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 0, t=10502 jiffies, g=20453, q=80)
task:kworker/u4:0    state:R  running task     stack:21376 pid:    9 ppid:     2 flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6780
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:rcu_read_lock include/linux/rcupdate.h:740 [inline]
RIP: 0010:batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
RIP: 0010:batadv_nc_worker+0xeb/0x5c0 net/batman-adv/network-coding.c:723
Code: d5 e6 f7 e8 67 7c 00 00 e8 52 b1 2a 00 89 c5 31 ff 89 c6 e8 97 45 fa f7 85 ed 74 10 e8 ae 2a e6 f7 84 c0 74 0e e8 25 42 fa f7 <eb> 56 e8 1e 42 fa f7 eb 4f e8 27 b1 2a 00 89 c5 31 ff 89 c6 e8 6c
RSP: 0018:ffffc90000ce7be0 EFLAGS: 00000293
RAX: ffffffff897d81fb RBX: dffffc0000000000 RCX: ffff88813fed0000
RDX: 0000000000000000 RSI: ffffffff8a599320 RDI: ffffffff8a5992e0
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff1ff6e19
R10: fffffbfff1ff6e19 R11: 1ffffffff1ff6e18 R12: 00000000000001fe
R13: ffff888019380ff0 R14: ffff88807abbcc80 R15: ffff88801a1946d0
 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 10512 jiffies! g20453 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:27008 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 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 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.15.189-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:finish_lock_switch+0x134/0x280 kernel/sched/core.c:4785
Code: be ff ff ff ff e8 ec be 54 08 85 c0 74 4a 4d 85 ff 75 66 e9 fe 00 00 00 48 89 df e8 36 29 5e 08 e8 21 71 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 99 10 fe ff 43 80 3c
RSP: 0018:ffffffff8be07b48 EFLAGS: 00000286
RAX: 4a2411c015827f00 RBX: ffff8880b903a300 RCX: 4a2411c015827f00
RDX: dffffc0000000000 RSI: ffffffff8a0b15c0 RDI: ffffffff8a599340
RBP: 1ffff1101720760b R08: dffffc0000000000 R09: ffffed1017207461
R10: ffffed1017207461 R11: 1ffff11017207460 R12: ffff8880b903b048
R13: dffffc0000000000 R14: ffff8880b903adc8 R15: 0000000000000000
 finish_task_switch+0x12f/0x640 kernel/sched/core.c:4902
 context_switch kernel/sched/core.c:5033 [inline]
 __schedule+0x11c0/0x43b0 kernel/sched/core.c:6376
 schedule_idle+0x4a/0x90 kernel/sched/core.c:6487
 do_idle+0x556/0x5b0 kernel/sched/idle.c:334
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403
 start_kernel+0x486/0x530 init/main.c:1140
 secondary_startup_64_no_verify+0xb1/0xbb
 </TASK>