============================================ WARNING: possible recursive locking detected 5.16.0-rc4-syzkaller #0 Not tainted -------------------------------------------- syz-executor.4/22173 is trying to acquire lock: ffffffff90f563f0 (&port_lock_key){-.-.}-{2:2}, at: uart_write+0xfe/0x920 drivers/tty/serial/serial_core.c:577 but task is already holding lock: ffffffff90f563f0 (&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 5 locks held by syz-executor.4/22173: #0: ffff8880229dd3d8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] #0: ffff8880229dd3d8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: zap_pte_range+0x28d/0x1ba0 mm/memory.c:1323 #1: ffffffff8cb1dd00 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 #2: ffff888078468fb0 (&i->lock){-.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] #2: ffff888078468fb0 (&i->lock){-.-.}-{2:2}, at: serial8250_interrupt+0x39/0x1e0 drivers/tty/serial/8250/8250_core.c:116 #3: ffffffff90f563f0 (&port_lock_key){-.-.}-{2:2}, at: serial8250_handle_irq+0x3f/0x3e0 drivers/tty/serial/8250/8250_port.c:1908 #4: ffff8880796b2098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref+0x18/0x80 drivers/tty/tty_ldisc.c:273 stack backtrace: CPU: 1 PID: 22173 Comm: syz-executor.4 Not tainted 5.16.0-rc4-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+0x9f/0xc0 arch/x86/kernel/irq.c:240 asm_common_interrupt+0x1e/0x40 RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:91 [inline] RIP: 0010:lock_release+0xd5/0x810 kernel/locking/lockdep.c:5650 Code: 9c 7e 85 c0 0f 85 d4 04 00 00 65 48 8b 04 25 c0 6f 02 00 48 89 44 24 10 48 8d 98 5c 0a 00 00 48 89 d8 48 c1 e8 03 42 8a 04 20 <84> c0 0f 85 55 05 00 00 83 3b 00 0f 85 a3 04 00 00 4c 89 74 24 58 RSP: 0018:ffffc900058af2a0 EFLAGS: 00000a07 RAX: 1ffff11003a98c00 RBX: ffff88801d4c615c RCX: 0000000080000002 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000 RBP: ffffc900058af3d0 R08: dffffc0000000000 R09: fffffbfff1bfd27e R10: fffffbfff1bfd27e R11: 0000000000000000 R12: dffffc0000000000 R13: 1ffff92000b15e60 R14: ffffffff81d60de0 R15: 00fff0000000000a zap_pte_range+0xa25/0x1ba0 mm/memory.c:1357 zap_pmd_range mm/memory.c:1467 [inline] zap_pud_range mm/memory.c:1496 [inline] zap_p4d_range mm/memory.c:1517 [inline] unmap_page_range+0x745/0xa20 mm/memory.c:1538 unmap_vmas+0x202/0x390 mm/memory.c:1615 exit_mmap+0x3c6/0x6f0 mm/mmap.c:3170 __mmput+0x111/0x3a0 kernel/fork.c:1113 exit_mm+0x211/0x2f0 kernel/exit.c:507 do_exit+0x688/0x24f0 kernel/exit.c:819 do_group_exit+0x168/0x2d0 kernel/exit.c:929 get_signal+0x1740/0x2120 kernel/signal.c:2852 arch_do_signal_or_restart+0x9c/0x730 arch/x86/kernel/signal.c:868 handle_signal_work kernel/entry/common.c:148 [inline] exit_to_user_mode_loop kernel/entry/common.c:172 [inline] exit_to_user_mode_prepare+0x191/0x220 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x2e/0x70 kernel/entry/common.c:300 do_syscall_64+0x53/0xd0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f02e863ee99 Code: Unable to access opcode bytes at RIP 0x7f02e863ee6f. RSP: 002b:00007f02e6fb4218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f02e8751f68 RCX: 00007f02e863ee99 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f02e8751f68 RBP: 00007f02e8751f60 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f02e8751f6c R13: 00007ffde84974ff R14: 00007f02e6fb4300 R15: 0000000000022000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 85 c0 test %eax,%eax 2: 0f 85 d4 04 00 00 jne 0x4dc 8: 65 48 8b 04 25 c0 6f mov %gs:0x26fc0,%rax f: 02 00 11: 48 89 44 24 10 mov %rax,0x10(%rsp) 16: 48 8d 98 5c 0a 00 00 lea 0xa5c(%rax),%rbx 1d: 48 89 d8 mov %rbx,%rax 20: 48 c1 e8 03 shr $0x3,%rax 24: 42 8a 04 20 mov (%rax,%r12,1),%al * 28: 84 c0 test %al,%al <-- trapping instruction 2a: 0f 85 55 05 00 00 jne 0x585 30: 83 3b 00 cmpl $0x0,(%rbx) 33: 0f 85 a3 04 00 00 jne 0x4dc 39: 4c 89 74 24 58 mov %r14,0x58(%rsp)