FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 1
======================================================
WARNING: possible circular locking dependency detected
5.15.173-syzkaller #0 Not tainted
------------------------------------------------------
syz.3.98/4767 is trying to acquire lock:
ffffffff8c9147e0 (console_owner){....}-{0:0}, at: console_trylock_spinning+0x185/0x3f0 kernel/printk/printk.c:1879

but task is already holding lock:
ffff88807642a958 (&port->lock){-.-.}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x3a/0x390 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}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
       tty_port_tty_get drivers/tty/tty_port.c:289 [inline]
       tty_port_default_wakeup+0x21/0x100 drivers/tty/tty_port.c:48
       serial8250_tx_chars+0x60d/0x800 drivers/tty/serial/8250/8250_port.c:1828
       serial8250_handle_irq+0x505/0x600 drivers/tty/serial/8250/8250_port.c:1924
       serial8250_default_handle_irq+0xc8/0x1e0 drivers/tty/serial/8250/8250_port.c:1941
       serial8250_interrupt+0xa1/0x1e0 drivers/tty/serial/8250/8250_core.c:127
       __handle_irq_event_percpu+0x292/0xa70 kernel/irq/handle.c:156
       handle_irq_event_percpu kernel/irq/handle.c:196 [inline]
       handle_irq_event+0xff/0x2b0 kernel/irq/handle.c:213
       handle_edge_irq+0x245/0xbf0 kernel/irq/chip.c:819
       generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
       handle_irq arch/x86/kernel/irq.c:231 [inline]
       __common_interrupt+0xd7/0x1f0 arch/x86/kernel/irq.c:250
       common_interrupt+0xae/0xd0 arch/x86/kernel/irq.c:240
       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]
       acpi_safe_halt drivers/acpi/processor_idle.c:108 [inline]
       acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:562
       acpi_idle_enter+0x352/0x4f0 drivers/acpi/processor_idle.c:697
       cpuidle_enter_state+0x521/0xef0 drivers/cpuidle/cpuidle.c:237
       cpuidle_enter+0x59/0x90 drivers/cpuidle/cpuidle.c:351
       call_cpuidle kernel/sched/idle.c:158 [inline]
       cpuidle_idle_call kernel/sched/idle.c:239 [inline]
       do_idle+0x3e4/0x670 kernel/sched/idle.c:306
       cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403
       start_secondary+0x371/0x500 arch/x86/kernel/smpboot.c:281
       secondary_startup_64_no_verify+0xb1/0xbb

-> #1 (&port_lock_key){-.-.}-{2:2}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162
       serial8250_console_write+0x19d/0x1180 drivers/tty/serial/8250/8250_port.c:3354
       console_unlock+0xced/0x12b0 kernel/printk/printk.c:2744
       vprintk_emit+0xbf/0x150 kernel/printk/printk.c:2274
       _printk+0xd1/0x120 kernel/printk/printk.c:2299
       register_console+0x65a/0x940 kernel/printk/printk.c:3107
       univ8250_console_init+0x41/0x50 drivers/tty/serial/8250/8250_core.c:690
       console_init+0x18c/0x660 kernel/printk/printk.c:3207
       start_kernel+0x301/0x540 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+0x1649/0x5930 kernel/locking/lockdep.c:3788
       __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       console_trylock_spinning+0x1a5/0x3f0 kernel/printk/printk.c:1896
       vprintk_emit+0xa6/0x150 kernel/printk/printk.c:2273
       _printk+0xd1/0x120 kernel/printk/printk.c:2299
       fail_dump lib/fault-inject.c:45 [inline]
       should_fail+0x36c/0x4c0 lib/fault-inject.c:146
       should_failslab+0x5/0x20 mm/slab_common.c:1344
       slab_pre_alloc_hook+0x53/0xc0 mm/slab.h:494
       slab_alloc_node mm/slub.c:3134 [inline]
       slab_alloc mm/slub.c:3228 [inline]
       __kmalloc+0x6e/0x300 mm/slub.c:4403
       kmalloc include/linux/slab.h:596 [inline]
       tty_buffer_alloc drivers/tty/tty_buffer.c:177 [inline]
       __tty_buffer_request_room+0x1ef/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+0x7c/0x390 drivers/tty/tty_buffer.c:586
       ppp_async_push+0x306/0x1b70 drivers/net/ppp/ppp_async.c:676
       ppp_async_send+0xd8/0x100 drivers/net/ppp/ppp_async.c:644
       __ppp_channel_push+0xff/0x1d0 drivers/net/ppp/ppp_generic.c:2164
       ppp_channel_push+0x196/0x220 drivers/net/ppp/ppp_generic.c:2191
       ppp_write+0x291/0x390 drivers/net/ppp/ppp_generic.c:537
       vfs_write+0x30c/0xe50 fs/read_write.c:592
       ksys_write+0x1a2/0x2c0 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 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 ***

4 locks held by syz.3.98/4767:
 #0: ffff88807dedc240 (&pch->upl){++..}-{2:2}, at: ppp_channel_push+0x2c/0x220 drivers/net/ppp/ppp_generic.c:2185
 #1: ffff88807dedc1e0 (&pch->downl){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
 #1: ffff88807dedc1e0 (&pch->downl){+...}-{2:2}, at: __ppp_channel_push+0x31/0x1d0 drivers/net/ppp/ppp_generic.c:2160
 #2: ffff888061f6c030 (&ap->xmit_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline]
 #2: ffff888061f6c030 (&ap->xmit_lock){+...}-{2:2}, at: ppp_async_push+0x9b/0x1b70 drivers/net/ppp/ppp_async.c:669
 #3: ffff88807642a958 (&port->lock){-.-.}-{2:2}, at: tty_insert_flip_string_and_push_buffer+0x3a/0x390 drivers/tty/tty_buffer.c:585

stack backtrace:
CPU: 0 PID: 4767 Comm: syz.3.98 Not tainted 5.15.173-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 check_noncircular+0x2f8/0x3b0 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+0x1649/0x5930 kernel/locking/lockdep.c:3788
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
 console_trylock_spinning+0x1a5/0x3f0 kernel/printk/printk.c:1896
 vprintk_emit+0xa6/0x150 kernel/printk/printk.c:2273
 _printk+0xd1/0x120 kernel/printk/printk.c:2299
 fail_dump lib/fault-inject.c:45 [inline]
 should_fail+0x36c/0x4c0 lib/fault-inject.c:146
 should_failslab+0x5/0x20 mm/slab_common.c:1344
 slab_pre_alloc_hook+0x53/0xc0 mm/slab.h:494
 slab_alloc_node mm/slub.c:3134 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 __kmalloc+0x6e/0x300 mm/slub.c:4403
 kmalloc include/linux/slab.h:596 [inline]
 tty_buffer_alloc drivers/tty/tty_buffer.c:177 [inline]
 __tty_buffer_request_room+0x1ef/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+0x7c/0x390 drivers/tty/tty_buffer.c:586
 ppp_async_push+0x306/0x1b70 drivers/net/ppp/ppp_async.c:676
 ppp_async_send+0xd8/0x100 drivers/net/ppp/ppp_async.c:644
 __ppp_channel_push+0xff/0x1d0 drivers/net/ppp/ppp_generic.c:2164
 ppp_channel_push+0x196/0x220 drivers/net/ppp/ppp_generic.c:2191
 ppp_write+0x291/0x390 drivers/net/ppp/ppp_generic.c:537
 vfs_write+0x30c/0xe50 fs/read_write.c:592
 ksys_write+0x1a2/0x2c0 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f0f6fd1d819
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0f6db95038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f0f6fed4fa0 RCX: 00007f0f6fd1d819
RDX: 0000000000000009 RSI: 00000000200002c0 RDI: 0000000000000005
RBP: 00007f0f6db95090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f0f6fed4fa0 R15: 00007ffffd3ba198
 </TASK>
CPU: 0 PID: 4767 Comm: syz.3.98 Not tainted 5.15.173-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail+0x38a/0x4c0 lib/fault-inject.c:146
 should_failslab+0x5/0x20 mm/slab_common.c:1344
 slab_pre_alloc_hook+0x53/0xc0 mm/slab.h:494
 slab_alloc_node mm/slub.c:3134 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 __kmalloc+0x6e/0x300 mm/slub.c:4403
 kmalloc include/linux/slab.h:596 [inline]
 tty_buffer_alloc drivers/tty/tty_buffer.c:177 [inline]
 __tty_buffer_request_room+0x1ef/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+0x7c/0x390 drivers/tty/tty_buffer.c:586
 ppp_async_push+0x306/0x1b70 drivers/net/ppp/ppp_async.c:676
 ppp_async_send+0xd8/0x100 drivers/net/ppp/ppp_async.c:644
 __ppp_channel_push+0xff/0x1d0 drivers/net/ppp/ppp_generic.c:2164
 ppp_channel_push+0x196/0x220 drivers/net/ppp/ppp_generic.c:2191
 ppp_write+0x291/0x390 drivers/net/ppp/ppp_generic.c:537
 vfs_write+0x30c/0xe50 fs/read_write.c:592
 ksys_write+0x1a2/0x2c0 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f0f6fd1d819
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0f6db95038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f0f6fed4fa0 RCX: 00007f0f6fd1d819
RDX: 0000000000000009 RSI: 00000000200002c0 RDI: 0000000000000005
RBP: 00007f0f6db95090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f0f6fed4fa0 R15: 00007ffffd3ba198
 </TASK>