FAULT_INJECTION: forcing a failure. name fail_usercopy, interval 1, probability 0, space 0, times 0 ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.6.1467/12244 is trying to acquire lock: ffffffff8e138b80 (console_owner){-.-.}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:317 [inline] ffffffff8e138b80 (console_owner){-.-.}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline] ffffffff8e138b80 (console_owner){-.-.}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline] ffffffff8e138b80 (console_owner){-.-.}-{0:0}, at: console_flush_one_record kernel/printk/printk.c:3194 [inline] ffffffff8e138b80 (console_owner){-.-.}-{0:0}, at: console_flush_all+0x11a/0xb00 kernel/printk/printk.c:3291 but task is already holding lock: ffff8880b863abe0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xba/0x150 kernel/sched/core.c:655 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&rq->__lock){-.-.}-{2:2}: _raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:378 raw_spin_rq_lock_nested+0x31/0x150 kernel/sched/core.c:647 raw_spin_rq_lock kernel/sched/sched.h:1613 [inline] _task_rq_lock+0xbc/0x470 kernel/sched/core.c:747 cgroup_move_task+0x92/0x2a0 kernel/sched/psi.c:1170 css_set_move_task+0x658/0x9e0 kernel/cgroup/cgroup.c:951 cgroup_post_fork+0x1ef/0x7a0 kernel/cgroup/cgroup.c:6913 copy_process+0x385e/0x3ba0 kernel/fork.c:2462 kernel_clone+0x21e/0x820 kernel/fork.c:2648 user_mode_thread+0xdd/0x140 kernel/fork.c:2724 rest_init+0x23/0x300 init/main.c:725 start_kernel+0x386/0x3d0 init/main.c:1210 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x147 -> #3 (&p->pi_lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline] _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:162 class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:573 [inline] try_to_wake_up+0x67/0x12c0 kernel/sched/core.c:4129 __wake_up_common kernel/sched/wait.c:108 [inline] __wake_up_common_lock+0x137/0x1f0 kernel/sched/wait.c:125 tty_ldisc_hangup+0x208/0x4b0 drivers/tty/tty_ldisc.c:709 __tty_hangup+0x40c/0x680 drivers/tty/tty_io.c:621 tty_vhangup drivers/tty/tty_io.c:691 [inline] tty_ioctl+0x757/0xde0 drivers/tty/tty_io.c:2732 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&tty->write_wait){-.-.}-{3:3}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline] _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:162 __wake_up_common_lock+0x2f/0x1f0 kernel/sched/wait.c:124 tty_port_default_wakeup+0xfb/0x170 drivers/tty/tty_port.c:67 serial8250_tx_chars+0x72e/0x970 drivers/tty/serial/8250/8250_port.c:1719 serial8250_handle_irq+0x633/0xbb0 drivers/tty/serial/8250/8250_port.c:1827 serial8250_default_handle_irq+0xbf/0x200 drivers/tty/serial/8250/8250_port.c:1846 serial8250_interrupt+0x8d/0x180 drivers/tty/serial/8250/8250_core.c:86 __handle_irq_event_percpu+0x217/0x970 kernel/irq/handle.c:209 handle_irq_event_percpu kernel/irq/handle.c:246 [inline] handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:263 handle_edge_irq+0x23b/0xa10 kernel/irq/chip.c:855 generic_handle_irq_desc include/linux/irqdesc.h:186 [inline] handle_irq arch/x86/kernel/irq.c:262 [inline] call_irq_handler arch/x86/kernel/irq.c:-1 [inline] __common_interrupt+0x141/0x1f0 arch/x86/kernel/irq.c:333 common_interrupt+0xb6/0xe0 arch/x86/kernel/irq.c:326 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline] _raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:410 [inline] uart_port_unlock_irqrestore include/linux/serial_core.h:788 [inline] uart_port_unlock_deref+0x111/0x2f0 drivers/tty/serial/serial_core.c:91 uart_write+0xe8/0x130 drivers/tty/serial/serial_core.c:634 process_output_block drivers/tty/n_tty.c:557 [inline] n_tty_write+0xd78/0x12a0 drivers/tty/n_tty.c:2366 iterate_tty_write drivers/tty/tty_io.c:1006 [inline] file_tty_write+0x559/0xa20 drivers/tty/tty_io.c:1081 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:688 ksys_write+0x145/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&port_lock_key){-.-.}-{3:3}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline] _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:162 uart_port_lock_irqsave include/linux/serial_core.h:717 [inline] serial8250_console_write+0x155/0x1b60 drivers/tty/serial/8250/8250_port.c:3301 console_emit_next_record kernel/printk/printk.c:3131 [inline] console_flush_one_record kernel/printk/printk.c:3217 [inline] console_flush_all+0x713/0xb00 kernel/printk/printk.c:3291 __console_flush_and_unlock kernel/printk/printk.c:3321 [inline] console_unlock+0xbb/0x190 kernel/printk/printk.c:3361 vprintk_emit+0x47b/0x550 kernel/printk/printk.c:2428 _printk+0xcf/0x120 kernel/printk/printk.c:2453 register_console+0xa8b/0xf90 kernel/printk/printk.c:4172 univ8250_console_init+0x3a/0x70 drivers/tty/serial/8250/8250_core.c:515 console_init+0xfc/0x3f0 kernel/printk/printk.c:4371 start_kernel+0x22c/0x3d0 init/main.c:1147 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x147 -> #0 (console_owner){-.-.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868 console_lock_spinning_enable kernel/printk/printk.c:1902 [inline] console_emit_next_record kernel/printk/printk.c:3125 [inline] console_flush_one_record kernel/printk/printk.c:3217 [inline] console_flush_all+0x6bc/0xb00 kernel/printk/printk.c:3291 __console_flush_and_unlock kernel/printk/printk.c:3321 [inline] console_unlock+0xbb/0x190 kernel/printk/printk.c:3361 vprintk_emit+0x47b/0x550 kernel/printk/printk.c:2428 _printk+0xcf/0x120 kernel/printk/printk.c:2453 fail_dump lib/fault-inject.c:66 [inline] should_fail_ex+0x3f5/0x560 lib/fault-inject.c:174 strncpy_from_user+0x36/0x2c0 lib/strncpy_from_user.c:118 strncpy_from_user_nofault+0x72/0x150 mm/maccess.c:192 bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:214 [inline] ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:309 [inline] bpf_probe_read_compat_str+0xe2/0x180 kernel/trace/bpf_trace.c:305 bpf_prog_d359f1fa6cfa10c1+0x78/0x80 bpf_dispatcher_nop_func include/linux/bpf.h:1394 [inline] __bpf_prog_run include/linux/filter.h:723 [inline] bpf_prog_run include/linux/filter.h:730 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2075 [inline] bpf_trace_run2+0x284/0x4c0 kernel/trace/bpf_trace.c:2116 __bpf_trace_tlb_flush+0xf5/0x150 include/trace/events/tlb.h:39 __do_trace_tlb_flush include/trace/events/tlb.h:39 [inline] trace_tlb_flush+0xff/0x120 include/trace/events/tlb.h:39 switch_mm_irqs_off+0x4cc/0x700 arch/x86/mm/tlb.c:-1 context_switch kernel/sched/core.c:5269 [inline] __schedule+0x101b/0x5030 kernel/sched/core.c:6902 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7229 irqentry_exit+0x5e3/0x670 kernel/entry/common.c:216 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 __exit_to_user_mode_loop kernel/entry/common.c:31 [inline] exit_to_user_mode_loop+0x5a/0x4e0 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2c1/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: console_owner --> &p->pi_lock --> &rq->__lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&rq->__lock); lock(&p->pi_lock); lock(&rq->__lock); lock(console_owner); *** DEADLOCK *** 4 locks held by syz.6.1467/12244: #0: ffff8880b863abe0 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xba/0x150 kernel/sched/core.c:655 #1: ffffffff8e144ce0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline] #1: ffffffff8e144ce0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline] #1: ffffffff8e144ce0 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2074 [inline] #1: ffffffff8e144ce0 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run2+0x186/0x4c0 kernel/trace/bpf_trace.c:2116 #2: ffffffff8e138be0 (console_lock){+.+.}-{0:0}, at: _printk+0xcf/0x120 kernel/printk/printk.c:2453 #3: ffffffff8e020498 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:317 [inline] #3: ffffffff8e020498 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline] #3: ffffffff8e020498 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline] #3: ffffffff8e020498 (console_srcu){....}-{0:0}, at: console_flush_one_record kernel/printk/printk.c:3194 [inline] #3: ffffffff8e020498 (console_srcu){....}-{0:0}, at: console_flush_all+0x11a/0xb00 kernel/printk/printk.c:3291 stack backtrace: CPU: 1 UID: 0 PID: 12244 Comm: syz.6.1467 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868 console_lock_spinning_enable kernel/printk/printk.c:1902 [inline] console_emit_next_record kernel/printk/printk.c:3125 [inline] console_flush_one_record kernel/printk/printk.c:3217 [inline] console_flush_all+0x6bc/0xb00 kernel/printk/printk.c:3291 __console_flush_and_unlock kernel/printk/printk.c:3321 [inline] console_unlock+0xbb/0x190 kernel/printk/printk.c:3361 vprintk_emit+0x47b/0x550 kernel/printk/printk.c:2428 _printk+0xcf/0x120 kernel/printk/printk.c:2453 fail_dump lib/fault-inject.c:66 [inline] should_fail_ex+0x3f5/0x560 lib/fault-inject.c:174 strncpy_from_user+0x36/0x2c0 lib/strncpy_from_user.c:118 strncpy_from_user_nofault+0x72/0x150 mm/maccess.c:192 bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:214 [inline] ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:309 [inline] bpf_probe_read_compat_str+0xe2/0x180 kernel/trace/bpf_trace.c:305 bpf_prog_d359f1fa6cfa10c1+0x78/0x80 bpf_dispatcher_nop_func include/linux/bpf.h:1394 [inline] __bpf_prog_run include/linux/filter.h:723 [inline] bpf_prog_run include/linux/filter.h:730 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2075 [inline] bpf_trace_run2+0x284/0x4c0 kernel/trace/bpf_trace.c:2116 __bpf_trace_tlb_flush+0xf5/0x150 include/trace/events/tlb.h:39 __do_trace_tlb_flush include/trace/events/tlb.h:39 [inline] trace_tlb_flush+0xff/0x120 include/trace/events/tlb.h:39 switch_mm_irqs_off+0x4cc/0x700 arch/x86/mm/tlb.c:-1 context_switch kernel/sched/core.c:5269 [inline] __schedule+0x101b/0x5030 kernel/sched/core.c:6902 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7229 irqentry_exit+0x5e3/0x670 kernel/entry/common.c:216 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:__exit_to_user_mode_loop kernel/entry/common.c:31 [inline] RIP: 0010:exit_to_user_mode_loop+0x5a/0x4e0 kernel/entry/common.c:75 Code: 00 00 e8 19 c8 b3 09 65 48 8b 04 25 08 70 a2 92 4c 8b 30 41 f7 c6 37 03 00 00 0f 84 c7 00 00 00 e8 ab eb 1d 00 fb 41 f6 c6 30 <74> 05 e8 bf d5 b4 09 41 f7 c6 00 01 00 00 74 08 48 89 df e8 4e f4 RSP: 0018:ffffc90004d0fea0 EFLAGS: 00000202 RAX: 0000000000000329 RBX: ffffc90004d0ff48 RCX: 0000000000000046 RDX: 0000000000000000 RSI: ffffffff8d9a7414 RDI: ffffffff8be09760 RBP: ffffc90004d0ff38 R08: ffffffff8fa2d9f7 R09: 1ffffffff1f45b3e R10: dffffc0000000000 R11: fffffbfff1f45b3f R12: 00000000ffffe000 R13: 0000000000000001 R14: 0000000000080010 R15: ffff888022338000 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2c1/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6a9458e1ff Code: Unable to access opcode bytes at 0x7f6a9458e1d5. RSP: 002b:00007f6a95445030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: 0000000000000001 RBX: 0000000000000004 RCX: 00007f6a9458e1ff RDX: 0000000000000001 RSI: 00007f6a95445090 RDI: 0000000000000004 RBP: 00007f6a95445090 R08: 0000000000000000 R09: 00007f6a95444df7 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001 R13: 00007f6a947e6038 R14: 00007f6a947e5fa0 R15: 00007fffc76ce5f8 CPU: 1 UID: 0 PID: 12244 Comm: syz.6.1467 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 fail_dump lib/fault-inject.c:73 [inline] should_fail_ex+0x414/0x560 lib/fault-inject.c:174 strncpy_from_user+0x36/0x2c0 lib/strncpy_from_user.c:118 strncpy_from_user_nofault+0x72/0x150 mm/maccess.c:192 bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:214 [inline] ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:309 [inline] bpf_probe_read_compat_str+0xe2/0x180 kernel/trace/bpf_trace.c:305 bpf_prog_d359f1fa6cfa10c1+0x78/0x80 bpf_dispatcher_nop_func include/linux/bpf.h:1394 [inline] __bpf_prog_run include/linux/filter.h:723 [inline] bpf_prog_run include/linux/filter.h:730 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2075 [inline] bpf_trace_run2+0x284/0x4c0 kernel/trace/bpf_trace.c:2116 __bpf_trace_tlb_flush+0xf5/0x150 include/trace/events/tlb.h:39 __do_trace_tlb_flush include/trace/events/tlb.h:39 [inline] trace_tlb_flush+0xff/0x120 include/trace/events/tlb.h:39 switch_mm_irqs_off+0x4cc/0x700 arch/x86/mm/tlb.c:-1 context_switch kernel/sched/core.c:5269 [inline] __schedule+0x101b/0x5030 kernel/sched/core.c:6902 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7229 irqentry_exit+0x5e3/0x670 kernel/entry/common.c:216 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:__exit_to_user_mode_loop kernel/entry/common.c:31 [inline] RIP: 0010:exit_to_user_mode_loop+0x5a/0x4e0 kernel/entry/common.c:75 Code: 00 00 e8 19 c8 b3 09 65 48 8b 04 25 08 70 a2 92 4c 8b 30 41 f7 c6 37 03 00 00 0f 84 c7 00 00 00 e8 ab eb 1d 00 fb 41 f6 c6 30 <74> 05 e8 bf d5 b4 09 41 f7 c6 00 01 00 00 74 08 48 89 df e8 4e f4 RSP: 0018:ffffc90004d0fea0 EFLAGS: 00000202 RAX: 0000000000000329 RBX: ffffc90004d0ff48 RCX: 0000000000000046 RDX: 0000000000000000 RSI: ffffffff8d9a7414 RDI: ffffffff8be09760 RBP: ffffc90004d0ff38 R08: ffffffff8fa2d9f7 R09: 1ffffffff1f45b3e R10: dffffc0000000000 R11: fffffbfff1f45b3f R12: 00000000ffffe000 R13: 0000000000000001 R14: 0000000000080010 R15: ffff888022338000 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x2c1/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6a9458e1ff Code: Unable to access opcode bytes at 0x7f6a9458e1d5. RSP: 002b:00007f6a95445030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: 0000000000000001 RBX: 0000000000000004 RCX: 00007f6a9458e1ff RDX: 0000000000000001 RSI: 00007f6a95445090 RDI: 0000000000000004 RBP: 00007f6a95445090 R08: 0000000000000000 R09: 00007f6a95444df7 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001 R13: 00007f6a947e6038 R14: 00007f6a947e5fa0 R15: 00007fffc76ce5f8 ---------------- Code disassembly (best guess): 0: 00 00 add %al,(%rax) 2: e8 19 c8 b3 09 call 0x9b3c820 7: 65 48 8b 04 25 08 70 mov %gs:0xffffffff92a27008,%rax e: a2 92 10: 4c 8b 30 mov (%rax),%r14 13: 41 f7 c6 37 03 00 00 test $0x337,%r14d 1a: 0f 84 c7 00 00 00 je 0xe7 20: e8 ab eb 1d 00 call 0x1debd0 25: fb sti 26: 41 f6 c6 30 test $0x30,%r14b * 2a: 74 05 je 0x31 <-- trapping instruction 2c: e8 bf d5 b4 09 call 0x9b4d5f0 31: 41 f7 c6 00 01 00 00 test $0x100,%r14d 38: 74 08 je 0x42 3a: 48 89 df mov %rbx,%rdi 3d: e8 .byte 0xe8 3e: 4e f4 rex.WRX hlt