rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5357/1:b..l rcu: (detected by 1, t=10503 jiffies, g=340201, q=4694 ncpus=2) task:crond state:R running task stack:24208 pid:5357 tgid:5357 ppid:1 task_flags:0x400000 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5504 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7228 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7552 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x14f/0x8f0 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:101 [inline] RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:238 [inline] RIP: 0010:unwind_next_frame+0x4c3/0x2550 arch/x86/kernel/unwind_orc.c:510 Code: 01 4c 8b 6c 24 50 49 bc 00 00 00 00 00 fc ff df 4c 8b 7c 24 10 49 8d 6e 38 0f 84 8a 16 00 00 e9 ee 01 00 00 49 89 d5 49 89 d7 <4c> 89 e0 4c 29 f8 48 89 c1 48 c1 f9 02 48 c1 e8 3f 48 01 c8 48 83 RSP: 0018:ffffc900035f7820 EFLAGS: 00000246 RAX: ffffffff90546fb8 RBX: ffffffff90546fbc RCX: ffffffff90546fc0 RDX: ffffffff90546f84 RSI: ffffffff90d55068 RDI: ffffffff8c2910c0 RBP: ffffffff8245c97d R08: 0000000000000010 R09: 0000000000000000 R10: ffffc900035f7918 R11: ffffffff81b10630 R12: ffffffff90546fc0 R13: ffffffff90546fbc R14: ffffc900035f78c8 R15: ffffffff90546fc0 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 save_stack+0x122/0x230 mm/page_owner.c:165 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1397 [inline] __free_frozen_pages+0xc0d/0xd20 mm/page_alloc.c:2938 __slab_free+0x274/0x2c0 mm/slub.c:5672 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4610 [inline] slab_alloc_node mm/slub.c:4939 [inline] kmem_cache_alloc_noprof+0x2b8/0x650 mm/slub.c:4946 alloc_filename fs/namei.c:147 [inline] do_getname+0x2e/0x250 fs/namei.c:187 class_filename_flags_constructor include/linux/fs.h:2566 [inline] do_sys_openat2+0xcc/0x200 fs/open.c:1394 do_sys_open fs/open.c:1401 [inline] __do_sys_openat fs/open.c:1417 [inline] __se_sys_openat fs/open.c:1412 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1412 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f63d50d0407 RSP: 002b:00007ffd50e7feb0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f63d4f80c80 RCX: 00007f63d50d0407 RDX: 0000000000000000 RSI: 00007f63d52c3764 RDI: ffffffffffffff9c RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007f63d52cf492 R13: 00007f63d52cf492 R14: 0000000000000001 R15: 0000000000000022 rcu: rcu_preempt kthread starved for 5032 jiffies! g340201 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:27176 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5504 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7228 __schedule_loop kernel/sched/core.c:7307 [inline] schedule+0x164/0x360 kernel/sched/core.c:7322 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 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: 3226 Comm: kworker/R-bat_e Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: bat_events batadv_tt_purge RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline] RIP: 0010:write_comp_data kernel/kcov.c:246 [inline] RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x2e/0x90 kernel/kcov.c:314 Code: 48 8b 04 24 65 48 8b 15 98 45 74 11 65 8b 0d b9 45 74 11 81 e1 00 01 ff 00 74 11 81 f9 00 01 00 00 75 5b 83 ba 1c 17 00 00 00 <74> 52 8b 8a f8 16 00 00 83 f9 03 75 47 48 8b 8a 00 17 00 00 44 8b RSP: 0018:ffffc90000a087b8 EFLAGS: 00000246 RAX: ffffffff8a83b8d2 RBX: 0000000000000000 RCX: 0000000000000100 RDX: ffff8880323cdd00 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000a088b0 R08: 0000000000000000 R09: 0000000000000000 R10: 00000000000002ff R11: 0200000000000000 R12: ffff88808258c000 R13: 1ffff920001410fc R14: ffff888084aa4e80 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88812537c000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8a25800218 CR3: 000000000e746000 CR4: 00000000003526f0 Call Trace: rcu_read_lock include/linux/rcupdate.h:841 [inline] nf_hook include/linux/netfilter.h:242 [inline] NF_HOOK include/linux/netfilter.h:316 [inline] br_nf_pre_routing_ipv6+0x472/0x6f0 net/bridge/br_netfilter_ipv6.c:183 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_bridge_pre net/bridge/br_input.c:291 [inline] br_handle_frame+0x127f/0x1510 net/bridge/br_input.c:442 __netif_receive_skb_core+0x989/0x30b0 net/core/dev.c:6093 __netif_receive_skb_one_core net/core/dev.c:6204 [inline] __netif_receive_skb net/core/dev.c:6319 [inline] process_backlog+0x706/0x1860 net/core/dev.c:6670 __napi_poll+0xaa/0x330 net/core/dev.c:7729 napi_poll net/core/dev.c:7792 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:7949 handle_softirqs+0x225/0x840 kernel/softirq.c:622 do_softirq+0x76/0xd0 kernel/softirq.c:523 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450 spin_unlock_bh include/linux/spinlock.h:396 [inline] batadv_tt_global_purge net/batman-adv/translation-table.c:2301 [inline] batadv_tt_purge+0x4ae/0xa10 net/batman-adv/translation-table.c:3566 process_one_work kernel/workqueue.c:3314 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3397 rescuer_thread+0x7b6/0x10b0 kernel/workqueue.c:3621 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245