syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=0814/1/0x4000000000000000 softirq=17439/17440 fqs=1
rcu: 	(detected by 0, t=10502 jiffies, g=12129, q=289 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 36 Comm: kworker/u8:2 Not tainted 6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:qdisc_dev include/net/sch_generic.h:574 [inline]
RIP: 0010:advance_sched+0x80/0xc90 net/sched/sch_taprio.c:916
Code: 00 fc ff df 80 3c 08 00 74 08 48 89 df e8 d8 df 94 f8 48 8b 1b 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 <74> 08 48 89 df e8 b6 df 94 f8 48 8b 1b 48 83 c3 36 48 89 d8 48 c1
RSP: 0018:ffffc90000a07dd0 EFLAGS: 00000046
RAX: 1ffff11004969000 RBX: ffff888024b48000 RCX: dffffc0000000000
RDX: 0000000000010100 RSI: 0000000000000000 RDI: ffff8880284fc340
RBP: ffffc90000a07fe8 R08: ffffffff8fa1f5f7 R09: 1ffffffff1f43ebe
R10: dffffc0000000000 R11: ffffffff898ed350 R12: ffff8880284fc340
R13: ffff8880284fc000 R14: dffffc0000000000 R15: ffff88801d2e64d8
FS:  0000000000000000(0000) GS:ffff888125d1b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5e8928ea10 CR3: 00000000761fc000 CR4: 0000000000350ef0
Call Trace:
 <IRQ>
 __run_hrtimer kernel/time/hrtimer.c:1761 [inline]
 __hrtimer_run_queues+0x52c/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:1039 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1050
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:210
Code: 89 fb e8 23 00 00 00 48 8b 3d c4 d0 fb 0b 48 89 de 5b e9 13 b9 58 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 8b 04 24 65 48 8b 0c 25 08 50 a0 92 65 8b 15 a8 1c
RSP: 0018:ffffc90000a08218 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88801d2e5a00
RDX: 0000000000000100 RSI: 00000000fffffffd RDI: 00000000fffffffd
RBP: ffffc90000a08378 R08: ffffc90000a084a0 R09: ffffc90000a084b0
R10: dffffc0000000000 R11: fffff52000141062 R12: 1ffff1100538510c
R13: ffff888029c288c0 R14: ffff888029c28800 R15: ffff888029c288c8
 __find_rr_leaf+0x2f9/0x6d0 net/ipv6/route.c:873
 find_rr_leaf net/ipv6/route.c:890 [inline]
 rt6_select net/ipv6/route.c:934 [inline]
 fib6_table_lookup+0x39f/0xa80 net/ipv6/route.c:2232
 ip6_pol_route+0x222/0x1180 net/ipv6/route.c:2268
 pol_lookup_func include/net/ip6_fib.h:617 [inline]
 fib6_rule_lookup+0x52f/0x6f0 net/ipv6/fib6_rules.c:120
 ip6_route_input_lookup net/ipv6/route.c:2337 [inline]
 ip6_route_input+0x6ce/0xa50 net/ipv6/route.c:2640
 ip6_rcv_finish+0x141/0x2d0 net/ipv6/ip6_input.c:77
 NF_HOOK+0x30c/0x3a0 include/linux/netfilter.h:317
 __netif_receive_skb_one_core net/core/dev.c:5977 [inline]
 __netif_receive_skb+0xd3/0x380 net/core/dev.c:6090
 process_backlog+0x60e/0x14f0 net/core/dev.c:6442
 __napi_poll+0xc7/0x480 net/core/dev.c:7414
 napi_poll net/core/dev.c:7478 [inline]
 net_rx_action+0x707/0xe30 net/core/dev.c:7605
 handle_softirqs+0x286/0x870 kernel/softirq.c:579
 do_softirq+0xec/0x180 kernel/softirq.c:480
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x17d/0x1c0 kernel/softirq.c:407
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:910 [inline]
 __dev_queue_xmit+0x1cd7/0x3a70 net/core/dev.c:4740
 neigh_output include/net/neighbour.h:539 [inline]
 ip6_finish_output2+0x11fe/0x16a0 net/ipv6/ip6_output.c:141
 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline]
 ip6_finish_output+0x234/0x7d0 net/ipv6/ip6_output.c:226
 NF_HOOK include/linux/netfilter.h:317 [inline]
 ndisc_send_skb+0xb47/0x1400 net/ipv6/ndisc.c:513
 ndisc_send_ns+0xcb/0x150 net/ipv6/ndisc.c:671
 addrconf_dad_work+0xaae/0x14b0 net/ipv6/addrconf.c:4281
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: rcu_preempt kthread starved for 10500 jiffies! g12129 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:27128 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5397 [inline]
 __schedule+0x16f5/0x4d00 kernel/sched/core.c:6786
 __schedule_loop kernel/sched/core.c:6864 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6879
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2054
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2256
 kthread+0x711/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 6043 Comm: sed Not tainted 6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline]
RIP: 0010:smp_call_function_many_cond+0xf69/0x12d0 kernel/smp.c:885
Code: 00 45 8b 2f 44 89 ee 83 e6 01 31 ff e8 d0 78 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 7b 74 0b 00 eb 37 f3 90 <43> 0f b6 04 2c 84 c0 75 10 41 f7 07 01 00 00 00 74 1e e8 60 74 0b
RSP: 0018:ffffc9000402f6e0 EFLAGS: 00000293
RAX: ffffffff81b4bf10 RBX: ffff8880b863b1c0 RCX: ffff88802b67da00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000402f840 R08: ffffffff8fa1f5f7 R09: 1ffffffff1f43ebe
R10: dffffc0000000000 R11: fffffbfff1f43ebf R12: 1ffff110170e7f5d
R13: dffffc0000000000 R14: 0000000000000001 R15: ffff8880b873fae8
FS:  0000000000000000(0000) GS:ffff888125c1b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4861bbe368 CR3: 000000000df38000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
 flush_tlb_mm_range+0x6b1/0x12c0 arch/x86/mm/tlb.c:1451
 tlb_flush arch/x86/include/asm/tlb.h:23 [inline]
 tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:490 [inline]
 tlb_flush_mmu+0x1a7/0x680 mm/mmu_gather.c:403
 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:497
 exit_mmap+0x44c/0xb50 mm/mmap.c:1297
 __mmput+0x118/0x420 kernel/fork.c:1121
 exit_mm+0x1da/0x2c0 kernel/exit.c:581
 do_exit+0x648/0x22e0 kernel/exit.c:952
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1105
 __do_sys_exit_group kernel/exit.c:1116 [inline]
 __se_sys_exit_group kernel/exit.c:1114 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1114
 x64_sys_call+0x21ba/0x21c0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5e893be6c5
Code: Unable to access opcode bytes at 0x7f5e893be69b.
RSP: 002b:00007fff2e137de8 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f5e894bffe8 RCX: 00007f5e893be6c5
RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5e894be680 R15: 00007f5e894c0000
 </TASK>