audit: type=1804 audit(1673611832.361:101): pid=14453 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.2" name="/root/syzkaller-testdir3245506085/syzkaller.sqml6b/79/file0" dev="sda1" ino=14430 res=1 ============================================ WARNING: possible recursive locking detected 4.19.211-syzkaller #0 Not tainted -------------------------------------------- syz-fuzzer/10226 is trying to acquire lock: audit: type=1804 audit(1673611832.361:102): pid=14453 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.2" name="/root/syzkaller-testdir3245506085/syzkaller.sqml6b/79/file0" dev="sda1" ino=14430 res=1 0000000056d3b4e9 (&port_lock_key){-.-.}, at: uart_write+0x1ce/0x6f0 drivers/tty/serial/serial_core.c:591 but task is already holding lock: 0000000056d3b4e9 (&port_lock_key){-.-.}, at: serial8250_handle_irq.part.0+0x21/0x3d0 drivers/tty/serial/8250/8250_port.c:1876 other info that might help us debug this: audit: type=1804 audit(1673611832.361:103): pid=14453 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.2" name="/root/syzkaller-testdir3245506085/syzkaller.sqml6b/79/file0" dev="sda1" ino=14430 res=1 Possible unsafe locking scenario: CPU0 ---- lock(&port_lock_key); audit: type=1804 audit(1673611832.361:104): pid=14453 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor.2" name="/root/syzkaller-testdir3245506085/syzkaller.sqml6b/79/file0" dev="sda1" ino=14430 res=1 lock(&port_lock_key); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz-fuzzer/10226: #0: 00000000741eba92 (&(&i->lock)->rlock){-.-.}, at: spin_lock include/linux/spinlock.h:329 [inline] #0: 00000000741eba92 (&(&i->lock)->rlock){-.-.}, at: serial8250_interrupt+0x3a/0x240 drivers/tty/serial/8250/8250_core.c:115 #1: 0000000056d3b4e9 (&port_lock_key){-.-.}, at: serial8250_handle_irq.part.0+0x21/0x3d0 drivers/tty/serial/8250/8250_port.c:1876 #2: 00000000d50785ad (&tty->ldisc_sem){++++}, at: tty_ldisc_ref+0x1d/0x80 drivers/tty/tty_ldisc.c:293 stack backtrace: CPU: 1 PID: 10226 Comm: syz-fuzzer Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 print_deadlock_bug kernel/locking/lockdep.c:1764 [inline] check_deadlock kernel/locking/lockdep.c:1808 [inline] validate_chain kernel/locking/lockdep.c:2404 [inline] __lock_acquire.cold+0x121/0x57e kernel/locking/lockdep.c:3416 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:152 uart_write+0x1ce/0x6f0 drivers/tty/serial/serial_core.c:591 n_hdlc_send_frames+0x278/0x470 drivers/tty/n_hdlc.c:403 n_hdlc_tty_wakeup+0xa0/0xc0 drivers/tty/n_hdlc.c:479 tty_wakeup+0xd4/0x110 drivers/tty/tty_io.c:534 tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:50 serial8250_tx_chars+0x490/0xaf0 drivers/tty/serial/8250/8250_port.c:1813 serial8250_handle_irq.part.0+0x31f/0x3d0 drivers/tty/serial/8250/8250_port.c:1900 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1873 [inline] serial8250_default_handle_irq+0xae/0x220 drivers/tty/serial/8250/8250_port.c:1916 serial8250_interrupt+0x101/0x240 drivers/tty/serial/8250/8250_core.c:125 __handle_irq_event_percpu+0x27e/0x8e0 kernel/irq/handle.c:149 handle_irq_event_percpu kernel/irq/handle.c:189 [inline] handle_irq_event+0x102/0x290 kernel/irq/handle.c:206 handle_edge_irq+0x260/0xcf0 kernel/irq/chip.c:800 generic_handle_irq_desc include/linux/irqdesc.h:155 [inline] handle_irq+0x35/0x50 arch/x86/kernel/irq_64.c:87 do_IRQ+0x93/0x1c0 arch/x86/kernel/irq.c:246 common_interrupt+0xf/0xf arch/x86/entry/entry_64.S:670 RIP: 0033:0x40ce41 Code: 8b 5c 24 40 48 01 43 08 49 89 c1 48 89 c8 48 89 44 24 38 4c 89 4c 24 30 e8 2c 87 05 00 45 0f 57 ff 64 4c 8b 34 25 f8 ff ff ff <83> 3d b4 e4 b6 01 00 74 1b 48 8b 5c 24 58 48 8b 44 24 28 48 8b 4c RSP: 002b:000000c001dc1610 EFLAGS: 00000206 ORIG_RAX: ffffffffffffffd5 RAX: 0000000000000010 RBX: 00007fa0f8e02108 RCX: 0000000000000010 RDX: 0000000000980200 RSI: 0000000000000010 RDI: 0000000000000044 RBP: 000000c001dc1680 R08: 0000000000000010 R09: 0000000000000008 R10: 00007fa0d15cb8f8 R11: 0000000000000000 R12: 0000000000203003 R13: 0000000000c0bbe8 R14: 000000c000083040 R15: 00007fa0d13f7988