FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 1
======================================================
WARNING: possible circular locking dependency detected
5.15.187-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/4637 is trying to acquire lock:
ffffffff8c110d20 (console_owner){....}-{0:0}, at: console_trylock_spinning+0x150/0x350 kernel/printk/printk.c:1879

but task is already holding lock:
ffff88807bb96958 (&port->lock){-.-.}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x39/0x370 drivers/tty/tty_buffer.c:585

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&port->lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
       tty_port_tty_get drivers/tty/tty_port.c:289 [inline]
       tty_port_default_wakeup+0x1f/0xf0 drivers/tty/tty_port.c:48
       serial8250_tx_chars+0x629/0x830 drivers/tty/serial/8250/8250_port.c:1828
       serial8250_handle_irq+0x519/0x610 drivers/tty/serial/8250/8250_port.c:1924
       serial8250_default_handle_irq+0xb4/0x1a0 drivers/tty/serial/8250/8250_port.c:1941
       serial8250_interrupt+0x9b/0x1c0 drivers/tty/serial/8250/8250_core.c:127
       __handle_irq_event_percpu+0x291/0x9b0 kernel/irq/handle.c:156
       handle_irq_event_percpu kernel/irq/handle.c:196 [inline]
       handle_irq_event+0xa5/0x220 kernel/irq/handle.c:213
       handle_edge_irq+0x243/0xb20 kernel/irq/chip.c:819
       generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
       handle_irq arch/x86/kernel/irq.c:233 [inline]
       __common_interrupt+0xd7/0x1e0 arch/x86/kernel/irq.c:252
       common_interrupt+0xb0/0xd0 arch/x86/kernel/irq.c:242
       asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:667
       native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
       arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
       default_idle+0xb/0x10 arch/x86/kernel/process.c:728
       default_idle_call+0x81/0xc0 kernel/sched/idle.c:112
       cpuidle_idle_call kernel/sched/idle.c:194 [inline]
       do_idle+0x21b/0x5b0 kernel/sched/idle.c:306
       cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403
       start_kernel+0x486/0x530 init/main.c:1140
       secondary_startup_64_no_verify+0xb1/0xbb

-> #1 (&port_lock_key){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
       serial8250_console_write+0x170/0xf80 drivers/tty/serial/8250/8250_port.c:3363
       call_console_drivers kernel/printk/printk.c:-1 [inline]
       console_unlock+0xc86/0x1200 kernel/printk/printk.c:2744
       vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
       _printk+0xcc/0x110 kernel/printk/printk.c:2299
       register_console+0x682/0x960 kernel/printk/printk.c:3107
       univ8250_console_init+0x41/0x50 drivers/tty/serial/8250/8250_core.c:690
       console_init+0x177/0x5d0 kernel/printk/printk.c:3207
       start_kernel+0x2f9/0x530 init/main.c:1076
       secondary_startup_64_no_verify+0xb1/0xbb

-> #0 (console_owner){....}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
       lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
       console_trylock_spinning+0x170/0x350 kernel/printk/printk.c:1896
       vprintk_emit+0xa7/0x150 kernel/printk/printk.c:2273
       _printk+0xcc/0x110 kernel/printk/printk.c:2299
       fail_dump lib/fault-inject.c:45 [inline]
       should_fail+0x36d/0x4c0 lib/fault-inject.c:146
       should_failslab+0x5/0x20 mm/slab_common.c:1350
       slab_pre_alloc_hook+0x51/0xc0 mm/slab.h:494
       slab_alloc_node mm/slub.c:3134 [inline]
       slab_alloc mm/slub.c:3228 [inline]
       __kmalloc+0x6b/0x330 mm/slub.c:4403
       kmalloc include/linux/slab.h:609 [inline]
       tty_buffer_alloc drivers/tty/tty_buffer.c:177 [inline]
       __tty_buffer_request_room+0x1dd/0x500 drivers/tty/tty_buffer.c:276
       tty_insert_flip_string_fixed_flag drivers/tty/tty_buffer.c:322 [inline]
       tty_insert_flip_string include/linux/tty_flip.h:41 [inline]
       tty_insert_flip_string_and_push_buffer+0x7e/0x370 drivers/tty/tty_buffer.c:586
       n_tty_write+0x5d5/0x1210 drivers/tty/n_tty.c:2362
       do_tty_write drivers/tty/tty_io.c:1038 [inline]
       file_tty_write+0x557/0x910 drivers/tty/tty_io.c:1110
       do_iter_readv_writev+0x497/0x600 fs/read_write.c:-1
       do_iter_write+0x205/0x7b0 fs/read_write.c:855
       iter_file_splice_write+0x65f/0xc40 fs/splice.c:689
       do_splice_from fs/splice.c:767 [inline]
       direct_splice_actor+0xe1/0x130 fs/splice.c:936
       splice_direct_to_actor+0x4dc/0xb50 fs/splice.c:891
       do_splice_direct+0x1b9/0x2c0 fs/splice.c:979
       do_sendfile+0x5d5/0xec0 fs/read_write.c:1249
       __do_sys_sendfile64 fs/read_write.c:1317 [inline]
       __se_sys_sendfile64+0x13b/0x190 fs/read_write.c:1303
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  console_owner --> &port_lock_key --> &port->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&port->lock);
                               lock(&port_lock_key);
                               lock(&port->lock);
  lock(console_owner);

 *** DEADLOCK ***

5 locks held by syz-executor.0/4637:
 #0: ffff888073b95098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffff888073b95130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: tty_write_lock drivers/tty/tty_io.c:961 [inline]
 #1: ffff888073b95130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: do_tty_write drivers/tty/tty_io.c:984 [inline]
 #1: ffff888073b95130 (&tty->atomic_write_lock){+.+.}-{3:3}, at: file_tty_write+0x271/0x910 drivers/tty/tty_io.c:1110
 #2: ffff888073b952e8 (&tty->termios_rwsem){++++}-{3:3}, at: n_tty_write+0x1df/0x1210 drivers/tty/n_tty.c:2322
 #3: ffffc90001178378 (&ldata->output_lock){+.+.}-{3:3}, at: n_tty_write+0x58b/0x1210 drivers/tty/n_tty.c:2361
 #4: ffff88807bb96958 (&port->lock){-.-.}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x39/0x370 drivers/tty/tty_buffer.c:585

stack backtrace:
CPU: 1 PID: 4637 Comm: syz-executor.0 Not tainted 5.15.187-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
 console_trylock_spinning+0x170/0x350 kernel/printk/printk.c:1896
 vprintk_emit+0xa7/0x150 kernel/printk/printk.c:2273
 _printk+0xcc/0x110 kernel/printk/printk.c:2299
 fail_dump lib/fault-inject.c:45 [inline]
 should_fail+0x36d/0x4c0 lib/fault-inject.c:146
 should_failslab+0x5/0x20 mm/slab_common.c:1350
 slab_pre_alloc_hook+0x51/0xc0 mm/slab.h:494
 slab_alloc_node mm/slub.c:3134 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 __kmalloc+0x6b/0x330 mm/slub.c:4403
 kmalloc include/linux/slab.h:609 [inline]
 tty_buffer_alloc drivers/tty/tty_buffer.c:177 [inline]
 __tty_buffer_request_room+0x1dd/0x500 drivers/tty/tty_buffer.c:276
 tty_insert_flip_string_fixed_flag drivers/tty/tty_buffer.c:322 [inline]
 tty_insert_flip_string include/linux/tty_flip.h:41 [inline]
 tty_insert_flip_string_and_push_buffer+0x7e/0x370 drivers/tty/tty_buffer.c:586
 n_tty_write+0x5d5/0x1210 drivers/tty/n_tty.c:2362
 do_tty_write drivers/tty/tty_io.c:1038 [inline]
 file_tty_write+0x557/0x910 drivers/tty/tty_io.c:1110
 do_iter_readv_writev+0x497/0x600 fs/read_write.c:-1
 do_iter_write+0x205/0x7b0 fs/read_write.c:855
 iter_file_splice_write+0x65f/0xc40 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0xe1/0x130 fs/splice.c:936
 splice_direct_to_actor+0x4dc/0xb50 fs/splice.c:891
 do_splice_direct+0x1b9/0x2c0 fs/splice.c:979
 do_sendfile+0x5d5/0xec0 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1317 [inline]
 __se_sys_sendfile64+0x13b/0x190 fs/read_write.c:1303
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f3b43602da9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3b429840c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f3b43731f80 RCX: 00007f3b43602da9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007f3b42984120 R08: 0000000000000000 R09: 0000000000000000
R10: 0001000000201005 R11: 0000000000000246 R12: 0000000000000002
R13: 000000000000000b R14: 00007f3b43731f80 R15: 00007ffe81dcd5c8
 </TASK>
CPU: 1 PID: 4637 Comm: syz-executor.0 Not tainted 5.15.187-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail+0x38c/0x4c0 lib/fault-inject.c:146
 should_failslab+0x5/0x20 mm/slab_common.c:1350
 slab_pre_alloc_hook+0x51/0xc0 mm/slab.h:494
 slab_alloc_node mm/slub.c:3134 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 __kmalloc+0x6b/0x330 mm/slub.c:4403
 kmalloc include/linux/slab.h:609 [inline]
 tty_buffer_alloc drivers/tty/tty_buffer.c:177 [inline]
 __tty_buffer_request_room+0x1dd/0x500 drivers/tty/tty_buffer.c:276
 tty_insert_flip_string_fixed_flag drivers/tty/tty_buffer.c:322 [inline]
 tty_insert_flip_string include/linux/tty_flip.h:41 [inline]
 tty_insert_flip_string_and_push_buffer+0x7e/0x370 drivers/tty/tty_buffer.c:586
 n_tty_write+0x5d5/0x1210 drivers/tty/n_tty.c:2362
 do_tty_write drivers/tty/tty_io.c:1038 [inline]
 file_tty_write+0x557/0x910 drivers/tty/tty_io.c:1110
 do_iter_readv_writev+0x497/0x600 fs/read_write.c:-1
 do_iter_write+0x205/0x7b0 fs/read_write.c:855
 iter_file_splice_write+0x65f/0xc40 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0xe1/0x130 fs/splice.c:936
 splice_direct_to_actor+0x4dc/0xb50 fs/splice.c:891
 do_splice_direct+0x1b9/0x2c0 fs/splice.c:979
 do_sendfile+0x5d5/0xec0 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1317 [inline]
 __se_sys_sendfile64+0x13b/0x190 fs/read_write.c:1303
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f3b43602da9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3b429840c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f3b43731f80 RCX: 00007f3b43602da9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007f3b42984120 R08: 0000000000000000 R09: 0000000000000000
R10: 0001000000201005 R11: 0000000000000246 R12: 0000000000000002
R13: 000000000000000b R14: 00007f3b43731f80 R15: 00007ffe81dcd5c8
 </TASK>