============================================ WARNING: possible recursive locking detected 4.19.211-syzkaller #0 Not tainted -------------------------------------------- systemd-udevd/4696 is trying to acquire lock: 0000000068197685 (&port_lock_key){-.-.}, at: uart_write+0x1ce/0x6f0 drivers/tty/serial/serial_core.c:591 but task is already holding lock: 0000000068197685 (&port_lock_key){-.-.}, at: serial8250_handle_irq.part.0+0x21/0x3d0 drivers/tty/serial/8250/8250_port.c:1876 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 6 locks held by systemd-udevd/4696: #0: 00000000b6c5f7b3 (&dup_mmap_sem){++++}, at: dup_mmap kernel/fork.c:435 [inline] #0: 00000000b6c5f7b3 (&dup_mmap_sem){++++}, at: dup_mm kernel/fork.c:1285 [inline] #0: 00000000b6c5f7b3 (&dup_mmap_sem){++++}, at: copy_mm kernel/fork.c:1341 [inline] #0: 00000000b6c5f7b3 (&dup_mmap_sem){++++}, at: copy_process.part.0+0x2bb3/0x8260 kernel/fork.c:1913 #1: 00000000611cd619 (&mm->mmap_sem){++++}, at: dup_mmap kernel/fork.c:436 [inline] #1: 00000000611cd619 (&mm->mmap_sem){++++}, at: dup_mm kernel/fork.c:1285 [inline] #1: 00000000611cd619 (&mm->mmap_sem){++++}, at: copy_mm kernel/fork.c:1341 [inline] #1: 00000000611cd619 (&mm->mmap_sem){++++}, at: copy_process.part.0+0x2bcf/0x8260 kernel/fork.c:1913 #2: 000000002e01348c (&mm->mmap_sem/1){+.+.}, at: dup_mmap kernel/fork.c:445 [inline] #2: 000000002e01348c (&mm->mmap_sem/1){+.+.}, at: dup_mm kernel/fork.c:1285 [inline] #2: 000000002e01348c (&mm->mmap_sem/1){+.+.}, at: copy_mm kernel/fork.c:1341 [inline] #2: 000000002e01348c (&mm->mmap_sem/1){+.+.}, at: copy_process.part.0+0x2c1c/0x8260 kernel/fork.c:1913 #3: 00000000a61375e3 (&(&i->lock)->rlock){-.-.}, at: spin_lock include/linux/spinlock.h:329 [inline] #3: 00000000a61375e3 (&(&i->lock)->rlock){-.-.}, at: serial8250_interrupt+0x3a/0x240 drivers/tty/serial/8250/8250_core.c:115 #4: 0000000068197685 (&port_lock_key){-.-.}, at: serial8250_handle_irq.part.0+0x21/0x3d0 drivers/tty/serial/8250/8250_port.c:1876 #5: 00000000df98f16e (&tty->ldisc_sem){++++}, at: tty_ldisc_ref+0x1d/0x80 drivers/tty/tty_ldisc.c:293 stack backtrace: CPU: 1 PID: 4696 Comm: systemd-udevd Not tainted 4.19.211-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef lib/dump_stack.c:118 print_deadlock_bug kernel/locking/lockdep.c:1764 [inline] check_deadlock kernel/locking/lockdep.c:1808 [inline] validate_chain kernel/locking/lockdep.c:2404 [inline] __lock_acquire.cold+0x121/0x57e kernel/locking/lockdep.c:3416 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:152 uart_write+0x1ce/0x6f0 drivers/tty/serial/serial_core.c:591 n_hdlc_send_frames+0x278/0x470 drivers/tty/n_hdlc.c:403 n_hdlc_tty_wakeup+0xa0/0xc0 drivers/tty/n_hdlc.c:479 tty_wakeup+0xd4/0x110 drivers/tty/tty_io.c:534 tty_port_default_wakeup+0x26/0x40 drivers/tty/tty_port.c:50 serial8250_tx_chars+0x490/0xaf0 drivers/tty/serial/8250/8250_port.c:1813 serial8250_handle_irq.part.0+0x31f/0x3d0 drivers/tty/serial/8250/8250_port.c:1900 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1873 [inline] serial8250_default_handle_irq+0xae/0x220 drivers/tty/serial/8250/8250_port.c:1916 serial8250_interrupt+0x101/0x240 drivers/tty/serial/8250/8250_core.c:125 __handle_irq_event_percpu+0x27e/0x8e0 kernel/irq/handle.c:149 handle_irq_event_percpu kernel/irq/handle.c:189 [inline] handle_irq_event+0x102/0x290 kernel/irq/handle.c:206 handle_edge_irq+0x260/0xcf0 kernel/irq/chip.c:800 generic_handle_irq_desc include/linux/irqdesc.h:155 [inline] handle_irq+0x35/0x50 arch/x86/kernel/irq_64.c:87 do_IRQ+0x93/0x1c0 arch/x86/kernel/irq.c:246 common_interrupt+0xf/0xf arch/x86/entry/entry_64.S:670 RIP: 0010:preempt_latency_start kernel/sched/core.c:3218 [inline] RIP: 0010:preempt_count_add+0xde/0x190 kernel/sched/core.c:3241 Code: 48 8b 2c 25 c0 df 01 00 48 8d bd 38 12 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 8e 00 00 00 <48> 89 9d 38 12 00 00 5b 5d c3 31 ff 31 db e8 ff 14 0a 00 eb c0 e8 RSP: 0018:ffff88809cabf7e8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffd2 RAX: dffffc0000000000 RBX: ffffffff815a0d10 RCX: 0000000000000000 RDX: 1ffff11013956f17 RSI: 0000000000000004 RDI: ffff88809cab78b8 RBP: ffff88809cab6680 R08: 0000000000000000 R09: ffffed101742455a R10: ffff8880ba122ad3 R11: 0000000000074071 R12: ffff88809cabf900 R13: 0000000000000000 R14: ffff88813be45c80 R15: 00000000000000a8 is_module_text_address+0x10/0x50 kernel/module.c:4439 kernel_text_address kernel/extable.c:146 [inline] kernel_text_address+0x62/0xf0 kernel/extable.c:122 __kernel_text_address+0x9/0x30 kernel/extable.c:107 unwind_get_return_address arch/x86/kernel/unwind_orc.c:297 [inline] unwind_get_return_address+0x51/0x90 arch/x86/kernel/unwind_orc.c:292 __save_stack_trace+0xaf/0x190 arch/x86/kernel/stacktrace.c:45 save_stack mm/kasan/kasan.c:448 [inline] set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:553 slab_post_alloc_hook mm/slab.h:445 [inline] slab_alloc mm/slab.c:3397 [inline] kmem_cache_alloc+0x110/0x370 mm/slab.c:3557 anon_vma_alloc mm/rmap.c:82 [inline] anon_vma_fork+0xed/0x630 mm/rmap.c:341 dup_mmap kernel/fork.c:504 [inline] dup_mm kernel/fork.c:1285 [inline] copy_mm kernel/fork.c:1341 [inline] copy_process.part.0+0x360f/0x8260 kernel/fork.c:1913 copy_process kernel/fork.c:1710 [inline] _do_fork+0x22f/0xf30 kernel/fork.c:2219 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fca635ec38b Code: db 45 85 f6 0f 85 95 01 00 00 64 4c 8b 04 25 10 00 00 00 31 d2 4d 8d 90 d0 02 00 00 31 f6 bf 11 00 20 01 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 de 00 00 00 85 c0 41 89 c5 0f 85 e5 00 00 RSP: 002b:00007fff28104ab0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007fff28104ab0 RCX: 00007fca635ec38b RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007fff28104b00 R08: 00007fca6479d8c0 R09: 0000000000000210 R10: 00007fca6479db90 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000020 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess): 0: 48 8b 2c 25 c0 df 01 mov 0x1dfc0,%rbp 7: 00 8: 48 8d bd 38 12 00 00 lea 0x1238(%rbp),%rdi f: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 16: fc ff df 19: 48 89 fa mov %rdi,%rdx 1c: 48 c1 ea 03 shr $0x3,%rdx 20: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) 24: 0f 85 8e 00 00 00 jne 0xb8 * 2a: 48 89 9d 38 12 00 00 mov %rbx,0x1238(%rbp) <-- trapping instruction 31: 5b pop %rbx 32: 5d pop %rbp 33: c3 retq 34: 31 ff xor %edi,%edi 36: 31 db xor %ebx,%ebx 38: e8 ff 14 0a 00 callq 0xa153c 3d: eb c0 jmp 0xffffffff 3f: e8 .byte 0xe8