kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
watchdog: BUG: soft lockup - CPU#0 stuck for 226s! [kworker/0:4:756]
Modules linked in:
CPU: 0 PID: 756 Comm: kworker/0:4 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events fqdir_free_fn
RIP: 0010:csd_lock_wait kernel/smp.c:453 [inline]
RIP: 0010:smp_call_function_single+0x1fd/0x470 kernel/smp.c:787
Code: ff e8 37 77 09 00 41 83 e6 01 49 bc 00 00 00 00 00 fc ff df 75 0a e8 02 73 09 00 e9 a9 00 00 00 f3 90 f7 44 24 48 01 00 00 00 <0f> 84 94 00 00 00 e8 e8 72 09 00 eb e9 e8 81 0f 87 03 89 c3 41 89
RSP: 0018:ffffc9000e1d7b60 EFLAGS: 00000202
RAX: ffffffff8166b6d8 RBX: 0000000000000000 RCX: ffff888110100000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000e1d7c50 R08: dffffc0000000000 R09: fffff52001c3af45
R10: 0000000000000000 R11: ffffffff81343830 R12: dffffc0000000000
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff92001c3af70
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffa CR3: 000000013016b000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000602
Call Trace:
 <TASK>
 rcu_barrier+0x32e/0x600 kernel/rcu/tree.c:4126
 fqdir_free_fn+0x32/0x140 net/ipv4/inet_fragment.c:168
 process_one_work+0x71f/0xc40 kernel/workqueue.c:2302
 process_scheduled_works kernel/workqueue.c:2365 [inline]
 worker_thread+0xd2e/0x11f0 kernel/workqueue.c:2451
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 15 Comm: rcub/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:native_halt arch/x86/include/asm/irqflags.h:57 [inline]
RIP: 0010:halt arch/x86/include/asm/irqflags.h:98 [inline]
RIP: 0010:kvm_wait+0xcc/0x140 arch/x86/kernel/kvm.c:1058
Code: 20 f6 44 24 21 02 75 24 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 48 0f b6 07 40 38 f0 75 a6 66 90 0f 00 2d 95 96 13 04 f4 <eb> 9a fa 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 3f 0f b6 07
RSP: 0018:ffffc900000f73e0 EFLAGS: 00000046
RAX: 0000000000000003 RBX: ffff88810fe9a140 RCX: ffffffff84f48de2
RDX: dffffc0000000000 RSI: 0000000000000003 RDI: ffff88810fe9a140
RBP: ffffc900000f7470 R08: dffffc0000000000 R09: ffffed1021fd3429
R10: ffffed1021fd3429 R11: 1ffff11021fd3428 R12: 1ffff1103ee20001
R13: ffff8881f7138cf4 R14: dffffc0000000000 R15: 1ffff9200001ee7c
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffa CR3: 0000000113cfe000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 pv_wait arch/x86/include/asm/paravirt.h:603 [inline]
 pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
 __pv_queued_spin_lock_slowpath+0x690/0xc40 kernel/locking/qspinlock.c:511
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
 queued_spin_lock_slowpath+0x47/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock include/linux/spinlock.h:187 [inline]
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
 _raw_spin_lock_irqsave+0x108/0x110 kernel/locking/spinlock.c:162
 __queue_map_get+0xe4/0x3d0 kernel/bpf/queue_stack_maps.c:109
 queue_map_peek_elem+0x1f/0x30 kernel/bpf/queue_stack_maps.c:171
 bpf_prog_00798911c748094f+0x3a/0x3e
 bpf_dispatcher_nop_func include/linux/bpf.h:987 [inline]
 __bpf_prog_run include/linux/filter.h:596 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2283 [inline]
 bpf_trace_run2+0x1a7/0x250 kernel/trace/bpf_trace.c:2322
 __bpf_trace_contention_end+0xb/0x10 include/trace/events/lock.h:122
 __traceiter_contention_end+0x8c/0xc0 include/trace/events/lock.h:122
 trace_contention_end include/trace/events/lock.h:122 [inline]
 __pv_queued_spin_lock_slowpath+0xbff/0xc40 kernel/locking/qspinlock.c:560
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
 queued_spin_lock_slowpath+0x47/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock include/linux/spinlock.h:187 [inline]
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
 _raw_spin_lock_irqsave+0x108/0x110 kernel/locking/spinlock.c:162
 __queue_map_get+0xe4/0x3d0 kernel/bpf/queue_stack_maps.c:109
 queue_map_peek_elem+0x1f/0x30 kernel/bpf/queue_stack_maps.c:171
 bpf_prog_00798911c748094f+0x3a/0x3e
 bpf_dispatcher_nop_func include/linux/bpf.h:987 [inline]
 __bpf_prog_run include/linux/filter.h:596 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2283 [inline]
 bpf_trace_run2+0x1a7/0x250 kernel/trace/bpf_trace.c:2322
 __bpf_trace_contention_end+0xb/0x10 include/trace/events/lock.h:122
 __traceiter_contention_end+0x8c/0xc0 include/trace/events/lock.h:122
 trace_contention_end include/trace/events/lock.h:122 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1659 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1674 [inline]
 rt_mutex_slowlock+0x3e3/0x400 kernel/locking/rtmutex.c:1703
 __rt_mutex_lock kernel/locking/rtmutex.c:1715 [inline]
 __rt_mutex_lock_common kernel/locking/rtmutex_api.c:31 [inline]
 rt_mutex_lock+0x102/0x1b0 kernel/locking/rtmutex_api.c:73
 rcu_boost kernel/rcu/tree_plugin.h:1114 [inline]
 rcu_boost_kthread+0x239/0x650 kernel/rcu/tree_plugin.h:1139
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>