INFO: task syz-executor0:8102 blocked for more than 140 seconds. Not tainted 4.20.0+ #2 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D19448 8102 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2831 [inline] __schedule+0x897/0x1e90 kernel/sched/core.c:3472 schedule+0xfe/0x350 kernel/sched/core.c:3516 __rwsem_down_write_failed_common+0xa4d/0x1620 kernel/locking/rwsem-xadd.c:577 rwsem_down_write_failed+0xe/0x10 kernel/locking/rwsem-xadd.c:606 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117 __down_write arch/x86/include/asm/rwsem.h:142 [inline] down_write+0xa5/0x130 kernel/locking/rwsem.c:72 inode_lock include/linux/fs.h:757 [inline] vfs_unlink+0xd1/0x500 fs/namei.c:3990 do_unlinkat+0x52a/0x9e0 fs/namei.c:4062 __do_sys_unlink fs/namei.c:4109 [inline] __se_sys_unlink fs/namei.c:4107 [inline] __x64_sys_unlink+0x42/0x50 fs/namei.c:4107 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457c17 Code: 47 4f 1c 01 48 89 4c 24 10 e8 15 b2 fc ff 48 8b 44 24 20 48 8d 50 01 48 8b 44 24 28 0f b6 4c 24 1f 48 83 fa 40 7d 1b 84 c9 74 <0b> 0f b6 98 c0 00 00 00 84 db 75 0c 48 8b 1d 6e 42 1a 01 48 85 db RSP: 002b:00007ffd7044f0b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000457c17 RDX: 00007ffd7044f0d0 RSI: 00007ffd7044f0d0 RDI: 00007ffd7044f160 RBP: 00000000000016fd R08: 0000000000000000 R09: 0000000000000014 R10: 0000000000000005 R11: 0000000000000246 R12: 00007ffd70450250 R13: 0000000001f03980 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 1 lock held by khungtaskd/1039: #0: 0000000035a18d5d (rcu_read_lock){....}, at: debug_show_all_locks+0xc6/0x41d kernel/locking/lockdep.c:4389 1 lock held by rsyslogd/7977: #0: 00000000e2e9fd6f (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1b3/0x1f0 fs/file.c:795 2 locks held by getty/8068: #0: 000000005e2cfb46 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 0000000072d678e8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 2 locks held by getty/8069: #0: 00000000bd401f05 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 0000000081331fb5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 2 locks held by getty/8070: #0: 00000000bc5ace6d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 0000000065a4eed5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 2 locks held by getty/8071: #0: 000000004b756d59 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000dc752a6d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 2 locks held by getty/8072: #0: 000000001d5bcc92 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 000000007a441074 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 2 locks held by getty/8073: #0: 00000000d0b76f8b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000b8a8c4cb (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 2 locks held by getty/8074: #0: 00000000e8c541e7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000a66402d2 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 3 locks held by syz-executor0/8102: #0: 00000000033e7c49 (sb_writers#3){.+.+}, at: sb_start_write include/linux/fs.h:1602 [inline] #0: 00000000033e7c49 (sb_writers#3){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 #1: 00000000e709052b (&type->i_mutex_dir_key#3/1){+.+.}, at: inode_lock_nested include/linux/fs.h:792 [inline] #1: 00000000e709052b (&type->i_mutex_dir_key#3/1){+.+.}, at: do_unlinkat+0x394/0x9e0 fs/namei.c:4048 #2: 000000006717ab24 (&sb->s_type->i_mutex_key#10){++++}, at: inode_lock include/linux/fs.h:757 [inline] #2: 000000006717ab24 (&sb->s_type->i_mutex_key#10){++++}, at: vfs_unlink+0xd1/0x500 fs/namei.c:3990 3 locks held by syz-executor0/29373: #0: 0000000073412614 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1b3/0x1f0 fs/file.c:795 #1: 00000000033e7c49 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2815 [inline] #1: 00000000033e7c49 (sb_writers#3){.+.+}, at: vfs_write+0x429/0x580 fs/read_write.c:548 #2: 000000006717ab24 (&sb->s_type->i_mutex_key#10){++++}, at: inode_trylock include/linux/fs.h:777 [inline] #2: 000000006717ab24 (&sb->s_type->i_mutex_key#10){++++}, at: ext4_file_write_iter+0x28b/0x1410 fs/ext4/file.c:232 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1039 Comm: khungtaskd Not tainted 4.20.0+ #2 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+0x1db/0x2d0 lib/dump_stack.c:113 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1be/0x236 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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xbd2/0x10b0 kernel/hung_task.c:289 kthread+0x357/0x430 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x2/0x10 arch/x86/include/asm/irqflags.h:57