RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ====================================================== WARNING: possible circular locking dependency detected 4.17.0+ #111 Not tainted ------------------------------------------------------ syz-executor0/4774 is trying to acquire lock: (ptrval) (console_owner){-...}, at: log_next kernel/printk/printk.c:496 [inline] (ptrval) (console_owner){-...}, at: console_unlock+0x583/0x1100 kernel/printk/printk.c:2382 but task is already holding lock: (ptrval) (&(&port->lock)->rlock){-.-.}, at: pty_write+0xf9/0x1f0 drivers/tty/pty.c:119 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+0x96/0xc0 kernel/locking/spinlock.c:152 tty_port_tty_get+0x20/0x80 drivers/tty/tty_port.c:288 tty_port_default_wakeup+0x15/0x40 drivers/tty/tty_port.c:47 tty_port_tty_wakeup+0x5d/0x70 drivers/tty/tty_port.c:390 uart_write_wakeup+0x44/0x60 drivers/tty/serial/serial_core.c:103 serial8250_tx_chars+0x4be/0xb60 drivers/tty/serial/8250/8250_port.c:1808 serial8250_handle_irq.part.25+0x1ee/0x280 drivers/tty/serial/8250/8250_port.c:1881 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1867 [inline] serial8250_default_handle_irq+0xc8/0x150 drivers/tty/serial/8250/8250_port.c:1897 serial8250_interrupt+0xfa/0x1d0 drivers/tty/serial/8250/8250_core.c:125 __handle_irq_event_percpu+0x1c0/0xad0 kernel/irq/handle.c:149 handle_irq_event_percpu+0x98/0x1c0 kernel/irq/handle.c:189 handle_irq_event+0xa7/0x135 kernel/irq/handle.c:206 handle_edge_irq+0x20f/0x870 kernel/irq/chip.c:791 generic_handle_irq_desc include/linux/irqdesc.h:159 [inline] handle_irq+0x18c/0x2e7 arch/x86/kernel/irq_64.c:77 do_IRQ+0x78/0x190 arch/x86/kernel/irq.c:245 ret_from_intr+0x0/0x1e native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline] default_idle+0xc2/0x440 arch/x86/kernel/process.c:500 arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:491 default_idle_call+0x6d/0x90 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x395/0x560 kernel/sched/idle.c:262 cpu_startup_entry+0x104/0x120 kernel/sched/idle.c:368 start_secondary+0x42b/0x5c0 arch/x86/kernel/smpboot.c:265 secondary_startup_64+0xa5/0xb0 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+0x96/0xc0 kernel/locking/spinlock.c:152 serial8250_console_write+0x8d5/0xb00 drivers/tty/serial/8250/8250_port.c:3230 univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:590 call_console_drivers kernel/printk/printk.c:1718 [inline] console_unlock+0xac2/0x1100 kernel/printk/printk.c:2395 vprintk_emit+0x6ad/0xdd0 kernel/printk/printk.c:1907 vprintk_default+0x28/0x30 kernel/printk/printk.c:1947 vprintk_func+0x7a/0xe7 kernel/printk/printk_safe.c:379 printk+0x9e/0xba kernel/printk/printk.c:1980 register_console+0x7e7/0xc00 kernel/printk/printk.c:2714 univ8250_console_init+0x3f/0x4b drivers/tty/serial/8250/8250_core.c:685 console_init+0x6d9/0xa38 kernel/printk/printk.c:2798 start_kernel+0x608/0x92d init/main.c:661 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452 x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242 -> #0 (console_owner){-...}: lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3924 console_lock_spinning_enable kernel/printk/printk.c:1581 [inline] console_unlock+0x5ef/0x1100 kernel/printk/printk.c:2392 vprintk_emit+0x6ad/0xdd0 kernel/printk/printk.c:1907 vprintk_default+0x28/0x30 kernel/printk/printk.c:1947 vprintk_func+0x7a/0xe7 kernel/printk/printk_safe.c:379 printk+0x9e/0xba kernel/printk/printk.c:1980 fail_dump lib/fault-inject.c:44 [inline] should_fail+0x97a/0xbcd lib/fault-inject.c:149 __should_failslab+0x124/0x180 mm/failslab.c:32 should_failslab+0x9/0x14 mm/slab_common.c:1522 slab_pre_alloc_hook mm/slab.h:423 [inline] slab_alloc mm/slab.c:3378 [inline] __do_kmalloc mm/slab.c:3716 [inline] __kmalloc+0x63/0x760 mm/slab.c:3727 kmalloc include/linux/slab.h:517 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:170 [inline] __tty_buffer_request_room+0x2d2/0x7f0 drivers/tty/tty_buffer.c:268 tty_insert_flip_string_fixed_flag+0x8d/0x1f0 drivers/tty/tty_buffer.c:313 tty_insert_flip_string include/linux/tty_flip.h:37 [inline] pty_write+0x12c/0x1f0 drivers/tty/pty.c:121 tty_put_char+0x129/0x150 drivers/tty/tty_io.c:2865 __process_echoes+0x4d9/0x8d0 drivers/tty/n_tty.c:703 process_echoes+0xfc/0x170 drivers/tty/n_tty.c:781 n_tty_set_termios+0xb56/0xe80 drivers/tty/n_tty.c:1837 tty_set_termios+0x7a0/0xac0 drivers/tty/tty_ioctl.c:341 set_termios+0x41e/0x7d0 drivers/tty/tty_ioctl.c:414 tty_mode_ioctl+0x871/0xb50 drivers/tty/tty_ioctl.c:781 n_tty_ioctl_helper+0x54/0x3b0 drivers/tty/tty_ioctl.c:940 n_tty_ioctl+0x54/0x320 drivers/tty/n_tty.c:2441 tty_ioctl+0x5e1/0x1870 drivers/tty/tty_io.c:2655 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x1cf/0x16f0 fs/ioctl.c:684 __do_compat_sys_ioctl fs/compat_ioctl.c:1483 [inline] __se_compat_sys_ioctl fs/compat_ioctl.c:1407 [inline] __ia32_compat_sys_ioctl+0x43e/0x640 fs/compat_ioctl.c:1407 do_syscall_32_irqs_on arch/x86/entry/common.c:323 [inline] do_fast_syscall_32+0x345/0xf9b arch/x86/entry/common.c:394 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 *** 6 locks held by syz-executor0/4774: #0: (ptrval) (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: (ptrval) (&o_tty->termios_rwsem/1){++++}, at: tty_set_termios+0xfd/0xac0 drivers/tty/tty_ioctl.c:328 #2: (ptrval) (&tty->ldisc_sem){++++}, at: tty_ldisc_ref+0x22/0x90 drivers/tty/tty_ldisc.c:284 #3: (ptrval) (&ldata->output_lock){+.+.}, at: process_echoes+0xb6/0x170 drivers/tty/n_tty.c:779 #4: (ptrval) (&(&port->lock)->rlock){-.-.}, at: pty_write+0xf9/0x1f0 drivers/tty/pty.c:119 #5: (ptrval) (console_lock){+.+.}, at: console_trylock_spinning kernel/printk/printk.c:1643 [inline] #5: (ptrval) (console_lock){+.+.}, at: vprintk_emit+0x694/0xdd0 kernel/printk/printk.c:1906 stack backtrace: CPU: 1 PID: 4774 Comm: syz-executor0 Not tainted 4.17.0+ #111 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+0x1b9/0x294 lib/dump_stack.c:113 print_circular_bug.isra.36.cold.56+0x1bd/0x27d kernel/locking/lockdep.c:1227 check_prev_add kernel/locking/lockdep.c:1867 [inline] check_prevs_add kernel/locking/lockdep.c:1980 [inline] validate_chain kernel/locking/lockdep.c:2421 [inline] __lock_acquire+0x343e/0x5140 kernel/locking/lockdep.c:3435 lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3924 console_lock_spinning_enable kernel/printk/printk.c:1581 [inline] console_unlock+0x5ef/0x1100 kernel/printk/printk.c:2392 vprintk_emit+0x6ad/0xdd0 kernel/printk/printk.c:1907 vprintk_default+0x28/0x30 kernel/printk/printk.c:1947 vprintk_func+0x7a/0xe7 kernel/printk/printk_safe.c:379 printk+0x9e/0xba kernel/printk/printk.c:1980 fail_dump lib/fault-inject.c:44 [inline] should_fail+0x97a/0xbcd lib/fault-inject.c:149 __should_failslab+0x124/0x180 mm/failslab.c:32 should_failslab+0x9/0x14 mm/slab_common.c:1522 slab_pre_alloc_hook mm/slab.h:423 [inline] slab_alloc mm/slab.c:3378 [inline] __do_kmalloc mm/slab.c:3716 [inline] __kmalloc+0x63/0x760 mm/slab.c:3727 kmalloc include/linux/slab.h:517 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:170 [inline] __tty_buffer_request_room+0x2d2/0x7f0 drivers/tty/tty_buffer.c:268 tty_insert_flip_string_fixed_flag+0x8d/0x1f0 drivers/tty/tty_buffer.c:313 tty_insert_flip_string include/linux/tty_flip.h:37 [inline] pty_write+0x12c/0x1f0 drivers/tty/pty.c:121 tty_put_char+0x129/0x150 drivers/tty/tty_io.c:2865 __process_echoes+0x4d9/0x8d0 drivers/tty/n_tty.c:703 process_echoes+0xfc/0x170 drivers/tty/n_tty.c:781 n_tty_set_termios+0xb56/0xe80 drivers/tty/n_tty.c:1837 tty_set_termios+0x7a0/0xac0 drivers/tty/tty_ioctl.c:341 set_termios+0x41e/0x7d0 drivers/tty/tty_ioctl.c:414 tty_mode_ioctl+0x871/0xb50 drivers/tty/tty_ioctl.c:781 n_tty_ioctl_helper+0x54/0x3b0 drivers/tty/tty_ioctl.c:940 n_tty_ioctl+0x54/0x320 drivers/tty/n_tty.c:2441 tty_ioctl+0x5e1/0x1870 drivers/tty/tty_io.c:2655 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x1cf/0x16f0 fs/ioctl.c:684 __do_compat_sys_ioctl fs/compat_ioctl.c:1483 [inline] __se_compat_sys_ioctl fs/compat_ioctl.c:1407 [inline] __ia32_compat_sys_ioctl+0x43e/0x640 fs/compat_ioctl.c:1407