rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5843/1:b..l P6154/3:b..l P37/1:b..l rcu: (detected by 1, t=10502 jiffies, g=12481, q=848 ncpus=2) task:kworker/u8:3 state:R running task stack:22840 pid:37 tgid:37 ppid:2 task_flags:0x4208060 flags:0x00004000 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x16e2/0x4cd0 kernel/sched/core.c:6767 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7090 irqentry_exit+0x6f/0x90 kernel/entry/common.c:354 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:763 [inline] RIP: 0010:batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:833 [inline] RIP: 0010:batadv_iv_ogm_schedule+0x4aa/0xea0 net/batman-adv/bat_iv_ogm.c:876 Code: 05 38 c5 49 04 01 48 c7 c7 c0 a0 92 8c be 4b 03 00 00 48 c7 c2 00 a1 92 8c e8 52 40 7f f6 48 89 d8 48 c1 e8 03 42 80 3c 20 00 <74> 08 48 89 df e8 5c c0 02 f7 48 8b 1b 48 85 db 0f 94 c0 48 81 c3 RSP: 0018:ffffc90000ae7940 EFLAGS: 00000246 RAX: 1ffff1100b90fae4 RBX: ffff88805c87d720 RCX: ffff88801caf1e00 RDX: 0000000000000000 RSI: ffffffff8bc1d800 RDI: ffffffff8bc1d7c0 RBP: ffffc90000ae7a70 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8b1f2988 R12: dffffc0000000000 R13: dffffc0000000000 R14: 0000000000000001 R15: ffff8880776d58b4 batadv_iv_send_outstanding_bat_ogm_packet+0x6c6/0x7e0 net/batman-adv/bat_iv_ogm.c:1720 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xade/0x17a0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x4e/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 task:syz.0.60 state:R running task stack:27096 pid:6154 tgid:6154 ppid:5828 task_flags:0x400040 flags:0x00000000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x16e2/0x4cd0 kernel/sched/core.c:6767 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:6947 preempt_schedule+0xae/0xc0 kernel/sched/core.c:6971 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] filemap_map_pages+0x1115/0x1740 mm/filemap.c:3748 do_fault_around mm/memory.c:5476 [inline] do_read_fault mm/memory.c:5509 [inline] do_fault mm/memory.c:5652 [inline] do_pte_missing mm/memory.c:4160 [inline] handle_pte_fault mm/memory.c:5997 [inline] __handle_mm_fault+0x34db/0x5380 mm/memory.c:6140 handle_mm_fault+0x3f6/0x8c0 mm/memory.c:6309 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1337 handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0033:0x7fb43f06ecad RSP: 002b:00007ffcae19db60 EFLAGS: 00010212 RAX: 000000110c394000 RBX: 00007fb43fee5720 RCX: 0000000000000005 RDX: 00000000000015b2 RSI: 00000000000029d6 RDI: 0000000000000020 RBP: ffffffff85ea75af R08: 00007fb43f3b6038 R09: 00007fb43f3a2000 R10: 00007fb43e7ff008 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: ffffffff85ea7a5d R15: 000000000001917f task:udevd state:R running task stack:24088 pid:5843 tgid:5843 ppid:5195 task_flags:0x400140 flags:0x00000002 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x16e2/0x4cd0 kernel/sched/core.c:6767 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:6947 preempt_schedule+0xae/0xc0 kernel/sched/core.c:6971 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:108 sock_def_readable+0x1fb/0x550 net/core/sock.c:3533 unix_dgram_sendmsg+0xe41/0x17c0 net/unix/af_unix.c:2154 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:727 sock_write_iter+0x258/0x330 net/socket.c:1131 new_sync_write fs/read_write.c:591 [inline] vfs_write+0x54b/0xa90 fs/read_write.c:684 ksys_write+0x145/0x250 fs/read_write.c:736 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fce8b6a7407 RSP: 002b:00007ffe36cc0750 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fce8bd75880 RCX: 00007fce8b6a7407 RDX: 0000000000000000 RSI: 00007ffe36cc07f7 RDI: 000000000000000a RBP: 000000000000000a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007fce8bd756e8 R13: 0000000000000000 R14: 0000000000000000 R15: 0000564b04f54a40 rcu: rcu_preempt kthread starved for 10142 jiffies! g12481 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:27032 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x16e2/0x4cd0 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0x165/0x360 kernel/sched/core.c:6860 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2046 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2248 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x4e/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.15.0-rc6-syzkaller-00051-g405e6c37c89e #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:81 Code: ee fd b9 f5 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d a3 cf 11 00 f3 0f 1e fa fb f4 c3 fd b9 f5 cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90000197de0 EFLAGS: 00000286 RAX: 4473e3be253c0000 RBX: ffffffff81977128 RCX: 4473e3be253c0000 RDX: 0000000000000001 RSI: ffffffff8d74c03c RDI: ffffffff8bc1d820 RBP: ffffc90000197f20 R08: ffff8880b8932b5b R09: 1ffff1101712656b R10: dffffc0000000000 R11: ffffed101712656c R12: ffffffff8f7efb70 R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff110038d8b40 FS: 0000000000000000(0000) GS:ffff8881261c7000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c3989f6 CR3: 000000002f360000 CR4: 0000000000350ef0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:748 default_idle_call+0x74/0xb0 kernel/sched/idle.c:117 cpuidle_idle_call kernel/sched/idle.c:185 [inline] do_idle+0x1e8/0x510 kernel/sched/idle.c:325 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:423 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:315 common_startup_64+0x13e/0x147