rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5879/1:b..l P5607/1:b..l P5606/1:b..l P6636/1:b..l rcu: (detected by 0, t=10502 jiffies, g=26209, q=1240086 ncpus=1) task:udevd state:R running task stack:24840 pid:6636 tgid:6636 ppid:4964 task_flags:0x40014c flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7556 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+0x205/0xa00 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872 Code: 05 bb 3b 7d 12 83 f8 07 0f 87 da 00 00 00 48 0f a3 05 46 8e 3b 0f 0f 82 ac 02 00 00 8b 35 0e c2 3b 0f 85 f6 0f 85 c7 00 00 00 <48> 8b 44 24 30 65 48 2b 05 5d 3b 7d 12 0f 85 ec 02 00 00 48 83 c4 RSP: 0018:ffffc90005c674c8 EFLAGS: 00000206 RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8e183208 RDI: ffffffff8c400380 RBP: ffffffff8ebe8200 R08: 000000000b2d5154 R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:300 [inline] rcu_read_lock include/linux/rcupdate.h:840 [inline] class_rcu_constructor include/linux/rcupdate.h:1183 [inline] unwind_next_frame+0xd1/0x2090 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 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/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] kmem_cache_free+0x127/0x6b0 mm/slub.c:6504 anon_vma_chain_free mm/rmap.c:147 [inline] unlink_anon_vmas+0x4c1/0x8e0 mm/rmap.c:539 free_pgtables+0x2e7/0xd80 mm/memory.c:414 exit_mmap+0x44c/0xa00 mm/mmap.c:1312 __mmput+0x12a/0x410 kernel/fork.c:1187 mmput+0x67/0x80 kernel/fork.c:1210 exit_mm kernel/exit.c:615 [inline] do_exit+0x8b1/0x2ae0 kernel/exit.c:997 do_group_exit+0xd5/0x2a0 kernel/exit.c:1152 __do_sys_exit_group kernel/exit.c:1163 [inline] __se_sys_exit_group kernel/exit.c:1161 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1161 x64_sys_call+0x102c/0x1530 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa7ec8f16c5 RSP: 002b:00007ffedb355288 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000557bc0253230 RCX: 00007fa7ec8f16c5 RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000 RBP: 0000557bbffe22c0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffedb3552d0 R14: 0000000000000000 R15: 0000000000000000 task:udevd state:R running task stack:26136 pid:5606 tgid:5606 ppid:4964 task_flags:0x40014c flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7556 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+0x205/0xa00 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_release+0x19e/0x310 kernel/locking/lockdep.c:5893 Code: ff 65 0f c1 05 a3 7b 7d 12 83 f8 01 0f 85 27 01 00 00 9c 58 f6 c4 02 0f 85 12 01 00 00 41 f7 c6 00 02 00 00 0f 85 c8 00 00 00 <48> 8b 44 24 10 65 48 2b 05 ad 34 7d 12 0f 85 4d 01 00 00 48 83 c4 RSP: 0018:ffffc900043f7610 EFLAGS: 00000206 RAX: 0000000000000046 RBX: ffffffff8ebe8200 RCX: ffffc900043f761c RDX: 0000000000000001 RSI: ffffffff8e183208 RDI: ffffffff8c400380 RBP: ffffffff828743df R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff88807b388000 R13: 0000000000000001 R14: 0000000000000202 R15: 0000000000000002 rcu_lock_release include/linux/rcupdate.h:310 [inline] rcu_read_unlock include/linux/rcupdate.h:871 [inline] __page_table_check_zero+0x284/0x410 mm/page_table_check.c:145 page_table_check_free include/linux/page_table_check.h:46 [inline] __free_pages_prepare mm/page_alloc.c:1407 [inline] free_unref_folios+0xa35/0x1710 mm/page_alloc.c:3011 folios_put_refs+0x585/0xaa0 mm/swap.c:1057 free_pages_and_swap_cache+0x22d/0x3b0 mm/swap_state.c:586 __tlb_batch_free_encoded_pages+0xe9/0x280 mm/mmu_gather.c:138 tlb_batch_pages_flush mm/mmu_gather.c:151 [inline] tlb_flush_mmu_free mm/mmu_gather.c:417 [inline] tlb_flush_mmu mm/mmu_gather.c:424 [inline] tlb_finish_mmu+0x1b0/0x810 mm/mmu_gather.c:549 exit_mmap+0x454/0xa00 mm/mmap.c:1313 __mmput+0x12a/0x410 kernel/fork.c:1187 mmput+0x67/0x80 kernel/fork.c:1210 exit_mm kernel/exit.c:615 [inline] do_exit+0x8b1/0x2ae0 kernel/exit.c:997 do_group_exit+0xd5/0x2a0 kernel/exit.c:1152 __do_sys_exit_group kernel/exit.c:1163 [inline] __se_sys_exit_group kernel/exit.c:1161 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1161 x64_sys_call+0x102c/0x1530 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa7ec8f16c5 RSP: 002b:00007ffedb355288 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000557bc0230210 RCX: 00007fa7ec8f16c5 RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000 RBP: 0000557bbffe22c0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffedb3552d0 R14: 0000000000000000 R15: 0000000000000000 task:udevd state:R running task stack:26600 pid:5607 tgid:5607 ppid:4964 task_flags:0x40014c flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7413 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline] _raw_spin_unlock_irqrestore+0x61/0x80 kernel/locking/spinlock.c:198 spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] lruvec_unlock_irqrestore include/linux/memcontrol.h:1535 [inline] folios_put_refs+0x4f2/0xaa0 mm/swap.c:1049 free_pages_and_swap_cache+0x22d/0x3b0 mm/swap_state.c:586 __tlb_batch_free_encoded_pages+0xe9/0x280 mm/mmu_gather.c:138 tlb_batch_pages_flush mm/mmu_gather.c:151 [inline] tlb_flush_mmu_free mm/mmu_gather.c:417 [inline] tlb_flush_mmu mm/mmu_gather.c:424 [inline] tlb_finish_mmu+0x1b0/0x810 mm/mmu_gather.c:549 exit_mmap+0x454/0xa00 mm/mmap.c:1313 __mmput+0x12a/0x410 kernel/fork.c:1187 mmput+0x67/0x80 kernel/fork.c:1210 exit_mm kernel/exit.c:615 [inline] do_exit+0x8b1/0x2ae0 kernel/exit.c:997 do_group_exit+0xd5/0x2a0 kernel/exit.c:1152 __do_sys_exit_group kernel/exit.c:1163 [inline] __se_sys_exit_group kernel/exit.c:1161 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1161 x64_sys_call+0x102c/0x1530 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa7ec8f16c5 RSP: 002b:00007ffedb355288 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000557bc0231150 RCX: 00007fa7ec8f16c5 RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000 RBP: 0000557bbffe22c0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffedb3552d0 R14: 0000000000000000 R15: 0000000000000000 task:udevd state:R running task stack:26600 pid:5879 tgid:5879 ppid:4964 task_flags:0x40014c flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 preempt_schedule_notrace+0x5f/0xd0 kernel/sched/core.c:7506 preempt_schedule_notrace_thunk+0x16/0x30 arch/x86/entry/thunk.S:13 rcu_is_watching+0x8e/0xc0 kernel/rcu/tree.c:753 rcu_read_lock include/linux/rcupdate.h:841 [inline] class_rcu_constructor include/linux/rcupdate.h:1183 [inline] is_module_text_address+0x19e/0x220 kernel/module/main.c:3921 kernel_text_address kernel/extable.c:119 [inline] kernel_text_address+0x81/0x100 kernel/extable.c:94 __kernel_text_address+0xd/0x30 kernel/extable.c:79 unwind_get_return_address+0x59/0xa0 arch/x86/kernel/unwind_orc.c:385 arch_stack_walk+0xa6/0xf0 arch/x86/kernel/stacktrace.c:26 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 save_stack+0x162/0x1e0 mm/page_owner.c:165 __reset_page_owner+0x84/0x190 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1406 [inline] free_unref_folios+0xa44/0x1710 mm/page_alloc.c:3011 folios_put_refs+0x585/0xaa0 mm/swap.c:1057 free_pages_and_swap_cache+0x22d/0x3b0 mm/swap_state.c:586 __tlb_batch_free_encoded_pages+0xe9/0x280 mm/mmu_gather.c:138 tlb_batch_pages_flush mm/mmu_gather.c:151 [inline] tlb_flush_mmu_free mm/mmu_gather.c:417 [inline] tlb_flush_mmu mm/mmu_gather.c:424 [inline] tlb_finish_mmu+0x1b0/0x810 mm/mmu_gather.c:549 exit_mmap+0x454/0xa00 mm/mmap.c:1313 __mmput+0x12a/0x410 kernel/fork.c:1187 mmput+0x67/0x80 kernel/fork.c:1210 exit_mm kernel/exit.c:615 [inline] do_exit+0x8b1/0x2ae0 kernel/exit.c:997 do_group_exit+0xd5/0x2a0 kernel/exit.c:1152 __do_sys_exit_group kernel/exit.c:1163 [inline] __se_sys_exit_group kernel/exit.c:1161 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1161 x64_sys_call+0x102c/0x1530 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa7ec8f16c5 RSP: 002b:00007ffedb355288 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000557bc0253490 RCX: 00007fa7ec8f16c5 RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000 RBP: 0000557bbffe22c0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffedb3552d0 R14: 0000000000000000 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 718 jiffies! g26209 f0x2 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:27592 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7326 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2325 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 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: 3215 Comm: kworker/R-bat_e Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Workqueue: bat_events batadv_tt_purge RIP: 0010:debug_lockdep_rcu_enabled+0x2e/0x40 kernel/rcu/update.c:322 Code: 8b 05 4e d1 66 05 85 c0 74 20 8b 05 00 04 67 05 85 c0 74 16 65 48 8b 05 68 7d a8 08 8b 80 9c 0b 00 00 85 c0 0f 94 c0 0f b6 c0 cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 90 90 90 90 RSP: 0018:ffffc90000006ee0 EFLAGS: 00000246 RAX: 0000000000000001 RBX: ffffc90000007cb8 RCX: ffffffff92585601 RDX: ffffc90000007cc0 RSI: ffffc90000007c98 RDI: ffffc90000006f68 RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000088d9f R12: ffffc90000006fa8 R13: ffffc90000006f58 R14: ffffc90000007cb8 R15: ffffc90000006f8c FS: 0000000000000000(0000) GS:ffff888123dec000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffcc9905160 CR3: 000000007da87000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000006800 DR2: 0000000000009951 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: rcu_read_unlock include/linux/rcupdate.h:869 [inline] class_rcu_destructor include/linux/rcupdate.h:1183 [inline] unwind_next_frame+0x3a8/0x2090 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:4584 [inline] slab_alloc_node mm/slub.c:4917 [inline] kmem_cache_alloc_noprof+0x26b/0x6a0 mm/slub.c:4931 kmem_alloc_batch+0x49/0x170 lib/debugobjects.c:371 fill_pool lib/debugobjects.c:420 [inline] debug_objects_fill_pool lib/debugobjects.c:780 [inline] debug_objects_fill_pool+0x24d/0x5a0 lib/debugobjects.c:758 debug_object_activate+0x103/0x4b0 lib/debugobjects.c:869 debug_rcu_head_queue kernel/rcu/rcu.h:236 [inline] __call_rcu_common.constprop.0+0x35/0x9b0 kernel/rcu/tree.c:3144 call_rcu_hurry include/linux/rcupdate.h:125 [inline] dst_release net/core/dst.c:178 [inline] dst_release+0x259/0x330 net/core/dst.c:166 refdst_drop include/net/dst.h:272 [inline] skb_dst_drop include/net/dst.h:284 [inline] skb_release_head_state+0x293/0x400 net/core/skbuff.c:1171 skb_release_all net/core/skbuff.c:1195 [inline] __kfree_skb net/core/skbuff.c:1211 [inline] consume_skb net/core/skbuff.c:1445 [inline] consume_skb+0x8a/0x110 net/core/skbuff.c:1439 nft_synproxy_eval_v4 net/netfilter/nft_synproxy.c:60 [inline] nft_synproxy_do_eval+0xa24/0xce0 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:158 [inline] nf_hook_slow+0xbf/0x220 net/netfilter/core.c:619 nf_hook.constprop.0+0x2a6/0x750 include/linux/netfilter.h:273 NF_HOOK include/linux/netfilter.h:316 [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:318 [inline] NF_HOOK include/linux/netfilter.h:312 [inline] ip_rcv+0x33a/0x3c0 net/ipv4/ip_input.c:612 __netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:6212 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6325 process_backlog+0x37a/0x1580 net/core/dev.c:6676 __napi_poll.constprop.0+0xaf/0x450 net/core/dev.c:7735 napi_poll net/core/dev.c:7798 [inline] net_rx_action+0xa40/0xf20 net/core/dev.c:7955 handle_softirqs+0x1ea/0x9b0 kernel/softirq.c:622 do_softirq kernel/softirq.c:523 [inline] do_softirq+0xac/0xe0 kernel/softirq.c:510 __local_bh_enable_ip+0xf8/0x120 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+0x25d/0xbd0 net/batman-adv/translation-table.c:3566 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] rescuer_thread+0x905/0x14a0 kernel/workqueue.c:3629 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245