INFO: rcu detected stall in addrconf_dad_work

Status: upstream: reported C repro on 2024/11/22 07:19
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+fd6143dd441e0102ac4b@syzkaller.appspotmail.com
First crash: 618d, last: 204d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2024/11/23 upstream (ToT) 42d9e8b7ccdd C [report] INFO: rcu detected stall in tc_modify_qdisc
▶ ▼ Similar bugs (12)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in addrconf_dad_work (5) prio:low net 1 syz, C done inconclusive 20 65d 2155d 0/29 upstream: reported C repro on 2020/09/07 15:59
upstream INFO: rcu detected stall in addrconf_dad_work (4) mm cgroups 1 8 2398d 2398d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in addrconf_dad_work (3) mm 1 6 2398d 2398d 0/29 closed as invalid on 2020/01/08 05:23
linux-4.14 INFO: rcu detected stall in addrconf_dad_work 1 syz, C done 18 2515d 2521d 1/1 fixed on 2019/12/06 10:33
upstream INFO: rcu detected stall in addrconf_dad_work (2) mm 1 15 2433d 2435d 0/29 closed as invalid on 2019/12/04 14:14
upstream INFO: rcu detected stall in addrconf_dad_work 1 syz, C done 126 2513d 2518d 13/29 fixed on 2019/10/09 10:54
linux-4.19 INFO: rcu detected stall in addrconf_dad_work (2) 1 syz, C done 1 2417d 2417d 1/1 fixed on 2020/01/19 15:05
linux-5.15 INFO: rcu detected stall in addrconf_dad_work origin:lts-only 1 syz done 5 380d 701d 0/3 upstream: reported syz repro on 2024/09/01 00:22
linux-4.19 INFO: rcu detected stall in addrconf_dad_work 1 syz, C done 19 2509d 2521d 1/1 fixed on 2019/12/07 19:18
linux-5.15 BUG: soft lockup in addrconf_dad_work 1 1 1112d 1112d 0/3 auto-obsoleted due to no activity on 2023/10/25 16:01
linux-4.19 BUG: soft lockup in addrconf_dad_work 1 syz, C error 55 1290d 1631d 0/1 upstream: reported C repro on 2022/02/13 10:05
android-5-15 BUG: soft lockup in addrconf_dad_work 1 3 772d 827d 0/2 auto-obsoleted due to no activity on 2024/09/19 17:30
▶ ▼ Fix bisection attempts (12)
Created Duration User Patch Repo Result
2026/02/09 08:44 3m bisect fix linux-6.1.y error job log
2025/12/26 04:09 2h28m bisect fix linux-6.1.y OK (0) job log log
2025/11/21 18:54 4h43m bisect fix linux-6.1.y OK (0) job log log
2025/10/20 22:06 1h46m bisect fix linux-6.1.y OK (0) job log log
2025/09/15 13:58 1h56m bisect fix linux-6.1.y OK (0) job log log
2025/08/08 22:53 1h49m bisect fix linux-6.1.y OK (0) job log log
2025/07/08 10:17 1h40m bisect fix linux-6.1.y OK (0) job log log
2025/06/07 22:45 2h01m bisect fix linux-6.1.y OK (0) job log log
2025/05/08 02:34 2h45m bisect fix linux-6.1.y OK (0) job log log
2025/04/06 17:05 1h55m bisect fix linux-6.1.y OK (0) job log log
2025/02/13 22:14 1h40m bisect fix linux-6.1.y OK (0) job log log
2025/01/11 00:05 2h07m bisect fix linux-6.1.y OK (0) job log log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=2a34/1/0x4000000000000000 softirq=10327/10328 fqs=0
	(detected by 0, t=10506 jiffies, g=10653, q=23 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4307 Comm: kworker/1:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
RIP: 0010:_raw_spin_lock_irqsave+0x9f/0xf0 kernel/locking/spinlock.c:162
Code: 02 00 00 74 05 e8 d1 c3 6c f7 bf 01 00 00 00 e8 07 45 3d f7 48 8d 7b 18 31 f6 31 d2 31 c9 41 b8 01 00 00 00 45 31 c9 ff 75 08 <e8> 5c 86 48 f7 48 83 c4 08 48 89 df e8 d0 c9 49 f7 48 c7 04 24 0e
RSP: 0018:ffffc900001e0bf8 EFLAGS: 00000046
RAX: 0000000000010003 RBX: ffffffff96c07180 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff96c07198
RBP: ffffc900001e0c88 R08: 0000000000000001 R09: 0000000000000000
R10: ffffed1005d4b86b R11: 1ffff11005d4b868 R12: dffffc0000000000
R13: ffffffff96c07178 R14: 0000000000000802 R15: 1ffff9200003c180
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000300 CR3: 0000000026a91000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 debug_object_deactivate+0x63/0x340 lib/debugobjects.c:753
 debug_hrtimer_deactivate kernel/time/hrtimer.c:453 [inline]
 debug_deactivate+0x29/0x240 kernel/time/hrtimer.c:509
 __run_hrtimer kernel/time/hrtimer.c:1715 [inline]
 __hrtimer_run_queues+0x2df/0xd60 kernel/time/hrtimer.c:1811
 hrtimer_interrupt+0x3c5/0x9c0 kernel/time/hrtimer.c:1873
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:49 [inline]
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:178 [inline]
RIP: 0010:unwind_next_frame+0x1380/0x20b0 arch/x86/kernel/unwind_orc.c:448
Code: 0f b6 04 08 84 c0 75 27 49 63 06 4c 01 f0 49 8d 4e 04 48 39 e8 4c 0f 46 e9 49 8d 46 fc 4c 0f 47 e0 4d 0f 46 fe 4d 39 e5 76 a8 <e9> d6 ee ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 7c cc 4c 89 f7 48
RSP: 0018:ffffc90004407410 EFLAGS: 00000202
RAX: ffffffff8e66022c RBX: ffffc900044074e8 RCX: ffffffff8e660234
RDX: ffffffff8f011e12 RSI: ffffffff8e660230 RDI: ffffffff8138655f
RBP: ffffffff88dc7f6d R08: 0000000000000001 R09: 0000000000000006
R10: fffff52000880ea9 R11: 1ffff92000880ea7 R12: ffffffff8e660230
R13: ffffffff8e660234 R14: ffffffff8e660230 R15: ffffffff8e660230
 arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 __kasan_slab_alloc+0x6b/0x80 mm/kasan/common.c:328
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4b/0x480 mm/slab.h:737
 slab_alloc_node mm/slub.c:3359 [inline]
 kmem_cache_alloc_node+0x14d/0x320 mm/slub.c:3404
 __alloc_skb+0xfc/0x7e0 net/core/skbuff.c:505
 alloc_skb include/linux/skbuff.h:1271 [inline]
 ndisc_alloc_skb+0xa6/0x450 net/ipv6/ndisc.c:423
 ndisc_ns_create+0x1ce/0x620 net/ipv6/ndisc.c:626
 ndisc_send_ns+0xab/0x150 net/ipv6/ndisc.c:668
 addrconf_dad_work+0xa15/0x14d0 net/ipv6/addrconf.c:4219
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: rcu_preempt kthread starved for 10506 jiffies! g10653 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:27840 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 4421 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:csd_lock_wait kernel/smp.c:424 [inline]
RIP: 0010:smp_call_function_many_cond+0xe7b/0x1270 kernel/smp.c:998
Code: 00 00 00 41 8b 1f 89 de 83 e6 01 31 ff e8 5d d9 0a 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 e9 d5 0a 00 eb 37 f3 90 <41> 0f b6 04 1c 84 c0 75 10 41 f7 07 01 00 00 00 74 1e e8 ce d5 0a
RSP: 0018:ffffc90003357760 EFLAGS: 00000293
RAX: ffffffff81760a02 RBX: dffffc0000000000 RCX: ffff88807c639dc0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900033578c0 R08: dffffc0000000000 R09: fffffbfff211904f
R10: fffffbfff211904f R11: 1ffffffff211904e R12: 1ffff110171e81c9
R13: ffff8880b8e3bb80 R14: 0000000000000001 R15: ffff8880b8f40e48
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc9c153910 CR3: 000000000c68e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1165
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:87 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:970 [inline]
 flush_tlb_mm_range+0x409/0x610 arch/x86/mm/tlb.c:1058
 tlb_flush arch/x86/include/asm/tlb.h:20 [inline]
 tlb_flush_mmu_tlbonly+0x1b1/0x3f0 include/asm-generic/tlb.h:430
 tlb_flush_mmu+0x28/0x210 mm/mmu_gather.c:260
 tlb_finish_mmu+0xbd/0x1c0 mm/mmu_gather.c:361
 exit_mmap+0x343/0x8e0 mm/mmap.c:3262
 __mmput+0x118/0x3c0 kernel/fork.c:1200
 exit_mm+0x1e6/0x2c0 kernel/exit.c:565
 do_exit+0x8c1/0x2400 kernel/exit.c:867
 do_group_exit+0x217/0x2d0 kernel/exit.c:1022
 __do_sys_exit_group kernel/exit.c:1033 [inline]
 __se_sys_exit_group kernel/exit.c:1031 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1031
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f46dad8f749
Code: Unable to access opcode bytes at 0x7f46dad8f71f.
RSP: 002b:00007ffc9c09f258 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f46dad8f749
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: 0000000b9c09f34f R09: 00007f46dafb4280
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f46dafb4280 R14: 0000000000000003 R15: 00007ffc9c09f310
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/10 08:40 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in addrconf_dad_work
2024/11/22 07:18 linux-6.1.y b67dc5c9ade9 4b25d554 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in addrconf_dad_work
2025/03/03 23:57 linux-6.1.y 3a8358583626 c3901742 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: rcu detected stall in addrconf_dad_work
* Struck through repros no longer work on HEAD.