syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=0684/1/0x4000000000000000 softirq=10347/10348 fqs=5
	(detected by 1, t=10502 jiffies, g=10041, q=12 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4438 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:timerqueue_getnext include/linux/timerqueue.h:36 [inline]
RIP: 0010:__hrtimer_run_queues+0x714/0xd60 kernel/time/hrtimer.c:1791
Code: 0f 00 48 8b 44 24 58 42 80 3c 28 00 74 08 48 89 df e8 d0 07 60 00 48 c7 03 00 00 00 00 48 8b 84 24 c8 00 00 00 42 80 3c 28 00 <74> 08 4c 89 f7 e8 32 07 60 00 4d 8b 26 4d 85 e4 0f 84 60 05 00 00
RSP: 0018:ffffc90000007d20 EFLAGS: 00000046
RAX: 1ffff110171c54fb RBX: ffff8880b8e2a7c8 RCX: ffff88801cf6bb80
RDX: 0000000000010000 RSI: 1ffff110171c54f2 RDI: ffff88801df9b340
RBP: ffffc90000007e88 R08: dffffc0000000000 R09: ffff88801df9b340
R10: ffffed1003bf366b R11: 1ffff11003bf3668 R12: ffff88801df9b340
R13: dffffc0000000000 R14: ffff8880b8e2a7d8 R15: ffff8880b8e2a780
FS:  00007f62dac3f6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f62dac1df98 CR3: 000000002f200000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 hrtimer_interrupt+0x3c5/0x9c0 kernel/time/hrtimer.c:1873
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lockdep_unregister_key+0x4c3/0x530 kernel/locking/lockdep.c:6370
Code: 81 87 90 48 c7 c6 70 a9 63 81 e8 a8 93 07 00 e8 03 a7 07 00 e9 86 fc ff ff e8 99 c3 ac 08 41 f7 c4 00 02 00 00 74 d1 fb 84 db <75> d0 eb e1 0f 0b eb a1 0f 0b e9 11 ff ff ff 0f 0b e9 5e ff ff ff
RSP: 0018:ffffc900036e6ee0 EFLAGS: 00000246
RAX: 885f6b5ec1953a00 RBX: 0000000000000000 RCX: 885f6b5ec1953a00
RDX: 0000000000000001 RSI: ffffffff8a6c12e0 RDI: ffffffff8abef920
RBP: ffffc900036e6fc0 R08: dffffc0000000000 R09: fffffbfff210f1a1
R10: fffffbfff210f1a1 R11: 1ffffffff210f1a0 R12: 0000000000000202
R13: ffff88807d1bb299 R14: ffffffff90878198 R15: 1ffff920006dcde0
 __qdisc_destroy+0x128/0x430 net/sched/sch_generic.c:1081
 taprio_attach+0x26b/0x420 net/sched/sch_taprio.c:1844
 qdisc_graft+0x1165/0x1570 net/sched/sch_api.c:1129
 tc_modify_qdisc+0xe78/0x1cc0 net/sched/sch_api.c:1761
 rtnetlink_rcv_msg+0x79b/0xed0 net/core/rtnetlink.c:6150
 netlink_rcv_skb+0x1de/0x420 net/netlink/af_netlink.c:2511
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x74d/0x8d0 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x89e/0xbc0 net/netlink/af_netlink.c:1872
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x59b/0x970 net/socket.c:2519
 ___sys_sendmsg+0x21c/0x290 net/socket.c:2573
 __sys_sendmsg net/socket.c:2602 [inline]
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg+0x19e/0x270 net/socket.c:2609
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f62d9d8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f62dac3f038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f62d9fe5fa0 RCX: 00007f62d9d8f749
RDX: 0000000000000000 RSI: 00002000000007c0 RDI: 0000000000000004
RBP: 00007f62d9e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f62d9fe6038 R14: 00007f62d9fe5fa0 R15: 00007ffd96347498
 </TASK>
rcu: rcu_preempt kthread starved for 10492 jiffies! g10041 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:27200 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 4320 Comm: kworker/u4:5 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:424 [inline]
RIP: 0010:smp_call_function_many_cond+0xe7b/0x1270 kernel/smp.c:998
Code: 00 00 00 41 8b 1f 89 de 83 e6 01 31 ff e8 5d d9 0a 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 e9 d5 0a 00 eb 37 f3 90 <41> 0f b6 04 1c 84 c0 75 10 41 f7 07 01 00 00 00 74 1e e8 ce d5 0a
RSP: 0018:ffffc900042a7800 EFLAGS: 00000293
RAX: ffffffff81760a02 RBX: dffffc0000000000 RCX: ffff88802bae9dc0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900042a7960 R08: dffffc0000000000 R09: fffffbfff2119049
R10: fffffbfff2119049 R11: 1ffffffff2119048 R12: 1ffff110171c85b5
R13: ffff8880b8f3bb80 R14: 0000000000000000 R15: ffff8880b8e42da8
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005600e3a27630 CR3: 000000000c68e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1165
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:1574 [inline]
 text_poke_bp_batch+0x2b0/0x7d0 arch/x86/kernel/alternative.c:1774
 text_poke_flush arch/x86/kernel/alternative.c:1965 [inline]
 text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1972
 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x11f/0x240 kernel/jump_label.c:207
 static_key_enable+0x16/0x20 kernel/jump_label.c:220
 toggle_allocation_gate+0xb4/0x430 mm/kfence/core.c:805
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>