INFO: task syz-executor5:5755 blocked for more than 140 seconds. Not tainted 4.19.0+ #82 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor5 D18440 5755 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x8cf/0x21d0 kernel/sched/core.c:3474 schedule+0xfe/0x460 kernel/sched/core.c:3518 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3576 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0xaff/0x16f0 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 __pipe_lock fs/pipe.c:83 [inline] pipe_write+0xc0/0xec0 fs/pipe.c:366 call_write_iter include/linux/fs.h:1808 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x6b8/0x9f0 fs/read_write.c:487 vfs_write+0x1fc/0x560 fs/read_write.c:549 ksys_write+0x101/0x260 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x410f40 Code: 40 48 89 6c 24 38 48 8d 6c 24 38 48 8b 44 24 48 48 8d 88 00 20 00 00 48 39 c1 0f 82 e0 00 00 00 48 89 c1 48 c1 e8 0d 48 f7 c1 1f 00 00 74 03 48 ff c0 48 89 44 24 28 48 89 c1 48 c1 e0 0d 48 RSP: 002b:00007ffddc141738 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 000000000000000f RCX: 0000000000410f40 RDX: 000000000000000f RSI: 00007ffddc1418d0 RDI: 0000000000000002 RBP: 00007ffddc1418d0 R08: 0000000000dd6940 R09: 000000000000000f R10: 0000000000dd6940 R11: 0000000000000246 R12: 000000000000000f R13: 0000000000000001 R14: 000000000070bf20 R15: 0000000000000005 Showing all locks held in the system: 1 lock held by khungtaskd/981: #0: 00000000becac124 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4379 1 lock held by rsyslogd/5482: #0: 00000000e1c0e3b4 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by getty/5572: #0: 00000000ab370237 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000003c3d9ce0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5573: #0: 00000000c9a3bcc8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000dcdd8df8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5574: #0: 0000000035ca891f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000ac4e774d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5575: #0: 0000000093a1a415 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000001bf2793 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5576: #0: 00000000ec167424 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000000c8a0853 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5577: #0: 00000000b2628ebc (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000006571a675 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5578: #0: 00000000bc518ad8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000cce80718 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 1 lock held by syz-executor5/5755: #0: 00000000f268235f (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000f268235f (&pipe->mutex/1){+.+.}, at: pipe_write+0xc0/0xec0 fs/pipe.c:366 1 lock held by syz-executor5/20244: #0: 00000000f268235f (&pipe->mutex/1){+.+.}, at: pipe_lock_nested fs/pipe.c:62 [inline] #0: 00000000f268235f (&pipe->mutex/1){+.+.}, at: pipe_lock+0x6e/0x80 fs/pipe.c:70 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 981 Comm: khungtaskd Not tainted 4.19.0+ #82 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x244/0x39d lib/dump_stack.c:113 nmi_cpu_backtrace.cold.1+0x5c/0xa1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b3/0x1ed lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:144 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline] watchdog+0xb3e/0x1050 kernel/hung_task.c:265 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:350 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57