NILFS (loop1): broken superblock, retrying with spare superblock (blocksize = 1024) NILFS (loop1): mounting unchecked fs NILFS (loop1): recovery complete NILFS (loop1): segctord starting. Construction interval = 5 seconds, CP frequency < 30 seconds ============================================ WARNING: possible recursive locking detected 4.14.305-syzkaller #0 Not tainted -------------------------------------------- syz-executor.3/10154 is trying to acquire lock: (&port_lock_key){-.-.}, at: [] uart_write+0x109/0x560 drivers/tty/serial/serial_core.c:611 but task is already holding lock: (&port_lock_key){-.-.}, at: [] serial8250_handle_irq.part.0+0x20/0x390 drivers/tty/serial/8250/8250_port.c:1894 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&port_lock_key); NILFS error (device loop1): nilfs_readdir: zero-length directory entry lock(&port_lock_key); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz-executor.3/10154: #0: (&(&i->lock)->rlock){-.-.}, at: [] spin_lock include/linux/spinlock.h:317 [inline] #0: (&(&i->lock)->rlock){-.-.}, at: [] serial8250_interrupt+0x3a/0x210 drivers/tty/serial/8250/8250_core.c:119 Remounting filesystem read-only #1: (&port_lock_key){-.-.}, at: [] serial8250_handle_irq.part.0+0x20/0x390 drivers/tty/serial/8250/8250_port.c:1894 #2: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref+0x1b/0x80 drivers/tty/tty_ldisc.c:305 stack backtrace: CPU: 1 PID: 10154 Comm: syz-executor.3 Not tainted 4.14.305-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 print_deadlock_bug kernel/locking/lockdep.c:1800 [inline] check_deadlock kernel/locking/lockdep.c:1847 [inline] validate_chain kernel/locking/lockdep.c:2448 [inline] __lock_acquire.cold+0x180/0x97c kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:160 uart_write+0x109/0x560 drivers/tty/serial/serial_core.c:611 n_hdlc_send_frames+0x241/0x410 drivers/tty/n_hdlc.c:404 n_hdlc_tty_wakeup+0x95/0xb0 drivers/tty/n_hdlc.c:480 tty_wakeup+0xc3/0xf0 drivers/tty/tty_io.c:533 tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:49 serial8250_tx_chars+0x3fe/0xc70 drivers/tty/serial/8250/8250_port.c:1828 serial8250_handle_irq.part.0+0x2c7/0x390 drivers/tty/serial/8250/8250_port.c:1918 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1891 [inline] serial8250_default_handle_irq+0x8a/0x1f0 drivers/tty/serial/8250/8250_port.c:1934 serial8250_interrupt+0xf3/0x210 drivers/tty/serial/8250/8250_core.c:129 __handle_irq_event_percpu+0xee/0x7f0 kernel/irq/handle.c:147 handle_irq_event_percpu kernel/irq/handle.c:187 [inline] handle_irq_event+0xed/0x240 kernel/irq/handle.c:204 handle_edge_irq+0x224/0xc40 kernel/irq/chip.c:770 generic_handle_irq_desc include/linux/irqdesc.h:159 [inline] handle_irq+0x35/0x50 arch/x86/kernel/irq_64.c:87 do_IRQ+0x93/0x1d0 arch/x86/kernel/irq.c:230 common_interrupt+0x93/0x93 arch/x86/entry/entry_64.S:578 RIP: 0033:0x7fdc90491215 RSP: 002b:00007ffd60168660 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffc8 RAX: 00007fdc9001d3a8 RBX: 00007fdc900199f8 RCX: ffffffff831a8c20 RDX: ffffffff831a8c20 RSI: 00007fdc90019a00 RDI: ffffffff831a8c20 RBP: 00007fdc900187c8 R08: 00007fdc9001ec28 R09: 00000000f308dccf R10: 0000000000000000 R11: 0000000000000000 R12: 00007fdc900187c0 R13: 00007fdc900199f8 R14: 00007fdc900187b8 R15: 0000000000000019 NILFS (loop1): discard dirty page: offset=77824, ino=12 NILFS (loop1): discard dirty block: blocknr=0, size=1024 NILFS (loop1): discard dirty block: blocknr=0, size=1024 NILFS (loop1): discard dirty block: blocknr=0, size=1024 NILFS (loop1): discard dirty block: blocknr=0, size=1024