INFO: task syz-executor.4:7294 blocked for more than 140 seconds. Not tainted 4.14.164-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D25168 7294 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384 schedule+0x92/0x1c0 kernel/sched/core.c:3428 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:588 [inline] rwsem_down_write_failed+0x5ce/0xb50 kernel/locking/rwsem-xadd.c:617 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105 __down_write arch/x86/include/asm/rwsem.h:126 [inline] down_write+0x53/0x90 kernel/locking/rwsem.c:56 inode_lock include/linux/fs.h:718 [inline] vfs_unlink+0xc6/0x480 fs/namei.c:4015 do_unlinkat+0x33d/0x600 fs/namei.c:4089 SYSC_unlink fs/namei.c:4136 [inline] SyS_unlink+0x1b/0x20 fs/namei.c:4134 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45ac97 RSP: 002b:00007fff0a8948d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045ac97 RDX: 00007fff0a8948f0 RSI: 00007fff0a8948f0 RDI: 00007fff0a894980 RBP: 0000000000000ee0 R08: 0000000000000000 R09: 000000000000000c R10: 0000000000000005 R11: 0000000000000246 R12: 00007fff0a895a10 R13: 00000000020ed940 R14: 0000000000000000 R15: 00007fff0a895a10 Showing all locks held in the system: 1 lock held by khungtaskd/1059: #0: (tasklist_lock){.+.?}, at: [] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544 1 lock held by rsyslogd/7122: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0xab/0xd0 fs/file.c:769 2 locks held by getty/7244: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7245: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7246: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7247: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7248: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7249: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 2 locks held by getty/7250: #0: (&tty->ldisc_sem){++++}, at: [] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156 3 locks held by syz-executor.4/7294: #0: (sb_writers#4){.+.+}, at: [] sb_start_write include/linux/fs.h:1548 [inline] #0: (sb_writers#4){.+.+}, at: [] mnt_want_write+0x3f/0xb0 fs/namespace.c:386 #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [] inode_lock_nested include/linux/fs.h:753 [inline] #1: (&type->i_mutex_dir_key#3/1){+.+.}, at: [] do_unlinkat+0x22f/0x600 fs/namei.c:4075 #2: (&sb->s_type->i_mutex_key#9){+.+.}, at: [] inode_lock include/linux/fs.h:718 [inline] #2: (&sb->s_type->i_mutex_key#9){+.+.}, at: [] vfs_unlink+0xc6/0x480 fs/namei.c:4015 2 locks held by syz-executor.4/21844: #0: (sb_writers#4){.+.+}, at: [] file_start_write include/linux/fs.h:2707 [inline] #0: (sb_writers#4){.+.+}, at: [] vfs_write+0x3af/0x500 fs/read_write.c:543 #1: (&sb->s_type->i_mutex_key#9){+.+.}, at: [] inode_trylock include/linux/fs.h:738 [inline] #1: (&sb->s_type->i_mutex_key#9){+.+.}, at: [] ext4_file_write_iter+0x1f4/0xe90 fs/ext4/file.c:234 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1059 Comm: khungtaskd Not tainted 4.14.164-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x142/0x197 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x141/0x189 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:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5e7/0xb90 kernel/hung_task.c:274 kthread+0x319/0x430 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff866a5c9e