INFO: rcu detected stall in garp_join_timer

Status: upstream: reported on 2026/07/10 02:05
Reported-by: syzbot+c2f53e12f3f8aeaa2211@syzkaller.appspotmail.com
First crash: 25d, last: 25d
▶ ▼ Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: rcu detected stall in garp_join_timer 1 7 2368d 2400d 0/1 auto-closed as invalid on 2020/06/07 13:30
upstream INFO: rcu detected stall in garp_join_timer (3) net 1 3 759d 829d 0/29 auto-obsoleted due to no activity on 2024/10/03 12:56
linux-4.19 BUG: soft lockup in garp_join_timer 1 19 1372d 1880d 0/1 auto-obsoleted due to no activity on 2023/03/01 00:21
upstream INFO: rcu detected stall in garp_join_timer net 1 1 2440d 2440d 0/29 closed as invalid on 2019/11/29 14:24
upstream INFO: rcu detected stall in garp_join_timer (2) net 1 25 1661d 2361d 0/29 auto-closed as invalid on 2022/05/15 13:33
linux-4.14 INFO: rcu detected stall in garp_join_timer 1 4 2364d 2379d 0/1 auto-closed as invalid on 2020/06/12 11:13
linux-4.19 INFO: rcu detected stall in garp_join_timer (2) 1 1 2236d 2236d 0/1 auto-closed as invalid on 2020/10/18 11:34
linux-4.19 INFO: rcu detected stall in garp_join_timer (3) 1 1 2028d 2028d 0/1 auto-closed as invalid on 2021/05/13 13:34
upstream BUG: soft lockup in garp_join_timer (4) net 1 1 302d 302d 0/29 closed as invalid on 2025/11/11 16:41
linux-5.15 BUG: soft lockup in garp_join_timer 1 1 1052d 1052d 0/3 auto-obsoleted due to no activity on 2023/12/25 14:40
upstream BUG: soft lockup in garp_join_timer (5) net 1 1 210d 210d 0/29 closed as invalid on 2026/02/10 10:22
upstream BUG: soft lockup in garp_join_timer (3) net 1 3 437d 469d 0/29 auto-obsoleted due to no activity on 2025/08/31 15:42
upstream BUG: soft lockup in garp_join_timer (2) net 1 2 559d 577d 0/29 closed as invalid on 2025/02/20 20:55

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (1 GPs behind) idle=b73/1/0x4000000000000000 softirq=93395/93396 fqs=6 
	(t=10501 jiffies g=113173 q=546)
rcu: rcu_preempt kthread starved for 1117 jiffies! g113173 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:27792 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11f0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 24708 Comm: syz.1.6545 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:tk_clock_read kernel/time/timekeeping.c:195 [inline]
RIP: 0010:timekeeping_get_delta kernel/time/timekeeping.c:255 [inline]
RIP: 0010:timekeeping_get_ns kernel/time/timekeeping.c:388 [inline]
RIP: 0010:ktime_get_update_offsets_now+0xe9/0x3e0 kernel/time/timekeeping.c:2303
Code: c9 0a 41 f6 c6 01 74 07 e8 04 a2 0f 00 eb ea e8 fd a1 0f 00 48 8b 1d 8e c6 c9 0a 48 89 d8 48 c1 e8 03 4d 89 ef 42 80 3c 28 00 <74> 08 48 89 df e8 5d c0 54 00 48 89 df ff 13 48 89 c5 4c 8b 25 76
RSP: 0018:ffffc900000078d8 EFLAGS: 00000046
RAX: 1ffffffff182bd20 RBX: ffffffff8c15e900 RCX: ffff888050ea9dc0
RDX: 0000000000010100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880b902a290 R08: ffffffff8d8aeaef R09: 1ffffffff1b15d5d
R10: dffffc0000000000 R11: fffffbfff1b15d5e R12: ffff8880b902a240
R13: dffffc0000000000 R14: 000000000002774e R15: dffffc0000000000
FS:  00007f0ca250d6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32812ff8 CR3: 00000000625e1000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 hrtimer_update_base kernel/time/hrtimer.c:621 [inline]
 hrtimer_interrupt+0x121/0x8b0 kernel/time/hrtimer.c:1793
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:rb_first+0x1e/0x70 lib/rbtree.c:470
Code: 5c 41 5d 41 5e 41 5f 5d ff e0 66 90 41 57 41 56 53 48 89 fb 49 bf 00 00 00 00 00 fc ff df 48 89 f8 48 c1 e8 03 42 80 3c 38 00 <74> 08 48 89 df e8 28 84 b3 fd 48 8b 03 48 85 c0 75 13 31 db 48 89
RSP: 0018:ffffc90000007b30 EFLAGS: 00000246
RAX: 1ffff11005657220 RBX: ffff88802b2b9100 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff88802b2b9100
RBP: ffffc90000007c70 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000000f58 R12: ffff88802b2b9010
R13: ffffffff8802e420 R14: ffff88802b2b9060 R15: dffffc0000000000
 garp_gid_event net/802/garp.c:398 [inline]
 garp_join_timer+0x2d/0x120 net/802/garp.c:419
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:finish_lock_switch+0x12f/0x290 kernel/sched/core.c:4804
Code: 83 c7 18 be ff ff ff ff e8 fe cc 6a 08 85 c0 74 46 4d 85 ff 75 62 0f 1f 44 00 00 48 89 df e8 c8 3b 74 08 e8 d3 cc 2a 00 fb 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 2f 0e fe ff 43 80 3c 2c
RSP: 0018:ffffc9000301ec78 EFLAGS: 00000282
RAX: b24889fb4ccadf00 RBX: ffff88807d975940 RCX: b24889fb4ccadf00
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a2a40
RBP: 1ffff11017207613 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 R12: 1ffff110172075c1
R13: dffffc0000000000 R14: ffff8880b903ae08 R15: 0000000000000000
 finish_task_switch+0x12f/0x650 kernel/sched/core.c:4921
 context_switch kernel/sched/core.c:5052 [inline]
 __schedule+0x11cb/0x4350 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:stack_trace_consume_entry+0x9a/0x270 kernel/stacktrace.c:93
Code: 74 21 41 ff cc 41 0f b6 04 17 84 c0 0f 85 73 01 00 00 44 89 23 b0 01 e9 99 00 00 00 31 c0 e9 92 00 00 00 48 89 f8 48 c1 e8 03 <80> 3c 10 00 74 29 49 89 ff 48 89 74 24 08 49 89 d4 4c 89 04 24 4c
RSP: 0018:ffffc9000301f058 EFLAGS: 00000a02
RAX: 1ffff92000603e2c RBX: ffffc9000301f16c RCX: 0000000080000001
RDX: dffffc0000000000 RSI: ffffffff8186a01f RDI: ffffc9000301f160
RBP: 1ffff92000603e2e R08: ffffc9000301f170 R09: 0000000000000008
R10: dffffc0000000000 R11: fffff52000603e21 R12: 0000000000000000
R13: 1ffff92000603e2d R14: ffffc9000301f168 R15: 1ffff92000603e2d
 arch_stack_walk+0x100/0x140 arch/x86/kernel/stacktrace.c:27
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xec/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4564
 free_func_state kernel/bpf/verifier.c:914 [inline]
 free_verifier_state+0xdd/0x230 kernel/bpf/verifier.c:930
 do_check_common+0xeaf/0x16e0 kernel/bpf/verifier.c:13521
 do_check_main kernel/bpf/verifier.c:13578 [inline]
 bpf_check+0x88c1/0xf6b0 kernel/bpf/verifier.c:14149
 bpf_prog_load+0xfdf/0x14e0 kernel/bpf/syscall.c:2354
 __sys_bpf+0x532/0x6f0 kernel/bpf/syscall.c:4657
 __do_sys_bpf kernel/bpf/syscall.c:4761 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4759 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4759
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f0ca42b4e59
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:00007f0ca250d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f0ca453cfa0 RCX: 00007f0ca42b4e59
RDX: 0000000000000080 RSI: 0000200000000600 RDI: 0000000000000005
RBP: 00007f0ca434ae6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0ca453d038 R14: 00007f0ca453cfa0 R15: 00007ffe77d56a58
 </TASK>
NMI backtrace for cpu 1
CPU: 1 PID: 24692 Comm: syz.4.6539 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_dump_cpu_stacks+0x22d/0x380 kernel/rcu/tree_stall.h:349
 print_cpu_stall+0x31f/0x5f0 kernel/rcu/tree_stall.h:633
 check_cpu_stall kernel/rcu/tree_stall.h:727 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x6ec/0x1120 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:2021
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4b0/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_acquire+0x208/0x400 kernel/locking/lockdep.c:5627
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f1 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc90000dd07e0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 295af833ead46400
RDX: 0000000000000000 RSI: ffffffff8a2b3e80 RDI: ffffffff8a7a2a40
RBP: ffffc90000dd08f8 R08: dffffc0000000000 R09: 1ffffffff203d218
R10: dffffc0000000000 R11: fffffbfff203d219 R12: ffffffff8c31ef20
R13: 1ffff920001ba108 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 ipv6_get_ifaddr+0x11c/0x6e0 net/ipv6/addrconf.c:2054
 ndisc_send_rs+0x9a/0x700 net/ipv6/ndisc.c:676
 addrconf_rs_timer+0x367/0x640 net/ipv6/addrconf.c:3959
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline]
RIP: 0010:smp_call_function_many_cond+0xba3/0xd80 kernel/smp.c:969
Code: 0f b6 44 05 00 84 c0 0f 85 9a 00 00 00 41 8b 1e 89 de 83 e6 01 31 ff e8 fb 67 0b 00 83 e3 01 75 07 e8 91 64 0b 00 eb 42 f3 90 <48> b8 00 00 00 00 00 fc ff df 41 0f b6 44 05 00 84 c0 75 10 41 f7
RSP: 0018:ffffc9000310f800 EFLAGS: 00000287
RAX: ffffffff816d8e35 RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc9001431c000 RSI: 000000000000258c RDI: 000000000000258d
RBP: ffffc9000310f940 R08: ffffffff901e90c7 R09: 1ffffffff203d218
R10: dffffc0000000000 R11: fffffbfff203d219 R12: ffff8880b913b3c0
R13: 1ffff11017208509 R14: ffff8880b9042848 R15: 0000000000000000
 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1134
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:1442 [inline]
 text_poke_bp_batch+0x2b0/0x830 arch/x86/kernel/alternative.c:1642
 text_poke_flush arch/x86/kernel/alternative.c:1833 [inline]
 text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1840
 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x11f/0x240 kernel/jump_label.c:177
 static_key_enable+0x16/0x20 kernel/jump_label.c:190
 tracepoint_add_func+0x985/0xa10 kernel/tracepoint.c:363
 tracepoint_probe_register_prio kernel/tracepoint.c:513 [inline]
 tracepoint_probe_register+0x5a/0x90 kernel/tracepoint.c:533
 perf_trace_event_reg kernel/trace/trace_event_perf.c:129 [inline]
 perf_trace_event_init+0x492/0x950 kernel/trace/trace_event_perf.c:202
 perf_trace_init+0x234/0x2d0 kernel/trace/trace_event_perf.c:226
 perf_tp_event_init+0x89/0x110 kernel/events/core.c:10102
 perf_try_init_event+0x12b/0x3d0 kernel/events/core.c:11601
 perf_init_event kernel/events/core.c:11665 [inline]
 perf_event_alloc+0xf78/0x21d0 kernel/events/core.c:11957
 __do_sys_perf_event_open kernel/events/core.c:12495 [inline]
 __se_sys_perf_event_open+0x6f5/0x1bb0 kernel/events/core.c:12387
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f52912e5e59
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:00007f528f53e028 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 00007f529156dfa0 RCX: 00007f52912e5e59
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 0000200000000000
RBP: 00007f529137be6f R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f529156e038 R14: 00007f529156dfa0 R15: 00007ffcf3e1f008
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/10 02:04 linux-5.15.y c86c4726e7f0 4167ee25 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in garp_join_timer
* Struck through repros no longer work on HEAD.