INFO: task syz-executor5:9518 blocked for more than 140 seconds. Not tainted 4.19.0-rc6+ #262 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor5 D23816 9518 5521 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x86c/0x1ed0 kernel/sched/core.c:3473 schedule+0xfe/0x460 kernel/sched/core.c:3517 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3575 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0xbe7/0x1700 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 __fdget_pos+0x1bb/0x200 fs/file.c:766 fdget_pos include/linux/file.h:70 [inline] ksys_write+0x7f/0x260 fs/read_write.c:593 __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: 0033:0x457579 Code: 24 08 48 89 01 e8 d7 2d fc ff e8 22 7a fc ff b8 02 00 00 00 48 8d 0d 6a 60 09 01 87 01 8b 05 62 60 09 01 83 f8 01 0f 85 8a 00 <00> 00 b8 01 00 00 00 88 05 9e 65 09 01 84 c0 74 72 b8 01 00 00 00 RSP: 002b:00007f6dbc87ac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457579 RDX: 000000000000000b RSI: 0000000020000040 RDI: 0000000000000005 RBP: 000000000072c040 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6dbc87b6d4 R13: 00000000004c5343 R14: 00000000004d8a90 R15: 00000000ffffffff Showing all locks held in the system: 3 locks held by kworker/u4:3/430: #0: 00000000ea9c88d9 ((wq_completion)"writeback"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000ea9c88d9 ((wq_completion)"writeback"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000ea9c88d9 ((wq_completion)"writeback"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000ea9c88d9 ((wq_completion)"writeback"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 00000000ea9c88d9 ((wq_completion)"writeback"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000ea9c88d9 ((wq_completion)"writeback"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000ea9c88d9 ((wq_completion)"writeback"){+.+.}, at: process_one_work+0xb43/0x1b90 kernel/workqueue.c:2124 #1: 00000000d401f913 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0xb9a/0x1b90 kernel/workqueue.c:2128 #2: 000000008b173217 (&type->s_umount_key#54){++++}, at: trylock_super+0x22/0x110 fs/super.c:412 1 lock held by khungtaskd/980: #0: 000000006f1a53be (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4435 1 lock held by rsyslogd/5246: 2 locks held by getty/5336: #0: 0000000002f6f57f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000525f0c3a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5337: #0: 00000000f53c6520 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000b69f90a7 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5338: #0: 00000000d1e6cb4c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000eeee4744 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5339: #0: 0000000020f03e74 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000d49d7857 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5340: #0: 0000000033c68b69 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000b48e8edd (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5341: #0: 000000002f2d0597 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000003e8f042a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5342: #0: 000000001c378c7f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000001d0ff3bf (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 3 locks held by syz-executor5/9483: #0: 00000000736e55c5 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 #1: 00000000061e0e17 (sb_writers#19){.+.+}, at: file_start_write include/linux/fs.h:2759 [inline] #1: 00000000061e0e17 (sb_writers#19){.+.+}, at: vfs_write+0x42a/0x560 fs/read_write.c:548 #2: 000000001a337c4c (&sb->s_type->i_mutex_key#25){+.+.}, at: inode_lock include/linux/fs.h:738 [inline] #2: 000000001a337c4c (&sb->s_type->i_mutex_key#25){+.+.}, at: generic_file_write_iter+0xed/0x870 mm/filemap.c:3289 1 lock held by syz-executor5/9518: #0: 00000000736e55c5 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by syz-executor5/9519: #0: 00000000061e0e17 (sb_writers#19){.+.+}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 00000000061e0e17 (sb_writers#19){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 #1: 000000007afe6440 (&sb->s_type->i_mutex_key#25){+.+.}, at: inode_lock include/linux/fs.h:738 [inline] #1: 000000007afe6440 (&sb->s_type->i_mutex_key#25){+.+.}, at: do_last fs/namei.c:3321 [inline] #1: 000000007afe6440 (&sb->s_type->i_mutex_key#25){+.+.}, at: path_openat+0x15c7/0x5160 fs/namei.c:3534 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 980 Comm: khungtaskd Not tainted 4.19.0-rc6+ #262 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+0x1c4/0x2b4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.3+0x63/0xa2 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:413 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