INFO: rcu detected stall in mac80211_hwsim_beacon (5)

Status: upstream: reported on 2026/08/31 13:05
Reported-by: syzbot+7c8ae9bdfa75efc44756@syzkaller.appspotmail.com
First crash: 23d, last: 3d18h
▶ ▼ Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in mac80211_hwsim_beacon (4) origin:lts-only 1 syz, C error 15 3d15h 161d 0/3 upstream: reported C repro on 2026/04/15 21:01
upstream INFO: rcu detected stall in mac80211_hwsim_beacon kernel 1 syz, C error inconclusive 1904 1611d 2191d 0/29 closed as invalid on 2022/10/12 18:37
linux-6.1 INFO: rcu detected stall in mac80211_hwsim_beacon (3) 1 1 399d 399d 0/3 auto-obsoleted due to no activity on 2025/11/28 14:14
linux-5.15 INFO: rcu detected stall in mac80211_hwsim_beacon 1 1 1069d 1069d 0/3 auto-obsoleted due to no activity on 2024/01/28 07:17
linux-5.15 INFO: rcu detected stall in mac80211_hwsim_beacon (3) 1 3 723d 730d 0/3 auto-obsoleted due to no activity on 2025/01/08 17:17
linux-6.1 INFO: rcu detected stall in mac80211_hwsim_beacon (2) 1 1 608d 608d 0/3 auto-obsoleted due to no activity on 2025/05/03 16:43
linux-5.15 INFO: rcu detected stall in mac80211_hwsim_beacon (4) 1 8 140d 379d 0/3 auto-obsoleted due to no activity on 2026/08/14 16:41
linux-6.1 INFO: rcu detected stall in mac80211_hwsim_beacon 1 3 723d 748d 0/3 auto-obsoleted due to no activity on 2025/01/08 20:04
linux-6.6 INFO: rcu detected stall in mac80211_hwsim_beacon origin:lts-only 1 syz, C 3 4h27m 105d 0/2 upstream: reported C repro on 2026/06/10 10:49
upstream BUG: soft lockup in mac80211_hwsim_beacon (2) wireless prio:high 1 syz, C error inconclusive 171 165d 926d 0/29 auto-obsoleted due to no activity on 2026/06/21 00:56
linux-5.15 INFO: rcu detected stall in mac80211_hwsim_beacon (2) 1 1 946d 946d 0/3 auto-obsoleted due to no activity on 2024/05/30 17:39
upstream BUG: soft lockup in mac80211_hwsim_beacon wireless 1 syz error unreliable 180 1611d 2184d 0/29 auto-obsoleted due to no activity on 2023/01/21 14:41
upstream BUG: soft lockup in mac80211_hwsim_beacon (3) prio:normal virt 1 2 58d 55d 0/29 moderation: reported on 2026/07/30 07:17

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (1 GPs behind) idle=735/1/0x4000000000000000 softirq=10447/10448 fqs=4573 
	(t=10500 jiffies g=11869 q=1602)
NMI backtrace for cpu 0
CPU: 0 PID: 5756 Comm: syz.3.343 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+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:seqcount_lockdep_reader_access+0x196/0x1d0 include/linux/seqlock.h:106
Code: 00 4d 85 e4 75 16 e8 29 08 10 00 eb 15 e8 22 08 10 00 e8 6d 28 58 08 4d 85 e4 74 ea e8 13 08 10 00 fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 3e 00 00 00 00 43 c7 44 3e 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc90000007b40 EFLAGS: 00000246
RAX: ffffffff81690c8d RBX: 0000000000000000 RCX: ffff8880251e1dc0
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000007bf8 R08: ffffffff901f11cf R09: 1ffffffff203e239
R10: dffffc0000000000 R11: fffffbfff203e23a R12: 0000000000000200
R13: 00000068bbf413d2 R14: 1ffff92000000f68 R15: dffffc0000000000
 timekeeping_get_delta kernel/time/timekeeping.c:254 [inline]
 timekeeping_get_ns kernel/time/timekeeping.c:388 [inline]
 ktime_get+0x7b/0x270 kernel/time/timekeeping.c:831
 hrtimer_forward_now include/linux/hrtimer.h:508 [inline]
 mac80211_hwsim_beacon+0x13b/0x180 drivers/net/wireless/mac80211_hwsim.c:1874
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4ea/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766
 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:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 2e c4 92 f7 48 89 df e8 66 9b 93 f7 e8 a1 97 b4 f7 fb bf 01 00 00 00 <e8> b6 b0 87 f7 65 8b 05 e7 c6 37 76 85 c0 74 02 5b c3 e8 24 d4 35
RSP: 0018:ffffc9000360f870 EFLAGS: 00000282
RAX: 73f980340ec8dd00 RBX: ffff88802112a408 RCX: 73f980340ec8dd00
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: 0000000000000001
RBP: ffffc9000360f960 R08: ffffffff901f11cf R09: 1ffffffff203e239
R10: dffffc0000000000 R11: fffffbfff203e23a R12: dffffc0000000000
R13: ffff888077c76ca8 R14: ffff88805b088bf0 R15: 1ffff1100ef8ed95
 perf_event_release_kernel+0x1bf/0x850 kernel/events/core.c:5309
 perf_release+0x37/0x40 kernel/events/core.c:5403
 __fput+0x212/0x8c0 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0x635/0x2110 kernel/exit.c:890
 do_group_exit+0x12c/0x2f0 kernel/exit.c:1004
 get_signal+0x7eb/0x12e0 kernel/signal.c:2913
 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:157 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:217
 __syscall_exit_to_user_mode_work kernel/entry/common.c:299 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:310
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1c40a27159
Code: Unable to access opcode bytes at RIP 0x7f1c40a2712f.
RSP: 002b:00007f1c3ec7f028 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: 0000000000000005 RBX: 00007f1c40caefa0 RCX: 00007f1c40a27159
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 00002000000003c0
RBP: 00007f1c40abe06b R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1c40caf038 R14: 00007f1c40caefa0 R15: 00007ffdb4e62b58
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/20 07:59 linux-5.15.y 0248c33e835e 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in mac80211_hwsim_beacon
2026/09/02 05:21 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 mac80211_hwsim_beacon
2026/08/31 13:04 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 mac80211_hwsim_beacon
* Struck through repros no longer work on HEAD.