rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4974/1:b..l rcu: (detected by 1, t=10502 jiffies, g=85797, q=1660 ncpus=2) task:udevd state:R running task stack:23400 pid:4974 tgid:4974 ppid:1 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7556 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:unwind_next_frame+0x46e/0x2550 arch/x86/kernel/unwind_orc.c:520 Code: d1 48 89 15 a4 7b fb 11 48 85 d2 0f 84 2e 02 00 00 48 8d 5a 04 48 89 54 24 18 4c 8d 6a 05 48 89 d8 48 c1 e8 03 42 0f b6 04 20 <84> c0 0f 85 b4 19 00 00 4c 89 e8 48 c1 e8 03 42 0f b6 04 20 84 c0 RSP: 0018:ffffc90003267280 EFLAGS: 00000217 RAX: 0000000000000000 RBX: ffffffff90fc999c RCX: ffffffff907a0ca4 RDX: ffffffff90fc9998 RSI: ffffffff90fc9992 RDI: ffffffff8c4bbe20 RBP: ffffffff8234963f R08: 0000000000000007 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8eb59c60 R12: dffffc0000000000 R13: ffffffff90fc999d R14: ffffc90003267328 R15: ffffffff907a0ca0 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2677 [inline] slab_free mm/slub.c:6377 [inline] kfree+0x1c5/0x640 mm/slub.c:6692 tomoyo_check_open_permission+0x32c/0x470 security/tomoyo/file.c:791 security_file_open+0xa9/0x240 security/security.c:2739 do_dentry_open+0x4a0/0x1380 fs/open.c:924 vfs_open+0x3b/0x340 fs/open.c:1052 do_open fs/namei.c:4700 [inline] path_openat+0x2e44/0x3830 fs/namei.c:4863 do_file_open+0x23e/0x4a0 fs/namei.c:4892 do_sys_openat2+0x115/0x200 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1385 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: 0033:0x7ff20f915c3a RSP: 002b:00007ffcd73ba5a8 EFLAGS: 00000206 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000561e62a34210 RCX: 00007ff20f915c3a RDX: 0000000000090800 RSI: 0000561e629f7380 RDI: 00000000ffffff9c RBP: 0000561e629f7380 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000206 R12: 0000561e62a017b0 R13: 00000000000000fe R14: 0000561e52c13be0 R15: 00007ffcd73ba870 rcu: rcu_preempt kthread starved for 238 jiffies! g85797 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:27752 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7326 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: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 3212 Comm: kworker/R-bat_e Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Workqueue: bat_events batadv_tt_purge RIP: 0010:ipt_do_table+0x1381/0x15d0 include/linux/bottom_half.h:-1 Code: 12 0e 8d e8 d1 04 71 01 8b 84 24 84 00 00 00 65 01 05 93 77 0e 09 48 8b bc 24 08 01 00 00 be 00 02 00 00 e8 11 b0 28 f7 31 c0 <80> bc 24 5e 01 00 00 00 0f 44 c3 43 c7 44 3c 04 f8 f8 f8 f8 48 c7 RSP: 0018:ffffc90000006f40 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000080000101 RDX: 0000000000000002 RSI: ffffffff8e228aee RDI: ffffffff8c4bbe80 RBP: ffffc90000007120 R08: ffffffff90574737 R09: 1ffffffff20ae8e6 R10: dffffc0000000000 R11: fffffbfff20ae8e7 R12: 1ffff92000000e0c R13: 0000000000000001 R14: ffff8880321462a0 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff888124f55000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fffd2e31e1c CR3: 000000005b768000 CR4: 0000000000350ef0 Call Trace: nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619 nf_hook+0x22a/0x3a0 include/linux/netfilter.h:273 NF_HOOK_COND include/linux/netfilter.h:306 [inline] ip_output+0x269/0x450 net/ipv4/ip_output.c:437 synproxy_send_client_synack+0x89b/0xde0 net/netfilter/nf_synproxy_core.c:487 nft_synproxy_eval_v4+0x362/0x4e0 net/netfilter/nft_synproxy.c:59 nft_synproxy_do_eval+0x335/0x550 net/netfilter/nft_synproxy.c:141 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x48d/0x1b10 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x360/0x4b0 net/netfilter/nft_chain_filter.c:162 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK+0x21f/0x3c0 include/linux/netfilter.h:316 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318 __netif_receive_skb_one_core net/core/dev.c:6212 [inline] __netif_receive_skb net/core/dev.c:6325 [inline] process_backlog+0xa34/0x1860 net/core/dev.c:6676 __napi_poll+0xaa/0x330 net/core/dev.c:7735 napi_poll net/core/dev.c:7798 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:7955 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:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 rescuer_thread+0x7b6/0x10b0 kernel/workqueue.c:3629 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