rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 ticks this GP) idle=454c/1/0x4000000000000000 softirq=11837/11837 fqs=0
rcu: 	(detected by 1, t=10502 jiffies, g=9429, q=61 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 9 Comm: kworker/0:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events release_one_tty
RIP: 0010:__run_hrtimer kernel/time/hrtimer.c:1716 [inline]
RIP: 0010:__hrtimer_run_queues+0x26f/0xc40 kernel/time/hrtimer.c:1814
Code: 36 48 89 df 4c 89 f6 e8 4f dd 0f 00 4c 39 f3 0f 8c 06 09 00 00 48 8b 84 24 90 00 00 00 42 0f b6 04 28 84 c0 0f 85 b2 04 00 00 <8b> 1d 47 a0 d4 0c 31 ff 89 de e8 c2 de 0f 00 85 db 74 2c 48 8b bc
RSP: 0018:ffffc90000007d40 EFLAGS: 00000046
RAX: 0000000000000000 RBX: 1bc16d674ee0237a RCX: ffff88801ba50000
RDX: 0000000000010000 RSI: 188cf18ca8000000 RDI: 1bc16d674ee0237a
RBP: ffffc90000007e90 R08: ffff88806064d357 R09: 0000000000000000
R10: ffff88806064d340 R11: ffffed100c0c9a6b R12: ffff88806064d340
R13: dffffc0000000000 R14: 188cf18ca8000000 R15: ffff8880b8e2b800
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000003c80 CR3: 000000001e7ea000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1876
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:lock_acquire+0x1f2/0x410 kernel/locking/lockdep.c:5758
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 66 43 c7 44 3c 09 00 00 43 c6 44 3c 0b 00
RSP: 0018:ffffc900000e7aa0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 20aa178acda49700
RDX: 0000000000000001 RSI: ffffffff8aaace60 RDI: ffffffff8afc6f80
RBP: ffffc900000e7ba8 R08: dffffc0000000000 R09: 1ffffffff26c6691
R10: dffffc0000000000 R11: fffffbfff26c6692 R12: 1ffff9200001cf60
R13: ffffc900000e7d00 R14: 0000000000000246 R15: dffffc0000000000
 process_one_work kernel/workqueue.c:2610 [inline]
 process_scheduled_works+0x98f/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: rcu_preempt kthread starved for 10502 jiffies! g9429 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:27752 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 42 Comm: kworker/u4:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: netns cleanup_net
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:212
Code: 00 0f 0b 0f 1f 80 00 00 00 00 f3 0f 1e fa 53 48 89 fb e8 13 00 00 00 48 8b 3d 9c 92 c4 0c 48 89 de 5b e9 43 9d 56 00 cc cc cc <f3> 0f 1e fa 48 8b 04 24 65 48 8b 0d f0 24 7e 7e 65 8b 15 f1 24 7e
RSP: 0018:ffffc90000b2f878 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffffc90000b2f8c8 RCX: ffff888018ac1e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000b2f980 R08: ffffffff8e4a212f R09: 1ffffffff1c94425
R10: dffffc0000000000 R11: fffffbfff1c94426 R12: 1ffff92000165f19
R13: dffffc0000000000 R14: 1ffff92000165f14 R15: 1ffff92000165f14
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff62985940 CR3: 000000002635a000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 csd_lock_wait kernel/smp.c:311 [inline]
 smp_call_function_single+0x3c0/0x580 kernel/smp.c:650
 rcu_barrier+0x367/0x580 kernel/rcu/tree.c:4141
 l2tp_exit_net+0x23a/0x2e0 net/l2tp/l2tp_core.c:1683
 ops_exit_list net/core/net_namespace.c:173 [inline]
 cleanup_net+0x6f4/0xb90 net/core/net_namespace.c:652
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>