rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9/1:b..l
	(detected by 1, t=10503 jiffies, g=11385, q=333)
task:kworker/u4:0    state:R  running task     stack:20896 pid:    9 ppid:     2 flags:0x00004000
Workqueue: events_unbound linkwatch_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:batadv_hardif_get_by_netdev+0x14e/0x390 net/batman-adv/hard-interface.c:70
Code: 84 8d 01 00 00 48 89 5c 24 10 4d 8d 66 18 4c 89 e0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 e7 e8 28 91 3f f8 49 39 1c 24 74 0a <e8> ed 2a fb f7 e9 e8 00 00 00 4d 8d 66 20 4c 89 e7 be 04 00 00 00
RSP: 0018:ffffc90000ce78e0 EFLAGS: 00000287
RAX: 1ffff11004ffbe03 RBX: ffff88807b7e0000 RCX: ffff88813fed0000
RDX: 0000000000000000 RSI: ffffffff8a59a220 RDI: ffffffff8a59a1e0
RBP: ffffc90000ce7998 R08: dffffc0000000000 R09: fffffbfff1ff7619
R10: fffffbfff1ff7619 R11: 1ffffffff1ff7618 R12: ffff888027fdf018
R13: dffffc0000000000 R14: ffff888027fdf000 R15: dffffc0000000000
 batadv_hard_if_event+0x7e/0x17e0 net/batman-adv/hard-interface.c:955
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
 netdev_state_change+0xd2/0x140 net/core/dev.c:1440
 linkwatch_do_dev+0x10d/0x160 net/core/link_watch.c:167
 __linkwatch_run_queue+0x4a9/0x7b0 net/core/link_watch.c:213
 linkwatch_event+0x48/0x50 net/core/link_watch.c:252
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: rcu_preempt kthread starved for 10527 jiffies! g11385 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:28032 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 5438 Comm: syz.1.115 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x10c8/0x1220 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x831/0x1110 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1690 [inline]
 __hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_is_held_type+0x13a/0x190 kernel/locking/lockdep.c:5671
Code: 75 40 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 75 46 41 f7 c5 00 02 00 00 74 01 fb 65 48 8b 04 25 28 00 00 00 <48> 3b 44 24 08 75 3c 89 e8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f
RSP: 0018:ffffc900034bfb38 EFLAGS: 00000206
RAX: f61314cfa5f4d500 RBX: ffff88802a061dc0 RCX: f61314cfa5f4d500
RDX: 0000000000000000 RSI: ffffffff8a0b28c0 RDI: ffffffff8a59a240
RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffc900034bfd60
R10: 0000000000000000 R11: 0000000000000018 R12: dffffc0000000000
R13: 0000000000000246 R14: ffffffff8c11c4c0 R15: 00000000ffffffff
 lock_is_held include/linux/lockdep.h:287 [inline]
 ___might_sleep+0xa3/0x600 kernel/sched/core.c:9624
 __might_fault+0x6b/0x110 mm/memory.c:5354
 _copy_from_user+0x29/0x170 lib/usercopy.c:14
 copy_from_user include/linux/uaccess.h:192 [inline]
 restore_sigcontext arch/x86/kernel/signal.c:91 [inline]
 __ia32_sys_rt_sigreturn+0x1e6/0x790 arch/x86/kernel/signal.c:674
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f35e976cdb9
Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 04 25
RSP: 002b:00007f35e8e3fb40 EFLAGS: 00000206 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007f35e9a07fa8 RCX: 00007f35e976cdb9
RDX: 00007f35e8e3fb40 RSI: 00007f35e8e3fc70 RDI: 0000000000000021
RBP: 00007f35e9a07fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f35e9a08038 R14: 00007ffe9cef1910 R15: 00007ffe9cef19f8
 </TASK>