====================================================== WARNING: possible circular locking dependency detected 5.5.0-rc5-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/776 is trying to acquire lock: ffffffff899992a0 (console_owner){-.-.}, at: console_trylock_spinning kernel/printk/printk.c:1724 [inline] ffffffff899992a0 (console_owner){-.-.}, at: vprintk_emit+0x3fd/0x700 kernel/printk/printk.c:1995 but task is already holding lock: ffff888024f74940 (&(&port->lock)->rlock){-.-.}, at: pty_write+0xff/0x200 drivers/tty/pty.c:120 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&(&port->lock)->rlock){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 tty_port_tty_get+0x24/0x100 drivers/tty/tty_port.c:287 tty_port_default_wakeup+0x16/0x40 drivers/tty/tty_port.c:47 tty_port_tty_wakeup+0x57/0x70 drivers/tty/tty_port.c:387 uart_write_wakeup+0x46/0x70 drivers/tty/serial/serial_core.c:104 serial8250_tx_chars+0x495/0xaf0 drivers/tty/serial/8250/8250_port.c:1761 serial8250_handle_irq.part.0+0x261/0x2b0 drivers/tty/serial/8250/8250_port.c:1834 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1820 [inline] serial8250_default_handle_irq+0xc0/0x150 drivers/tty/serial/8250/8250_port.c:1850 serial8250_interrupt+0xf1/0x1a0 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x15d/0x970 kernel/irq/handle.c:149 handle_irq_event_percpu+0x74/0x160 kernel/irq/handle.c:189 handle_irq_event+0xa7/0x134 kernel/irq/handle.c:206 handle_edge_irq+0x25e/0x8d0 kernel/irq/chip.c:830 generic_handle_irq_desc include/linux/irqdesc.h:156 [inline] do_IRQ+0xde/0x280 arch/x86/kernel/irq.c:250 ret_from_intr+0x0/0x36 native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:690 default_idle_call+0x84/0xb0 kernel/sched/idle.c:94 cpuidle_idle_call kernel/sched/idle.c:154 [inline] do_idle+0x3c8/0x6e0 kernel/sched/idle.c:269 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:361 start_secondary+0x2f4/0x410 arch/x86/kernel/smpboot.c:264 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242 -> #1 (&port_lock_key){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x95/0xcd kernel/locking/spinlock.c:159 serial8250_console_write+0x253/0x9a0 drivers/tty/serial/8250/8250_port.c:3142 univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:587 call_console_drivers kernel/printk/printk.c:1791 [inline] console_unlock+0xb7a/0xf00 kernel/printk/printk.c:2473 vprintk_emit+0x2a0/0x700 kernel/printk/printk.c:1996 vprintk_default+0x28/0x30 kernel/printk/printk.c:2023 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:386 printk+0xba/0xed kernel/printk/printk.c:2056 register_console+0x745/0xb50 kernel/printk/printk.c:2798 univ8250_console_init+0x3e/0x4b drivers/tty/serial/8250/8250_core.c:682 console_init+0x461/0x67b kernel/printk/printk.c:2884 start_kernel+0x653/0x943 init/main.c:712 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:490 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:471 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242 -> #0 (console_owner){-.-.}: check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain kernel/locking/lockdep.c:2971 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485 console_trylock_spinning kernel/printk/printk.c:1745 [inline] vprintk_emit+0x43a/0x700 kernel/printk/printk.c:1995 vprintk_default+0x28/0x30 kernel/printk/printk.c:2023 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:386 printk+0xba/0xed kernel/printk/printk.c:2056 fail_dump lib/fault-inject.c:45 [inline] should_fail+0x708/0x852 lib/fault-inject.c:144 __should_failslab+0x121/0x190 mm/failslab.c:33 should_failslab+0x9/0x14 mm/slab_common.c:1810 slab_pre_alloc_hook mm/slab.h:567 [inline] slab_alloc mm/slab.c:3306 [inline] __do_kmalloc mm/slab.c:3654 [inline] __kmalloc+0x71/0x770 mm/slab.c:3665 kmalloc include/linux/slab.h:561 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:175 [inline] __tty_buffer_request_room+0x1fb/0x5c0 drivers/tty/tty_buffer.c:273 tty_insert_flip_string_fixed_flag+0x93/0x1f0 drivers/tty/tty_buffer.c:318 tty_insert_flip_string include/linux/tty_flip.h:37 [inline] pty_write+0x133/0x200 drivers/tty/pty.c:122 do_output_char+0x5f7/0x880 drivers/tty/n_tty.c:447 process_output drivers/tty/n_tty.c:514 [inline] n_tty_write+0x4d2/0x1080 drivers/tty/n_tty.c:2345 do_tty_write drivers/tty/tty_io.c:962 [inline] tty_write+0x496/0x7f0 drivers/tty/tty_io.c:1046 __vfs_write+0x8a/0x110 fs/read_write.c:494 vfs_write+0x268/0x5d0 fs/read_write.c:558 ksys_write+0x14f/0x290 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __ia32_sys_write+0x71/0xb0 fs/read_write.c:620 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline] do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 other info that might help us debug this: Chain exists of: console_owner --> &port_lock_key --> &(&port->lock)->rlock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&port->lock)->rlock); lock(&port_lock_key); lock(&(&port->lock)->rlock); lock(console_owner); *** DEADLOCK *** 5 locks held by syz-executor.1/776: #0: ffff88802ad13090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffff88802ad13118 (&tty->atomic_write_lock){+.+.}, at: tty_write_lock+0x23/0x90 drivers/tty/tty_io.c:888 #2: ffff88802ad132a0 (&o_tty->termios_rwsem/1){++++}, at: n_tty_write+0x1b5/0x1080 drivers/tty/n_tty.c:2316 #3: ffffc9000756c360 (&ldata->output_lock){+.+.}, at: process_output drivers/tty/n_tty.c:511 [inline] #3: ffffc9000756c360 (&ldata->output_lock){+.+.}, at: n_tty_write+0x4bd/0x1080 drivers/tty/n_tty.c:2345 #4: ffff888024f74940 (&(&port->lock)->rlock){-.-.}, at: pty_write+0xff/0x200 drivers/tty/pty.c:120 stack backtrace: CPU: 1 PID: 776 Comm: syz-executor.1 Not tainted 5.5.0-rc5-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 print_circular_bug.isra.0.cold+0x163/0x172 kernel/locking/lockdep.c:1685 check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1809 check_prev_add kernel/locking/lockdep.c:2476 [inline] check_prevs_add kernel/locking/lockdep.c:2581 [inline] validate_chain kernel/locking/lockdep.c:2971 [inline] __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485 console_trylock_spinning kernel/printk/printk.c:1745 [inline] vprintk_emit+0x43a/0x700 kernel/printk/printk.c:1995 vprintk_default+0x28/0x30 kernel/printk/printk.c:2023 vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:386 printk+0xba/0xed kernel/printk/printk.c:2056 fail_dump lib/fault-inject.c:45 [inline] should_fail+0x708/0x852 lib/fault-inject.c:144 __should_failslab+0x121/0x190 mm/failslab.c:33 should_failslab+0x9/0x14 mm/slab_common.c:1810 slab_pre_alloc_hook mm/slab.h:567 [inline] slab_alloc mm/slab.c:3306 [inline] __do_kmalloc mm/slab.c:3654 [inline] __kmalloc+0x71/0x770 mm/slab.c:3665 kmalloc include/linux/slab.h:561 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:175 [inline] __tty_buffer_request_room+0x1fb/0x5c0 drivers/tty/tty_buffer.c:273 tty_insert_flip_string_fixed_flag+0x93/0x1f0 drivers/tty/tty_buffer.c:318 tty_insert_flip_string include/linux/tty_flip.h:37 [inline] pty_write+0x133/0x200 drivers/tty/pty.c:122 do_output_char+0x5f7/0x880 drivers/tty/n_tty.c:447 process_output drivers/tty/n_tty.c:514 [inline] n_tty_write+0x4d2/0x1080 drivers/tty/n_tty.c:2345 do_tty_write drivers/tty/tty_io.c:962 [inline] tty_write+0x496/0x7f0 drivers/tty/tty_io.c:1046 __vfs_write+0x8a/0x110 fs/read_write.c:494 vfs_write+0x268/0x5d0 fs/read_write.c:558 ksys_write+0x14f/0x290 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __ia32_sys_write+0x71/0xb0 fs/read_write.c:620 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline] do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7fd5a39 Code: 00 00 00 89 d3 5b 5e 5f 5d c3 b8 80 96 98 00 eb c4 8b 04 24 c3 8b 1c 24 c3 8b 34 24 c3 8b 3c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 002b:00000000f5dd10cc EFLAGS: 00000296 ORIG_RAX: 0000000000000004 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000020000000 RDX: 0000000000000304 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000