rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P12/1:b..l P5199/1:b..l rcu: (detected by 0, t=10503 jiffies, g=17265, q=387 ncpus=2) task:udevd state:R running task stack:23288 pid:5199 tgid:5199 ppid:1 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5258 [inline] __schedule+0x150e/0x5070 kernel/sched/core.c:6866 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7050 preempt_schedule+0xae/0xc0 kernel/sched/core.c:7074 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock_irqrestore+0xfd/0x110 kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] __wake_up_common_lock+0x190/0x1f0 kernel/sched/wait.c:127 sock_def_readable+0x1eb/0x530 net/core/sock.c:3611 __netlink_sendskb net/netlink/af_netlink.c:1263 [inline] netlink_sendskb+0xa1/0x140 net/netlink/af_netlink.c:1269 netlink_unicast+0x397/0x9e0 net/netlink/af_netlink.c:1359 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec+0x18f/0x1d0 net/socket.c:737 __sock_sendmsg net/socket.c:752 [inline] ____sys_sendmsg+0x577/0x880 net/socket.c:2610 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2664 __sys_sendmsg net/socket.c:2696 [inline] __do_sys_sendmsg net/socket.c:2701 [inline] __se_sys_sendmsg net/socket.c:2699 [inline] __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2699 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fad4baa7407 RSP: 002b:00007ffe303f5de0 EFLAGS: 00000202 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fad4c143880 RCX: 00007fad4baa7407 RDX: 0000000000000000 RSI: 00007ffe303f5e40 RDI: 0000000000000004 RBP: 000055fc03709990 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000006e R13: 000055fc036ec9e0 R14: 0000000000000000 R15: 0000000000000000 task:kworker/u8:0 state:R running task stack:21152 pid:12 tgid:12 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: context_switch kernel/sched/core.c:5258 [inline] __schedule+0x150e/0x5070 kernel/sched/core.c:6866 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7193 irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:get_current arch/x86/include/asm/current.h:25 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:216 Code: 8b 3d b4 94 d9 0b 48 89 de 5b e9 03 34 5b 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0c 25 08 e0 7e 92 65 8b 15 b8 2e bd 10 81 e2 00 01 ff 00 RSP: 0018:ffffc90000117878 EFLAGS: 00000202 RAX: ffffffff8b24c50a RBX: 0000000000000001 RCX: 3767d9dc3cdf0000 RDX: ffff88801ce8db80 RSI: ffffffff8bc08440 RDI: ffffffff8bc08400 RBP: ffffc900001179d0 R08: ffffffff8b24c4c0 R09: ffffffff8df41b20 R10: dffffc0000000000 R11: ffffed100fa2ef17 R12: ffff88802814ad80 R13: ffff88802814ad90 R14: dffffc0000000000 R15: ffff8880285d1d90 rcu_read_lock include/linux/rcupdate.h:868 [inline] batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:761 [inline] batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:833 [inline] batadv_iv_ogm_schedule+0x47a/0xf00 net/batman-adv/bat_iv_ogm.c:873 batadv_iv_send_outstanding_bat_ogm_packet+0x6c6/0x7e0 net/batman-adv/bat_iv_ogm.c:1709 process_one_work+0x93a/0x15a0 kernel/workqueue.c:3279 process_scheduled_works kernel/workqueue.c:3362 [inline] worker_thread+0x9b0/0xee0 kernel/workqueue.c:3443 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: rcu_preempt kthread starved for 10560 jiffies! g17265 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:27200 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5258 [inline] __schedule+0x150e/0x5070 kernel/sched/core.c:6866 __schedule_loop kernel/sched/core.c:6948 [inline] schedule+0x165/0x360 kernel/sched/core.c:6963 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82 Code: cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d b3 70 0c 00 f3 0f 1e fa fb f4 48 ee 02 00 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffffff8dc07d80 EFLAGS: 000002c6 RAX: 66b58a2319a07e00 RBX: ffffffff8197928a RCX: 66b58a2319a07e00 RDX: 0000000000000001 RSI: ffffffff8d793d57 RDI: ffffffff8bc08460 RBP: ffffffff8dc07ea8 R08: ffff8880b86336db R09: 1ffff110170c66db R10: dffffc0000000000 R11: ffffed10170c66dc R12: ffffffff8f822c70 R13: 1ffffffff1b92a68 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888125e32000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c45ee6c CR3: 0000000061ad8000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x73/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:191 [inline] do_idle+0x1ea/0x520 kernel/sched/idle.c:332 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:430 rest_init+0x2de/0x300 init/main.c:757 start_kernel+0x3a7/0x400 init/main.c:1206 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x147