syzbot
INFO: rcu detected stall in ep_eventpoll_release (2)
Status: auto-obsoleted due to no activity on 2026/10/07 10:41
Subsystems:
mm
Labels:
prio:high
[Documentation on labels]
First crash: 99d, last: 99d
Sample crash report:
bridge0: received packet on veth1_to_bridge with own address as source address (addr:fe:8c:62:e7:55:e4, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6801/2:b..l P6852/1:b..l P6825/1:b..l
rcu: (detected by 1, t=10503 jiffies, g=19173, q=1117 ncpus=2)
task:syz.4.281 state:R running task stack:25640 pid:6825 tgid:6825 ppid:5633 task_flags:0x480040 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556
irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_release+0x2d7/0x3c0 kernel/locking/lockdep.c:5893
Code: 5e ca 11 00 00 00 00 eb b5 e8 a5 0e 2c 0a f7 c3 00 02 00 00 74 b9 65 48 8b 05 95 19 ca 11 48 3b 44 24 28 75 44 fb 48 83 c4 30 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 52 a6 b8
RSP: 0018:ffffc9001b5cf588 EFLAGS: 00000286
RAX: 231da0d1ac9b2800 RBX: 0000000000000206 RCX: 0000000000000046
RDX: 0000000000000001 RSI: ffffffff8e4ae921 RDI: ffffffff8c4bd280
RBP: ffff888053d88bc8 R08: ffffc9001b5cfd18 R09: 0000000000000000
R10: ffffc9001b5cf6b8 R11: fffff520036b9ed9 R12: 0000000000000001
R13: 0000000000000001 R14: ffffffff8eb59c20 R15: ffff888053d88000
rcu_lock_release include/linux/rcupdate.h:310 [inline]
rcu_read_unlock include/linux/rcupdate.h:871 [inline]
class_rcu_destructor include/linux/rcupdate.h:1183 [inline]
unwind_next_frame+0x1baa/0x2550 arch/x86/kernel/unwind_orc.c:709
arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
save_stack+0x122/0x230 mm/page_owner.c:165
__reset_page_owner+0x71/0x1f0 mm/page_owner.c:320
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0xc1e/0xd10 mm/page_alloc.c:2950
__slab_free+0x274/0x2c0 mm/slub.c:5767
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4612 [inline]
slab_alloc_node mm/slub.c:4945 [inline]
__kmalloc_cache_noprof+0x2ab/0x660 mm/slub.c:5511
_kmalloc_noprof include/linux/slab.h:969 [inline]
_kzalloc_noprof include/linux/slab.h:1290 [inline]
kobject_uevent_env+0x289/0x9e0 lib/kobject_uevent.c:543
device_del+0x74d/0x8f0 drivers/base/core.c:3979
device_unregister+0x21/0xf0 drivers/base/core.c:4002
wakeup_source_unregister+0x159/0x3f0 drivers/base/power/wakeup.c:239
ep_free fs/eventpoll.c:1043 [inline]
ep_clear_and_put+0x381/0x4d0 fs/eventpoll.c:1234
ep_eventpoll_release+0x45/0x60 fs/eventpoll.c:1263
__fput+0x418/0xa50 fs/file_table.c:512
task_work_run+0x1d9/0x270 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
exit_to_user_mode_loop+0x1fa/0x730 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f606839de59
RSP: 002b:00007ffc52e79f88 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffc52e7a070 RCX: 00007f606839de59
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000001b50f R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b33620000 R11: 0000000000000246 R12: 00007ffc52e7a0b0
R13: 00007f6068625fac R14: 000000000001b611 R15: 00007f6068625fa0
</TASK>
task:syz.0.285 state:R running task stack:22648 pid:6852 tgid:6845 ppid:5624 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556
irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_release+0xb/0x3c0 kernel/locking/lockdep.c:5876
Code: bf 2f 00 00 00 e9 06 ff ff ff 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 41 57 41 56 41 55 <41> 54 53 48 83 ec 30 49 89 f5 49 89 fe 65 48 8b 05 40 1c ca 11 48
RSP: 0018:ffffc9001ba865a8 EFLAGS: 00000283
RAX: ffffffff823de86f RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc9001099a000 RSI: ffffffff823de4ae RDI: ffffffff8eb59c20
RBP: ffff88801c5ecf74 R08: ffff88801c5ecf37 R09: 1ffff110038bd9e6
R10: dffffc0000000000 R11: ffffed10038bd9e7 R12: 0000000000026291
R13: dffffc0000000000 R14: ffffffff823de4ae R15: ffff88801c5ecf80
rcu_lock_release include/linux/rcupdate.h:310 [inline]
rcu_read_unlock include/linux/rcupdate.h:871 [inline]
__update_page_owner_free_handle+0x456/0x470 mm/page_owner.c:295
__reset_page_owner+0x85/0x1f0 mm/page_owner.c:321
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0xc1e/0xd10 mm/page_alloc.c:2950
__slab_free+0x274/0x2c0 mm/slub.c:5767
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4612 [inline]
slab_alloc_node mm/slub.c:4945 [inline]
kmem_cache_alloc_noprof+0x2a0/0x5f0 mm/slub.c:4959
__kernfs_new_node+0xe6/0x980 fs/kernfs/dir.c:665
kernfs_new_node fs/kernfs/dir.c:751 [inline]
kernfs_create_dir_ns+0xfe/0x230 fs/kernfs/dir.c:1120
sysfs_create_dir_ns+0x12f/0x2a0 fs/sysfs/dir.c:59
create_dir lib/kobject.c:73 [inline]
kobject_add_internal+0x622/0xcd0 lib/kobject.c:240
kobject_add_varg lib/kobject.c:374 [inline]
kobject_init_and_add+0x12b/0x1a0 lib/kobject.c:457
netdev_queue_add_kobject net/core/net-sysfs.c:1976 [inline]
netdev_queue_update_kobjects+0x249/0x6b0 net/core/net-sysfs.c:2035
register_queue_kobjects net/core/net-sysfs.c:2098 [inline]
netdev_register_kobject+0x258/0x310 net/core/net-sysfs.c:2341
register_netdevice+0x1433/0x1eb0 net/core/dev.c:11440
bond_newlink+0x48/0xd0 drivers/net/bonding/bond_netlink.c:625
rtnl_newlink_create+0x310/0xb00 net/core/rtnetlink.c:3913
__rtnl_newlink net/core/rtnetlink.c:4044 [inline]
rtnl_newlink+0x167f/0x1bd0 net/core/rtnetlink.c:4159
rtnetlink_rcv_msg+0x802/0xc00 net/core/rtnetlink.c:7076
netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
__sock_sendmsg net/socket.c:790 [inline]
____sys_sendmsg+0x54e/0x850 net/socket.c:2684
___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
__sys_sendmsg net/socket.c:2770 [inline]
__do_sys_sendmsg net/socket.c:2775 [inline]
__se_sys_sendmsg net/socket.c:2773 [inline]
__x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc08af9de59
RSP: 002b:00007fc08bd9e028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fc08b226180 RCX: 00007fc08af9de59
RDX: 0000000000000000 RSI: 0000200000000080 RDI: 0000000000000007
RBP: 00007fc08b033e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc08b226218 R14: 00007fc08b226180 R15: 00007fffe52d5228
</TASK>
task:syz.3.277 state:R running task stack:26320 pid:6801 tgid:6800 ppid:5632 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7413
preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12
__local_bh_enable_ip+0xe1/0x130 kernel/softirq.c:457
local_bh_enable include/linux/bottom_half.h:33 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:914 [inline]
__dev_queue_xmit+0x1ed7/0x37f0 net/core/dev.c:4907
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x337/0x540 net/ipv6/ip6_output.c:246
ip6_send_skb+0x1cd/0x380 net/ipv6/ip6_output.c:2014
rawv6_push_pending_frames+0x69f/0x860 net/ipv6/raw.c:590
rawv6_sendmsg+0x134f/0x18c0 net/ipv6/raw.c:920
sock_sendmsg_nosec+0x10e/0x180 net/socket.c:776
__sock_sendmsg net/socket.c:790 [inline]
____sys_sendmsg+0x54e/0x850 net/socket.c:2684
___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
__sys_sendmmsg+0x273/0x4d0 net/socket.c:2827
__do_sys_sendmmsg net/socket.c:2854 [inline]
__se_sys_sendmmsg net/socket.c:2851 [inline]
__x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2851
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3ec4f9de59
RSP: 002b:00007f3ec5eac028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f3ec5225fa0 RCX: 00007f3ec4f9de59
RDX: 00000000000004ff RSI: 00002000000092c0 RDI: 0000000000000004
RBP: 00007f3ec5033e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3ec5226038 R14: 00007f3ec5225fa0 R15: 00007ffc531dbac8
</TASK>
rcu: rcu_preempt kthread starved for 6623 jiffies! g19173 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:27496 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
__schedule_loop kernel/sched/core.c:7311 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7326
schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 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:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 35 Comm: kworker/u8:2 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:check_preemption_disabled+0x1/0xe0 lib/smp_processor_id.c:13
Code: 20 d2 4b 8c 48 c7 c6 60 d2 4b 8c eb 1c 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 <41> 57 41 56 53 65 8b 05 f7 ed 9d 07 65 8b 0d ec ed 9d 07 f7 c1 ff
RSP: 0018:ffffc90000006e08 EFLAGS: 00000046
RAX: 0ac0d5affe09d4ff RBX: 0000000000000206 RCX: 0000000080000101
RDX: 0000000000000004 RSI: ffffffff8e4ae921 RDI: ffffffff8c4bd280
RBP: ffff888020e8ca40 R08: ffffc900000072c0 R09: 0000000000000000
R10: ffffc90000006f78 R11: fffff52000000df1 R12: 0000000000000004
R13: 0000000000000004 R14: ffffffff8eb59c20 R15: ffff888020e8be00
FS: 0000000000000000(0000) GS:ffff888124f59000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555670a14e8 CR3: 0000000026c30000 CR4: 00000000003526f0
Call Trace:
<IRQ>
lockdep_recursion_finish kernel/locking/lockdep.c:470 [inline]
lock_release+0x259/0x3c0 kernel/locking/lockdep.c:5891
rcu_lock_release include/linux/rcupdate.h:310 [inline]
rcu_read_unlock include/linux/rcupdate.h:871 [inline]
class_rcu_destructor include/linux/rcupdate.h:1183 [inline]
unwind_next_frame+0x1baa/0x2550 arch/x86/kernel/unwind_orc.c:709
arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
unpoison_slab_object mm/kasan/common.c:340 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4612 [inline]
slab_alloc_node mm/slub.c:4945 [inline]
kmem_cache_alloc_noprof+0x2a0/0x5f0 mm/slub.c:4959
skb_clone+0x212/0x3a0 net/core/skbuff.c:2110
deliver_clone net/bridge/br_forward.c:125 [inline]
maybe_deliver net/bridge/br_forward.c:191 [inline]
br_flood+0x3c3/0x8d0 net/bridge/br_forward.c:245
br_handle_frame_finish+0x1175/0x1990 net/bridge/br_input.c:229
br_nf_hook_thresh+0x3dd/0x4c0 net/bridge/br_netfilter_hooks.c:-1
br_nf_pre_routing_finish_ipv6+0x90c/0xc40 net/bridge/br_netfilter_ipv6.c:-1
NF_HOOK include/linux/netfilter.h:318 [inline]
br_nf_pre_routing_ipv6+0x382/0x6f0 net/bridge/br_netfilter_ipv6.c:183
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_bridge_pre net/bridge/br_input.c:291 [inline]
br_handle_frame+0x127f/0x1510 net/bridge/br_input.c:442
__netif_receive_skb_core+0x989/0x30b0 net/core/dev.c:6093
__netif_receive_skb_one_core net/core/dev.c:6204 [inline]
__netif_receive_skb net/core/dev.c:6319 [inline]
process_backlog+0x706/0x1860 net/core/dev.c:6670
__napi_poll+0xaa/0x330 net/core/dev.c:7729
napi_poll net/core/dev.c:7792 [inline]
net_rx_action+0x61d/0xf50 net/core/dev.c:7949
handle_softirqs+0x225/0x840 kernel/softirq.c:622
do_softirq+0x76/0xd0 kernel/softirq.c:523
</IRQ>
<TASK>
__local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450
spin_unlock_bh include/linux/spinlock.h:396 [inline]
cfg80211_inform_single_bss_data+0x1491/0x1be0 net/wireless/scan.c:2395
cfg80211_inform_bss_data+0x258/0x3c40 net/wireless/scan.c:3238
cfg80211_inform_bss_frame_data+0x3c7/0x730 net/wireless/scan.c:3329
ieee80211_bss_info_update+0x791/0xa50 net/mac80211/scan.c:230
ieee80211_rx_bss_info net/mac80211/ibss.c:1064 [inline]
ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1545 [inline]
ieee80211_ibss_rx_queued_mgmt+0x1c8b/0x2be0 net/mac80211/ibss.c:1572
ieee80211_iface_process_skb net/mac80211/iface.c:1763 [inline]
ieee80211_iface_work+0x78a/0x1010 net/mac80211/iface.c:1817
cfg80211_wiphy_work+0x29e/0x420 net/wireless/core.c:538
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
net_ratelimit: 12611 callbacks suppressed
bridge0: received packet on veth1_to_bridge with own address as source address (addr:fe:8c:62:e7:55:e4, vlan:0)
bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:fe:8c:62:e7:55:e4, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:fe:8c:62:e7:55:e4, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:fe:8c:62:e7:55:e4, vlan:0)
bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:fe:8c:62:e7:55:e4, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
net_ratelimit: 20697 callbacks suppressed
bridge0: received packet on veth1_to_bridge with own address as source address (addr:fe:8c:62:e7:55:e4, vlan:0)
bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:fe:8c:62:e7:55:e4, vlan:0)
bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:fe:8c:62:e7:55:e4, vlan:0)
bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:fe:8c:62:e7:55:e4, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:fe:8c:62:e7:55:e4, vlan:0)
bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
* Struck through repros no longer work on HEAD.