BUG: soft lockup in mac80211_hwsim_beacon (3)

Status: moderation: reported on 2026/07/30 07:17
Subsystems: virt
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+463a704e1172c29bba77@syzkaller.appspotmail.com
First crash: 4d04h, last: 3d03h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
a59d4cd4 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ BUG: soft lockup in mac80211_hwsim_beacon (3) 2026/07/28 02:22 2026/07/28 02:22 2026/07/28 03:08 4cb2b096

			
		
Similar bugs (12)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: soft lockup in mac80211_hwsim_beacon wireless 1 syz error unreliable 180 1556d 2128d 0/29 auto-obsoleted due to no activity on 2023/01/21 14:41
upstream BUG: soft lockup in mac80211_hwsim_beacon (2) wireless prio:high 1 syz, C error inconclusive 171 109d 870d 0/29 auto-obsoleted due to no activity on 2026/06/21 00:56
linux-6.1 INFO: rcu detected stall in mac80211_hwsim_beacon (4) origin:lts-only 1 syz, C error 13 6d19h 105d 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 1556d 2135d 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 343d 343d 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 1014d 1014d 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 667d 674d 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 552d 552d 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 84d 323d 0/3 upstream: reported on 2025/09/09 14:58
linux-6.1 INFO: rcu detected stall in mac80211_hwsim_beacon 1 3 667d 692d 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 2 13d 50d 0/2 upstream: reported C repro on 2026/06/10 10:49
linux-5.15 INFO: rcu detected stall in mac80211_hwsim_beacon (2) 1 1 890d 890d 0/3 auto-obsoleted due to no activity on 2024/05/30 17:39

Sample crash report:
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
sched: DL replenish lagged too much
watchdog: BUG: soft lockup - CPU#0 stuck for 220s! [kworker/u8:4:58]
Modules linked in:
irq event stamp: 252177
hardirqs last  enabled at (252176): [<ffffffff81b76dff>] kvm_wait arch/x86/kernel/kvm.c:1096 [inline]
hardirqs last  enabled at (252176): [<ffffffff81b76dff>] kvm_wait+0x11f/0x160 arch/x86/kernel/kvm.c:1078
hardirqs last disabled at (252177): [<ffffffff8bb9a31e>] sysvec_apic_timer_interrupt+0xe/0xc0 arch/x86/kernel/apic/apic.c:1062
softirqs last  enabled at (158208): [<ffffffff81c8d222>] __do_softirq kernel/softirq.c:656 [inline]
softirqs last  enabled at (158208): [<ffffffff81c8d222>] invoke_softirq kernel/softirq.c:496 [inline]
softirqs last  enabled at (158208): [<ffffffff81c8d222>] __irq_exit_rcu+0x162/0x210 kernel/softirq.c:735
softirqs last disabled at (158217): [<ffffffff81c8d222>] __do_softirq kernel/softirq.c:656 [inline]
softirqs last disabled at (158217): [<ffffffff81c8d222>] invoke_softirq kernel/softirq.c:496 [inline]
softirqs last disabled at (158217): [<ffffffff81c8d222>] __irq_exit_rcu+0x162/0x210 kernel/softirq.c:735
CPU: 0 UID: 0 PID: 58 Comm: kworker/u8:4 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: writeback wb_workfn (flush-8:0)
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64
Code: 66 8d 02 e9 8e 98 56 f5 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d c3 de 11 00 fb f4 <e9> 67 98 56 f5 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffc90000007970 EFLAGS: 00000252
RAX: 000000000003d910 RBX: 0000000000000003 RCX: 0000000000000004
RDX: 0000000000000000 RSI: ffffffff8e1a9f82 RDI: ffffffff8c400980
RBP: ffffffff8ffb6540 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: 0000000000000003 R14: ffff8880b843c600 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888123dde000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c35a1d7 CR3: 000000005a286000 CR4: 0000000000350ef0
Call Trace:
 <IRQ>
 arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline]
 kvm_wait arch/x86/kernel/kvm.c:1096 [inline]
 kvm_wait+0x124/0x160 arch/x86/kernel/kvm.c:1078
 pv_wait arch/x86/include/asm/paravirt-spinlock.h:83 [inline]
 pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:466 [inline]
 __pv_queued_spin_lock_slowpath+0x4b0/0xc00 kernel/locking/qspinlock.c:325
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt-spinlock.h:35 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/paravirt-spinlock.h:66 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x1e0/0x260 kernel/locking/spinlock_debug.c:116
 spin_lock include/linux/spinlock.h:342 [inline]
 mac80211_hwsim_tx_frame_no_nl+0x745/0x1830 drivers/net/wireless/virtual/mac80211_hwsim_main.c:1963
 mac80211_hwsim_tx_frame+0x1b7/0x250 drivers/net/wireless/virtual/mac80211_hwsim_main.c:2417
 __mac80211_hwsim_beacon_tx drivers/net/wireless/virtual/mac80211_hwsim_main.c:2430 [inline]
 mac80211_hwsim_beacon_tx+0x56c/0xa00 drivers/net/wireless/virtual/mac80211_hwsim_main.c:2493
 __iterate_interfaces+0x2e6/0x650 net/mac80211/util.c:775
 ieee80211_iterate_active_interfaces_atomic+0x71/0x1b0 net/mac80211/util.c:811
 mac80211_hwsim_beacon+0xe5/0x2a0 drivers/net/wireless/virtual/mac80211_hwsim_main.c:2525
 __run_hrtimer kernel/time/hrtimer.c:2032 [inline]
 __hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2096
 hrtimer_run_softirq+0x17d/0x2c0 kernel/time/hrtimer.c:2113
 handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x162/0x210 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1062
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0x58e/0x1870 kernel/smp.c:912
Code: b8 00 00 00 00 00 fc ff df 48 8b 54 24 08 49 89 d5 49 89 d4 49 c1 ed 03 41 83 e4 07 49 01 c5 41 83 c4 03 e8 54 99 0c 00 f3 90 <41> 0f b6 45 00 41 38 c4 7c 08 84 c0 0f 85 a8 10 00 00 8b 45 08 31
RSP: 0018:ffffc900015f6848 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81fda5f2
RDX: ffff88801e725d00 RSI: ffffffff81fda5cc RDI: ffff88801e725d00
RBP: ffff8880b8541380 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: ffffed10170a8271 R14: 0000000000000001 R15: ffff8880b843c9c0
 on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1077
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
 flush_tlb_mm_range+0x45f/0x16f0 arch/x86/mm/tlb.c:1451
 flush_tlb_page arch/x86/include/asm/tlbflush.h:345 [inline]
 ptep_clear_flush+0x148/0x170 mm/pgtable-generic.c:104
 page_vma_mkclean_one.constprop.0+0x3a2/0x7b0 mm/rmap.c:1138
 page_mkclean_one+0x1cd/0x2b0 mm/rmap.c:1186
 __rmap_walk_file+0x383/0x680 mm/rmap.c:3064
 rmap_walk_file+0x1d8/0x2a0 mm/rmap.c:3097
 rmap_walk mm/rmap.c:3108 [inline]
 folio_mkclean+0x2af/0x4e0 mm/rmap.c:1218
 folio_clear_dirty_for_io+0x1ba/0x960 mm/page-writeback.c:2909
 mpage_submit_folio+0x84/0x330 fs/ext4/inode.c:2085
 mpage_map_and_submit_buffers+0x5f2/0xb50 fs/ext4/inode.c:2347
 mpage_map_and_submit_extent fs/ext4/inode.c:2537 [inline]
 ext4_do_writepages+0x23a4/0x3ed0 fs/ext4/inode.c:2949
 ext4_writepages+0x347/0x750 fs/ext4/inode.c:3043
 do_writepages+0x278/0x600 mm/page-writeback.c:2571
 __writeback_single_inode+0x164/0x1300 fs/fs-writeback.c:1787
 writeback_sb_inodes+0x766/0x1c50 fs/fs-writeback.c:2079
 __writeback_inodes_wb+0xf8/0x2d0 fs/fs-writeback.c:2155
 wb_writeback+0x6f6/0xb50 fs/fs-writeback.c:2266
 wb_check_old_data_flush fs/fs-writeback.c:2370 [inline]
 wb_do_writeback fs/fs-writeback.c:2449 [inline]
 wb_workfn+0x93f/0xc80 fs/fs-writeback.c:2477
 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
 process_scheduled_works kernel/workqueue.c:3405 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5624 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:mark_lock+0x76/0xa20 kernel/locking/lockdep.c:4774
Code: a3 05 4e 3e 85 14 73 5b 48 8d 04 80 48 8d 04 80 48 8d 04 c5 e0 ed 6a 96 4c 89 f1 48 23 48 60 0f 84 03 03 00 00 b8 01 00 00 00 <48> 8b 54 24 68 65 48 2b 15 45 74 7e 12 0f 85 ea 07 00 00 48 8d 65
RSP: 0018:ffffc90000a08010 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffff8880355d4b30 RDI: ffff8880355d3e00
RBP: ffffc90000a080b0 R08: 0000000000000001 R09: 0000000000000003
R10: 000000000000000a R11: 000000000000000a R12: ffff8880355d4b30
R13: ffff8880355d3e00 R14: 0000000000000001 R15: 0000000000000001
FS:  0000555590080500(0000) GS:ffff888123ede000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8aabb556b8 CR3: 000000005a278000 CR4: 0000000000350ef0
Call Trace:
 <IRQ>
 mark_usage kernel/locking/lockdep.c:4639 [inline]
 __lock_acquire+0x10a8/0x1a40 kernel/locking/lockdep.c:5191
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
 __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158
 spin_lock include/linux/spinlock.h:342 [inline]
 advance_sched+0xe5/0xd20 net/sched/sch_taprio.c:930
 __run_hrtimer kernel/time/hrtimer.c:2032 [inline]
 __hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2096
 hrtimer_interrupt+0x3e5/0x940 kernel/time/hrtimer.c:2215
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
 __sysvec_apic_timer_interrupt+0x109/0x470 arch/x86/kernel/apic/apic.c:1068
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x51/0xc0 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872
Code: 05 fb 4d 7e 12 83 f8 07 0f 87 da 00 00 00 48 0f a3 05 86 cc 3c 0f 0f 82 ac 02 00 00 8b 35 2e 00 3d 0f 85 f6 0f 85 c7 00 00 00 <48> 8b 44 24 30 65 48 2b 05 9d 4d 7e 12 0f 85 ec 02 00 00 48 83 c4
RSP: 0018:ffffc90000a084e0 EFLAGS: 00000206
RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8e1840ee RDI: ffffffff8c400980
RBP: ffffffff8ebe8180 R08: 00000000cda50cb6 R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 rcu_read_lock include/linux/rcupdate.h:840 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
 unwind_next_frame+0xd1/0x2090 arch/x86/kernel/unwind_orc.c:495
 __unwind_start+0x3cd/0x7e0 arch/x86/kernel/unwind_orc.c:787
 unwind_start arch/x86/include/asm/unwind.h:64 [inline]
 arch_stack_walk+0x73/0xf0 arch/x86/kernel/stacktrace.c:24
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4584 [inline]
 slab_alloc_node mm/slub.c:4917 [inline]
 kmem_cache_alloc_node_noprof+0x27d/0x6b0 mm/slub.c:4989
 kmalloc_reserve+0x148/0x350 net/core/skbuff.c:615
 __alloc_skb+0x185/0x710 net/core/skbuff.c:715
 skb_copy+0x1ca/0x3a0 net/core/skbuff.c:2185
 mac80211_hwsim_tx_frame_no_nl+0xc7f/0x1830 drivers/net/wireless/virtual/mac80211_hwsim_main.c:2020
 mac80211_hwsim_tx_frame+0x1b7/0x250 drivers/net/wireless/virtual/mac80211_hwsim_main.c:2417
 __mac80211_hwsim_beacon_tx drivers/net/wireless/virtual/mac80211_hwsim_main.c:2430 [inline]
 mac80211_hwsim_beacon_tx+0x56c/0xa00 drivers/net/wireless/virtual/mac80211_hwsim_main.c:2493
 __iterate_interfaces+0x2e6/0x650 net/mac80211/util.c:775
 ieee80211_iterate_active_interfaces_atomic+0x71/0x1b0 net/mac80211/util.c:811
 mac80211_hwsim_beacon+0xe5/0x2a0 drivers/net/wireless/virtual/mac80211_hwsim_main.c:2525
 __run_hrtimer kernel/time/hrtimer.c:2032 [inline]
 __hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2096
 hrtimer_run_softirq+0x17d/0x2c0 kernel/time/hrtimer.c:2113
 handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x162/0x210 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1062
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:__folio_rmap_sanity_checks include/linux/rmap.h:335 [inline]
RIP: 0010:__folio_dup_file_rmap include/linux/rmap.h:498 [inline]
RIP: 0010:folio_dup_file_rmap_pte include/linux/rmap.h:544 [inline]
RIP: 0010:copy_present_ptes mm/memory.c:1192 [inline]
RIP: 0010:copy_pte_range mm/memory.c:1320 [inline]
RIP: 0010:copy_pmd_range mm/memory.c:1408 [inline]
RIP: 0010:copy_pud_range mm/memory.c:1445 [inline]
RIP: 0010:copy_p4d_range mm/memory.c:1469 [inline]
RIP: 0010:copy_page_range+0x1d2c/0x5b20 mm/memory.c:1555
Code: 90 0f 0b 90 e9 3e 15 00 00 e8 90 fe aa ff bd 00 10 00 00 83 44 24 38 01 bb 08 00 00 00 e9 e5 fd ff ff e8 77 fe aa ff 44 89 ee <bf> f4 00 00 00 e8 da f8 aa ff 41 81 fd f4 00 00 00 0f 84 61 25 00
RSP: 0018:ffffc90002f37548 EFLAGS: 00000293
RAX: 0000000000000000 RBX: ffffea00015f8680 RCX: ffffffff825f3643
RDX: ffff8880355d3e00 RSI: 0000000000000000 RDI: ffff8880355d3e00
RBP: ffffea00015f86b4 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffea00015f8698
R13: 0000000000000000 R14: ffff88805a29c098 R15: ffffea00015f8680
 dup_mmap+0xd44/0x21b0 mm/mmap.c:1840
 dup_mm kernel/fork.c:1543 [inline]
 copy_mm kernel/fork.c:1595 [inline]
 copy_process+0x4588/0x8030 kernel/fork.c:2289
 kernel_clone+0x176/0x9d0 kernel/fork.c:2748
 __do_sys_clone+0xd9/0x120 kernel/fork.c:2889
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8aaadc6912
Code: 89 e7 e8 71 8b f7 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffdc2535310 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffdc2535310 RCX: 00007f8aaadc6912
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffdc253549c R08: 0000000000000000 R09: 0000000000000001
R10: 00005555900807d0 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000000927c0 R14: 000000000001a791 R15: 00007ffdc25354f0
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/27 08:25 upstream 4235cb24ec1e 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root BUG: soft lockup in mac80211_hwsim_beacon
2026/07/26 07:10 upstream 3dab139d4795 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root BUG: soft lockup in mac80211_hwsim_beacon
* Struck through repros no longer work on HEAD.