rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P458/1:b..l (detected by 0, t=10502 jiffies, g=7449, q=63) task:kworker/u4:3 state:R running task stack:22464 pid: 458 ppid: 2 flags:0x00004000 Workqueue: bat_events batadv_nc_worker Call Trace: 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:lock_acquire+0x1f2/0x3f0 kernel/locking/lockdep.c:5627 Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f6 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 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b RSP: 0018:ffffc9000347faa0 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 42581a54ce0d8b00 RDX: 0000000000000000 RSI: ffffffff8a0b2e80 RDI: ffffffff8a59e800 RBP: ffffc9000347fbc0 R08: dffffc0000000000 R09: fffffbfff1ff5419 R10: fffffbfff1ff5419 R11: 1ffffffff1ff5418 R12: ffffffff8c11c720 R13: 1ffff9200068ff60 R14: 0000000000000246 R15: dffffc0000000000 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313 rcu_read_lock include/linux/rcupdate.h:740 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline] batadv_nc_worker+0xc9/0x5c0 net/batman-adv/network-coding.c:723 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 rcu: rcu_preempt kthread starved for 10526 jiffies! g7449 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:27008 pid: 15 ppid: 2 flags:0x00004000 Call Trace: 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 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 4529 Comm: syz.1.48 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:ksoftirqd_running kernel/softirq.c:95 [inline] RIP: 0010:invoke_softirq kernel/softirq.c:440 [inline] RIP: 0010:__irq_exit_rcu+0x10c/0x220 kernel/softirq.c:659 Code: 08 65 48 8b 3d 6d f6 b9 7e 41 f6 c6 41 0f 95 c0 48 85 ff 0f 94 c1 08 c1 75 27 4c 8d 77 18 4c 89 f0 48 c1 e8 03 42 0f b6 04 20 <84> c0 0f 85 9e 00 00 00 41 83 3e 00 75 09 e8 81 a6 06 00 84 c0 74 RSP: 0018:ffffc90000dd0f40 EFLAGS: 00000806 RAX: 0000000000000000 RBX: ffff88801d955940 RCX: 37917f4157bb9b00 RDX: 1ffffffff1dd7e08 RSI: ffffffff8a0a03e0 RDI: ffff88813fe78000 RBP: ffffc90000dd0fe0 R08: ffffffff8eebf048 R09: ffffffff8eebf058 R10: ffffffff8eebf050 R11: ffffffff8eebf043 R12: dffffc0000000000 R13: 0000000000000000 R14: ffff88813fe78018 R15: 1ffff920001ba1e8 FS: 00007f6b3a2706c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 000000001dec8000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: irq_exit_rcu+0x5/0x20 kernel/softirq.c:671 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108 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: f6 ff 0f 1f 00 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 be 2b b1 f7 48 89 df e8 86 00 b2 f7 e8 21 9a d2 f7 fb bf 01 00 00 00 56 22 a6 f7 65 8b 05 e7 1f 57 76 85 c0 74 02 5b c3 e8 f4 2a 55 RSP: 0018:ffffc900030efbc0 EFLAGS: 00000282 RAX: 37917f4157bb9b00 RBX: ffff888058a1c0c0 RCX: 37917f4157bb9b00 RDX: dffffc0000000000 RSI: ffffffff8a0b1be0 RDI: 0000000000000001 RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed100b143819 R10: ffffed100b143819 R11: 1ffff1100b143818 R12: ffff888058a1c0c0 R13: 0000000000000011 R14: dffffc0000000000 R15: 0000000004000000 spin_unlock_irq include/linux/spinlock.h:414 [inline] get_signal+0x11d6/0x12c0 kernel/signal.c:2903 arch_do_signal_or_restart+0xc1/0x1300 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: 0033:0x7f6b3bed90eb Code: 3c 25 c0 fe ff ff eb 20 0f 1f 80 00 00 00 00 45 31 c0 31 c9 ba 80 00 00 00 48 89 de bf ca 00 00 00 31 c0 e8 47 06 13 00 8b 03 <85> c0 74 e1 c7 45 08 00 00 00 00 45 84 e4 74 2d 80 3d e3 65 eb 00 RSP: 002b:00007f6b3a2700f0 EFLAGS: 00000286 RAX: 0000000000000000 RBX: 00007f6b3c25ffa8 RCX: ffffffffffffffa8 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f6b3c25ffa8 RBP: 00007f6b3c25ffa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6b3c260038 R14: 00007ffef652e460 R15: 00007ffef652e548 sched: RT throttling activated