============================================
WARNING: possible recursive locking detected
5.16.0-rc4-syzkaller #0 Not tainted
--------------------------------------------
systemd-udevd/2968 is trying to acquire lock:
ffffffff9078d3f0 (&port_lock_key){-.-.}-{2:2}, at: uart_write+0x12c/0x570 drivers/tty/serial/serial_core.c:577
but task is already holding lock:
ffffffff9078d3f0 (&port_lock_key){-.-.}-{2:2}, at: serial8250_handle_irq.part.0+0x21/0x3d0 drivers/tty/serial/8250/8250_port.c:1908
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&port_lock_key);
lock(&port_lock_key);
*** DEADLOCK ***
May be due to missing lock nesting notation
4 locks held by systemd-udevd/2968:
#0: ffffffff8bd5abd0 (kernfs_rwsem){++++}-{3:3}, at: kernfs_dop_revalidate+0x93/0x520 fs/kernfs/dir.c:1069
#1: ffff8880222c42b0 (&i->lock){-.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline]
#1: ffff8880222c42b0 (&i->lock){-.-.}-{2:2}, at: serial8250_interrupt+0x3a/0x200 drivers/tty/serial/8250/8250_core.c:116
#2: ffffffff9078d3f0 (&port_lock_key){-.-.}-{2:2}, at: serial8250_handle_irq.part.0+0x21/0x3d0 drivers/tty/serial/8250/8250_port.c:1908
#3: ffff88806809f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x1d/0x80 drivers/tty/tty_ldisc.c:273
stack backtrace:
CPU: 0 PID: 2968 Comm: systemd-udevd Not tainted 5.16.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_deadlock_bug kernel/locking/lockdep.c:2956 [inline]
check_deadlock kernel/locking/lockdep.c:2999 [inline]
validate_chain kernel/locking/lockdep.c:3788 [inline]
__lock_acquire.cold+0x149/0x3ab kernel/locking/lockdep.c:5027
lock_acquire kernel/locking/lockdep.c:5637 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5602
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
uart_write+0x12c/0x570 drivers/tty/serial/serial_core.c:577
n_hdlc_send_frames+0x24b/0x490 drivers/tty/n_hdlc.c:290
tty_wakeup+0xe1/0x120 drivers/tty/tty_io.c:534
tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:51
serial8250_tx_chars+0x4f3/0xad0 drivers/tty/serial/8250/8250_port.c:1845
serial8250_handle_irq.part.0+0x328/0x3d0 drivers/tty/serial/8250/8250_port.c:1932
serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1905 [inline]
serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1949
serial8250_interrupt+0xfd/0x200 drivers/tty/serial/8250/8250_core.c:126
__handle_irq_event_percpu+0x303/0x8f0 kernel/irq/handle.c:158
handle_irq_event_percpu kernel/irq/handle.c:198 [inline]
handle_irq_event+0x102/0x280 kernel/irq/handle.c:215
handle_edge_irq+0x25f/0xd00 kernel/irq/chip.c:822
generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
handle_irq arch/x86/kernel/irq.c:231 [inline]
__common_interrupt+0x9d/0x210 arch/x86/kernel/irq.c:250
common_interrupt+0xa4/0xc0 arch/x86/kernel/irq.c:240
asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:629
RIP: 0010:strcmp+0x5c/0xb0 lib/string.c:347
Code: 83 e2 07 42 0f b6 04 28 38 d0 7f 04 84 c0 75 50 0f b6 6b ff 4c 8d 66 01 48 89 f0 48 89 f2 48 c1 e8 03 83 e2 07 42 0f b6 04 28 <38> d0 7f 04 84 c0 75 24 41 3a 6c 24 ff 74 ae 19 c0 48 83 c4 08 5b
RSP: 0018:ffffc90001a3f918 EFLAGS: 00000246
RAX: 0000000000000006 RBX: ffff8880700cb211 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8a035240 RDI: ffff8880700cb210
RBP: 0000000000000062 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff81f3b336 R11: 0000000000000000 R12: ffffffff8a035241
R13: dffffc0000000000 R14: ffff888011359d60 R15: ffffc90001a3fbb8
kernfs_dop_revalidate+0x1b2/0x520 fs/kernfs/dir.c:1080
d_revalidate fs/namei.c:854 [inline]
d_revalidate fs/namei.c:851 [inline]
lookup_fast+0x385/0x6d0 fs/namei.c:1618
walk_component+0xcf/0x6a0 fs/namei.c:1966
lookup_last fs/namei.c:2425 [inline]
path_lookupat+0x1bb/0x860 fs/namei.c:2449
filename_lookup+0x1c6/0x590 fs/namei.c:2478
user_path_at_empty+0x42/0x60 fs/namei.c:2801
user_path_at include/linux/namei.h:57 [inline]
vfs_statx+0x142/0x390 fs/stat.c:221
vfs_fstatat fs/stat.c:243 [inline]
vfs_lstat include/linux/fs.h:3357 [inline]
__do_sys_newlstat+0x91/0x110 fs/stat.c:398
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7efe1e852335
Code: 69 db 2b 00 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 83 ff 01 48 89 f0 77 30 48 89 c7 48 89 d6 b8 06 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 03 f3 c3 90 48 8b 15 31 db 2b 00 f7 d8 64 89
RSP: 002b:00007ffd04c9d988 EFLAGS: 00000246 ORIG_RAX: 0000000000000006
RAX: ffffffffffffffda RBX: 000055c8a5742660 RCX: 00007efe1e852335
RDX: 00007ffd04c9d9c0 RSI: 00007ffd04c9d9c0 RDI: 000055c8a5741660
RBP: 00007ffd04c9da80 R08: 00007efe1eb11248 R09: 0000000000001010
R10: 0000000000000020 R11: 0000000000000246 R12: 000055c8a5741660
R13: 000055c8a574167a R14: 000055c8a574cd25 R15: 000055c8a574cd2a
----------------
Code disassembly (best guess):
0: 83 e2 07 and $0x7,%edx
3: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax
8: 38 d0 cmp %dl,%al
a: 7f 04 jg 0x10
c: 84 c0 test %al,%al
e: 75 50 jne 0x60
10: 0f b6 6b ff movzbl -0x1(%rbx),%ebp
14: 4c 8d 66 01 lea 0x1(%rsi),%r12
18: 48 89 f0 mov %rsi,%rax
1b: 48 89 f2 mov %rsi,%rdx
1e: 48 c1 e8 03 shr $0x3,%rax
22: 83 e2 07 and $0x7,%edx
25: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax
* 2a: 38 d0 cmp %dl,%al <-- trapping instruction
2c: 7f 04 jg 0x32
2e: 84 c0 test %al,%al
30: 75 24 jne 0x56
32: 41 3a 6c 24 ff cmp -0x1(%r12),%bpl
37: 74 ae je 0xffffffe7
39: 19 c0 sbb %eax,%eax
3b: 48 83 c4 08 add $0x8,%rsp
3f: 5b pop %rbx