rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4260/1:b..l (detected by 0, t=10502 jiffies, g=33257, q=37) task:kworker/u4:6 state:R running task stack:20920 pid: 4260 ppid: 2 flags:0x00004000 Workqueue: bat_events batadv_nc_worker Call Trace: context_switch kernel/sched/core.c:5030 [inline] __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6780 irqentry_exit+0x53/0x80 kernel/entry/common.c:432 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681 RIP: 0010:rcu_preempt_read_exit kernel/rcu/tree_plugin.h:380 [inline] RIP: 0010:__rcu_read_unlock+0x2f/0x100 kernel/rcu/tree_plugin.h:419 Code: 41 55 41 54 53 49 bc 00 00 00 00 00 fc ff df 65 4c 8b 35 c4 6e 96 7e 4d 8d ae 3c 04 00 00 4c 89 eb 48 c1 eb 03 42 0f b6 04 23 <84> c0 75 61 41 8b 6d 00 ff cd 42 0f b6 04 23 84 c0 75 69 41 89 6d RSP: 0018:ffffc900032cfbc0 EFLAGS: 00000a07 RAX: 0000000000000000 RBX: 1ffff11004244087 RCX: ffff888021220000 RDX: 0000000000000000 RSI: ffffffff8af9fc60 RDI: ffffffff8af9fc20 RBP: 0000000000000001 R08: ffffffff8a1ce955 R09: fffffbfff2132219 R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000 R13: ffff88802122043c R14: ffff888021220000 R15: ffff888021b62a40 rcu_read_unlock include/linux/rcupdate.h:771 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:416 [inline] batadv_nc_worker+0x234/0x5b0 net/batman-adv/network-coding.c:723 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457 kthread+0x3f6/0x4f0 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 rcu: rcu_preempt kthread starved for 10522 jiffies! g33257 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:27000 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5030 [inline] __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6780 irqentry_exit+0x53/0x80 kernel/entry/common.c:432 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681 RIP: 0010:prepare_to_swait_event+0x1/0x340 kernel/sched/swait.c:104 Code: 48 8b 74 24 20 48 83 c4 28 5b 41 5c 41 5d 41 5e 41 5f 5d e9 e1 a3 e9 08 0f 0b eb 9c 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 55 <41> 57 41 56 41 55 41 54 53 48 83 ec 28 89 d3 49 89 f5 49 89 fc 49 RSP: 0018:ffffc90000d47c90 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffc90000d47d68 RCX: ffff88813ff23b80 RDX: 0000000000000402 RSI: ffffc90000d47d60 RDI: ffffffff8cb23960 RBP: ffffc90000d47df0 R08: ffffffff8a497222 R09: ffffc90000d47a40 R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000000 R13: ffffc90000d47d60 R14: 0000000000000000 R15: 0000000000000000 rcu_gp_fqs_loop+0x28a/0x1080 kernel/rcu/tree.c:1972 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145 kthread+0x3f6/0x4f0 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: NMI backtrace for cpu 0 CPU: 0 PID: 8139 Comm: syz.3.932 Not tainted 5.15.180-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline] rcu_check_gp_kthread_starvation+0x1d2/0x240 kernel/rcu/tree_stall.h:487 print_other_cpu_stall+0x137a/0x14d0 kernel/rcu/tree_stall.h:592 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline] rcu_pending kernel/rcu/tree.c:3932 [inline] rcu_sched_clock_irq+0xa38/0x1150 kernel/rcu/tree.c:2619 update_process_times+0x196/0x200 kernel/time/timer.c:1818 tick_sched_handle kernel/time/tick-sched.c:254 [inline] tick_sched_timer+0x386/0x550 kernel/time/tick-sched.c:1473 __run_hrtimer kernel/time/hrtimer.c:1690 [inline] __hrtimer_run_queues+0x55b/0xcf0 kernel/time/hrtimer.c:1754 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1816 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline] __sysvec_apic_timer_interrupt+0x13b/0x4b0 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 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:raw_spin_rq_unlock_irq+0x19/0x80 kernel/sched/sched.h:1339 Code: 38 c1 7c cb 4c 89 f7 e8 75 c4 70 00 eb c1 0f 1f 00 41 57 41 56 53 48 89 fb eb 14 48 89 df e8 9e f0 ef 08 e8 59 4f 2d 00 fb 5b <41> 5e 41 5f c3 49 bf 00 00 00 00 00 fc ff df 4c 8d b3 58 0d 00 00 RSP: 0018:ffffc900038ff708 EFLAGS: 00000286 RAX: 3a63a23ffc56ec00 RBX: ffff8880b8e3a300 RCX: ffffffff96a97f03 RDX: dffffc0000000000 RSI: ffffffff8aab2b60 RDI: ffffffff8af9fc80 RBP: ffffc900038ff900 R08: ffffffff81871c90 R09: ffffed10171c7461 R10: 0000000000000000 R11: dffffc0000000001 R12: ffff8880202e1dc0 R13: dffffc0000000000 R14: ffff8880b8e3b058 R15: dffffc0000000000 __schedule+0x1462/0x45b0 kernel/sched/core.c:6382 schedule+0x11b/0x1f0 kernel/sched/core.c:6459 freezable_schedule include/linux/freezer.h:172 [inline] futex_wait_queue_me+0x25b/0x480 kernel/futex/core.c:2863 futex_wait+0x2f8/0x740 kernel/futex/core.c:2964 do_futex+0x1414/0x1810 kernel/futex/core.c:3982 __do_sys_futex kernel/futex/core.c:4059 [inline] __se_sys_futex+0x407/0x490 kernel/futex/core.c:4040 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f59cf713169 Code: 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 01 48 RSP: 002b:00007f59cd55a0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: ffffffffffffffda RBX: 00007f59cf93b088 RCX: 00007f59cf713169 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f59cf93b088 RBP: 00007f59cf93b080 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f59cf93b08c R13: 0000000000000000 R14: 00007ffc9f455920 R15: 00007ffc9f455a08