syzbot

======================================================
WARNING: possible circular locking dependency detected
5.12.0-rc8-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor079/10407 is trying to acquire lock:
ffffffff8be830a0 (console_owner){....}-{0:0}, at: console_unlock+0x2f2/0xc80 kernel/printk/printk.c:2551

but task is already holding lock:
ffffffff900fed38 (&port->lock){-.-.}-{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}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x39/0x50 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+0xfd/0x200 drivers/tty/serial/8250/8250_core.c:126
       __handle_irq_event_percpu+0x303/0x8f0 kernel/irq/handle.c:156
       handle_irq_event_percpu kernel/irq/handle.c:196 [inline]
       handle_irq_event+0x102/0x290 kernel/irq/handle.c:213
       handle_edge_irq+0x25f/0xd00 kernel/irq/chip.c:819
       generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
       handle_irq arch/x86/kernel/irq.c:231 [inline]
       __common_interrupt+0x9e/0x200 arch/x86/kernel/irq.c:250
       common_interrupt+0x9f/0xd0 arch/x86/kernel/irq.c:240
       asm_common_interrupt+0x1e/0x40 arch/x86/include/asm/idtentry.h:623
       native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
       arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
       acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
       acpi_idle_do_entry+0x1c9/0x250 drivers/acpi/processor_idle.c:517
       acpi_idle_enter+0x361/0x500 drivers/acpi/processor_idle.c:652
       cpuidle_enter_state+0x1b1/0xc80 drivers/cpuidle/cpuidle.c:237
       cpuidle_enter+0x4a/0xa0 drivers/cpuidle/cpuidle.c:351
       call_cpuidle kernel/sched/idle.c:158 [inline]
       cpuidle_idle_call kernel/sched/idle.c:239 [inline]
       do_idle+0x3e1/0x590 kernel/sched/idle.c:300
       cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:397
       start_kernel+0x475/0x496 init/main.c:1064
       secondary_startup_64_no_verify+0xb0/0xbb

-> #1 (&port_lock_key){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
       serial8250_console_write+0x8b2/0xae0 drivers/tty/serial/8250/8250_port.c:3292
       call_console_drivers kernel/printk/printk.c:1862 [inline]
       console_unlock+0x895/0xc80 kernel/printk/printk.c:2576
       vprintk_emit+0x1ca/0x560 kernel/printk/printk.c:2098
       vprintk_func+0x8d/0x1e0 kernel/printk/printk_safe.c:401
       printk+0xba/0xed kernel/printk/printk.c:2146
       register_console kernel/printk/printk.c:2927 [inline]
       register_console+0x606/0x840 kernel/printk/printk.c:2807
       univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:690
       console_init+0x3c7/0x596 kernel/printk/printk.c:3027
       start_kernel+0x306/0x496 init/main.c:993
       secondary_startup_64_no_verify+0xb0/0xbb

-> #0 (console_owner){....}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:2937 [inline]
       check_prevs_add kernel/locking/lockdep.c:3060 [inline]
       validate_chain kernel/locking/lockdep.c:3675 [inline]
       __lock_acquire+0x2b14/0x54c0 kernel/locking/lockdep.c:4901
       lock_acquire kernel/locking/lockdep.c:5511 [inline]
       lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5476
       console_lock_spinning_enable kernel/printk/printk.c:1714 [inline]
       console_unlock+0x371/0xc80 kernel/printk/printk.c:2573
       vprintk_emit+0x1ca/0x560 kernel/printk/printk.c:2098
       vprintk_func+0x8d/0x1e0 kernel/printk/printk_safe.c:401
       printk+0xba/0xed kernel/printk/printk.c:2146
       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+0x45e/0x1210 drivers/tty/tty_io.c:1779
       __fput+0x288/0x920 fs/file_table.c:280
       task_work_run+0xdd/0x1a0 kernel/task_work.c:140
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
       exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208
       __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
       syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
       entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:

Chain exists of:
  console_owner --> &port_lock_key --> &port->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&port->lock);
                               lock(&port_lock_key);
                               lock(&port->lock);
  lock(console_owner);

 *** DEADLOCK ***

3 locks held by syz-executor079/10407:
 #0: ffff8880232bd1c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_lock+0xbd/0x120 drivers/tty/tty_mutex.c:19
 #1: ffffffff900fed38 (&port->lock){-.-.}-{2:2}, at: tty_port_close_start.part.0+0x28/0x550 drivers/tty/tty_port.c:567
 #2: ffffffff8bf63420 (console_lock){+.+.}-{0:0}, at: vprintk_func+0x8d/0x1e0 kernel/printk/printk_safe.c:401

stack backtrace:
CPU: 1 PID: 10407 Comm: syz-executor079 Not tainted 5.12.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2128
 check_prev_add kernel/locking/lockdep.c:2937 [inline]
 check_prevs_add kernel/locking/lockdep.c:3060 [inline]
 validate_chain kernel/locking/lockdep.c:3675 [inline]
 __lock_acquire+0x2b14/0x54c0 kernel/locking/lockdep.c:4901
 lock_acquire kernel/locking/lockdep.c:5511 [inline]
 lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5476
 console_lock_spinning_enable kernel/printk/printk.c:1714 [inline]
 console_unlock+0x371/0xc80 kernel/printk/printk.c:2573
 vprintk_emit+0x1ca/0x560 kernel/printk/printk.c:2098
 vprintk_func+0x8d/0x1e0 kernel/printk/printk_safe.c:401
 printk+0xba/0xed kernel/printk/printk.c:2146
 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+0x45e/0x1210 drivers/tty/tty_io.c:1779
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x409aeb
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 03 fd ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 41 fd ff ff 8b 44
RSP: 002b:00007ffcb5f819b0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000409aeb
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000032 R08: 0000000000000000 R09: 000000000049e190
R10: 0000000000000000 R11: 0000000000000293 R12: 00000000004cf4dc
R13: 00007ffcb5f81a00 R14: 00007ffcb5f81a20 R15: 00007ffcb5f81a90