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INFO: rcu detected stall in mac80211_hwsim_beacon (4)

Status: upstream: reported C repro on 2026/04/15 21:01
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+987d7bcdd83938b2d9bd@syzkaller.appspotmail.com
First crash: 46d, last: 21d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/05/25 linux-6.1.y (ToT) dcbcab9d7079 C [report] INFO: rcu detected stall in __run_timers
2026/05/25 upstream (ToT) e7ae89a0c97c C Didn't crash
▶ ▼ Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in mac80211_hwsim_beacon kernel 1 C error inconclusive 1904 1497d 2077d 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 285d 285d 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 955d 955d 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 609d 616d 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 494d 494d 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 26d 265d 0/3 upstream: reported on 2025/09/09 14:58
linux-6.1 INFO: rcu detected stall in mac80211_hwsim_beacon 1 3 609d 633d 0/3 auto-obsoleted due to no activity on 2025/01/08 20:04
upstream BUG: soft lockup in mac80211_hwsim_beacon (2) wireless prio:high 1 C error inconclusive 171 50d 812d 0/29 upstream: reported C repro on 2024/03/11 14:28
linux-5.15 INFO: rcu detected stall in mac80211_hwsim_beacon (2) 1 1 832d 832d 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 1497d 2070d 0/29 auto-obsoleted due to no activity on 2023/01/21 14:41

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 4909 jiffies s: 3321 root: 0x2/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4566 Comm: syz.0.36 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:timekeeping_get_delta kernel/time/timekeeping.c:267 [inline]
RIP: 0010:timekeeping_get_ns kernel/time/timekeeping.c:388 [inline]
RIP: 0010:ktime_get+0x166/0x270 kernel/time/timekeeping.c:848
Code: f3 4c 89 f6 48 d1 ee 48 f7 d6 48 21 de b8 00 00 00 00 48 0f 45 d8 31 ff e8 77 c6 0f 00 49 89 dc 4d 31 f4 49 c1 ee 03 4c 89 e7 <4c> 89 f6 e8 62 c4 0f 00 4d 39 f4 0f 82 99 00 00 00 48 89 df 4c 89
RSP: 0018:ffffc900001e0358 EFLAGS: 00000807
RAX: ffffffff8172b2b9 RBX: 0000000001283178 RCX: ffff88802e769dc0
RDX: 0000000000010100 RSI: 0000000000000000 RDI: fffffffffed7ce87
RBP: 000000000000f2b2 R08: ffffffff8e1ff3ef R09: 1ffffffff1c3fe7d
R10: dffffc0000000000 R11: fffffbfff1c3fe7e R12: fffffffffed7ce87
R13: 000000ca25083f16 R14: 1fffffffffffffff R15: 000001fb700c3c76
FS:  00005555934ed500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30a63fff CR3: 000000007e1a0000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 clockevents_program_event+0xe2/0x310 kernel/time/clockevents.c:326
 hrtimer_interrupt+0x59d/0x9c0 kernel/time/hrtimer.c:1886
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1118
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__kernel_text_address+0x1d/0x30 kernel/extable.c:79
Code: 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 53 48 89 fb e8 27 00 00 00 48 81 fb 00 e0 67 8f 0f 93 c1 48 81 fb 8d 49 7d 8f 0f 92 c2 <20> ca 08 c2 0f b6 c2 5b c3 66 2e 0f 1f 84 00 00 00 00 00 55 41 56
RSP: 0018:ffffc900001e05f8 EFLAGS: 00000293
RAX: 0000000000000001 RBX: ffffffff814f749b RCX: 0000000000000100
RDX: ffffc900001e0601 RSI: dffffc0000000000 RDI: ffffffff814f749b
RBP: ffffc900001e06b0 R08: ffffc900001e0f30 R09: ffffc900001e0678
R10: dffffc0000000000 R11: fffff5200003c0d1 R12: ffff88802e769dc0
R13: ffffc900001e0a50 R14: dffffc0000000000 R15: 1ffff9200003c0ce
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3700
 skb_free_head net/core/skbuff.c:762 [inline]
 skb_release_data+0x5db/0x7c0 net/core/skbuff.c:791
 skb_release_all net/core/skbuff.c:856 [inline]
 __kfree_skb net/core/skbuff.c:870 [inline]
 consume_skb+0xa2/0x100 net/core/skbuff.c:1035
 mac80211_hwsim_beacon_tx+0x61e/0xae0 drivers/net/wireless/mac80211_hwsim.c:2121
 __iterate_interfaces+0x243/0x500 net/mac80211/util.c:788
 ieee80211_iterate_active_interfaces_atomic+0xd7/0x170 net/mac80211/util.c:824
 mac80211_hwsim_beacon+0xb7/0x1b0 drivers/net/wireless/mac80211_hwsim.c:2147
 __run_hrtimer kernel/time/hrtimer.c:1747 [inline]
 __hrtimer_run_queues+0x54a/0xd50 kernel/time/hrtimer.c:1811
 hrtimer_run_softirq+0x183/0x2a0 kernel/time/hrtimer.c:1828
 handle_softirqs+0x2a1/0x930 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:preempt_schedule_irq+0xb6/0x160 kernel/sched/core.c:6874
Code: 00 00 43 c6 44 37 04 f8 74 0b 0f 0b 48 f7 03 08 00 00 00 74 7f bf 01 00 00 00 e8 15 64 22 f7 e8 10 58 52 f7 fb bf 01 00 00 00 <e8> 75 b9 ff ff 43 c6 44 37 08 00 48 c7 44 24 40 00 00 00 00 9c 8f
RSP: 0018:ffffc900035c7c40 EFLAGS: 00000286
RAX: 96bf9a4178329b00 RBX: 0000000000000000 RCX: 96bf9a4178329b00
RDX: dffffc0000000000 RSI: ffffffff8a8c1120 RDI: 0000000000000001
RBP: ffffc900035c7cf0 R08: ffff8880b8f3580b R09: 1ffff110171e6b01
R10: dffffc0000000000 R11: ffffed10171e6b02 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff920006b8f88
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:rcu_preempt_read_exit kernel/rcu/tree_plugin.h:384 [inline]
RIP: 0010:__rcu_read_unlock+0x1b/0xd0 kernel/rcu/tree_plugin.h:423
Code: 03 38 c1 7c e3 48 89 df e8 52 47 66 00 eb d9 41 57 41 56 41 55 41 54 53 49 bf 00 00 00 00 00 fc ff df 65 48 8b 3d f5 34 95 7e <48> 8d 9f 3c 04 00 00 49 89 dc 49 c1 ec 03 43 0f b6 04 3c 84 c0 75
RSP: 0018:ffffc900035c7db0 EFLAGS: 00000293
RAX: ffffffff81e74062 RBX: ffffffff81e73f67 RCX: ffff88802e769dc0
RDX: 0000000000000000 RSI: ffffffff8adf1300 RDI: ffff88802e769dc0
RBP: 0000000000000001 R08: ffff88807f304adb R09: 1ffff1100fe6095b
R10: dffffc0000000000 R11: ffffed100fe6095c R12: ffffc900035c7e80
R13: dffffc0000000000 R14: ffff88807f304a48 R15: dffffc0000000000
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 dput+0x199/0x1d0 fs/dcache.c:906
 path_put fs/namei.c:561 [inline]
 do_unlinkat+0x4d5/0x580 fs/namei.c:4414
 __do_sys_unlink fs/namei.c:4446 [inline]
 __se_sys_unlink fs/namei.c:4444 [inline]
 __x64_sys_unlink+0x45/0x50 fs/namei.c:4444
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fdddf19cdd9
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:00007fff4da3f8f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00007fdddf415fa0 RCX: 00007fdddf19cdd9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00002000000000c0
RBP: 00007fdddf232d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdddf415fac R14: 00007fdddf415fa0 R15: 00007fdddf415fa0
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/10 21:20 linux-6.1.y ad16b162f21d 29233ece .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in mac80211_hwsim_beacon
2026/04/26 05:53 linux-6.1.y 7c87defbd336 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in mac80211_hwsim_beacon
2026/04/15 21:00 linux-6.1.y 8e8fc038cad5 c441f497 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in mac80211_hwsim_beacon
* Struck through repros no longer work on HEAD.