FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 ====================================================== WARNING: possible circular locking dependency detected 5.15.176-syzkaller #0 Not tainted ------------------------------------------------------ syz.4.809/7904 is trying to acquire lock: ffffffff8cb14860 (console_owner){-.-.}-{0:0}, at: console_lock_spinning_enable+0x2c/0x60 kernel/printk/printk.c:1802 but task is already holding lock: ffff888075ef3158 (&port->lock){-...}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x3a/0x390 drivers/tty/tty_buffer.c:585 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&port->lock){-...}-{2:2}: lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162 tty_port_tty_get drivers/tty/tty_port.c:289 [inline] tty_port_default_wakeup+0x21/0x100 drivers/tty/tty_port.c:48 serial8250_tx_chars+0x60d/0x800 drivers/tty/serial/8250/8250_port.c:1828 serial8250_handle_irq+0x505/0x600 drivers/tty/serial/8250/8250_port.c:1924 serial8250_default_handle_irq+0xc8/0x1e0 drivers/tty/serial/8250/8250_port.c:1941 serial8250_interrupt+0xa1/0x1e0 drivers/tty/serial/8250/8250_core.c:127 __handle_irq_event_percpu+0x292/0xa70 kernel/irq/handle.c:156 handle_irq_event_percpu kernel/irq/handle.c:196 [inline] handle_irq_event+0xff/0x2b0 kernel/irq/handle.c:213 handle_edge_irq+0x245/0xbf0 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+0xd7/0x1f0 arch/x86/kernel/irq.c:250 common_interrupt+0xae/0xd0 arch/x86/kernel/irq.c:240 asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:667 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] _raw_spin_unlock_irqrestore+0xd4/0x130 kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:418 [inline] uart_write+0x6af/0x930 drivers/tty/serial/serial_core.c:592 process_output_block drivers/tty/n_tty.c:592 [inline] n_tty_write+0xd7e/0x1280 drivers/tty/n_tty.c:2339 do_tty_write drivers/tty/tty_io.c:1038 [inline] file_tty_write+0x561/0x920 drivers/tty/tty_io.c:1110 call_write_iter include/linux/fs.h:2174 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0xacd/0xe50 fs/read_write.c:594 ksys_write+0x1a2/0x2c0 fs/read_write.c:647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #1 (&port_lock_key){-.-.}-{2:2}: lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162 serial8250_console_write+0x19d/0x1180 drivers/tty/serial/8250/8250_port.c:3354 console_unlock+0xced/0x12b0 kernel/printk/printk.c:2744 vprintk_emit+0xbf/0x150 kernel/printk/printk.c:2274 _printk+0xd1/0x120 kernel/printk/printk.c:2299 register_console+0x65a/0x940 kernel/printk/printk.c:3107 univ8250_console_init+0x41/0x50 drivers/tty/serial/8250/8250_core.c:690 console_init+0x18c/0x660 kernel/printk/printk.c:3207 start_kernel+0x301/0x540 init/main.c:1076 secondary_startup_64_no_verify+0xb1/0xbb -> #0 (console_owner){-.-.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623 console_lock_spinning_enable+0x51/0x60 kernel/printk/printk.c:1805 console_unlock+0xa47/0x12b0 kernel/printk/printk.c:2741 vprintk_emit+0xbf/0x150 kernel/printk/printk.c:2274 _printk+0xd1/0x120 kernel/printk/printk.c:2299 fail_dump lib/fault-inject.c:45 [inline] should_fail+0x36c/0x4c0 lib/fault-inject.c:146 should_failslab+0x5/0x20 mm/slab_common.c:1344 slab_pre_alloc_hook+0x53/0xc0 mm/slab.h:494 slab_alloc_node mm/slub.c:3134 [inline] slab_alloc mm/slub.c:3228 [inline] __kmalloc+0x6e/0x300 mm/slub.c:4403 kmalloc include/linux/slab.h:596 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:177 [inline] __tty_buffer_request_room+0x1ef/0x500 drivers/tty/tty_buffer.c:276 tty_insert_flip_string_fixed_flag drivers/tty/tty_buffer.c:322 [inline] tty_insert_flip_string include/linux/tty_flip.h:41 [inline] tty_insert_flip_string_and_push_buffer+0x7c/0x390 drivers/tty/tty_buffer.c:586 n_tty_write+0x63c/0x1280 drivers/tty/n_tty.c:2362 do_tty_write drivers/tty/tty_io.c:1038 [inline] file_tty_write+0x561/0x920 drivers/tty/tty_io.c:1110 call_write_iter include/linux/fs.h:2174 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0xacd/0xe50 fs/read_write.c:594 ksys_write+0x1a2/0x2c0 fs/read_write.c:647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 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 *** 6 locks held by syz.4.809/7904: #0: ffff88806226b098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252 #1: ffff88806226b130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_write_lock drivers/tty/tty_io.c:961 [inline] #1: ffff88806226b130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: do_tty_write drivers/tty/tty_io.c:984 [inline] #1: ffff88806226b130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: file_tty_write+0x24f/0x920 drivers/tty/tty_io.c:1110 #2: ffff88806226b2e8 (&tty->termios_rwsem){++++}-{3:3}, at: n_tty_write+0x252/0x1280 drivers/tty/n_tty.c:2322 #3: ffffc9000115e378 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_write+0x5ee/0x1280 drivers/tty/n_tty.c:2361 #4: ffff888075ef3158 (&port->lock){-...}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x3a/0x390 drivers/tty/tty_buffer.c:585 #5: ffffffff8c9fc5a0 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0xa6/0x150 kernel/printk/printk.c:2273 stack backtrace: CPU: 1 PID: 7904 Comm: syz.4.809 Not tainted 5.15.176-syzkaller #0 Hardware name: Google