rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-...!: (2 GPs behind) idle=c0ec/1/0x4000000000000000 softirq=16387/16387 fqs=2
rcu: (detected by 1, t=10505 jiffies, g=15669, q=125 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6025 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline]
RIP: 0010:raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline]
RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline]
RIP: 0010:rcu_is_watching+0x5a/0xb0 kernel/rcu/tree.c:752
Code: f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 7c 8c 86 00 48 c7 c3 d8 09 3f 93 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 <84> c0 75 34 8b 03 65 ff 0d 69 31 93 11 74 11 83 e0 04 c1 e8 02 5b
RSP: 0018:ffffc90000007c68 EFLAGS: 00000802
RAX: 0000000000000000 RBX: ffff8880b86339d8 RCX: 0000000000010003
RDX: 0000000000000000 RSI: ffffffff8c27efe0 RDI: ffffffff8c27efa0
RBP: ffffffff84b9ba73 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000000fac R12: 0000000000000000
R13: ffffffff9a7483d8 R14: ffffffff8e277790 R15: dffffc0000000000
FS: 0000555584931500(0000) GS:ffff888125243000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000012c0 CR3: 0000000032e34000 CR4: 00000000003526f0
Call Trace:
trace_lock_acquire include/trace/events/lock.h:24 [inline]
lock_acquire+0x5f/0x350 kernel/locking/lockdep.c:5831
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
_raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
debug_object_activate+0x83/0x580 lib/debugobjects.c:835
debug_hrtimer_activate kernel/time/hrtimer.c:485 [inline]
debug_activate kernel/time/hrtimer.c:528 [inline]
enqueue_hrtimer+0xa9/0x2c0 kernel/time/hrtimer.c:1109
__run_hrtimer kernel/time/hrtimer.c:1946 [inline]
__hrtimer_run_queues+0x4d2/0xa20 kernel/time/hrtimer.c:1994
hrtimer_interrupt+0x44b/0x950 kernel/time/hrtimer.c:2113
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
__sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1067
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lockdep_unregister_key+0x2d5/0x350 kernel/locking/lockdep.c:6616
Code: 81 0a 09 00 89 c6 48 c7 c7 70 29 46 96 e8 e3 5b 14 0a 90 e9 65 fe ff ff e8 f8 9a 11 0a 41 f7 c7 00 02 00 00 74 b3 fb 40 84 ed <75> b2 eb c3 90 0f 0b 90 e9 26 ff ff ff 90 0f 0b 90 e9 2e ff ff ff
RSP: 0018:ffffc900041470f0 EFLAGS: 00000246
RAX: 0000000000000046 RBX: ffff88807b685268 RCX: 0000000000000046
RDX: ffffffff9401a4d8 RSI: ffffffff8dfcfd91 RDI: ffffffff8c27f000
RBP: ffff888028ac5c00 R08: ffffffff81aee918 R09: ffffffff8e95d020
R10: dffffc0000000000 R11: fffffbfff2064337 R12: 0000000000000000
R13: ffff88807b685269 R14: 0000000000001000 R15: 0000000000000a87
qdisc_lock_uninit include/net/pkt_sched.h:332 [inline]
__qdisc_destroy+0x1ab/0x470 net/sched/sch_generic.c:1102
taprio_attach+0x25a/0x380 net/sched/sch_taprio.c:2160
qdisc_graft+0x11b6/0x15b0 net/sched/sch_api.c:1162
__tc_modify_qdisc net/sched/sch_api.c:1761 [inline]
tc_modify_qdisc+0x18a4/0x2290 net/sched/sch_api.c:1817
rtnetlink_rcv_msg+0x77e/0xbe0 net/core/rtnetlink.c:7004
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmsg net/socket.c:2784 [inline]
__do_sys_sendmsg net/socket.c:2789 [inline]
__se_sys_sendmsg net/socket.c:2787 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1b2bf9c819
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:00007ffd7ea3b528 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1b2c215fa0 RCX: 00007f1b2bf9c819
RDX: 0000000000000010 RSI: 00002000000012c0 RDI: 0000000000000006
RBP: 00007f1b2c032c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1b2c215fac R14: 00007f1b2c215fa0 R15: 00007f1b2c215fa0
rcu: rcu_preempt kthread starved for 10495 jiffies! g15669 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:27528 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5382 [inline]
__schedule+0x17b4/0x5680 kernel/sched/core.c:7183
__schedule_loop kernel/sched/core.c:7262 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7277
schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297
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
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xe32/0x1210 kernel/smp.c:892
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 77 e7 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 22 e3 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 06 e3
RSP: 0018:ffffc90000127700 EFLAGS: 00000293
RAX: ffffffff81b97aea RBX: 1ffff110170c8541 RCX: ffff88801dacdc40
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000127840 R08: ffffffff903219b7 R09: 1ffffffff2064336
R10: dffffc0000000000 R11: fffffbfff2064337 R12: ffff8880b8642a08
R13: dffffc0000000000 R14: ffff8880b873c148 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888125343000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000565009458138 CR3: 000000000e74a000 CR4: 00000000003526f0
Call Trace:
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057
on_each_cpu include/linux/smp.h:72 [inline]
smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2761 [inline]
smp_text_poke_batch_finish+0x5f5/0x1160 arch/x86/kernel/alternative.c:2971
arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
static_key_enable_cpuslocked+0x128/0x240 kernel/jump_label.c:210
static_key_enable+0x1a/0x20 kernel/jump_label.c:223
toggle_allocation_gate+0xab/0x290 mm/kfence/core.c:900
process_one_work kernel/workqueue.c:3288 [inline]
process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3371
worker_thread+0xa53/0xfc0 kernel/workqueue.c:3452
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