syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3529/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=12969, q=106 ncpus=2)
task:kworker/u4:12   state:R  running task     stack:24464 pid:3529  ppid:2      flags:0x00004000
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:__fib6_clean_all+0x2d9/0x3e0 net/ipv6/ip6_fib.c:2279
Code: f8 48 c1 e8 03 42 80 3c 30 00 74 08 4c 89 ff e8 ed cf 9d f8 4d 8b 3f 4d 85 ff 0f 85 09 ff ff ff e8 ac 98 45 f8 4c 8b 74 24 40 <49> ff c6 49 81 fe 00 01 00 00 48 8b 5c 24 38 74 0a e8 91 98 45 f8
RSP: 0018:ffffc9000d297760 EFLAGS: 00000293
RAX: ffffffff89418853 RBX: ffff8880258f2a80 RCX: ffff88802e2f1e00
RDX: 0000000000000000 RSI: ffffffff8b1c8fc0 RDI: ffffffff8b1c8f80
RBP: ffffc9000d2978d0 R08: dffffc0000000000 R09: 1ffffffff2238ca0
R10: dffffc0000000000 R11: fffffbfff2238ca1 R12: 1ffff92001a52ef8
R13: 00000000000001f5 R14: 000000000000009a R15: 0000000000000000
 fib6_flush_trees+0x148/0x1a0 net/ipv6/ip6_fib.c:2308
 rt_genid_bump_ipv6 include/net/net_namespace.h:543 [inline]
 addrconf_dad_completed+0x578/0xd90 net/ipv6/addrconf.c:4356
 addrconf_dad_work+0xc90/0x1530 net/ipv6/addrconf.c:-1
 process_one_work kernel/workqueue.c:2653 [inline]
 process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2730
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2811
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: rcu_preempt kthread starved for 10528 jiffies! g12969 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:R  running task     stack:27656 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 5974 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202
Code: 00 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 ea 87 d8 f6 48 89 df e8 a2 5c d9 f6 e8 1d 6f fd f6 fb bf 01 00 00 00 <e8> 82 63 cc f6 65 8b 05 c3 90 73 75 85 c0 74 02 5b c3 e8 40 78 70
RSP: 0018:ffffc90000007cb0 EFLAGS: 00000282
RAX: 68ab83040a19d500 RBX: ffff8880b8e29580 RCX: 68ab83040a19d500
RDX: dffffc0000000000 RSI: ffffffff8acac9e0 RDI: 0000000000000001
RBP: ffffc90000007e10 R08: ffffffff911c6617 R09: 1ffffffff2238cc2
R10: dffffc0000000000 R11: fffffbfff2238cc3 R12: ffff8880b8e29580
R13: 1ffff110171c52b8 R14: ffff8880266be700 R15: ffffc90000007d60
FS:  00005555864a2500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b34963fff CR3: 000000001f32c000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 expire_timers kernel/time/timer.c:1751 [inline]
 __run_timers+0x533/0x800 kernel/time/timer.c:2023
 run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:generic_exec_single+0x481/0x4f0 kernel/smp.c:418
Code: 75 11 e8 42 05 0b 00 48 85 db 75 16 e8 38 05 0b 00 eb 15 e8 31 05 0b 00 e8 0c 5e 0a 09 48 85 db 74 ea e8 22 05 0b 00 fb 31 c0 <48> c7 44 24 20 0e 36 e0 45 4b c7 04 2c 00 00 00 00 43 c7 44 2c 08
RSP: 0018:ffffc900032e7a00 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000200 RCX: ffff888030e45a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900032e7ad0 R08: ffffffff911c6617 R09: 1ffffffff2238cc2
R10: dffffc0000000000 R11: fffffbfff2238cc3 R12: 1ffff9200065cf44
R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff9200065cf65
 smp_call_function_single+0x36d/0x5a0 kernel/smp.c:647
 task_function_call kernel/events/core.c:120 [inline]
 perf_install_in_context+0x5be/0x920 kernel/events/core.c:2959
 __do_sys_perf_event_open kernel/events/core.c:12957 [inline]
 __se_sys_perf_event_open+0x1836/0x1c50 kernel/events/core.c:12609
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f75f719cdd9
Code: 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 01 48
RSP: 002b:00007fff038c82d8 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 00007f75f7415fa0 RCX: 00007f75f719cdd9
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 0000200000000140
RBP: 00007f75f7232d69 R08: 0000000000000002 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f75f7415fac R14: 00007f75f7415fa0 R15: 00007f75f7415fa0
 </TASK>