INFO: rcu detected stall in mac80211_hwsim_beacon

Status: upstream: reported C repro on 2026/06/10 10:49
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+041234f686df7074c647@syzkaller.appspotmail.com
First crash: 53d, last: 16d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/07/18 linux-6.6.y (ToT) da47cbc25466 C [report] INFO: rcu detected stall in perf_event_open
2026/07/18 upstream (ToT) 1229e2e57a5c C Didn't crash
▶ ▼ Similar bugs (12)
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 13 10d 108d 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 1559d 2138d 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 347d 347d 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 1017d 1017d 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 670d 678d 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 555d 555d 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 87d 327d 0/3 upstream: reported on 2025/09/09 14:58
linux-6.1 INFO: rcu detected stall in mac80211_hwsim_beacon 1 3 670d 695d 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 syz, C error inconclusive 171 112d 874d 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 893d 893d 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 1559d 2131d 0/29 auto-obsoleted due to no activity on 2023/01/21 14:41
upstream BUG: soft lockup in mac80211_hwsim_beacon (3) virt prio:normal 1 2 6d07h 3d08h 0/29 moderation: reported on 2026/07/30 07:17
▶ ▼ Fix bisection attempts (1)
Created Duration User Patch Repo Result
2026/07/11 06:25 3h05m bisect fix linux-6.6.y OK (0) job log log

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (10486 ticks this GP) idle=3974/1/0x4000000000000000 softirq=18130/18133 fqs=12
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:   637127        230            0
rcu: 	cputime:    11568      12238           15   ==> 23840(ms)
rcu: 	(t=10503 jiffies g=16881 q=675 ncpus=2)
rcu: rcu_preempt kthread starved for 2365 jiffies! g16881 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:27656 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </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: 6335 Comm: syz.6.78 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:unwind_get_return_address+0x68/0xc0 arch/x86/kernel/unwind_orc.c:369
Code: 48 49 89 df 49 c1 ef 03 43 80 3c 37 00 74 08 48 89 df e8 3b 35 a4 00 48 8b 3b e8 b3 56 1e 00 89 c5 31 ff 89 c6 e8 b8 f8 4b 00 <85> ed 74 20 e8 ff f4 4b 00 43 80 3c 37 00 74 08 48 89 df e8 10 35
RSP: 0018:ffffc90000006d98 EFLAGS: 00000046
RAX: ffffffff813b3688 RBX: ffffc90000006e68 RCX: 0000000000000100
RDX: ffff888028290000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffff888028290000 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000000100 R12: ffffc90000006f4c
R13: ffffc90000006e20 R14: dffffc0000000000 R15: 1ffff92000000dcd
FS:  00005555856ff500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe3e8a3ffd0 CR3: 000000002eb69000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 perf_callchain_kernel+0x304/0x690 arch/x86/events/core.c:2781
 get_perf_callchain+0x231/0x510 kernel/events/callchain.c:204
 perf_callchain kernel/events/core.c:7742 [inline]
 perf_sample_save_callchain include/linux/perf_event.h:1232 [inline]
 perf_prepare_sample+0x3c7/0x1df0 kernel/events/core.c:7786
 __perf_event_output kernel/events/core.c:7974 [inline]
 perf_event_output_forward+0x187/0x3e0 kernel/events/core.c:7995
 __perf_event_overflow+0x447/0x630 kernel/events/core.c:9720
 perf_swevent_overflow kernel/events/core.c:9803 [inline]
 perf_swevent_event+0x319/0x570 kernel/events/core.c:9854
 perf_tp_event+0x5f9/0x1520 kernel/events/core.c:10381
 perf_trace_run_bpf_submit+0xf4/0x1c0 kernel/events/core.c:10300
 perf_trace_preemptirq_template+0x269/0x330 include/trace/events/preemptirq.h:14
 trace_irq_enable+0xbb/0xe0 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x18/0x40 kernel/trace/trace_preemptirq.c:56
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:434 [inline]
RIP: 0010:__pv_queued_spin_lock_slowpath+0x532/0x9d0 kernel/locking/qspinlock.c:511
Code: 00 41 c6 45 00 00 48 8b 44 24 10 42 0f b6 04 38 84 c0 0f 85 1b 01 00 00 48 8b 44 24 08 c6 00 01 41 bd 00 80 ff ff eb 07 f3 90 <41> ff c5 74 47 43 0f b6 04 3e 84 c0 75 2b 80 3b 00 75 eb 48 89 df
RSP: 0018:ffffc900000077e0 EFLAGS: 00000206
RAX: 0000000000000000 RBX: ffffffff8dc68aa0 RCX: ffff888028290000
RDX: 0000000000000100 RSI: ffffffff8acacbe0 RDI: ffffffff8b1c9c20
RBP: ffffc900000078d0 R08: ffffffff911cd56f R09: 1ffffffff2239aad
R10: dffffc0000000000 R11: fffffbfff2239aae R12: 1ffff110171c0001
R13: 00000000ffffa8bc R14: 1ffffffff1b8d154 R15: dffffc0000000000
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x23e/0x2c0 kernel/locking/spinlock_debug.c:115
 spin_lock include/linux/spinlock.h:351 [inline]
 mac80211_hwsim_tx_frame_no_nl+0x735/0x11a0 drivers/net/wireless/virtual/mac80211_hwsim.c:1791
 mac80211_hwsim_tx_frame+0x1b5/0x200 drivers/net/wireless/virtual/mac80211_hwsim.c:2176
 mac80211_hwsim_beacon_tx+0x3e9/0x780 drivers/net/wireless/virtual/mac80211_hwsim.c:2269
 __iterate_interfaces+0x243/0x500 net/mac80211/util.c:766
 ieee80211_iterate_active_interfaces_atomic+0xdb/0x180 net/mac80211/util.c:802
 mac80211_hwsim_beacon+0xbb/0x1b0 drivers/net/wireless/virtual/mac80211_hwsim.c:2295
 __run_hrtimer kernel/time/hrtimer.c:1754 [inline]
 __hrtimer_run_queues+0x520/0xc40 kernel/time/hrtimer.c:1818
 hrtimer_run_softirq+0x187/0x2b0 kernel/time/hrtimer.c:1835
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:lock_is_held_type+0x13e/0x190 kernel/locking/lockdep.c:5830
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:ffffc90003c97938 EFLAGS: 00000206
RAX: 10f27dede5969a00 RBX: ffff888028290000 RCX: 10f27dede5969a00
RDX: 0000000000000000 RSI: ffffffff8acadd60 RDI: ffffffff8b1c9c20
RBP: 0000000000000000 R08: ffffc90003c97b1f R09: 0000000000000000
R10: ffffc90003c97b10 R11: fffff52000792f64 R12: 0000000000000002
R13: 0000000000000246 R14: ffffffff8d132220 R15: ffff888028290b30
 lock_is_held include/linux/lockdep.h:288 [inline]
 schedule_debug kernel/sched/core.c:5958 [inline]
 __schedule+0x22a/0x45a0 kernel/sched/core.c:6591
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0x111/0x120 kernel/locking/spinlock.c:194
 __do_sys_perf_event_open kernel/events/core.c:12958 [inline]
 __se_sys_perf_event_open+0x183e/0x1c50 kernel/events/core.c:12609
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff089b9ce59
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:00007ffc02c40f88 EFLAGS: 00000246 ORIG_RAX: 000000000000012a
RAX: ffffffffffffffda RBX: 00007ff089e15fa0 RCX: 00007ff089b9ce59
RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 00002000000003c0
RBP: 00007ff089c32d6f R08: 0000000000000000 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff089e15fac R14: 00007ff089e15fa0 R15: 00007ff089e15fa0
 </TASK>
CPU: 1 PID: 6334 Comm: syz.2.19 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:should_fail_ex+0x52/0x4d0 lib/fault-inject.c:125
Code: cc d4 a7 7b a9 00 01 ff 00 0f 84 ed 00 00 00 49 89 dd 49 c1 ed 03 43 80 7c 25 00 00 74 08 48 89 df e8 12 8a 83 fd 48 83 3b 00 <0f> 84 16 01 00 00 4c 8d 7b 20 4c 89 f8 48 c1 e8 03 42 0f b6 04 20
RSP: 0018:ffffc900001f07b0 EFLAGS: 00000246
RAX: 0000000000000102 RBX: ffffffff8d2302e0 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 00000000000000f0 RDI: ffffffff8d2302e0
RBP: 0000000000000820 R08: 0000000000000820 R09: 0000000000000002
R10: 0000000000000003 R11: 0000000000000100 R12: dffffc0000000000
R13: 1ffffffff1a4605c R14: 00000000000000f0 R15: 0000000000000001
FS:  000055559110c500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000005cf79 CR3: 0000000025622000 CR4: 00000000003506e0
Call Trace:
 <IRQ>
 should_failslab+0x9/0x20 mm/slab_common.c:1500
 slab_pre_alloc_hook+0x59/0x310 mm/slab.h:716
 slab_alloc_node mm/slub.c:3477 [inline]
 kmem_cache_alloc_node+0x60/0x320 mm/slub.c:3540
 __alloc_skb+0x103/0x2c0 net/core/skbuff.c:643
 skb_copy+0x13d/0x7a0 net/core/skbuff.c:1984
 mac80211_hwsim_tx_frame_no_nl+0xca9/0x11a0 drivers/net/wireless/virtual/mac80211_hwsim.c:1840
 mac80211_hwsim_tx_frame+0x1b5/0x200 drivers/net/wireless/virtual/mac80211_hwsim.c:2176
 mac80211_hwsim_beacon_tx+0x3e9/0x780 drivers/net/wireless/virtual/mac80211_hwsim.c:2269
 __iterate_interfaces+0x243/0x500 net/mac80211/util.c:766
 ieee80211_iterate_active_interfaces_atomic+0xdb/0x180 net/mac80211/util.c:802
 mac80211_hwsim_beacon+0xbb/0x1b0 drivers/net/wireless/virtual/mac80211_hwsim.c:2295
 __run_hrtimer kernel/time/hrtimer.c:1754 [inline]
 __hrtimer_run_queues+0x520/0xc40 kernel/time/hrtimer.c:1818
 hrtimer_run_softirq+0x187/0x2b0 kernel/time/hrtimer.c:1835
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:preempt_schedule_irq+0xba/0x150 kernel/sched/core.c:7010
Code: 00 00 43 c6 44 37 04 f8 74 0b 0f 0b 48 f7 03 08 00 00 00 74 6f bf 01 00 00 00 e8 a1 ea cb f6 e8 4c fd fc f6 fb bf 01 00 00 00 <e8> f1 b4 ff ff 43 c6 44 37 08 00 48 c7 44 24 40 00 00 00 00 9c 8f
RSP: 0018:ffffc90003c17c40 EFLAGS: 00000286
RAX: e6706419edc1be00 RBX: 0000000000000000 RCX: e6706419edc1be00
RDX: dffffc0000000000 RSI: ffffffff8acacbe0 RDI: 0000000000000001
RBP: ffffc90003c17cf0 R08: ffffffff8e8b666f R09: 1ffffffff1d16ccd
R10: dffffc0000000000 R11: fffffbfff1d16cce R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff92000782f88
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x4/0x90 kernel/kcov.c:314
Code: 48 c7 44 11 08 03 00 00 00 48 89 7c 11 10 48 89 74 11 18 48 89 44 11 20 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa <48> 8b 04 24 65 48 8b 15 f0 86 7c 7e 65 8b 0d f1 86 7c 7e 81 e1 00
RSP: 0018:ffffc90003c17db0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff88802f647900 RCX: 0000000000000000
RDX: ffff88801eae5a00 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000400140 R08: ffff88802f64795f R09: 1ffff11005ec8f2b
R10: dffffc0000000000 R11: ffffed1005ec8f2c R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff88801eae5a00 R15: ffff88801eae5a2c
 fput+0xa2/0x1a0 fs/file_table.c:438
 filp_close+0x10f/0x150 fs/open.c:1547
 __range_close fs/file.c:698 [inline]
 __close_range+0x368/0x660 fs/file.c:755
 __do_sys_close_range fs/open.c:1599 [inline]
 __se_sys_close_range fs/open.c:1596 [inline]
 __x64_sys_close_range+0x7a/0x90 fs/open.c:1596
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f60a379ce59
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:00007ffd8dc69608 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: ffffffffffffffda RBX: 00007ffd8dc696f0 RCX: 00007f60a379ce59
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000005cf79 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b31820000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f60a3a15fac R14: 00007f60a3a15fa8 R15: 00007f60a3a15fa0
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/10 10:48 linux-6.6.y 924b4a879cbb 34dab4be .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in mac80211_hwsim_beacon
2026/07/17 05:53 linux-6.6.y da47cbc25466 7f27c57a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in mac80211_hwsim_beacon
* Struck through repros no longer work on HEAD.