INFO: rcu detected stall in inet6_rtm_newaddr

Status: upstream: reported syz repro on 2026/09/19 07:01
Reported-by: syzbot+6732caa806cf47908257@syzkaller.appspotmail.com
First crash: 12d, last: 12d
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/09/20 upstream (ToT) [unknown] syz Failed due to an error; will retry later
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in inet6_rtm_newaddr net 1 syz, C error 1 926d 926d 0/29 closed as invalid on 2024/04/25 09:04
upstream INFO: rcu detected stall in inet6_rtm_newaddr (3) prio:high sctp 1 syz, C error error 8 13d 505d 0/29 upstream: reported C repro on 2025/05/14 07:22
upstream INFO: rcu detected stall in inet6_rtm_newaddr (2) net 1 1 819d 819d 0/29 auto-obsoleted due to no activity on 2024/10/02 18:47

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=e004/1/0x4000000000000000 softirq=13562/13563 fqs=2
rcu: 	(detected by 1, t=10503 jiffies, g=12777, q=466 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5910 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:kasan_check_range+0x1c3/0x290 mm/kasan/generic.c:187
Code: 24 07 4d 85 e4 49 0f 49 dc 48 83 e3 f8 49 29 dc 74 0e 41 80 3b 00 75 6b 49 ff c3 49 ff cc 75 f2 5b 41 5c 41 5d 41 5e 41 5f 5d <c3> 45 84 ff 0f 85 91 00 00 00 41 f7 c7 00 ff 00 00 0f 85 89 00 00
RSP: 0018:ffffc90000007878 EFLAGS: 00000056
RAX: 0000000000000001 RBX: 000000000000006b RCX: ffffffff8168ac57
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff911eb508
RBP: ffffc90000007ac8 R08: ffffffff911eb50f R09: 1ffffffff223d6a1
R10: dffffc0000000000 R11: fffffbfff223d6a2 R12: 00000000d4c9f0e4
R13: ffff888029750000 R14: 0000000022e098f3 R15: ffff888029750b58
FS:  00005555607f3500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000300 CR3: 000000005ce02000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 hlock_class kernel/locking/lockdep.c:228 [inline]
 __lock_acquire+0x1077/0x7d80 kernel/locking/lockdep.c:5133
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5756
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xb4/0x100 kernel/locking/spinlock.c:162
 debug_object_activate+0x6c/0x500 lib/debugobjects.c:747
 debug_hrtimer_activate kernel/time/hrtimer.c:450 [inline]
 debug_activate kernel/time/hrtimer.c:504 [inline]
 enqueue_hrtimer+0x34/0x380 kernel/time/hrtimer.c:1100
 __run_hrtimer kernel/time/hrtimer.c:1771 [inline]
 __hrtimer_run_queues+0x62f/0xc10 kernel/time/hrtimer.c:1818
 hrtimer_interrupt+0x39d/0x980 kernel/time/hrtimer.c:1880
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x9f/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:mod_delayed_work_on+0x16f/0x1c0 kernel/workqueue.c:2053
Code: 2f 00 eb 1c e8 a2 97 2f 00 eb 15 e8 9b 97 2f 00 e8 26 57 39 09 4d 85 ff 74 e3 e8 8c 97 2f 00 fb 49 bf 00 00 00 00 00 fc ff df <31> ff 89 de e8 28 9b 2f 00 85 db 0f 95 c0 48 c7 44 24 20 0e 36 e0
RSP: 0018:ffffc900046a7280 EFLAGS: 00000293
RAX: ffffffff8157f3c4 RBX: 0000000000000000 RCX: ffff888029750000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900046a7338 R08: ffffffff911eb50f R09: 1ffffffff223d6a1
R10: dffffc0000000000 R11: fffffbfff223d6a2 R12: 0000000000000000
R13: 0000000000000008 R14: 1ffff920008d4e54 R15: dffffc0000000000
 mod_delayed_work include/linux/workqueue.h:594 [inline]
 addrconf_mod_dad_work+0x76/0x120 net/ipv6/addrconf.c:331
 inet6_addr_add+0x79e/0xb30 net/ipv6/addrconf.c:3079
 inet6_rtm_newaddr+0x6fd/0x9d0 net/ipv6/addrconf.c:5043
 rtnetlink_rcv_msg+0x843/0xf90 net/core/rtnetlink.c:6484
 netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x4a9/0x6b0 net/socket.c:2201
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2209
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f31a495e98e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007ffc84d1ece8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00005555607f3500 RCX: 00007f31a495e98e
RDX: 0000000000000040 RSI: 00007f31a5754670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffc84d1ed64 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f31a5754670 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10493 jiffies! g12777 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:27848 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x30d/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: 1 PID: 147 Comm: kworker/u4:5 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:311 [inline]
RIP: 0010:smp_call_function_many_cond+0xd85/0x1190 kernel/smp.c:855
Code: 45 8b 34 24 44 89 f6 83 e6 01 31 ff e8 34 01 0b 00 41 83 e6 01 49 be 00 00 00 00 00 fc ff df 75 07 e8 6f fd 0a 00 eb 38 f3 90 <42> 0f b6 04 33 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 53 fd
RSP: 0018:ffffc90002d3f780 EFLAGS: 00000293
RAX: ffffffff817c8dfd RBX: 1ffff110171c87a5 RCX: ffff88801abe0000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90002d3f900 R08: ffffffff911eb507 R09: 1ffffffff223d6a0
R10: dffffc0000000000 R11: fffffbfff223d6a1 R12: ffff8880b8e43d28
R13: ffff8880b8f3d380 R14: dffffc0000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00003a8e1f065000 CR3: 000000000cf32000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1022
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:2222 [inline]
 text_poke_bp_batch+0x31e/0x980 arch/x86/kernel/alternative.c:2432
 text_poke_flush arch/x86/kernel/alternative.c:2623 [inline]
 text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2630
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x123/0x240 kernel/jump_label.c:207
 static_key_enable+0x1a/0x20 kernel/jump_label.c:220
 toggle_allocation_gate+0xa8/0x260 mm/kfence/core.c:847
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
 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>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/19 07:00 linux-6.6.y 79643295eba1 853b104b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: rcu detected stall in inet6_rtm_newaddr
* Struck through repros no longer work on HEAD.