INFO: rcu detected stall in napi_threaded_poll

Status: closed as invalid on 2026/08/26 17:16
Subsystems: wireguard
Labels: prio:normal
[Documentation on labels]
First crash: 353d, last: 229d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
3c622711 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: rcu detected stall in napi_threaded_poll 2026/05/13 04:09 2026/05/13 04:09 2026/05/13 04:54 ac1aeadb
▶ ▼ Last patch testing requests (6)
Created Duration User Patch Repo Result
2026/07/02 22:56 1h14m retest repro net-next log
2026/04/20 17:57 25m retest repro net-next report log
2026/01/29 13:19 2h21m retest repro net-next no crash log
2026/01/29 12:40 2h46m retest repro net-next no crash log
2025/11/20 10:36 1h36m retest repro net-next report log
2025/09/22 15:32 18m retest repro net-next report log
▶ ▼ Fix bisection attempts (4)
Created Duration User Patch Repo Result
2026/02/09 16:26 1m bisect fix net-next error job log
2026/01/10 10:21 6h03m bisect fix net-next OK (0) job log log
2025/12/09 08:36 4h41m bisect fix net-next OK (0) job log log
2025/10/11 05:11 4h45m bisect fix net-next OK (0) job log log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (2 ticks this GP) idle=ebcc/1/0x4000000000000000 softirq=18122/18122 fqs=4
rcu: 	(detected by 1, t=10506 jiffies, g=10733, q=2039 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6027 Comm: napi/wg1-0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:check_preemption_disabled+0x6/0x120 lib/smp_processor_id.c:13
Code: c7 c6 60 38 e3 8b eb 1c 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 41 56 53 <48> 83 ec 10 65 48 8b 05 be 2e 26 07 48 89 44 24 08 65 8b 05 c6 2e
RSP: 0018:ffffc90000007b18 EFLAGS: 00000007
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8be33860 RDI: ffffffff8be33820
RBP: ffffffff84d059aa R08: 0000000000000001 R09: 0000000000000000
R10: ffffc90000007cb0 R11: fffff52000000f98 R12: 0000000000000000
R13: ffffffff99cf9ee0 R14: 0000000000000000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff888125c14000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c001c8cea0 CR3: 00000000327de000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
 rcu_is_watching+0x15/0xb0 kernel/rcu/tree.c:751
 trace_lock_acquire include/trace/events/lock.h:24 [inline]
 lock_acquire+0x5f/0x360 kernel/locking/lockdep.c:5831
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
 debug_object_deactivate+0x9a/0x250 lib/debugobjects.c:873
 debug_hrtimer_deactivate kernel/time/hrtimer.c:450 [inline]
 debug_deactivate+0x1d/0x200 kernel/time/hrtimer.c:490
 __run_hrtimer kernel/time/hrtimer.c:1729 [inline]
 __hrtimer_run_queues+0x2b0/0xc60 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+0x108/0x410 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x70/0x360 kernel/locking/lockdep.c:5833
Code: f8 08 0f 83 b8 01 00 00 89 c0 48 0f a3 05 a8 34 06 0e 73 16 e8 61 02 09 00 84 c0 75 0d f6 05 a2 1b f0 0d 01 0f 84 d7 01 00 00 <83> 3d b9 65 06 0e 00 0f 84 f0 00 00 00 48 8b b4 24 90 00 00 00 4c
RSP: 0018:ffffc900030f7860 EFLAGS: 00000202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 101bc0945caca000
RDX: 0000000000000000 RSI: ffffffff8be33860 RDI: ffffffff8be33820
RBP: ffffffff866f217d R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000000a R11: 0000000000000000 R12: 0000000000000002
R13: ffffffff8e139f80 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock_bh include/linux/rcupdate.h:894 [inline]
 keep_key_fresh drivers/net/wireguard/receive.c:228 [inline]
 wg_packet_consume_data_done drivers/net/wireguard/receive.c:351 [inline]
 wg_packet_rx_poll+0xbf7/0x24a0 drivers/net/wireguard/receive.c:474
 __napi_poll+0xc7/0x360 net/core/dev.c:7555
 napi_threaded_poll_loop+0x2e3/0x6c0 net/core/dev.c:7674
 napi_threaded_poll+0x1be/0x2b0 net/core/dev.c:7701
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 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 7655 jiffies! g10733 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:27160 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 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: 1 UID: 0 PID: 5528 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xd33/0x12d0 kernel/smp.c:877
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 06 63 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 b1 5e 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 95 5e
RSP: 0018:ffffc90003a1f540 EFLAGS: 00000293
RAX: ffffffff81b44fbb RBX: 1ffff110170c8341 RCX: ffff88802e660000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90003a1f6c0 R08: ffffffff8fa39237 R09: 1ffffffff1f47246
R10: dffffc0000000000 R11: fffffbfff1f47247 R12: ffff8880b8641a08
R13: dffffc0000000000 R14: ffff8880b873b1c0 R15: 0000000000000000
FS:  00007f591e6aa740(0000) GS:ffff888125d14000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2df5fc2008 CR3: 000000002f366000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1044
 __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+0x6b1/0x12d0 arch/x86/mm/tlb.c:1451
 dup_mmap+0x15a0/0x1ac0 mm/mmap.c:1873
 dup_mm kernel/fork.c:1485 [inline]
 copy_mm+0x13c/0x4b0 kernel/fork.c:1537
 copy_process+0x1706/0x3c00 kernel/fork.c:2175
 kernel_clone+0x21e/0x840 kernel/fork.c:2605
 __do_sys_clone kernel/fork.c:2748 [inline]
 __se_sys_clone kernel/fork.c:2732 [inline]
 __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2732
 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: 0033:0x7f591e77e636
Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffd8bc5d0b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffd8bc5d0b8 RCX: 00007f591e77e636
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffd8bc7d600 R08: 0000000000000000 R09: 0000000000000001
R10: 00007f591e6aaa10 R11: 0000000000000246 R12: 00007ffd8bc5d1f0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000559539888ac0
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/08 14:45 net-next c6142e1913de d291dd2d .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: rcu detected stall in napi_threaded_poll
2025/11/05 23:33 net-next 89aec171d9d1 a6c9c731 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce INFO: rcu detected stall in napi_threaded_poll
* Struck through repros no longer work on HEAD.