======================================================
WARNING: possible circular locking dependency detected
5.9.0-rc2-next-20200828-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.5/10242 is trying to acquire lock:
ffffffff89bcb540 (console_owner){-.-.}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1788 [inline]
ffffffff89bcb540 (console_owner){-.-.}-{0:0}, at: vprintk_emit+0x3d4/0x740 kernel/printk/printk.c:2068
but task is already holding lock:
ffffffff8d579f58 (&port->lock#2){-.-.}-{2:2}, at: tty_port_close_start.part.0+0x28/0x550 drivers/tty/tty_port.c:567
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&port->lock#2){-.-.}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:159
tty_port_tty_get+0x1f/0x100 drivers/tty/tty_port.c:288
tty_port_default_wakeup+0x11/0x40 drivers/tty/tty_port.c:47
serial8250_tx_chars+0x487/0xa80 drivers/tty/serial/8250/8250_port.c:1832
serial8250_handle_irq.part.0+0x328/0x3d0 drivers/tty/serial/8250/8250_port.c:1919
serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1892 [inline]
serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1935
serial8250_interrupt+0xe6/0x190 drivers/tty/serial/8250/8250_core.c:126
__handle_irq_event_percpu+0x223/0xa30 kernel/irq/handle.c:156
handle_irq_event_percpu kernel/irq/handle.c:196 [inline]
handle_irq_event+0x102/0x285 kernel/irq/handle.c:213
handle_edge_irq+0x25f/0xd00 kernel/irq/chip.c:819
asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
__run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
handle_irq arch/x86/kernel/irq.c:230 [inline]
__common_interrupt arch/x86/kernel/irq.c:249 [inline]
common_interrupt+0x115/0x1f0 arch/x86/kernel/irq.c:239
asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:572
arch_local_irq_restore arch/x86/include/asm/paravirt.h:653 [inline]
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
_raw_spin_unlock_irqrestore+0x8c/0xe0 kernel/locking/spinlock.c:191
spin_unlock_irqrestore include/linux/spinlock.h:409 [inline]
uart_write+0x30d/0x56a drivers/tty/serial/serial_core.c:615
do_output_char+0x5de/0x850 drivers/tty/n_tty.c:447
process_output drivers/tty/n_tty.c:514 [inline]
n_tty_write+0x481/0xf80 drivers/tty/n_tty.c:2345
do_tty_write drivers/tty/tty_io.c:962 [inline]
tty_write+0x4d9/0x870 drivers/tty/tty_io.c:1046
redirected_tty_write+0xaa/0xb0 drivers/tty/tty_io.c:1067
do_loop_readv_writev fs/read_write.c:737 [inline]
do_loop_readv_writev fs/read_write.c:721 [inline]
do_iter_write+0x489/0x670 fs/read_write.c:1020
vfs_writev+0x1aa/0x2e0 fs/read_write.c:1091
do_writev+0x139/0x300 fs/read_write.c:1134
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #1 (&port->lock){-.-.}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:159
serial8250_console_write+0x211/0xb70 drivers/tty/serial/8250/8250_port.c:3289
call_console_drivers kernel/printk/printk.c:1866 [inline]
console_unlock+0xb21/0xe90 kernel/printk/printk.c:2542
vprintk_emit+0x2c0/0x740 kernel/printk/printk.c:2069
vprintk_func+0x8f/0x1a6 kernel/printk/printk_safe.c:393
printk+0xba/0xed kernel/printk/printk.c:2117
register_console kernel/printk/printk.c:2893 [inline]
register_console+0x55f/0x7e0 kernel/printk/printk.c:2773
univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:690
console_init+0x421/0x619 kernel/printk/printk.c:2993
start_kernel+0x2d5/0x46a init/main.c:975
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243
-> #0 (console_owner){-.-.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:2496 [inline]
check_prevs_add kernel/locking/lockdep.c:2601 [inline]
validate_chain kernel/locking/lockdep.c:3218 [inline]
__lock_acquire+0x2a6b/0x5640 kernel/locking/lockdep.c:4426
lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:5005
console_trylock_spinning kernel/printk/printk.c:1809 [inline]
vprintk_emit+0x411/0x740 kernel/printk/printk.c:2068
vprintk_func+0x8f/0x1a6 kernel/printk/printk_safe.c:393
printk+0xba/0xed kernel/printk/printk.c:2117
tty_port_close_start.part.0+0x503/0x550 drivers/tty/tty_port.c:569
tty_port_close_start drivers/tty/tty_port.c:641 [inline]
tty_port_close+0x46/0x170 drivers/tty/tty_port.c:634
tty_release+0x455/0xf60 drivers/tty/tty_io.c:1679
__fput+0x285/0x920 fs/file_table.c:281
task_work_run+0xdd/0x190 kernel/task_work.c:141
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop kernel/entry/common.c:140 [inline]
exit_to_user_mode_prepare+0x195/0x1c0 kernel/entry/common.c:167
syscall_exit_to_user_mode+0x59/0x2b0 kernel/entry/common.c:242
entry_SYSCALL_64_after_hwframe+0x44/0xa9
other info that might help us debug this:
Chain exists of:
console_owner --> &port->lock --> &port->lock#2
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&port->lock#2);
lock(&port->lock);
lock(&port->lock#2);
lock(console_owner);
*** DEADLOCK ***
2 locks held by syz-executor.5/10242:
#0: ffff8880a78ac1c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_lock+0xbd/0x120 drivers/tty/tty_mutex.c:19
#1: ffffffff8d579f58 (&port->lock#2){-.-.}-{2:2}, at: tty_port_close_start.part.0+0x28/0x550 drivers/tty/tty_port.c:567
stack backtrace:
CPU: 1 PID: 10242 Comm: syz-executor.5 Not tainted 5.9.0-rc2-next-20200828-syzkaller #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+0x18f/0x20d lib/dump_stack.c:118
check_noncircular+0x324/0x3e0 kernel/locking/lockdep.c:1827
check_prev_add kernel/locking/lockdep.c:2496 [inline]
check_prevs_add kernel/locking/lockdep.c:2601 [inline]
validate_chain kernel/locking/lockdep.c:3218 [inline]
__lock_acquire+0x2a6b/0x5640 kernel/locking/lockdep.c:4426
lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:5005
console_trylock_spinning kernel/printk/printk.c:1809 [inline]
vprintk_emit+0x411/0x740 kernel/printk/printk.c:2068
vprintk_func+0x8f/0x1a6 kernel/printk/printk_safe.c:393
printk+0xba/0xed kernel/printk/printk.c:2117
tty_port_close_start.part.0+0x503/0x550 drivers/tty/tty_port.c:569
tty_port_close_start drivers/tty/tty_port.c:641 [inline]
tty_port_close+0x46/0x170 drivers/tty/tty_port.c:634
tty_release+0x455/0xf60 drivers/tty/tty_io.c:1679
__fput+0x285/0x920 fs/file_table.c:281
task_work_run+0xdd/0x190 kernel/task_work.c:141
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop kernel/entry/common.c:140 [inline]
exit_to_user_mode_prepare+0x195/0x1c0 kernel/entry/common.c:167
syscall_exit_to_user_mode+0x59/0x2b0 kernel/entry/common.c:242
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x416f01
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffd2abc4330 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000416f01
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000001190120 R09: 0000000000000000
R10: 00007ffd2abc4410 R11: 0000000000000293 R12: 0000000001190128
R13: 0000000000000000 R14: ffffffffffffffff R15: 000000000118cf4c