rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P12/1:b..l rcu: (detected by 0, t=10502 jiffies, g=73217, q=1167200 ncpus=1) task:kworker/u8:0 state:R running task stack:25208 pid:12 tgid:12 ppid:2 task_flags:0x24248060 flags:0x00080000 Workqueue: writeback wb_workfn (flush-8:0) Call Trace: context_switch kernel/sched/core.c:5520 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7270 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:7592 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x205/0xa10 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_is_held_type+0xf5/0x140 kernel/locking/lockdep.c:5963 Code: ff ff ff ff 65 0f c1 15 f1 f6 be 08 83 fa 01 8b 44 24 04 75 2d 9c 5a 80 e6 02 75 47 41 f7 c5 00 02 00 00 74 01 fb 48 83 c4 08 <5b> 5d 41 5c 41 5d 41 5e 41 5f e9 cc 45 03 00 e9 c7 45 03 00 31 c0 RSP: 0018:ffffc90000116f58 EFLAGS: 00000282 RAX: 0000000000000001 RBX: ffffffff8ede9de0 RCX: 0000000000000001 RDX: 0000000000000046 RSI: ffffffff8e3be7fb RDI: ffffffff8c61c980 RBP: ffff88801eebcb00 R08: 0000000000000006 R09: 0000000000001000 R10: 0000000000000000 R11: 0000000000000001 R12: 00000000ffffffff R13: 0000000000000246 R14: ffff88801eebd770 R15: 0000000000000005 lookup_page_ext+0x6e/0x100 mm/page_ext.c:258 page_ext_iter_begin include/linux/page_ext.h:137 [inline] __page_table_check_zero+0x11c/0x410 mm/page_table_check.c:139 page_table_check_free include/linux/page_table_check.h:46 [inline] __free_pages_prepare mm/page_alloc.c:1419 [inline] __free_frozen_pages+0x790/0x10f0 mm/page_alloc.c:2962 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4683 [inline] slab_alloc_node mm/slub.c:4996 [inline] kmem_cache_alloc_noprof+0x269/0x6a0 mm/slub.c:5010 ext4_init_io_end+0x24/0x170 fs/ext4/page-io.c:302 ext4_do_writepages+0x992/0x3e80 fs/ext4/inode.c:2879 ext4_writepages+0x34a/0x750 fs/ext4/inode.c:3032 do_writepages+0x278/0x600 mm/page-writeback.c:2560 __writeback_single_inode+0x164/0x1560 fs/fs-writeback.c:1788 writeback_sb_inodes+0x766/0x1c50 fs/fs-writeback.c:2099 __writeback_inodes_wb+0xf8/0x2d0 fs/fs-writeback.c:2175 wb_writeback+0x6f6/0xb50 fs/fs-writeback.c:2286 wb_check_old_data_flush fs/fs-writeback.c:2390 [inline] wb_do_writeback fs/fs-writeback.c:2469 [inline] wb_workfn+0x93f/0xc80 fs/fs-writeback.c:2497 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387 process_scheduled_works kernel/workqueue.c:3470 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: rcu_preempt kthread starved for 966 jiffies! g73217 f0x2 RCU_GP_WAIT_FQS(5) ->state=R ->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:27576 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5520 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7270 __schedule_loop kernel/sched/core.c:7347 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7362 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x8f0 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x17a/0x220 kernel/rcu/tree.c:2330 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 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: 0 UID: 0 PID: 3219 Comm: kworker/R-bat_e Tainted: G L syzkaller #0 PREEMPT(lazy) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026 Workqueue: bat_events batadv_tt_purge RIP: 0010:lock_release+0x7d/0x310 kernel/locking/lockdep.c:5899 Code: 01 00 00 65 8b 05 1b 55 a4 12 85 c0 0f 85 39 01 00 00 65 4c 8b 25 4b 0e a4 12 41 8b bc 24 a4 0b 00 00 85 ff 0f 85 21 01 00 00 <48> 81 3b 40 39 8f 94 0f 84 14 01 00 00 9c 41 5e fa 48 c7 c7 f2 b8 RSP: 0018:ffffc90000006fa8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffffff8ede9de0 RCX: ffffffff929c3701 RDX: 0000000000000000 RSI: ffffffff8c61c900 RDI: 0000000000000000 RBP: ffffffff81b8d46e R08: 0000000000000001 R09: 0000000000000007 R10: 0000000000000200 R11: 00000000000a9a34 R12: ffff8880342fa580 R13: ffffc90000007060 R14: ffffc9000e2ffa60 R15: ffffc90000007094 FS: 0000000000000000(0000) GS:ffff888123b79000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000555571b6a4e8 CR3: 0000000037df2000 CR4: 00000000003526f0 Call Trace: rcu_lock_release include/linux/rcupdate.h:319 [inline] rcu_read_unlock include/linux/rcupdate.h:880 [inline] class_rcu_destructor include/linux/rcupdate.h:1216 [inline] unwind_next_frame+0x3c3/0x2090 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4683 [inline] slab_alloc_node mm/slub.c:4996 [inline] kmem_cache_alloc_node_noprof+0x282/0x6e0 mm/slub.c:5068 kmalloc_reserve+0x148/0x350 net/core/skbuff.c:615 __alloc_skb+0x185/0x710 net/core/skbuff.c:715 alloc_skb include/linux/skbuff.h:1384 [inline] synproxy_send_client_synack+0x19e/0x970 net/netfilter/nf_synproxy_core.c:463 nft_synproxy_eval_v4 net/netfilter/nft_synproxy.c:59 [inline] nft_synproxy_do_eval+0xa1c/0xce0 net/netfilter/nft_synproxy.c:141 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x2e5/0x19d0 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0xf3/0x400 net/netfilter/nft_chain_filter.c:162 nf_hook_entry_hookfn include/linux/netfilter.h:165 [inline] nf_hook_slow+0xbf/0x220 net/netfilter/core.c:619 nf_hook.constprop.0+0x2a6/0x750 include/linux/netfilter.h:280 NF_HOOK include/linux/netfilter.h:323 [inline] ip_local_deliver+0x163/0x1f0 net/ipv4/ip_input.c:262 dst_input include/net/dst.h:480 [inline] ip_rcv_finish net/ipv4/ip_input.c:492 [inline] NF_HOOK include/linux/netfilter.h:325 [inline] NF_HOOK include/linux/netfilter.h:319 [inline] ip_rcv+0x33a/0x3c0 net/ipv4/ip_input.c:612 __netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:6264 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6377 process_backlog+0x487/0x1600 net/core/dev.c:6728 __napi_poll.constprop.0+0xaf/0x450 net/core/dev.c:7787 napi_poll net/core/dev.c:7850 [inline] net_rx_action+0xa40/0xf20 net/core/dev.c:8007 handle_softirqs+0x1e6/0x9d0 kernel/softirq.c:645 do_softirq kernel/softirq.c:546 [inline] do_softirq+0xaf/0xf0 kernel/softirq.c:533 __local_bh_enable_ip+0xff/0x120 kernel/softirq.c:473 spin_unlock_bh include/linux/spinlock.h:407 [inline] batadv_tt_local_purge+0x21c/0x3d0 net/batman-adv/translation-table.c:1402 batadv_tt_purge+0x8b/0xbd0 net/batman-adv/translation-table.c:3753 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387 process_scheduled_works kernel/workqueue.c:3470 [inline] rescuer_thread+0x918/0x14e0 kernel/workqueue.c:3694 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245