watchdog: BUG: soft lockup - CPU#1 stuck for 123s! [syz.8.149:6727] Modules linked in: irq event stamp: 30442783 hardirqs last enabled at (30442782): [] irqentry_exit+0x74/0x90 kernel/entry/common.c:357 hardirqs last disabled at (30442783): [] sysvec_apic_timer_interrupt+0xe/0xc0 arch/x86/kernel/apic/apic.c:1049 softirqs last enabled at (30440040): [] __do_softirq kernel/softirq.c:613 [inline] softirqs last enabled at (30440040): [] invoke_softirq kernel/softirq.c:453 [inline] softirqs last enabled at (30440040): [] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680 softirqs last disabled at (30440043): [] __do_softirq kernel/softirq.c:613 [inline] softirqs last disabled at (30440043): [] invoke_softirq kernel/softirq.c:453 [inline] softirqs last disabled at (30440043): [] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680 CPU: 1 UID: 0 PID: 6727 Comm: syz.8.149 Not tainted 6.15.0-rc4-syzkaller-gb69d4413aa19 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025 RIP: 0010:lock_release+0x2b5/0x3e0 kernel/locking/lockdep.c:5891 Code: 51 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 75 56 f7 c3 00 02 00 00 74 01 fb 65 48 8b 05 7b 20 d7 10 <48> 3b 44 24 28 0f 85 8b 00 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e RSP: 0018:ffffc90000a084b0 EFLAGS: 00000206 RAX: f9a0c0af0e053d00 RBX: 0000000000000206 RCX: f9a0c0af0e053d00 RDX: 0000000000000003 RSI: ffffffff8d935248 RDI: ffffffff8bc1cde0 RBP: ffff888024a46568 R08: ffffc9000b59f6b0 R09: 0000000000000000 R10: ffffc90000a08638 R11: fffff520001410c9 R12: 0000000000000003 R13: 0000000000000003 R14: ffffffff8df3b860 R15: ffff888024a45a00 FS: 0000000000000000(0000) GS:ffff8881261cc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000561491933470 CR3: 0000000023dec000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_lock_release include/linux/rcupdate.h:341 [inline] rcu_read_unlock include/linux/rcupdate.h:871 [inline] class_rcu_destructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0x19a9/0x2390 arch/x86/kernel/unwind_orc.c:680 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:319 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:345 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4161 [inline] slab_alloc_node mm/slub.c:4210 [inline] kmem_cache_alloc_node_noprof+0x1bb/0x3c0 mm/slub.c:4262 __alloc_skb+0x112/0x2d0 net/core/skbuff.c:658 alloc_skb include/linux/skbuff.h:1340 [inline] ndisc_alloc_skb+0x9f/0x480 net/ipv6/ndisc.c:423 ndisc_send_rs+0x2b5/0x630 net/ipv6/ndisc.c:707 addrconf_rs_timer+0x369/0x670 net/ipv6/addrconf.c:4038 call_timer_fn+0x17b/0x5f0 kernel/time/timer.c:1789 expire_timers kernel/time/timer.c:1840 [inline] __run_timers kernel/time/timer.c:2414 [inline] __run_timer_base+0x61a/0x860 kernel/time/timer.c:2426 run_timer_base kernel/time/timer.c:2435 [inline] run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2445 handle_softirqs+0x283/0x870 kernel/softirq.c:579 __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_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_is_held_type+0x137/0x190 kernel/locking/lockdep.c:5943 Code: 01 75 44 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 4c 41 f7 c4 00 02 00 00 74 01 fb 65 48 8b 05 89 64 1f 07 <48> 3b 44 24 08 75 43 89 d8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f RSP: 0018:ffffc9000b59e818 EFLAGS: 00000206 RAX: f9a0c0af0e053d00 RBX: 0000000000000000 RCX: f9a0c0af0e053d00 RDX: 0000000000000000 RSI: ffffffff8d935248 RDI: ffffffff8bc1cde0 RBP: 00000000ffffffff R08: ffffffff8f7ed377 R09: 1ffffffff1efda6e R10: dffffc0000000000 R11: fffffbfff1efda6f R12: 0000000000000246 R13: ffff888024a45a00 R14: ffffffff8df3b920 R15: 0000000000000002 lock_is_held include/linux/lockdep.h:249 [inline] schedule_debug kernel/sched/core.c:5968 [inline] __schedule+0x274/0x4cd0 kernel/sched/core.c:6666 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7090 irqentry_exit+0x6f/0x90 kernel/entry/common.c:354 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:debug_lockdep_rcu_enabled+0x2d/0x40 kernel/rcu/update.c:320 Code: fa 31 c0 83 3d 27 f6 28 04 00 74 1e 83 3d ea 23 29 04 00 74 15 65 48 8b 0c 25 08 40 75 92 31 c0 83 b9 ec 0a 00 00 00 0f 94 c0 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 RSP: 0018:ffffc9000b59ebf0 EFLAGS: 00000246 RAX: 0000000000000001 RBX: ffffffff820d9ac0 RCX: ffff888024a45a00 RDX: 0000000000000000 RSI: ffffffff8d935248 RDI: ffffffff8bc1cde0 RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff817199f5 R12: 1ffff920016b3d99 R13: ffffc9000b59ed00 R14: ffffc9000b59ecc8 R15: ffffffff817199f5 rcu_read_lock include/linux/rcupdate.h:842 [inline] class_rcu_constructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0xcb/0x2390 arch/x86/kernel/unwind_orc.c:479 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 save_stack+0xf7/0x1f0 mm/page_owner.c:156 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:308 reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1262 [inline] free_unref_folios+0xb81/0x14a0 mm/page_alloc.c:2782 folios_put_refs+0x559/0x640 mm/swap.c:992 free_pages_and_swap_cache+0x4be/0x520 mm/swap_state.c:270 __tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline] tlb_batch_pages_flush mm/mmu_gather.c:149 [inline] tlb_flush_mmu_free mm/mmu_gather.c:397 [inline] tlb_flush_mmu+0x3a0/0x680 mm/mmu_gather.c:404 zap_pte_range mm/memory.c:1770 [inline] zap_pmd_range mm/memory.c:1823 [inline] zap_pud_range mm/memory.c:1852 [inline] zap_p4d_range mm/memory.c:1873 [inline] unmap_page_range+0x37fd/0x4210 mm/memory.c:1894 unmap_vmas+0x25d/0x3c0 mm/memory.c:1984 exit_mmap+0x245/0xba0 mm/mmap.c:1284 __mmput+0x118/0x420 kernel/fork.c:1379 exit_mm+0x1da/0x2c0 kernel/exit.c:589 do_exit+0x859/0x2550 kernel/exit.c:940 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: 0033:0x7f365cf8e969 Code: Unable to access opcode bytes at 0x7f365cf8e93f. RSP: 002b:00007f365dd34038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: 0000000000000006 RBX: 00007f365d1b5fa0 RCX: 00007f365cf8e969 RDX: 0000000000109801 RSI: 0000200000000080 RDI: ffffffffffffff9c RBP: 00007f365d010ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f365d1b5fa0 R15: 00007ffc13431c08 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.15.0-rc4-syzkaller-gb69d4413aa19 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025 RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:409 Code: e8 9e 3c 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 0f 35 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:ffffc90000a87778 EFLAGS: 00000006 RAX: 1ffffffff3369705 RBX: 00000000000003f9 RCX: 0000000000000000 RDX: 00000000000003f9 RSI: 0000000000000000 RDI: 0000000000000020 RBP: ffffc90000a87950 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: ffffffff853d81e0 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: 00007fb763f27000 CR3: 000000006f2a0000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 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 check_hung_task kernel/hung_task.c:181 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:265 [inline] watchdog+0xb4f/0x1030 kernel/hung_task.c:437 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245