syzbot


INFO: rcu detected stall in wait4 (8)

Status: auto-obsoleted due to no activity on 2026/07/03 08:08
Subsystems: fs
Labels: prio:normal
[Documentation on labels]
First crash: 112d, last: 93d
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
5603513c-073c-418b-993c-1bb760b92e4f assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ INFO: rcu detected stall in wait4 (8) 2026/05/17 20:44 2026/05/17 20:44 2026/05/17 21:28 de5aae85e5f28e2fa1c7deefcc24fe286abe5140

			
		
Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in wait4 (3) kernel 1 2 1239d 1244d 0/29 auto-obsoleted due to no activity on 2023/05/14 12:43
upstream INFO: rcu detected stall in wait4 kernel 1 2 1856d 1912d 0/29 auto-closed as invalid on 2021/09/04 10:15
upstream INFO: rcu detected stall in wait4 (5) fs 1 6 612d 643d 0/29 auto-obsoleted due to no activity on 2025/01/30 05:34
upstream INFO: rcu detected stall in wait4 (4) kernel 1 C error done 35 756d 1084d 0/29 auto-obsoleted due to no activity on 2024/09/18 16:22
upstream INFO: rcu detected stall in wait4 (7) kernel 1 1 262d 262d 0/29 auto-obsoleted due to no activity on 2026/01/14 18:39
upstream INFO: rcu detected stall in wait4 (2) kernel 1 2 1441d 1522d 0/29 auto-obsoleted due to no activity on 2022/10/24 16:24
upstream INFO: rcu detected stall in wait4 (6) kernel 1 1 493d 493d 0/29 auto-obsoleted due to no activity on 2025/05/29 01:55
upstream INFO: rcu detected stall in __do_sys_wait4 kernel 1 2 2123d 2153d 0/29 auto-closed as invalid on 2020/12/11 15:32

Sample crash report:
bridge0: received packet on veth0_to_bridge with own address as source address (addr:42:3a:c6:34:e6:da, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5909/1:b..l P5182/1:b..l P5974/1:b..l P5971/2:b..l P5891/1:b..l P9/1:b..l P13/1:b..l P5809/1:b..l
rcu: 	(detected by 0, t=10504 jiffies, g=12709, q=1106 ncpus=2)
task:syz-executor    state:S stack:23720 pid:5809  tgid:5809  ppid:5808   task_flags:0x400100 flags:0x00080802
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7238
 irqentry_exit+0x17b/0x670 kernel/entry/common.c:239
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_release+0x19e/0x320 kernel/locking/lockdep.c:5893
Code: ff 65 0f c1 05 cb cd 29 12 83 f8 01 0f 85 3d 01 00 00 9c 58 f6 c4 02 0f 85 28 01 00 00 41 f7 c6 00 02 00 00 0f 85 de 00 00 00 <48> 8b 44 24 10 65 48 2b 05 1d 86 29 12 0f 85 63 01 00 00 48 83 c4
RSP: 0018:ffffc90003bd72a0 EFLAGS: 00000206
RAX: 0000000000000046 RBX: ffffffff8e7e7760 RCX: ffffc90003bd72ac
RDX: 0000000000000000 RSI: ffffffff8de5cea9 RDI: ffffffff8c1b1da0
RBP: ffffffff81b7c2fe R08: 0000000000000001 R09: 0000000000000007
R10: 0000000000000200 R11: 000000000000c865 R12: ffff88807ae6db80
R13: ffffc90003bd7358 R14: 0000000000000202 R15: 0000000000000001
 rcu_lock_release include/linux/rcupdate.h:322 [inline]
 rcu_read_unlock include/linux/rcupdate.h:881 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1193 [inline]
 unwind_next_frame+0x3c3/0x1ea0 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_record_aux_stack+0xa7/0xc0 mm/kasan/generic.c:556
 __call_rcu_common.constprop.0+0xa5/0x9b0 kernel/rcu/tree.c:3131
 destroy_inode+0x134/0x1c0 fs/inode.c:402
 evict+0x599/0xad0 fs/inode.c:870
 iput_final fs/inode.c:1966 [inline]
 iput.part.0+0x605/0xf50 fs/inode.c:2015
 iput+0x35/0x40 fs/inode.c:1981
 proc_invalidate_siblings_dcache+0x27e/0x750 fs/proc/inode.c:152
 release_task+0xd41/0x1ab0 kernel/exit.c:291
 wait_task_zombie kernel/exit.c:1280 [inline]
 wait_consider_task+0x1791/0x3e00 kernel/exit.c:1507
 do_wait_pid kernel/exit.c:1646 [inline]
 __do_wait+0x762/0x8b0 kernel/exit.c:1681
 do_wait+0x1ec/0x5a0 kernel/exit.c:1722
 kernel_wait4+0x16d/0x280 kernel/exit.c:1881
 __do_sys_wait4+0x161/0x170 kernel/exit.c:1909
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcd5d557997
RSP: 002b:00007ffccc1970a0 EFLAGS: 00000202 ORIG_RAX: 000000000000003d
RAX: ffffffffffffffda RBX: 000055555b7df540 RCX: 00007fcd5d557997
RDX: 0000000040000000 RSI: 00007ffccc1970fc RDI: 00000000000016b8
RBP: 000055555b7f3f80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffccc1970fc
R13: 000055555b7f5540 R14: 000055555b7f7920 R15: 00007ffccc1971b0
 </TASK>
task:kworker/u8:1    state:R  running task     stack:25480 pid:13    tgid:13    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: events_unbound cfg80211_wiphy_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7238
 irqentry_exit+0x17b/0x670 kernel/entry/common.c:239
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__orc_find+0x13/0xf0 arch/x86/kernel/unwind_orc.c:86
Code: 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 41 57 41 56 41 55 49 89 cd 89 d1 41 54 4c 8d 64 8f fc 55 <53> 48 83 ec 08 85 d2 0f 84 99 00 00 00 49 89 fe 48 89 f0 49 39 fc
RSP: 0018:ffffc900001276c0 EFLAGS: 00000202
RAX: ffffffff92209ee6 RBX: 0000000000000001 RCX: 0000000000000001
RDX: 0000000000000001 RSI: ffffffff92209ee6 RDI: ffffffff91622578
RBP: ffffc900001277a8 R08: ffffffff92209eec R09: 0000000000000007
R10: 0000000000000200 R11: 000000000009dad2 R12: ffffffff91622578
R13: ffffffff8adad2d5 R14: ffffc90000127795 R15: ffffffff8adad2d5
 orc_find arch/x86/kernel/unwind_orc.c:238 [inline]
 unwind_next_frame+0x2ec/0x1ea0 arch/x86/kernel/unwind_orc.c:510
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 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
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2685 [inline]
 slab_free mm/slub.c:6165 [inline]
 kmem_cache_free+0x124/0x6a0 mm/slub.c:6295
 kfree_skbmem+0x19a/0x210 net/core/skbuff.c:1151
 __kfree_skb net/core/skbuff.c:1218 [inline]
 consume_skb net/core/skbuff.c:1450 [inline]
 consume_skb+0xd1/0x110 net/core/skbuff.c:1444
 ieee80211_iface_work+0x468/0x13d0 net/mac80211/iface.c:1804
 cfg80211_wiphy_work+0x446/0x5c0 net/wireless/core.c:440
 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276
 process_scheduled_works kernel/workqueue.c:3359 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
task:kworker/0:0     state:R  running task     stack:26840 pid:9     tgid:9     ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: events_power_efficient gc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7238
 irqentry_exit+0x17b/0x670 kernel/entry/common.c:239
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__seqprop_spinlock_sequence include/linux/seqlock.h:228 [inline]
RIP: 0010:nf_conntrack_get_ht include/net/netfilter/nf_conntrack.h:343 [inline]
RIP: 0010:gc_worker+0x2bb/0x1630 net/netfilter/nf_conntrack_core.c:1548
Code: 00 00 48 c7 c7 48 b0 da 90 e8 e1 12 38 f8 9c 5b 81 e3 00 02 00 00 31 ff 48 89 de e8 6f de 5b f8 58 48 85 db 0f 85 97 0f 00 00 <e8> 80 e3 5b f8 8b 1d ba 4a 2e 07 89 dd 31 ff 83 e5 01 89 ee e8 1c
RSP: 0018:ffffc900000e7b48 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff89ac7016
RDX: ffff88801e2b5b80 RSI: ffffffff89ac7025 RDI: ffff88801e2b5b80
RBP: 000000000000418b R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000040000 R14: 00000000000020c6 R15: 0000000000001770
 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276
 process_scheduled_works kernel/workqueue.c:3359 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
task:kworker/0:4     state:R  running task     stack:27016 pid:5891  tgid:5891  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue:  0x0 (events)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7238
 irqentry_exit+0x17b/0x670 kernel/entry/common.c:239
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:rcu_is_watching+0x83/0xc0 kernel/rcu/tree.c:755
Code: c1 ea 03 0f b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 24 8b 03 c1 e8 02 83 e0 01 65 ff 0d c0 1a 21 12 74 07 5b <5d> c3 cc cc cc cc e8 f2 5d 89 ff 5b 5d e9 5b c6 a4 09 48 89 df e8
RSP: 0018:ffffc90004367848 EFLAGS: 00000286
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffffffff8c1b1d20 RDI: ffffffff8e1318e0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000200 R11: 000000000000ad3f R12: 0000000000000002
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 trace_lock_acquire include/trace/events/lock.h:24 [inline]
 lock_acquire+0x317/0x380 kernel/locking/lockdep.c:5831
 rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 rcu_read_lock include/linux/rcupdate.h:850 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1193 [inline]
 unwind_next_frame+0xd1/0x1ea0 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 save_stack+0x162/0x1e0 mm/page_owner.c:165
 __reset_page_owner+0x84/0x190 mm/page_owner.c:320
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0x7e1/0x10d0 mm/page_alloc.c:2978
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xe0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_kmalloc+0x8a/0xb0 mm/kasan/common.c:406
 kmalloc_node_noprof include/linux/slab.h:1077 [inline]
 alloc_worker kernel/workqueue.c:2660 [inline]
 create_worker+0x110/0x750 kernel/workqueue.c:2803
 maybe_create_worker kernel/workqueue.c:3075 [inline]
 manage_workers kernel/workqueue.c:3152 [inline]
 worker_thread+0x8e2/0xe50 kernel/workqueue.c:3415
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
task:syz.1.15        state:R  running task     stack:26544 pid:5971  tgid:5968  ppid:5820   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7095
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __local_bh_enable_ip+0xff/0x120 kernel/softirq.c:457
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 ip6t_do_table+0xbfa/0x1c90 net/ipv6/netfilter/ip6_tables.c:375
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xbf/0x220 net/netfilter/core.c:623
 nf_hook include/linux/netfilter.h:273 [inline]
 __ip6_local_out+0x4c0/0xaf0 net/ipv6/output_core.c:140
 ip6_local_out+0x2a/0x1f0 net/ipv6/output_core.c:150
 ip6_send_skb+0x112/0x430 net/ipv6/ip6_output.c:1984
 ip6_push_pending_frames+0x3b/0x50 net/ipv6/ip6_output.c:2005
 rawv6_push_pending_frames net/ipv6/raw.c:589 [inline]
 rawv6_sendmsg+0x2d0c/0x4420 net/ipv6/raw.c:919
 inet_sendmsg+0x11c/0x140 net/ipv4/af_inet.c:865
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0x98d/0xb70 net/socket.c:2592
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2646
 __sys_sendmmsg+0x205/0x430 net/socket.c:2735
 __do_sys_sendmmsg net/socket.c:2762 [inline]
 __se_sys_sendmmsg net/socket.c:2759 [inline]
 __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2759
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f730ad9c819
RSP: 002b:00007f730bcca028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f730b016090 RCX: 00007f730ad9c819
RDX: 00000000000009a6 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f730ae32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000007000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f730b016128 R14: 00007f730b016090 R15: 00007ffd478d2388
 </TASK>
task:kworker/u8:9    state:R  running task     stack:29192 pid:5974  tgid:5974  ppid:2      task_flags:0x4208060 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7238
 irqentry_exit+0x17b/0x670 kernel/entry/common.c:239
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_release+0x19e/0x320 kernel/locking/lockdep.c:5893
Code: ff 65 0f c1 05 cb cd 29 12 83 f8 01 0f 85 3d 01 00 00 9c 58 f6 c4 02 0f 85 28 01 00 00 41 f7 c6 00 02 00 00 0f 85 de 00 00 00 <48> 8b 44 24 10 65 48 2b 05 1d 86 29 12 0f 85 63 01 00 00 48 83 c4
RSP: 0018:ffffc90004537698 EFLAGS: 00000206
RAX: 0000000000000046 RBX: ffffffff8e7e7760 RCX: ffffc900045376a4
RDX: 0000000000000001 RSI: ffffffff8de5cea9 RDI: ffffffff8c1b1da0
RBP: ffffffff81b7c2fe R08: 0000000000000001 R09: 0000000000000007
R10: 0000000000000200 R11: 000000000000d194 R12: ffff888027bcbd00
R13: ffffc90004537750 R14: 0000000000000202 R15: 0000000000000002
 rcu_lock_release include/linux/rcupdate.h:322 [inline]
 rcu_read_unlock include/linux/rcupdate.h:881 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1193 [inline]
 unwind_next_frame+0x3c3/0x1ea0 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 save_stack+0x162/0x1e0 mm/page_owner.c:165
 __reset_page_owner+0x84/0x190 mm/page_owner.c:320
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0x7e1/0x10d0 mm/page_alloc.c:2978
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xe0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_kmalloc+0x8a/0xb0 mm/kasan/common.c:406
 kmalloc_noprof include/linux/slab.h:950 [inline]
 __kthread_create_on_node+0xce/0x3f0 kernel/kthread.c:483
 kthread_create_on_node+0xc7/0x100 kernel/kthread.c:559
 create_worker+0x420/0x750 kernel/workqueue.c:2815
 maybe_create_worker kernel/workqueue.c:3075 [inline]
 manage_workers kernel/workqueue.c:3152 [inline]
 worker_thread+0x8e2/0xe50 kernel/workqueue.c:3415
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
task:klogd           state:R  running task     stack:25416 pid:5182  tgid:5182  ppid:1      task_flags:0x400100 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7238
 irqentry_exit+0x17b/0x670 kernel/entry/common.c:239
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:unwind_next_frame+0x4d6/0x1ea0 arch/x86/kernel/unwind_orc.c:520
Code: e8 6f f3 ff ff 48 89 c1 48 85 c0 0f 84 2d 0b 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8d 79 05 4c 89 fa 48 c1 ea 03 0f b6 04 02 <4c> 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 bd 13 00 00 0f b6 41 05
RSP: 0018:ffffc90003b474b0 EFLAGS: 00000a07
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff916f0592
RDX: 1ffffffff22de0b2 RSI: 0000000000000000 RDI: ffffffff90ebbf40
RBP: ffffc90003b47568 R08: ffffffff916f065e R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000000001 R12: ffffc90003b47570
R13: ffffc90003b47520 R14: ffffc90003b47555 R15: ffffffff916f0597
 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
 save_stack+0x162/0x1e0 mm/page_owner.c:165
 __reset_page_owner+0x84/0x190 mm/page_owner.c:320
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0x7e1/0x10d0 mm/page_alloc.c:2978
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xe0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4538 [inline]
 slab_alloc_node mm/slub.c:4866 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_node_track_caller_noprof+0x2ba/0x850 mm/slub.c:5368
 kmalloc_reserve+0xe8/0x350 net/core/skbuff.c:635
 __alloc_skb+0x185/0x710 net/core/skbuff.c:713
 alloc_skb include/linux/skbuff.h:1383 [inline]
 alloc_skb_with_frags+0xe0/0x810 net/core/skbuff.c:6763
 sock_alloc_send_pskb+0x801/0x980 net/core/sock.c:2995
 unix_dgram_sendmsg+0x3c7/0x1820 net/unix/af_unix.c:2127
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 __sys_sendto+0x468/0x4b0 net/socket.c:2206
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2209
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1ef2322407
RSP: 002b:00007fff483b5880 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f1ef21d2c80 RCX: 00007f1ef2322407
RDX: 0000000000000075 RSI: 00007fff483b59c0 RDI: 0000000000000003
RBP: 00007fff483b5df0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000202 R12: 00007fff483b5e08
R13: 00007fff483b59c0 R14: 000000000000005a R15: 00007fff483b59c0
 </TASK>
task:kworker/1:7     state:R  running task     stack:27464 pid:5909  tgid:5909  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: mld mld_dad_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 preempt_schedule_notrace+0x5f/0xd0 kernel/sched/core.c:7188
 preempt_schedule_notrace_thunk+0x16/0x30 arch/x86/entry/thunk.S:13
 rcu_is_watching+0x8e/0xc0 kernel/rcu/tree.c:753
 trace_lock_release include/trace/events/lock.h:69 [inline]
 lock_release+0x263/0x320 kernel/locking/lockdep.c:5879
 rcu_lock_release include/linux/rcupdate.h:322 [inline]
 rcu_read_unlock include/linux/rcupdate.h:881 [inline]
 page_ext_put+0x43/0xd0 mm/page_ext.c:579
 __reset_page_owner+0x7a/0x190 mm/page_owner.c:312
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0x7e1/0x10d0 mm/page_alloc.c:2978
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x47/0xe0 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4538 [inline]
 slab_alloc_node mm/slub.c:4866 [inline]
 __do_kmalloc_node mm/slub.c:5259 [inline]
 __kmalloc_node_track_caller_noprof+0x2ba/0x850 mm/slub.c:5368
 kmalloc_reserve+0xe8/0x350 net/core/skbuff.c:635
 __alloc_skb+0x185/0x710 net/core/skbuff.c:713
 alloc_skb include/linux/skbuff.h:1383 [inline]
 mld_newpack.isra.0+0x18e/0xa20 net/ipv6/mcast.c:1775
 add_grhead+0x299/0x340 net/ipv6/mcast.c:1886
 add_grec+0x1380/0x1920 net/ipv6/mcast.c:2025
 mld_send_initial_cr+0x156/0x320 net/ipv6/mcast.c:2268
 mld_dad_work+0x32/0x1f0 net/ipv6/mcast.c:2294
 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276
 process_scheduled_works kernel/workqueue.c:3359 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: rcu_preempt kthread starved for 304 jiffies! g12709 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:27832 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6911
 __schedule_loop kernel/sched/core.c:6993 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7008
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:__kasan_check_byte+0x0/0x50 mm/kasan/common.c:572
Code: 8d 74 15 00 5d ba fe 00 00 00 41 5c 41 5d e9 b7 2c 00 00 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <0f> 1f 40 d6 41 54 49 89 f4 55 48 89 fd 53 e8 4d 20 00 00 89 c3 84
RSP: 0018:ffffc900000070c0 EFLAGS: 00000202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffffffff8b9162df RDI: ffff8880360ea458
RBP: ffff8880360ea458 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000002
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888124340000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffde9122dbc CR3: 000000002afb8000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 kasan_check_byte include/linux/kasan.h:402 [inline]
 lock_acquire kernel/locking/lockdep.c:5842 [inline]
 lock_acquire+0x148/0x380 kernel/locking/lockdep.c:5825
 __raw_read_lock_bh include/linux/rwlock_api_smp.h:190 [inline]
 _raw_read_lock_bh+0x3f/0x70 kernel/locking/spinlock.c:252
 ebt_do_table+0xe8/0x2250 net/bridge/netfilter/ebtables.c:211
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xbf/0x220 net/netfilter/core.c:623
 nf_hook.constprop.0+0x190/0x6b0 include/linux/netfilter.h:273
 NF_HOOK include/linux/netfilter.h:316 [inline]
 br_pass_frame_up+0x307/0x490 net/bridge/br_input.c:70
 br_handle_frame_finish+0xa74/0x1f60 net/bridge/br_input.c:235
 br_nf_hook_thresh+0x30d/0x420 net/bridge/br_netfilter_hooks.c:1167
 br_nf_pre_routing_finish_ipv6+0x769/0xfb0 net/bridge/br_netfilter_ipv6.c:154
 NF_HOOK include/linux/netfilter.h:318 [inline]
 br_nf_pre_routing_ipv6+0x39c/0x8b0 net/bridge/br_netfilter_ipv6.c:184
 br_nf_pre_routing+0x90d/0x1550 net/bridge/br_netfilter_hooks.c:508
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:291 [inline]
 br_handle_frame+0xcdd/0x1520 net/bridge/br_input.c:442
 __netif_receive_skb_core.constprop.0+0x6c5/0x3550 net/core/dev.c:6068
 __netif_receive_skb_one_core+0xb0/0x1e0 net/core/dev.c:6179
 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6294
 process_backlog+0x37a/0x1580 net/core/dev.c:6645
 __napi_poll.constprop.0+0xaf/0x450 net/core/dev.c:7709
 napi_poll net/core/dev.c:7772 [inline]
 net_rx_action+0xa40/0xf20 net/core/dev.c:7929
 handle_softirqs+0x1eb/0x9e0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xef/0x150 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1056
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
Code: a8 84 02 c3 cc cc cc cc 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 43 00 1d 00 fb f4 <e9> fc 35 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffffff8e407e00 EFLAGS: 00000242
RAX: 0000000000ffb349 RBX: ffffffff8e4975c0 RCX: ffffffff8b8e8c75
RDX: 0000000000000000 RSI: ffffffff8de82fd4 RDI: ffffffff8c1b1da0
RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed101708679d
R10: ffff8880b8433ceb R11: 0000000000000000 R12: 0000000000000000
R13: fffffbfff1c92eb8 R14: 0000000000000000 R15: ffffffff90d9fc10
 arch_safe_halt arch/x86/include/asm/paravirt.h:73 [inline]
 default_idle+0x9/0x10 arch/x86/kernel/process.c:767
 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:199 [inline]
 do_idle+0x464/0x590 kernel/sched/idle.c:352
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:451
 rest_init+0x251/0x260 init/main.c:760
 start_kernel+0x47f/0x480 init/main.c:1210
 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
 x86_64_start_kernel+0x12b/0x130 arch/x86/kernel/head64.c:291
 common_startup_64+0x13e/0x148
 </TASK>
bridge0: received packet on veth0_to_bridge with own address as source address (addr:42:3a:c6:34:e6:da, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:42:3a:c6:34:e6:da, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:42:3a:c6:34:e6:da, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:42:3a:c6:34:e6:da, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:42:3a:c6:34:e6:da, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:42:3a:c6:34:e6:da, vlan:0)

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/04 07:59 upstream 631919fb12fe 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in wait4
2026/03/15 21:51 upstream f338e7738378 ee8d34d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto INFO: rcu detected stall in wait4
* Struck through repros no longer work on HEAD.