INFO: task syz-executor.0:450 blocked for more than 143 seconds. Not tainted 5.4.0-rc1+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D24320 450 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:3384 [inline] __schedule+0x94f/0x1e70 kernel/sched/core.c:4069 schedule+0xd9/0x260 kernel/sched/core.c:4136 rwsem_down_write_slowpath+0x70b/0xf90 kernel/locking/rwsem.c:1238 __down_write kernel/locking/rwsem.c:1392 [inline] down_write+0x13c/0x150 kernel/locking/rwsem.c:1535 inode_lock include/linux/fs.h:791 [inline] vfs_unlink+0xd5/0x620 fs/namei.c:3982 do_unlinkat+0x3f7/0x6d0 fs/namei.c:4055 __do_sys_unlink fs/namei.c:4102 [inline] __se_sys_unlink fs/namei.c:4100 [inline] __x64_sys_unlink+0x42/0x50 fs/namei.c:4100 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4597a7 Code: 0f 0b 0f 0b e8 1a 07 fd ff 0f 0b e8 c3 07 00 00 e9 ce fc ff ff cc cc cc cc cc cc cc cc cc cc cc cc cc cc 64 48 8b 0c 25 f8 ff ff 48 3b 61 10 76 29 48 83 ec 18 48 89 6c 24 10 48 8d 6c 24 10 RSP: 002b:00007ffec3f60698 EFLAGS: 00000246 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004597a7 RDX: 00007ffec3f606b0 RSI: 00007ffec3f606b0 RDI: 00007ffec3f60740 RBP: 000000000000027d R08: 0000000000000000 R09: 0000000000000009 R10: 0000000000000003 R11: 0000000000000246 R12: 00007ffec3f617d0 R13: 0000000002594940 R14: 0000000000000000 R15: 00007ffec3f617d0 Showing all locks held in the system: 1 lock held by khungtaskd/1064: #0: ffffffff88faae00 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5337 2 locks held by rsyslogd/8926: #0: ffff8880a78c8920 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 #1: ffffffff89045060 (fs_reclaim){+.+.}, at: is_bpf_text_address+0x0/0x170 kernel/bpf/core.c:695 2 locks held by getty/9048: #0: ffff88808c704b90 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f512e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9049: #0: ffff8880a893ca90 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f3d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9050: #0: ffff8880a1d6b2d0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f352e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9051: #0: ffff88808c704310 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f552e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9052: #0: ffff888090d72950 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f2d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9053: #0: ffff8880837c4b10 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f492e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 2 locks held by getty/9054: #0: ffff8880a2326cd0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc90005f252e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 3 locks held by kworker/u4:5/10702: #0: ffff8880ae934d18 (&rq->lock){-.-.}, at: newidle_balance+0xa32/0xe90 kernel/sched/fair.c:9817 #1: ffffffff88faae00 (rcu_read_lock){....}, at: __update_idle_core+0x45/0x3f0 kernel/sched/fair.c:5825 #2: ffff8880ae924c18 (&base->lock){-.-.}, at: lock_timer_base+0x56/0x1b0 kernel/time/timer.c:936 3 locks held by syz-executor.0/450: #0: ffff88809bfa6da0 (sb_writers#4){.+.+}, at: sb_start_write include/linux/fs.h:1650 [inline] #0: ffff88809bfa6da0 (sb_writers#4){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:354 #1: ffff888057655948 (&type->i_mutex_dir_key#3/1){+.+.}, at: inode_lock_nested include/linux/fs.h:826 [inline] #1: ffff888057655948 (&type->i_mutex_dir_key#3/1){+.+.}, at: do_unlinkat+0x29f/0x6d0 fs/namei.c:4041 #2: ffff88802e848a48 (&sb->s_type->i_mutex_key#10){++++}, at: inode_lock include/linux/fs.h:791 [inline] #2: ffff88802e848a48 (&sb->s_type->i_mutex_key#10){++++}, at: vfs_unlink+0xd5/0x620 fs/namei.c:3982 2 locks held by syz-executor.0/7899: #0: ffff88809bfa6da0 (sb_writers#4){.+.+}, at: file_start_write include/linux/fs.h:2882 [inline] #0: ffff88809bfa6da0 (sb_writers#4){.+.+}, at: vfs_write+0x485/0x5d0 fs/read_write.c:557 #1: ffff88802e848a48 (&sb->s_type->i_mutex_key#10){++++}, at: inode_trylock include/linux/fs.h:811 [inline] #1: ffff88802e848a48 (&sb->s_type->i_mutex_key#10){++++}, at: ext4_file_write_iter+0x220/0x13c0 fs/ext4/file.c:234 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1064 Comm: khungtaskd Not tainted 5.4.0-rc1+ #0 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+0x172/0x1f0 lib/dump_stack.c:113 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b 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+0x9d0/0xef0 kernel/hung_task.c:289 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60