rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4392/1:b..l (detected by 0, t=10502 jiffies, g=25553, q=116) task:kworker/u4:8 state:R running task stack:24928 pid: 4392 ppid: 2 flags:0x00004000 Workqueue: bat_events batadv_nc_worker Call Trace: 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: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:ffffc900014ffa40 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 28df75fbe908f700 RDX: 0000000000000000 RSI: ffffffff8a0b2560 RDI: ffffffff8a59a340 RBP: ffffc900014ffb58 R08: dffffc0000000000 R09: fffffbfff1ff3419 R10: fffffbfff1ff3419 R11: 1ffffffff1ff3418 R12: ffffffff8c11d9e0 R13: 1ffff9200029ff54 R14: 0000000000000246 R15: dffffc0000000000 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:312 rcu_read_lock include/linux/rcupdate.h:739 [inline] batadv_nc_process_nc_paths+0xb2/0x350 net/batman-adv/network-coding.c:691 batadv_nc_worker+0x4e4/0x5c0 net/batman-adv/network-coding.c:739 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 10527 jiffies! g25553 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:27776 pid: 15 ppid: 2 flags:0x00004000 Call Trace: 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 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: 7176 Comm: syz.0.459 Not tainted 5.15.180-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 RIP: 0010:check_preemption_disabled+0x37/0x110 lib/smp_processor_id.c:55 Code: 04 25 28 00 00 00 48 89 44 24 08 65 8b 05 19 18 61 76 65 8b 0d 82 72 61 76 f7 c1 ff ff ff 7f 74 1f 65 48 8b 0c 25 28 00 00 00 <48> 3b 4c 24 08 0f 85 c4 00 00 00 48 83 c4 10 5b 41 5e 41 5f 5d c3 RSP: 0018:ffffc9000317f9a8 EFLAGS: 00000202 RAX: 0000000000000001 RBX: 0000000000000001 RCX: 593a0112b26e1900 RDX: 0000000000000000 RSI: ffffffff8a59a320 RDI: ffffffff8a59a2e0 RBP: ffffc9000317fb10 R08: dffffc0000000000 R09: fffffbfff1ad1706 R10: fffffbfff1ad1706 R11: 1ffffffff1ad1705 R12: dffffc0000000000 R13: dffffc0000000000 R14: ffff88802af970c8 R15: 1ffff9200062ff4c FS: 00007fe609a9b6c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000006b000 CR3: 0000000062538000 CR4: 00000000003506e0 DR0: 0000000000000007 DR1: 0000000000000002 DR2: 0000000000000008 DR3: 0000000000000006 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_dynticks_curr_cpu_in_eqs kernel/rcu/tree.c:331 [inline] rcu_is_watching+0x11/0xa0 kernel/rcu/tree.c:1123 trace_lock_release include/trace/events/lock.h:58 [inline] lock_release+0xba/0x870 kernel/locking/lockdep.c:5634 __copy_to_user include/linux/uaccess.h:143 [inline] save_xstate_epilog arch/x86/kernel/fpu/signal.c:104 [inline] copy_fpstate_to_sigframe+0x882/0xb90 arch/x86/kernel/fpu/signal.c:217 get_sigframe arch/x86/kernel/signal.c:295 [inline] __setup_rt_frame arch/x86/kernel/signal.c:471 [inline] setup_rt_frame arch/x86/kernel/signal.c:780 [inline] handle_signal arch/x86/kernel/signal.c:824 [inline] arch_do_signal_or_restart+0x67a/0x1300 arch/x86/kernel/signal.c:869 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+0xb1/0x140 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: 0033:0x7fe60bc33967 Code: ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 <0f> 05 48 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 RSP: 002b:00007fe609a9b0e8 EFLAGS: 00000246 RAX: 00000000000000ca RBX: 00007fe60be5afa8 RCX: 00007fe60bc33969 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fe60be5afa8 RBP: 00007fe60be5afa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe60be5afac R13: 0000000000000000 R14: 00007fffa810c370 R15: 00007fffa810c458