INFO: rcu detected stall in hsr_announce (4)

Status: upstream: reported on 2026/08/30 08:37
Reported-by: syzbot+c9e6bb99fa583786304e@syzkaller.appspotmail.com
First crash: 3d09h, last: 8h31m
▶ ▼ Similar bugs (20)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in hsr_announce 1 3 628d 729d 0/3 auto-obsoleted due to no activity on 2025/03/22 17:50
upstream INFO: rcu detected stall in hsr_announce (3) net 1 1 2465d 2464d 0/29 closed as invalid on 2019/12/04 14:04
linux-6.1 INFO: rcu detected stall in hsr_announce (2) 1 2 277d 304d 0/3 auto-obsoleted due to no activity on 2026/03/09 02:56
upstream INFO: rcu detected stall in hsr_announce (5) net 1 4 1752d 1764d 0/29 closed as invalid on 2022/02/08 10:00
linux-6.6 BUG: soft lockup in hsr_announce origin:lts-only 1 syz, C 4 5d01h 96d 0/2 upstream: reported C repro on 2026/05/28 20:15
upstream INFO: rcu detected stall in hsr_announce (6) kvm 1 2 1590d 1590d 0/29 auto-closed as invalid on 2022/06/25 07:59
linux-4.14 INFO: rcu detected stall in hsr_announce 1 syz, C error 25 2252d 2450d 0/1 upstream: reported C repro on 2019/12/17 23:42
upstream INFO: rcu detected stall in hsr_announce (4) net 1 1 2091d 2091d 0/29 auto-closed as invalid on 2021/03/11 15:56
linux-5.15 INFO: rcu detected stall in hsr_announce (3) 1 5 185d 246d 0/3 auto-obsoleted due to no activity on 2026/06/09 03:32
linux-6.1 INFO: rcu detected stall in hsr_announce (3) 1 3 54d 68d 0/3 upstream: reported on 2026/06/26 13:35
upstream INFO: rcu detected stall in hsr_announce net 1 1 2544d 2544d 0/29 auto-closed as invalid on 2019/11/13 18:24
linux-6.6 INFO: rcu detected stall in hsr_announce 1 1 260d 260d 0/2 auto-obsoleted due to no activity on 2026/03/26 05:20
upstream INFO: rcu detected stall in hsr_announce (2) net 1 3 2469d 2469d 0/29 closed as invalid on 2019/11/29 14:24
upstream INFO: rcu detected stall in hsr_announce (7) net 1 30 568d 568d 0/29 closed as invalid on 2025/03/17 11:18
linux-5.15 INFO: rcu detected stall in hsr_announce (2) 1 1 377d 377d 0/3 auto-obsoleted due to no activity on 2025/11/28 17:51
linux-5.15 INFO: rcu detected stall in hsr_announce 1 6 701d 747d 0/3 auto-obsoleted due to no activity on 2025/01/08 22:52
linux-4.19 INFO: rcu detected stall in hsr_announce 1 1 2164d 2164d 0/1 auto-closed as invalid on 2021/01/27 07:34
linux-4.19 BUG: soft lockup in hsr_announce (2) 1 7 1415d 1869d 0/1 auto-obsoleted due to no activity on 2023/02/15 11:56
upstream BUG: soft lockup in hsr_announce (2) net 1 3 1070d 1079d 0/29 auto-obsoleted due to no activity on 2023/12/27 12:08
upstream BUG: soft lockup in hsr_announce (3) prio:normal net 1 syz 38 67d 497d 0/29 upstream: reported syz repro on 2025/04/23 07:51

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (1 GPs behind) idle=263/1/0x4000000000000000 softirq=14348/14349 fqs=5247 
	(t=10502 jiffies g=16077 q=977)
NMI backtrace for cpu 0
CPU: 0 PID: 6682 Comm: syz.2.639 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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+0x9b/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:stack_trace_consume_entry+0x0/0x270 kernel/stacktrace.c:83
Code: 00 00 42 c7 44 33 08 00 00 00 00 65 48 8b 0c 25 28 00 00 00 48 3b 4c 24 78 75 09 48 8d 65 f0 5b 41 5e 5d c3 e8 31 d6 58 08 90 <55> 41 57 41 56 41 55 41 54 53 48 83 ec 18 48 ba 00 00 00 00 00 fc
RSP: 0000:ffffc9000358f400 EFLAGS: 00000286
RAX: ffffffff81be17c5 RBX: ffffc9000358f4c0 RCX: 0000000000000301
RDX: 0000000000000001 RSI: ffffffff81be17c5 RDI: ffffc9000358f4c0
RBP: ffffc9000358f490 R08: ffffc9000358f798 R09: ffffc9000358f458
R10: dffffc0000000000 R11: fffff520006b1e8d R12: ffff88807df43b80
R13: ffff888025b513c0 R14: ffffffff81677df0 R15: ffffc9000358f408
 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]
 kmem_cache_free+0x8f/0x210 mm/slub.c:3520
 kfree_skb include/linux/skbuff.h:1118 [inline]
 hsr_forward_skb+0x12f8/0x16b0 net/hsr/hsr_forward.c:594
 send_hsr_supervision_frame+0x5f7/0xb90 net/hsr/hsr_device.c:349
 hsr_announce+0x168/0x310 net/hsr/hsr_device.c:405
 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+0x52/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0033:0x7f6612f12159
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:00007f66111490e8 EFLAGS: 00000246
RAX: 0000000000000001 RBX: 00007f661319a098 RCX: 00007f6612f12159
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f661319a09c
RBP: 00007f661319a090 R08: 0002236882e1acc0 R09: 0000000000000000
R10: 000000000000000d R11: 0000000000000246 R12: 0000000000000000
R13: 00007f661319a128 R14: 00007fff42061c70 R15: 00007fff42061d58
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/02 09:06 linux-5.15.y 28c35638ec51 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in hsr_announce
2026/08/30 08:36 linux-5.15.y 28c35638ec51 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in hsr_announce
* Struck through repros no longer work on HEAD.