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: 47d, last: 4d07h
▶ ▼ 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 inconclusive 18 8h37m 184d 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 1635d 2215d 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 423d 423d 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 1093d 1093d 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 747d 754d 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 632d 632d 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 164d 403d 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 747d 771d 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 4 16d 129d 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 188d 950d 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 970d 970d 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 1635d 2208d 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 3 5d00h 79d 0/29 moderation: reported on 2026/07/30 07:17

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (4810 ticks this GP) idle=a51/1/0x4000000000000000 softirq=123645/123646 fqs=3860 
	(t=10502 jiffies g=176921 q=1543)
NMI backtrace for cpu 0
CPU: 0 PID: 8936 Comm: syz.1.10729 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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_is_held_type+0x13a/0x190 kernel/locking/lockdep.c:5813
Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc90000007b70 EFLAGS: 00000206
RAX: 085bf30bfe872300 RBX: ffff88801ec33b80 RCX: 085bf30bfe872300
RDX: 0000000000000100 RSI: ffffffff8a2b3e80 RDI: ffffffff8a7a4c00
RBP: 0000000000000000 R08: ffffffff8e6b282f R09: 1ffffffff1cd6505
R10: dffffc0000000000 R11: fffffbfff1cd6506 R12: 0000000000000004
R13: 0000000000000246 R14: ffff888060c50688 R15: ffff88801ec34710
 lock_is_held include/linux/lockdep.h:292 [inline]
 __iterate_interfaces+0x368/0x4c0 net/mac80211/util.c:799
 ieee80211_iterate_active_interfaces_atomic+0xb3/0x140 net/mac80211/util.c:829
 mac80211_hwsim_beacon+0x9b/0x180 drivers/net/wireless/mac80211_hwsim.c:1865
 __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:finish_lock_switch+0x12f/0x290 kernel/sched/core.c:4804
Code: 83 c7 18 be ff ff ff ff e8 be bc 6d 08 85 c0 74 46 4d 85 ff 75 62 0f 1f 44 00 00 48 89 df e8 58 2d 77 08 e8 a3 f2 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:ffffc9000322f518 EFLAGS: 00000282
RAX: 085bf30bfe872300 RBX: ffff88807cfd0000 RCX: 085bf30bfe872300
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4c00
RBP: 1ffff110171c7613 R08: ffffffff9101515f R09: 1ffffffff2202a2b
R10: dffffc0000000000 R11: fffffbfff2202a2c R12: 1ffff110171c75c1
R13: dffffc0000000000 R14: ffff8880b8e3ae08 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:435
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__d_lookup+0x196/0x760 include/linux/rculist_bl.h:-1
Code: db 4c 8b 74 24 10 4d 89 fd 0f 84 c8 04 00 00 e8 50 f9 a9 ff eb 14 e8 49 f9 a9 ff eb 05 e8 42 f9 a9 ff 4c 8b 74 24 10 4d 89 fd <4c> 8b 7c 24 08 4c 89 ee 48 83 e6 fe 31 ff e8 07 fd a9 ff 49 83 e5
RSP: 0018:ffffc9000322f8e0 EFLAGS: 00000287
RAX: ffffffff81cf2a10 RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc90015975000 RSI: 0000000000006abc RDI: 0000000000006abd
RBP: ffff8880484ae2f0 R08: ffffc90000603eff R09: 1ffff920000c07df
R10: dffffc0000000000 R11: fffff520000c07e0 R12: dffffc0000000000
R13: 0000000000000000 R14: 00000000be3df958 R15: 0000000000000000
 d_lookup+0x21/0x60 fs/dcache.c:2379
 lookup_open fs/namei.c:3435 [inline]
 open_last_lookups fs/namei.c:3583 [inline]
 path_openat+0x963/0x2fb0 fs/namei.c:3790
 do_filp_open+0x1df/0x400 fs/namei.c:3820
 do_sys_openat2+0x14b/0x500 fs/open.c:1255
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 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: 0033:0x7fb4ab2ba2d9
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:00007fb4a9512028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fb4ab541fa0 RCX: 00007fb4ab2ba2d9
RDX: 00000000000026e1 RSI: 0000200000000940 RDI: ffffffffffffff9c
RBP: 00007fb4ab351888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb4ab542038 R14: 00007fb4ab541fa0 R15: 00007ffddc86c3e8
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/13 13:11 linux-5.15.y a051a4bf909f 5a1eeac4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in mac80211_hwsim_beacon
2026/10/12 22:00 linux-5.15.y a051a4bf909f 745a967f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in mac80211_hwsim_beacon
2026/09/20 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.