watchdog: BUG: soft lockup - CPU#1 stuck for 123s! [syz.0.738:8693] Modules linked in: irq event stamp: 27799313 hardirqs last enabled at (27799312): [] handle_softirqs+0x1a8/0x870 kernel/softirq.c:563 hardirqs last disabled at (27799313): [] sysvec_apic_timer_interrupt+0xe/0xc0 arch/x86/kernel/apic/apic.c:1049 softirqs last enabled at (27799308): [] __do_softirq kernel/softirq.c:613 [inline] softirqs last enabled at (27799308): [] invoke_softirq kernel/softirq.c:453 [inline] softirqs last enabled at (27799308): [] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680 softirqs last disabled at (27799311): [] __do_softirq kernel/softirq.c:613 [inline] softirqs last disabled at (27799311): [] invoke_softirq kernel/softirq.c:453 [inline] softirqs last disabled at (27799311): [] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680 CPU: 1 UID: 0 PID: 8693 Comm: syz.0.738 Not tainted 6.15.0-rc4-syzkaller-gb4432656b36e #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:variable_ffs arch/x86/include/asm/bitops.h:321 [inline] RIP: 0010:handle_softirqs+0x1b0/0x870 kernel/softirq.c:567 Code: 89 64 24 30 0f b7 db 48 c7 c7 00 89 69 8b e8 07 38 d0 09 65 66 c7 05 45 85 ef 10 00 00 e8 38 81 41 00 fb 49 c7 c7 c0 c0 c0 8d ff ff ff ff 0f bc c3 41 89 c5 41 ff c5 0f 84 c2 03 00 00 89 5c RSP: 0018:ffffc90000a08e40 EFLAGS: 00000286 RAX: 0fa44ddd2ead7c00 RBX: 0000000000000200 RCX: 0fa44ddd2ead7c00 RDX: 0000000000000002 RSI: ffffffff8d749f78 RDI: ffffffff8bc1cde0 RBP: ffffc90000a08f50 R08: ffffffff8f7ed377 R09: 1ffffffff1efda6e R10: dffffc0000000000 R11: fffffbfff1efda6f R12: 000000000000000a R13: 0000000000000000 R14: dffffc0000000000 R15: ffffffff8dc0c0c0 FS: 0000555583d32500(0000) GS:ffff8881261cc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffdfa50000 CR3: 0000000034290000 CR4: 00000000003526f0 DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline] sysvec_irq_work+0xa3/0xc0 arch/x86/kernel/irq_work.c:17 asm_sysvec_irq_work+0x1a/0x20 arch/x86/include/asm/idtentry.h:738 RIP: 0010:rcu_read_unlock_special+0x87/0x4c0 kernel/rcu/tree_plugin.h:694 Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 e2 a3 cd 10 41 f7 c6 00 00 f0 00 74 49 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b RSP: 0018:ffffc9000f33fc20 EFLAGS: 00000206 RAX: 0fa44ddd2ead7c00 RBX: 1ffff92001e67f8c RCX: 0fa44ddd2ead7c00 RDX: 0000000000000006 RSI: ffffffff8d749f78 RDI: ffffffff8bc1cde0 RBP: ffffc9000f33fd10 R08: ffffffff8f7ed377 R09: 1ffffffff1efda6e R10: dffffc0000000000 R11: fffffbfff1efda6f R12: 0000000000000000 R13: dffffc0000000000 R14: 0000000000000246 R15: ffffffff8df40ca0 __rcu_read_unlock+0x84/0xe0 kernel/rcu/tree_plugin.h:438 dput+0x197/0x2b0 fs/dcache.c:901 __fput+0x68e/0xa70 fs/file_table.c:473 task_work_run+0x1d1/0x260 kernel/task_work.c:227 resume_user_mode_work+0x5e/0x80 include/linux/resume_user_mode.h:50 exit_to_user_mode_loop kernel/entry/common.c:114 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x9a/0x120 kernel/entry/common.c:218 do_syscall_64+0x103/0x210 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f196858e969 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:00007ffe638d8028 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 0000000000041a19 RCX: 00007f196858e969 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f19687b7ba0 R08: 0000000000000001 R09: 00000019638d831f R10: 00007f1968400000 R11: 0000000000000246 R12: 00007f19687b5fac R13: 00007f19687b5fa0 R14: ffffffffffffffff R15: 00007ffe638d8140 Sending NMI from CPU 1 to CPUs 0: rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 8665 Comm: syz.2.730 Not tainted 6.15.0-rc4-syzkaller-gb4432656b36e #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:409 Code: e8 1e 40 82 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 ff 34 e4 fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 cc cc cc cc cc 44 89 f9 80 e1 07 RSP: 0018:ffffc90000007438 EFLAGS: 00000006 RAX: 1ffffffff3369705 RBX: 00000000000003f9 RCX: 0000000000000000 RDX: 00000000000003f9 RSI: 0000000000000000 RDI: 0000000000000020 RBP: ffffc90000007610 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: ffffffff853d7e60 R12: dffffc0000000000 R13: dffffc0000000000 R14: ffffffff99b4bbc0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881260cc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffdfa50000 CR3: 00000000607b4000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000082 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: serial_port_in include/linux/serial_core.h:791 [inline] serial8250_console_write+0x581/0x1ba0 drivers/tty/serial/8250/8250_port.c:3420 console_emit_next_record kernel/printk/printk.c:3138 [inline] console_flush_all+0x725/0xc40 kernel/printk/printk.c:3226 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline] console_unlock+0xc4/0x270 kernel/printk/printk.c:3325 vprintk_emit+0x5b7/0x7a0 kernel/printk/printk.c:2450 _printk+0xcf/0x120 kernel/printk/printk.c:2475 print_other_cpu_stall+0x189/0x1370 kernel/rcu/tree_stall.h:598 check_cpu_stall kernel/rcu/tree_stall.h:795 [inline] rcu_pending kernel/rcu/tree.c:3630 [inline] rcu_sched_clock_irq+0x9cb/0x1080 kernel/rcu/tree.c:2669 update_process_times+0x23c/0x2f0 kernel/time/timer.c:2515 tick_sched_handle kernel/time/tick-sched.c:276 [inline] tick_nohz_handler+0x39a/0x520 kernel/time/tick-sched.c:297 __run_hrtimer kernel/time/hrtimer.c:1761 [inline] __hrtimer_run_queues+0x4dd/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline] __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1055 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:430 [inline] RIP: 0010:__pv_queued_spin_lock_slowpath+0x6ce/0xb60 kernel/locking/qspinlock.c:325 Code: ff ff 66 c7 84 24 90 00 00 00 00 01 48 b8 00 00 00 00 00 fc ff df 48 8b 4c 24 20 0f b6 04 01 84 c0 75 46 80 3b 00 74 09 f3 90 <41> ff c6 75 d3 eb 4b 48 89 df be 02 00 00 00 e8 3e 3a c9 f6 48 8d RSP: 0018:ffffc9000e3af740 EFLAGS: 00000206 RAX: 0000000000000000 RBX: ffff888148c7b7d8 RCX: 1ffff1102918f6fb RDX: 0000000000000000 RSI: ffffffff8d749f78 RDI: ffff8880b883aa94 RBP: ffffc9000e3af858 R08: ffffffff8f7ed377 R09: 1ffffffff1efda6e R10: dffffc0000000000 R11: fffffbfff1efda6f R12: 1ffffffff1bb48a4 R13: 0000000000000000 R14: 00000000ffffb36f R15: 1ffff1102918f6fb pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:572 [inline] queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x21f/0x290 kernel/locking/spinlock_debug.c:116 spin_lock include/linux/spinlock.h:351 [inline] lock_for_kill+0xdc/0x210 fs/dcache.c:710 dput+0x18a/0x2b0 fs/dcache.c:900 __fput+0x68e/0xa70 fs/file_table.c:473 task_work_run+0x1d1/0x260 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x8d6/0x2550 kernel/exit.c:953 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102 get_signal+0x125e/0x1310 kernel/signal.c:3034 arch_do_signal_or_restart+0x95/0x780 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x8b/0x120 kernel/entry/common.c:218 do_syscall_64+0x103/0x210 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f86f6f8e969 Code: Unable to access opcode bytes at 0x7f86f6f8e93f. RSP: 002b:00007f86f7d32038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: fffffffffffffffc RBX: 00007f86f71b5fa0 RCX: 00007f86f6f8e969 RDX: 0000000000000048 RSI: 0000200000000600 RDI: 000000000000000a RBP: 00007f86f7010ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f86f71b5fa0 R15: 00007fff7ee758b8