====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.771/7192 is trying to acquire lock: ffff88802a378a28 (&p->pi_lock){-.-.}-{2:2}, at: try_to_wake_up+0x5c/0x1050 kernel/sched/core.c:4049 but task is already holding lock: ffff888078a4e528 (&tty->write_wait){-...}-{2:2}, at: __wake_up_common_lock kernel/sched/wait.c:137 [inline] ffff888078a4e528 (&tty->write_wait){-...}-{2:2}, at: __wake_up+0xed/0x180 kernel/sched/wait.c:157 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&tty->write_wait){-...}-{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 __wake_up_common_lock kernel/sched/wait.c:137 [inline] __wake_up+0xed/0x180 kernel/sched/wait.c:157 tty_port_default_wakeup+0xa5/0xf0 drivers/tty/tty_port.c:51 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:729 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 -> #4 (&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:3362 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 -> #3 (console_owner){....}-{0:0}: console_lock_spinning_enable+0x51/0x60 kernel/printk/printk.c:1805 console_unlock+0x9f8/0x1200 kernel/printk/printk.c:2741 vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274 _printk+0xcc/0x110 kernel/printk/printk.c:2299 debug_objects_oom+0x89/0x2f0 lib/debugobjects.c:473 debug_object_activate+0x409/0x480 lib/debugobjects.c:699 debug_rcu_head_queue kernel/rcu/rcu.h:176 [inline] kvfree_call_rcu+0xb5/0x7c0 kernel/rcu/tree.c:3591 trie_update_elem+0x86e/0xc50 kernel/bpf/lpm_trie.c:396 bpf_map_update_value+0x57d/0x650 kernel/bpf/syscall.c:223 generic_map_update_batch+0x525/0x7c0 kernel/bpf/syscall.c:1430 bpf_map_do_batch+0x466/0x600 kernel/bpf/syscall.c:-1 __sys_bpf+0x601/0x670 kernel/bpf/syscall.c:-1 __do_sys_bpf kernel/bpf/syscall.c:4761 [inline] __se_sys_bpf kernel/bpf/syscall.c:4759 [inline] __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4759 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 -> #2 (&trie->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 trie_delete_elem+0x90/0x710 kernel/bpf/lpm_trie.c:467 0xffffffffa004a492 bpf_dispatcher_nop_func include/linux/bpf.h:888 [inline] __bpf_prog_run include/linux/filter.h:628 [inline] bpf_prog_run include/linux/filter.h:635 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:1878 [inline] bpf_trace_run2+0x15b/0x2d0 kernel/trace/bpf_trace.c:1915 trace_tlb_flush+0xe6/0x110 include/trace/events/tlb.h:38 switch_mm_irqs_off+0x6e3/0x9a0 arch/x86/mm/tlb.c:-1 context_switch kernel/sched/core.c:5035 [inline] __schedule+0x1024/0x4390 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 worker_thread+0xf5c/0x12a0 kernel/workqueue.c:2478 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 -> #1 (&rq->__lock){-.-.}-{2:2}: _raw_spin_lock_nested+0x2e/0x40 kernel/locking/spinlock.c:368 raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475 raw_spin_rq_lock kernel/sched/sched.h:1326 [inline] rq_lock kernel/sched/sched.h:1621 [inline] task_fork_fair+0x5c/0x350 kernel/sched/fair.c:11499 sched_cgroup_fork+0x2c6/0x320 kernel/sched/core.c:4485 copy_process+0x22d1/0x3e00 kernel/fork.c:2395 kernel_clone+0x219/0x930 kernel/fork.c:2679 kernel_thread+0xc8/0x120 kernel/fork.c:2731 rest_init+0x21/0x330 init/main.c:706 start_kernel+0x486/0x530 init/main.c:1140 secondary_startup_64_no_verify+0xb1/0xbb -> #0 (&p->pi_lock){-.-.}-{2:2}: 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 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 try_to_wake_up+0x5c/0x1050 kernel/sched/core.c:4049 __wake_up_common+0x2a4/0x4e0 kernel/sched/wait.c:108 __wake_up_common_lock kernel/sched/wait.c:138 [inline] __wake_up+0x108/0x180 kernel/sched/wait.c:157 pty_close+0x265/0x440 drivers/tty/pty.c:68 tty_release+0x400/0x16c0 drivers/tty/tty_io.c:1773 __fput+0x234/0x930 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 other info that might help us debug this: Chain exists of: &p->pi_lock --> &port_lock_key --> &tty->write_wait Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&tty->write_wait); lock(&port_lock_key); lock(&tty->write_wait); lock(&p->pi_lock); *** DEADLOCK *** 2 locks held by syz.2.771/7192: #0: ffff88801b7e21c0 (&tty->legacy_mutex/1){+.+.}-{3:3}, at: tty_release+0xa7/0x16c0 drivers/tty/tty_io.c:1755 #1: ffff888078a4e528 (&tty->write_wait){-...}-{2:2}, at: __wake_up_common_lock kernel/sched/wait.c:137 [inline] #1: ffff888078a4e528 (&tty->write_wait){-...}-{2:2}, at: __wake_up+0xed/0x180 kernel/sched/wait.c:157 stack backtrace: CPU: 0 PID: 7192 Comm: syz.2.771 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: 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 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162 try_to_wake_up+0x5c/0x1050 kernel/sched/core.c:4049 __wake_up_common+0x2a4/0x4e0 kernel/sched/wait.c:108 __wake_up_common_lock kernel/sched/wait.c:138 [inline] __wake_up+0x108/0x180 kernel/sched/wait.c:157 pty_close+0x265/0x440 drivers/tty/pty.c:68 tty_release+0x400/0x16c0 drivers/tty/tty_io.c:1773 __fput+0x234/0x930 fs/file_table.c:311 task_work_run+0x125/0x1a0 kernel/task_work.c:188 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fe1891d2c29 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:00007fffbda3d2c8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007fe18941bda0 RCX: 00007fe1891d2c29 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007fe18941bda0 R08: 00000000000000ac R09: 00000007bda3d5bf R10: 00007fe18941bcb0 R11: 0000000000000246 R12: 000000000005062d R13: 00007fe18941a090 R14: ffffffffffffffff R15: 00007fffbda3d3e0