rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4866/2:b..l
(detected by 1, t=10502 jiffies, g=10997, q=32)
task:syz.1.188 state:R running task stack:25304 pid: 4866 ppid: 4185 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
irqentry_exit+0x63/0x70 kernel/entry/common.c:432
asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:ipv6_defrag+0x1/0x3a0 net/ipv6/netfilter/nf_defrag_ipv6_hooks.c:54
Code: e8 c4 6b 0b f9 eb a3 89 d9 80 e1 07 80 c1 03 38 c1 7c c8 48 89 df e8 1e 6c 0b f9 eb be 66 2e 0f 1f 84 00 00 00 00 00 66 90 55 <41> 57 41 56 41 55 41 54 53 48 83 ec 10 49 89 d7 48 89 f3 48 bd 00
RSP: 0018:ffffc900032d6d60 EFLAGS: 00000246
RAX: 1ffff110049a83c2 RBX: ffff888024d41e10 RCX: ffff888020b88000
RDX: ffffc900032d6e20 RSI: ffff88802a652a00 RDI: 0000000000000000
RBP: dffffc0000000000 R08: dffffc0000000000 R09: 1ffffffff203a818
R10: dffffc0000000000 R11: fffffbfff203a819 R12: 0000000000000000
R13: ffff888024d41e08 R14: ffffffff88b2c0c0 R15: ffffc900032d6e20
nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
nf_hook_slow+0xb9/0x200 net/netfilter/core.c:584
nf_hook+0x205/0x360 include/linux/netfilter.h:257
NF_HOOK include/linux/netfilter.h:300 [inline]
ip6_xmit+0xfc9/0x16d0 net/ipv6/ip6_output.c:338
sctp_v6_xmit+0x985/0x11b0 net/sctp/ipv6.c:250
sctp_packet_transmit+0x239c/0x2910 net/sctp/output.c:652
sctp_packet_singleton+0x231/0x330 net/sctp/outqueue.c:780
sctp_outq_flush_ctrl net/sctp/outqueue.c:911 [inline]
sctp_outq_flush+0x4ac/0x3100 net/sctp/outqueue.c:1209
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:-1 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1199 [inline]
sctp_do_sm+0x4ee2/0x55f0 net/sctp/sm_sideeffect.c:1170
sctp_primitive_ASSOCIATE+0x91/0xc0 net/sctp/primitive.c:73
sctp_sendmsg_to_asoc+0x14a7/0x1d90 net/sctp/socket.c:1840
sctp_sendmsg+0x196a/0x2900 net/sctp/socket.c:2030
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
__sys_sendto+0x46d/0x620 net/socket.c:2072
__do_sys_sendto net/socket.c:2084 [inline]
__se_sys_sendto net/socket.c:2080 [inline]
__x64_sys_sendto+0xda/0xf0 net/socket.c:2080
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
RIP: 0033:0x7f36f276b819
RSP: 002b:00007f36f09c5028 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f36f29e4fa0 RCX: 00007f36f276b819
RDX: 0000000000000001 RSI: 0000200000000400 RDI: 0000000000000003
RBP: 00007f36f2801c91 R08: 0000200000000100 R09: 000000000000001c
R10: 0000000000008010 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f36f29e5038 R14: 00007f36f29e4fa0 R15: 00007ffdb1e007b8
rcu: rcu_preempt kthread starved for 10461 jiffies! g10997 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:I stack:27760 pid: 15 ppid: 2 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6571
preempt_schedule+0xbc/0xd0 kernel/sched/core.c:6596
preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
_raw_spin_unlock_irqrestore+0x10d/0x120 kernel/locking/spinlock.c:194
prepare_to_swait_event+0x331/0x350 kernel/sched/swait.c:120
rcu_gp_fqs_loop+0x289/0x11d0 kernel/rcu/tree.c:1972
rcu_gp_kthread+0x9b/0x370 kernel/rcu/tree.c:2145
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 4848 Comm: syz.0.183 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
print_other_cpu_stall+0x1110/0x1270 kernel/rcu/tree_stall.h:592
check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
rcu_pending kernel/rcu/tree.c:3936 [inline]
rcu_sched_clock_irq+0x843/0x1120 kernel/rcu/tree.c:2619
update_process_times+0x193/0x200 kernel/time/timer.c:2021
tick_sched_handle kernel/time/tick-sched.c:254 [inline]
tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x4b4/0xb70 kernel/time/hrtimer.c:1749
hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
__sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 be a9 97 f7 48 89 df e8 f6 81 98 f7 e8 61 74 b9 f7 fb bf 01 00 00 00 a6 89 8c f7 65 8b 05 47 97 3c 76 85 c0 74 02 5b c3 e8 94 a4 3a
RSP: 0018:ffffc9000349fbc0 EFLAGS: 00000282
RAX: 10b1ff499383ed00 RBX: ffff88807a9f6f00 RCX: 10b1ff499383ed00
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffff88807a9f6f03 R09: 1ffff1100f53ede0
R10: dffffc0000000000 R11: ffffed100f53ede1 R12: ffff88807a9f6f00
R13: 0000000000000021 R14: dffffc0000000000 R15: 000000001c000004
spin_unlock_irq include/linux/spinlock.h:414 [inline]
get_signal+0x11d6/0x12c0 kernel/signal.c:2903
arch_do_signal_or_restart+0xe7/0x12c0 arch/x86/kernel/signal.c:867
handle_signal_work kernel/entry/common.c:154 [inline]
exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
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: 0033:0x7f89a2df4817
Code: 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89
RSP: 002b:00007f89a104e0e8 EFLAGS: 00000246
RAX: 00000000000000ca RBX: 00007f89a306dfa8 RCX: 00007f89a2df4819
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f89a306dfa8
RBP: 00007f89a306dfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f89a306e038 R14: 00007ffd87b081d0 R15: 00007ffd87b082b8