============================================ WARNING: possible recursive locking detected 5.16.0-rc2-syzkaller #0 Not tainted -------------------------------------------- syz-fuzzer/6519 is trying to acquire lock: ffffffff90f54430 (&port_lock_key){-.-.}-{2:2}, at: uart_write+0xfe/0x920 drivers/tty/serial/serial_core.c:577 but task is already holding lock: ffffffff90f54430 (&port_lock_key){-.-.}-{2:2}, at: serial8250_handle_irq+0x3f/0x3e0 drivers/tty/serial/8250/8250_port.c:1908 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&port_lock_key); lock(&port_lock_key); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz-fuzzer/6519: #0: ffff888023a010b0 (&i->lock){-.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] #0: ffff888023a010b0 (&i->lock){-.-.}-{2:2}, at: serial8250_interrupt+0x39/0x1e0 drivers/tty/serial/8250/8250_core.c:116 #1: ffffffff90f54430 (&port_lock_key){-.-.}-{2:2}, at: serial8250_handle_irq+0x3f/0x3e0 drivers/tty/serial/8250/8250_port.c:1908 #2: ffff88809a5a1098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x18/0x80 drivers/tty/tty_ldisc.c:273 stack backtrace: CPU: 1 PID: 6519 Comm: syz-fuzzer Not tainted 5.16.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1dc/0x2d8 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2956 [inline] check_deadlock kernel/locking/lockdep.c:2999 [inline] validate_chain+0x5984/0x8240 kernel/locking/lockdep.c:3788 __lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5027 lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5637 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162 uart_write+0xfe/0x920 drivers/tty/serial/serial_core.c:577 n_hdlc_send_frames+0x34e/0xb20 drivers/tty/n_hdlc.c:290 tty_wakeup+0xb3/0xf0 drivers/tty/tty_io.c:534 tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:51 serial8250_tx_chars+0x68e/0x8a0 drivers/tty/serial/8250/8250_port.c:1845 serial8250_handle_irq+0x2fd/0x3e0 drivers/tty/serial/8250/8250_port.c:1932 serial8250_default_handle_irq+0xaf/0x190 drivers/tty/serial/8250/8250_port.c:1949 serial8250_interrupt+0xa3/0x1e0 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x20d/0x730 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:198 [inline] handle_irq_event+0x10a/0x300 kernel/irq/handle.c:215 handle_edge_irq+0x245/0xbe0 kernel/irq/chip.c:822 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline] handle_irq arch/x86/kernel/irq.c:231 [inline] __common_interrupt+0xce/0x1e0 arch/x86/kernel/irq.c:250 common_interrupt+0x4a/0xc0 arch/x86/kernel/irq.c:240 asm_common_interrupt+0x1e/0x40 RIP: 0033:0x40d6ec Code: 89 54 24 40 48 89 44 24 38 e8 b0 e9 05 00 83 3d 21 7c 48 01 00 0f 85 bc 01 00 00 48 8b 44 24 60 c7 80 f0 00 00 00 00 00 00 00 <90> 64 48 8b 0c 25 f8 ff ff ff 8b 90 08 01 00 00 8d 5a ff 89 98 08 RSP: 002b:000000c01a3beca8 EFLAGS: 00000246 RAX: 000000c0002da000 RBX: 0000000000000008 RCX: 00007f6d42bca108 RDX: 0000000000000028 RSI: 0000000000000028 RDI: 0000000000000000 RBP: 000000c01a3bed38 R08: 00007f6d1b166668 R09: 0000000000203003 R10: 0000000000000008 R11: 0000000000000074 R12: 00000000000000f4 R13: 0000000000000000 R14: 00000000008db717 R15: 0000000000000000 NMI backtrace for cpu 1 CPU: 1 PID: 6519 Comm: syz-fuzzer Not tainted 5.16.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:native_halt arch/x86/include/asm/irqflags.h:57 [inline] RIP: 0010:halt arch/x86/include/asm/irqflags.h:98 [inline] RIP: 0010:kvm_wait+0x138/0x1f0 arch/x86/kernel/kvm.c:991 Code: 89 e0 48 c1 e8 03 42 8a 04 28 84 c0 0f 85 9b 00 00 00 41 8a 04 24 3a 44 24 1c 0f 85 53 ff ff ff eb 07 0f 00 2d 19 46 31 09 f4 44 ff ff ff 4c 8d 7c 24 40 4d 89 fe 49 c1 ee 03 43 80 3c 2e 00 RSP: 0000:ffffc90001a9f620 EFLAGS: 00000046 RAX: 1ffffffff21ea803 RBX: 1ffff92000353ec8 RCX: ffffffff8167a3ef RDX: dffffc0000000000 RSI: 0000000000000003 RDI: ffffffff90f54418 RBP: ffffc90001a9f6f0 R08: dffffc0000000000 R09: fffffbfff21ea884 R10: fffffbfff21ea884 R11: 0000000000000000 R12: ffffffff90f54418 R13: dffffc0000000000 R14: ffffc90001a9f680 R15: 1ffff92000353ed0 FS: 000000c0002da090(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc957cfd560 CR3: 0000000072f8b000 CR4: 00000000003526e0 Call Trace: pv_wait arch/x86/include/asm/paravirt.h:603 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x76c/0xcb0 kernel/locking/qspinlock.c:508 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock+0x4c9/0x8e0 kernel/locking/spinlock_debug.c:115 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] _raw_spin_lock_irqsave+0xdd/0x120 kernel/locking/spinlock.c:162 uart_write+0xfe/0x920 drivers/tty/serial/serial_core.c:577 n_hdlc_send_frames+0x34e/0xb20 drivers/tty/n_hdlc.c:290 tty_wakeup+0xb3/0xf0 drivers/tty/tty_io.c:534 tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:51 serial8250_tx_chars+0x68e/0x8a0 drivers/tty/serial/8250/8250_port.c:1845 serial8250_handle_irq+0x2fd/0x3e0 drivers/tty/serial/8250/8250_port.c:1932 serial8250_default_handle_irq+0xaf/0x190 drivers/tty/serial/8250/8250_port.c:1949 serial8250_interrupt+0xa3/0x1e0 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x20d/0x730 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:198 [inline] handle_irq_event+0x10a/0x300 kernel/irq/handle.c:215 handle_edge_irq+0x245/0xbe0 kernel/irq/chip.c:822 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline] handle_irq arch/x86/kernel/irq.c:231 [inline] __common_interrupt+0xce/0x1e0 arch/x86/kernel/irq.c:250 common_interrupt+0x4a/0xc0 arch/x86/kernel/irq.c:240 asm_common_interrupt+0x1e/0x40 RIP: 0033:0x40d6ec Code: 89 54 24 40 48 89 44 24 38 e8 b0 e9 05 00 83 3d 21 7c 48 01 00 0f 85 bc 01 00 00 48 8b 44 24 60 c7 80 f0 00 00 00 00 00 00 00 <90> 64 48 8b 0c 25 f8 ff ff ff 8b 90 08 01 00 00 8d 5a ff 89 98 08 RSP: 002b:000000c01a3beca8 EFLAGS: 00000246 RAX: 000000c0002da000 RBX: 0000000000000008 RCX: 00007f6d42bca108 RDX: 0000000000000028 RSI: 0000000000000028 RDI: 0000000000000000 RBP: 000000c01a3bed38 R08: 00007f6d1b166668 R09: 0000000000203003 R10: 0000000000000008 R11: 0000000000000074 R12: 00000000000000f4 R13: 0000000000000000 R14: 00000000008db717 R15: 0000000000000000 NMI backtrace for cpu 1 CPU: 1 PID: 6519 Comm: syz-fuzzer Not tainted 5.16.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:native_halt arch/x86/include/asm/irqflags.h:57 [inline] RIP: 0010:halt arch/x86/include/asm/irqflags.h:98 [inline] RIP: 0010:kvm_wait+0x138/0x1f0 arch/x86/kernel/kvm.c:991 Code: 89 e0 48 c1 e8 03 42 8a 04 28 84 c0 0f 85 9b 00 00 00 41 8a 04 24 3a 44 24 1c 0f 85 53 ff ff ff eb 07 0f 00 2d 19 46 31 09 f4 44 ff ff ff 4c 8d 7c 24 40 4d 89 fe 49 c1 ee 03 43 80 3c 2e 00 RSP: 0000:ffffc90001a9f620 EFLAGS: 00000046 RAX: 1ffffffff21ea803 RBX: 1ffff92000353ec8 RCX: ffffffff8167a3ef RDX: dffffc0000000000 RSI: 0000000000000003 RDI: ffffffff90f54418 RBP: ffffc90001a9f6f0 R08: dffffc0000000000 R09: fffffbfff21ea884 R10: fffffbfff21ea884 R11: 0000000000000000 R12: ffffffff90f54418 R13: dffffc0000000000 R14: ffffc90001a9f680 R15: 1ffff92000353ed0 FS: 000000c0002da090(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc957cfd560 CR3: 0000000072f8b000 CR4: 00000000003526e0 Call Trace: pv_wait arch/x86/include/asm/paravirt.h:603 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x76c/0xcb0 kernel/locking/qspinlock.c:508 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock+0x4c9/0x8e0 kernel/locking/spinlock_debug.c:115 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] _raw_spin_lock_irqsave+0xdd/0x120 kernel/locking/spinlock.c:162 uart_write+0xfe/0x920 drivers/tty/serial/serial_core.c:577 n_hdlc_send_frames+0x34e/0xb20 drivers/tty/n_hdlc.c:290 tty_wakeup+0xb3/0xf0 drivers/tty/tty_io.c:534 tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:51 serial8250_tx_chars+0x68e/0x8a0 drivers/tty/serial/8250/8250_port.c:1845 serial8250_handle_irq+0x2fd/0x3e0 drivers/tty/serial/8250/8250_port.c:1932 serial8250_default_handle_irq+0xaf/0x190 drivers/tty/serial/8250/8250_port.c:1949 serial8250_interrupt+0xa3/0x1e0 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x20d/0x730 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:198 [inline] handle_irq_event+0x10a/0x300 kernel/irq/handle.c:215 handle_edge_irq+0x245/0xbe0 kernel/irq/chip.c:822 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline] handle_irq arch/x86/kernel/irq.c:231 [inline] __common_interrupt+0xce/0x1e0 arch/x86/kernel/irq.c:250 common_interrupt+0x4a/0xc0 arch/x86/kernel/irq.c:240 asm_common_interrupt+0x1e/0x40 RIP: 0033:0x40d6ec Code: 89 54 24 40 48 89 44 24 38 e8 b0 e9 05 00 83 3d 21 7c 48 01 00 0f 85 bc 01 00 00 48 8b 44 24 60 c7 80 f0 00 00 00 00 00 00 00 <90> 64 48 8b 0c 25 f8 ff ff ff 8b 90 08 01 00 00 8d 5a ff 89 98 08 RSP: 002b:000000c01a3beca8 EFLAGS: 00000246 RAX: 000000c0002da000 RBX: 0000000000000008 RCX: 00007f6d42bca108 RDX: 0000000000000028 RSI: 0000000000000028 RDI: 0000000000000000 RBP: 000000c01a3bed38 R08: 00007f6d1b166668 R09: 0000000000203003 R10: 0000000000000008 R11: 0000000000000074 R12: 00000000000000f4 R13: 0000000000000000 R14: 00000000008db717 R15: 0000000000000000 NMI backtrace for cpu 1 CPU: 1 PID: 6519 Comm: syz-fuzzer Not tainted 5.16.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:native_halt arch/x86/include/asm/irqflags.h:57 [inline] RIP: 0010:halt arch/x86/include/asm/irqflags.h:98 [inline] RIP: 0010:kvm_wait+0x138/0x1f0 arch/x86/kernel/kvm.c:991 Code: 89 e0 48 c1 e8 03 42 8a 04 28 84 c0 0f 85 9b 00 00 00 41 8a 04 24 3a 44 24 1c 0f 85 53 ff ff ff eb 07 0f 00 2d 19 46 31 09 f4 44 ff ff ff 4c 8d 7c 24 40 4d 89 fe 49 c1 ee 03 43 80 3c 2e 00 RSP: 0000:ffffc90001a9f620 EFLAGS: 00000046 RAX: 1ffffffff21ea803 RBX: 1ffff92000353ec8 RCX: ffffffff8167a3ef RDX: dffffc0000000000 RSI: 0000000000000003 RDI: ffffffff90f54418 RBP: ffffc90001a9f6f0 R08: dffffc0000000000 R09: fffffbfff21ea884 R10: fffffbfff21ea884 R11: 0000000000000000 R12: ffffffff90f54418 R13: dffffc0000000000 R14: ffffc90001a9f680 R15: 1ffff92000353ed0 FS: 000000c0002da090(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc957cfd560 CR3: 0000000072f8b000 CR4: 00000000003526e0 Call Trace: pv_wait arch/x86/include/asm/paravirt.h:603 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x76c/0xcb0 kernel/locking/qspinlock.c:508 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock+0x4c9/0x8e0 kernel/locking/spinlock_debug.c:115 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] _raw_spin_lock_irqsave+0xdd/0x120 kernel/locking/spinlock.c:162 uart_write+0xfe/0x920 drivers/tty/serial/serial_core.c:577 n_hdlc_send_frames+0x34e/0xb20 drivers/tty/n_hdlc.c:290 tty_wakeup+0xb3/0xf0 drivers/tty/tty_io.c:534 tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:51 serial8250_tx_chars+0x68e/0x8a0 drivers/tty/serial/8250/8250_port.c:1845 serial8250_handle_irq+0x2fd/0x3e0 drivers/tty/serial/8250/8250_port.c:1932 serial8250_default_handle_irq+0xaf/0x190 drivers/tty/serial/8250/8250_port.c:1949 serial8250_interrupt+0xa3/0x1e0 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x20d/0x730 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:198 [inline] handle_irq_event+0x10a/0x300 kernel/irq/handle.c:215 handle_edge_irq+0x245/0xbe0 kernel/irq/chip.c:822 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline] handle_irq arch/x86/kernel/irq.c:231 [inline] __common_interrupt+0xce/0x1e0 arch/x86/kernel/irq.c:250 common_interrupt+0x4a/0xc0 arch/x86/kernel/irq.c:240 asm_common_interrupt+0x1e/0x40 RIP: 0033:0x40d6ec Code: 89 54 24 40 48 89 44 24 38 e8 b0 e9 05 00 83 3d 21 7c 48 01 00 0f 85 bc 01 00 00 48 8b 44 24 60 c7 80 f0 00 00 00 00 00 00 00 <90> 64 48 8b 0c 25 f8 ff ff ff 8b 90 08 01 00 00 8d 5a ff 89 98 08 RSP: 002b:000000c01a3beca8 EFLAGS: 00000246 RAX: 000000c0002da000 RBX: 0000000000000008 RCX: 00007f6d42bca108 RDX: 0000000000000028 RSI: 0000000000000028 RDI: 0000000000000000 RBP: 000000c01a3bed38 R08: 00007f6d1b166668 R09: 0000000000203003 R10: 0000000000000008 R11: 0000000000000074 R12: 00000000000000f4 R13: 0000000000000000 R14: 00000000008db717 R15: 0000000000000000 ---------------- Code disassembly (best guess): 0: 89 e0 mov %esp,%eax 2: 48 c1 e8 03 shr $0x3,%rax 6: 42 8a 04 28 mov (%rax,%r13,1),%al a: 84 c0 test %al,%al c: 0f 85 9b 00 00 00 jne 0xad 12: 41 8a 04 24 mov (%r12),%al 16: 3a 44 24 1c cmp 0x1c(%rsp),%al 1a: 0f 85 53 ff ff ff jne 0xffffff73 20: eb 07 jmp 0x29 22: 0f 00 2d 19 46 31 09 verw 0x9314619(%rip) # 0x9314642 29: f4 hlt * 2a: e9 44 ff ff ff jmpq 0xffffff73 <-- trapping instruction 2f: 4c 8d 7c 24 40 lea 0x40(%rsp),%r15 34: 4d 89 fe mov %r15,%r14 37: 49 c1 ee 03 shr $0x3,%r14 3b: 43 80 3c 2e 00 cmpb $0x0,(%r14,%r13,1)