====================================================== WARNING: possible circular locking dependency detected 5.2.0-rc5+ #4 Not tainted ------------------------------------------------------ syz-executor216/7942 is trying to acquire lock: 00000000b812fd9a (console_owner){-.-.}, at: console_lock_spinning_enable+0x31/0x60 kernel/printk/printk.c:1641 but task is already holding lock: 000000000b1b0c63 (&(&port->lock)->rlock){-.-.}, at: pty_write+0xbd/0x190 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+0xa1/0xc0 kernel/locking/spinlock.c:159 tty_port_tty_get drivers/tty/tty_port.c:287 [inline] tty_port_default_wakeup+0x20/0xa0 drivers/tty/tty_port.c:47 tty_port_tty_wakeup+0x5a/0x70 drivers/tty/tty_port.c:387 uart_write_wakeup+0x48/0x60 drivers/tty/serial/serial_core.c:103 serial8250_tx_chars+0x623/0x830 drivers/tty/serial/8250/8250_port.c:1806 serial8250_handle_irq+0x255/0x390 drivers/tty/serial/8250/8250_port.c:1879 serial8250_default_handle_irq+0xc5/0x1d0 drivers/tty/serial/8250/8250_port.c:1895 serial8250_interrupt+0xad/0x190 drivers/tty/serial/8250/8250_core.c:125 __handle_irq_event_percpu+0x113/0x560 kernel/irq/handle.c:149 handle_irq_event_percpu kernel/irq/handle.c:189 [inline] handle_irq_event+0x10a/0x2f0 kernel/irq/handle.c:206 handle_edge_irq+0x29f/0xca0 kernel/irq/chip.c:822 generic_handle_irq_desc include/linux/irqdesc.h:156 [inline] handle_irq+0x3e/0x50 arch/x86/kernel/irq_64.c:34 do_IRQ+0xc4/0x1a0 arch/x86/kernel/irq.c:247 ret_from_intr+0x0/0x1e native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571 default_idle_call kernel/sched/idle.c:94 [inline] cpuidle_idle_call kernel/sched/idle.c:154 [inline] do_idle+0x18a/0x760 kernel/sched/idle.c:263 cpu_startup_entry+0x25/0x30 kernel/sched/idle.c:354 start_secondary+0x425/0x4c0 arch/x86/kernel/smpboot.c:265 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #1 (&port_lock_key){-.-.}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa1/0xc0 kernel/locking/spinlock.c:159 serial8250_console_write+0x1d1/0xba0 drivers/tty/serial/8250/8250_port.c:3245 univ8250_console_write+0x50/0x70 drivers/tty/serial/8250/8250_core.c:586 call_console_drivers kernel/printk/printk.c:1779 [inline] console_unlock+0x95f/0xf20 kernel/printk/printk.c:2463 vprintk_emit+0x239/0x3a0 kernel/printk/printk.c:1986 vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386 printk+0xc4/0x11d kernel/printk/printk.c:2046 register_console+0xa81/0xe30 kernel/printk/printk.c:2788 univ8250_console_init+0x4b/0x4d drivers/tty/serial/8250/8250_core.c:681 console_init+0x56/0x9c kernel/printk/printk.c:2874 start_kernel+0x49e/0x860 init/main.c:688 x86_64_start_reservations+0x18/0x2e arch/x86/kernel/head64.c:470 x86_64_start_kernel+0x7a/0x7d arch/x86/kernel/head64.c:451 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 -> #0 (console_owner){-.-.}: lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4303 console_lock_spinning_enable+0x56/0x60 kernel/printk/printk.c:1644 console_unlock+0x79f/0xf20 kernel/printk/printk.c:2460 vprintk_emit+0x239/0x3a0 kernel/printk/printk.c:1986 vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386 printk+0xc4/0x11d kernel/printk/printk.c:2046 fail_dump lib/fault-inject.c:45 [inline] should_fail+0x5c5/0x860 lib/fault-inject.c:144 __should_failslab+0x11a/0x160 mm/failslab.c:32 should_failslab+0x9/0x20 mm/slab_common.c:1610 slab_pre_alloc_hook mm/slab.h:420 [inline] slab_alloc mm/slab.c:3312 [inline] __do_kmalloc mm/slab.c:3658 [inline] __kmalloc+0x7a/0x310 mm/slab.c:3669 kmalloc include/linux/slab.h:552 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:175 [inline] __tty_buffer_request_room+0x1ef/0x560 drivers/tty/tty_buffer.c:273 tty_insert_flip_string_fixed_flag+0xa4/0x2b0 drivers/tty/tty_buffer.c:318 tty_insert_flip_string include/linux/tty_flip.h:37 [inline] pty_write+0xe2/0x190 drivers/tty/pty.c:122 process_output_block drivers/tty/n_tty.c:595 [inline] n_tty_write+0xd6c/0x12d0 drivers/tty/n_tty.c:2333 do_tty_write drivers/tty/tty_io.c:961 [inline] tty_write+0x581/0x860 drivers/tty/tty_io.c:1045 __vfs_write+0xf9/0x7d0 fs/read_write.c:494 vfs_write+0x227/0x510 fs/read_write.c:558 ksys_write+0x16b/0x2a0 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x7b/0x90 fs/read_write.c:620 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe 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-executor216/7942: #0: 00000000a4ee0c1b (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:272 #1: 000000008f28fb12 (&tty->atomic_write_lock){+.+.}, at: tty_write_lock drivers/tty/tty_io.c:887 [inline] #1: 000000008f28fb12 (&tty->atomic_write_lock){+.+.}, at: do_tty_write drivers/tty/tty_io.c:910 [inline] #1: 000000008f28fb12 (&tty->atomic_write_lock){+.+.}, at: tty_write+0x21d/0x860 drivers/tty/tty_io.c:1045 #2: 00000000da5bf69e (&o_tty->termios_rwsem/1){++++}, at: n_tty_write+0x22e/0x12d0 drivers/tty/n_tty.c:2316 #3: 000000002136c14a (&ldata->output_lock){+.+.}, at: process_output_block drivers/tty/n_tty.c:550 [inline] #3: 000000002136c14a (&ldata->output_lock){+.+.}, at: n_tty_write+0x69e/0x12d0 drivers/tty/n_tty.c:2333 #4: 000000000b1b0c63 (&(&port->lock)->rlock){-.-.}, at: pty_write+0xbd/0x190 drivers/tty/pty.c:120 #5: 000000000be34f20 (console_lock){+.+.}, at: vprintk_emit+0x21c/0x3a0 kernel/printk/printk.c:1985 stack backtrace: CPU: 1 PID: 7942 Comm: syz-executor216 Not tainted 5.2.0-rc5+ #4 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+0x1d8/0x2f8 lib/dump_stack.c:113 print_circular_bug+0xd34/0xf20 kernel/locking/lockdep.c:1564 check_prev_add kernel/locking/lockdep.c:2310 [inline] check_prevs_add kernel/locking/lockdep.c:2418 [inline] validate_chain+0x59d0/0x84f0 kernel/locking/lockdep.c:2800 __lock_acquire+0xcf7/0x1a40 kernel/locking/lockdep.c:3793 lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4303 console_lock_spinning_enable+0x56/0x60 kernel/printk/printk.c:1644 console_unlock+0x79f/0xf20 kernel/printk/printk.c:2460 vprintk_emit+0x239/0x3a0 kernel/printk/printk.c:1986 vprintk_default+0x28/0x30 kernel/printk/printk.c:2013 vprintk_func+0x158/0x170 kernel/printk/printk_safe.c:386 printk+0xc4/0x11d kernel/printk/printk.c:2046 fail_dump lib/fault-inject.c:45 [inline] should_fail+0x5c5/0x860 lib/fault-inject.c:144 __should_failslab+0x11a/0x160 mm/failslab.c:32 should_failslab+0x9/0x20 mm/slab_common.c:1610 slab_pre_alloc_hook mm/slab.h:420 [inline] slab_alloc mm/slab.c:3312 [inline] __do_kmalloc mm/slab.c:3658 [inline] __kmalloc+0x7a/0x310 mm/slab.c:3669 kmalloc include/linux/slab.h:552 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:175 [inline] __tty_buffer_request_room+0x1ef/0x560 drivers/tty/tty_buffer.c:273 tty_insert_flip_string_fixed_flag+0xa4/0x2b0 drivers/tty/tty_buffer.c:318 tty_insert_flip_string include/linux/tty_flip.h:37 [inline] pty_write+0xe2/0x190 drivers/tty/pty.c:122 process_output_block drivers/tty/n_tty.c:595 [inline] n_tty_write+0xd6c/0x12d0 drivers/tty/n_tty.c:2333 do_tty_write drivers/tty/tty_io.c:961 [inline] tty_write+0x581/0x860 drivers/tty/tty_io.c:1045 __vfs_write+0xf9/0x7d0 fs/read_write.c:494 vfs_write+0x227/0x510 fs/read_write.c:558 ksys_write+0x16b/0x2a0 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x7b/0x90 fs/read_write.c:620 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x440689 Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 3b 14 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffc27fb23d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007ffc27fb23f0 RCX: 0000000000440689 RDX: 00000000ffffff86 RSI: 0000000020000000 RDI: 0000000000000005 RBP: 0000000000000006 R08: 0000000000000001 R09: 00000000000000c2 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401f50 R13: 0000000000401fe0 R14: 0000000000000