ffff88801a251098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:252 #1: ffffc9000294b2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xcf0/0x1230 drivers/tty/n_tty.c:2113 2 locks held by kworker/u4:11/11619: #0: ffff88801a8d7938 ((wq_completion)nbd-del){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff88801a8d7938 ((wq_completion)nbd-del){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline] #0: ffff88801a8d7938 ((wq_completion)nbd-del){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1198 [inline] #0: ffff88801a8d7938 ((wq_completion)nbd-del){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:635 [inline] #0: ffff88801a8d7938 ((wq_completion)nbd-del){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:662 [inline] #0: ffff88801a8d7938 ((wq_completion)nbd-del){+.+.}-{0:0}, at: process_one_work+0x896/0x1690 kernel/workqueue.c:2269 #1: ffffc90002a6fdb0 ((work_completion)(&nbd->remove_work)){+.+.}-{0:0}, at: process_one_work+0x8ca/0x1690 kernel/workqueue.c:2273 1 lock held by syz-executor.2/22993: #0: ffff88807f474460 (sb_writers#5){.+.+}-{0:0}, at: __do_sys_sendfile64 fs/read_write.c:1310 [inline] #0: ffff88807f474460 (sb_writers#5){.+.+}-{0:0}, at: __se_sys_sendfile64 fs/read_write.c:1296 [inline] #0: ffff88807f474460 (sb_writers#5){.+.+}-{0:0}, at: __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1296 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 27 Comm: khungtaskd Not tainted 5.15.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1ae/0x220 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline] watchdog+0xc1d/0xf50 kernel/hung_task.c:295 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 22166 Comm: kworker/0:13 Not tainted 5.15.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events nsim_dev_trap_report_work RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:166 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:200 Code: 48 89 ef 5d e9 a1 19 46 00 5d be 03 00 00 00 e9 a6 0d 63 02 66 0f 1f 44 00 00 48 8b be b0 01 00 00 e8 b4 ff ff ff 31 c0 c3 90 <65> 8b 05 09 89 8a 7e 89 c1 48 8b 34 24 81 e1 00 01 00 00 65 48 8b RSP: 0018:ffffc90004f9fb88 EFLAGS: 00000093 RAX: 0000000000000000 RBX: ffff8880b9c28280 RCX: 0000000000000000 RDX: ffff8880180e8000 RSI: ffffffff8166f33b RDI: 0000000000000003 RBP: ffff888022a88048 R08: 0000000000028280 R09: 0000000000000003 R10: ffffffff8166f527 R11: 0000000000000000 R12: ffff8880b9c282c8 R13: ffff8880b9c28280 R14: 0000000000000000 R15: 00000000ffffffff FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f18008c9000 CR3: 0000000030be6000 CR4: 0000000000350ef0 Call Trace: debug_timer_activate kernel/time/timer.c:729 [inline] __mod_timer+0x76e/0xe30 kernel/time/timer.c:1050 __queue_delayed_work+0x1a7/0x270 kernel/workqueue.c:1678 queue_delayed_work_on+0x105/0x120 kernel/workqueue.c:1703 process_one_work+0x9b2/0x1690 kernel/workqueue.c:2298 worker_thread+0x658/0x11f0 kernel/workqueue.c:2445 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 ---------------- Code disassembly (best guess): 0: 48 89 ef mov %rbp,%rdi 3: 5d pop %rbp 4: e9 a1 19 46 00 jmpq 0x4619aa 9: 5d pop %rbp a: be 03 00 00 00 mov $0x3,%esi f: e9 a6 0d 63 02 jmpq 0x2630dba 14: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1) 1a: 48 8b be b0 01 00 00 mov 0x1b0(%rsi),%rdi 21: e8 b4 ff ff ff callq 0xffffffda 26: 31 c0 xor %eax,%eax 28: c3 retq 29: 90 nop * 2a: 65 8b 05 09 89 8a 7e mov %gs:0x7e8a8909(%rip),%eax # 0x7e8a893a <-- trapping instruction 31: 89 c1 mov %eax,%ecx 33: 48 8b 34 24 mov (%rsp),%rsi 37: 81 e1 00 01 00 00 and $0x100,%ecx 3d: 65 gs 3e: 48 rex.W 3f: 8b .byte 0x8b