rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P1443/1:b..l P3562/1:b..l
	(detected by 0, t=10502 jiffies, g=48377, q=239)
task:udevd           state:R  running task     stack:22672 pid: 3562 ppid:     1 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6571
 preempt_schedule+0xbc/0xd0 kernel/sched/core.c:6596
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock+0x36/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:404 [inline]
 lockref_get_not_dead+0x72/0xb0 lib/lockref.c:216
 __legitimize_path fs/namei.c:700 [inline]
 legitimize_path fs/namei.c:710 [inline]
 legitimize_root fs/namei.c:745 [inline]
 try_to_unlazy+0x2ad/0x6d0 fs/namei.c:781
 may_lookup fs/namei.c:1698 [inline]
 link_path_walk+0x294/0xd70 fs/namei.c:2253
 path_openat+0x28d/0x2fa0 fs/namei.c:3746
 do_filp_open+0x1e2/0x410 fs/namei.c:3777
 do_sys_openat2+0x150/0x4b0 fs/open.c:1255
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 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: 0033:0x7fecf2618407
RSP: 002b:00007ffe3264b9e0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fecf252a880 RCX: 00007fecf2618407
RDX: 0000000000080000 RSI: 00007ffe3264bb60 RDI: ffffffffffffff9c
RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055d8745807f5
R13: 000055d8745807f5 R14: 0000000000000001 R15: 00007ffe326501b0
 </TASK>
task:kworker/u4:4    state:R  running task     stack:21264 pid: 1443 ppid:     2 flags:0x00004000
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
 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:lock_acquire+0x208/0x400 kernel/locking/lockdep.c:5627
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f1 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0000:ffffc90006817900 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 486de331bd46c900
RDX: 0000000000000000 RSI: ffffffff8a2b3a20 RDI: ffffffff8a79f980
RBP: ffffc90006817a20 R08: dffffc0000000000 R09: 1ffffffff203a818
R10: dffffc0000000000 R11: fffffbfff203a819 R12: ffffffff8c31eaa0
R13: 1ffff92000d02f2c R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:754 [inline]
 batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:825 [inline]
 batadv_iv_ogm_schedule+0x432/0xec0 net/batman-adv/bat_iv_ogm.c:868
 batadv_iv_send_outstanding_bat_ogm_packet+0x72f/0x840 net/batman-adv/bat_iv_ogm.c:1712
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 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 10552 jiffies! g48377 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:28112 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9b/0x370 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: 12408 Comm: syz.1.1937 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 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+0x1110/0x1270 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+0x843/0x1120 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:2021
 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:1685 [inline]
 __hrtimer_run_queues+0x4b4/0xb70 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1811
 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:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 00 00 00 66 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 be a9 97 f7 48 89 df e8 f6 81 98 f7 e8 61 74 b9 f7 fb bf 01 00 00 00 <e8> a6 89 8c f7 65 8b 05 47 97 3c 76 85 c0 74 02 5b c3 e8 94 a4 3a
RSP: 0018:ffffc90004227bc0 EFLAGS: 00000282
RAX: 7d6befe3fe712000 RBX: ffff88807f3cb780 RCX: 7d6befe3fe712000
RDX: dffffc0000000000 RSI: ffffffff8a2b2780 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffff88807f3cb783 R09: 1ffff1100fe796f0
R10: dffffc0000000000 R11: ffffed100fe796f1 R12: ffff88807f3cb780
R13: 0000000000000021 R14: dffffc0000000000 R15: 000000001c000004
 spin_unlock_irq include/linux/spinlock.h:414 [inline]
 get_signal+0x11d6/0x12c0 kernel/signal.c:2903
 arch_do_signal_or_restart+0xe7/0x12c0 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fbce5896199
Code: 00 53 48 8b 1d 28 2c 3c 00 45 31 d2 31 c9 48 8b 17 45 31 db 4c 8d 83 00 00 40 00 48 89 d0 0f 1f 00 4c 39 c0 73 63 44 0f b6 08 <48> 83 c0 01 4c 89 ce 83 e6 7f 48 d3 e6 49 09 f2 45 84 c9 79 2a 83
RSP: 002b:00007ffcdd4f0960 EFLAGS: 00000287
RAX: 0000001b32f200ee RBX: 0000001b32f20000 RCX: 0000000000000000
RDX: 0000001b32f200ee RSI: 00007ffcdd4f0a90 RDI: 00007ffcdd4f0a50
RBP: 00007fbce5c58da0 R08: 0000001b33320000 R09: 00000000000000c6
R10: 0000000000000000 R11: 0000000000000000 R12: 00007ffcdd4f0a90
R13: 00007fbce5c56fac R14: 0000000000074c4f R15: 00007ffcdd4f0a70
 </TASK>