rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P26166/1:b..l.. rcu: (detected by 1, t=10503 jiffies, g=140973, q=2098 ncpus=2) task:syz.1.6212 state:R running task stack:26560 pid:26166 tgid:26163 ppid:25571 task_flags:0x40054c flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5583 [inline] __schedule+0x17dd/0x5830 kernel/sched/core.c:7382 preempt_schedule_common+0x7f/0xd0 kernel/sched/core.c:7561 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:201 [inline] _raw_spin_unlock+0x41/0x50 kernel/locking/spinlock.c:213 spin_unlock include/linux/spinlock.h:401 [inline] zap_pte_range mm/memory.c:2058 [inline] zap_pmd_range mm/memory.c:2114 [inline] zap_pud_range mm/memory.c:2142 [inline] zap_p4d_range mm/memory.c:2163 [inline] __zap_vma_range+0x40e1/0x4f70 mm/memory.c:2203 unmap_vmas+0x38b/0x550 mm/memory.c:2272 exit_mmap+0x290/0xa40 mm/mmap.c:1315 __mmput+0x118/0x420 kernel/fork.c:1192 exit_mm+0x18e/0x240 kernel/exit.c:586 do_exit+0x6a8/0x2360 kernel/exit.c:967 do_group_exit+0x22d/0x2f0 kernel/exit.c:1123 get_signal+0x1216/0x12c0 kernel/signal.c:3112 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x10e/0x770 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline] do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fcaa899fb19 RSP: 002b:00007fcaa97ec0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007fcaa8c25fa8 RCX: 00007fcaa899fb19 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fcaa8c25fa8 RBP: 00007fcaa8c25fa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fcaa8c26038 R14: 00007fff8cf13e70 R15: 00007fff8cf13f58 rcu: rcu_preempt kthread starved for 701 jiffies! g140973 f0x0 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:27496 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5583 [inline] __schedule+0x17dd/0x5830 kernel/sched/core.c:7382 __schedule_loop kernel/sched/core.c:7459 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7474 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x1230 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x9c/0x340 kernel/rcu/tree.c:2330 kthread+0x38b/0x480 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: 3229 Comm: kworker/R-bat_e Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026 Workqueue: bat_events batadv_tt_purge RIP: 0010:debug_lockdep_rcu_enabled+0xd/0x40 kernel/rcu/update.c:320 Code: 8e 67 48 0f b9 3a 90 eb bc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 31 c0 83 3d fb d6 9a 05 00 <74> 1d 83 3d ea 04 9b 05 00 74 14 65 48 8b 0d f8 63 bd 08 31 c0 83 RSP: 0018:ffffc90000006f38 EFLAGS: 00000202 RAX: 0000000000000000 RBX: ffffffff8190611d RCX: 8000000000000101 RDX: 00000000071bee9f RSI: ffffffff8e92d4a0 RDI: ffffffff8c8e8c80 RBP: 1ffff92000000e04 R08: ffffffff817879cf R09: 0000000000000000 R10: ffffc90000007038 R11: ffffffff81b3a880 R12: dffffc0000000000 R13: ffffffff817879cf R14: ffffc90000006fe8 R15: 1ffff92000000dfd FS: 0000000000000000(0000) GS:ffff888123620000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fea91400218 CR3: 000000000fd48000 CR4: 00000000003526f0 Call Trace: rcu_read_lock include/linux/rcupdate.h:850 [inline] class_rcu_constructor include/linux/rcupdate.h:1216 [inline] unwind_next_frame+0xb5/0x2550 arch/x86/kernel/unwind_orc.c:495 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:264 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:296 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2780 [inline] slab_free mm/slub.c:6630 [inline] kfree+0x1c5/0x650 mm/slub.c:6923 skb_release_all net/core/skbuff.c:1188 [inline] __kfree_skb+0x5d/0x210 net/core/skbuff.c:1202 nft_synproxy_eval_v4+0x36a/0x4e0 net/netfilter/nft_synproxy.c:-1 nft_synproxy_do_eval+0x389/0x5d0 net/netfilter/nft_synproxy.c:142 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:165 [inline] nf_hook_slow+0xc5/0x220 net/netfilter/core.c:633 nf_hook include/linux/netfilter.h:280 [inline] NF_HOOK+0x21f/0x3c0 include/linux/netfilter.h:323 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:325 __netif_receive_skb_one_core net/core/dev.c:6433 [inline] __netif_receive_skb net/core/dev.c:6546 [inline] process_backlog+0xa6b/0x18b0 net/core/dev.c:6897 __napi_poll+0xaa/0x330 net/core/dev.c:7966 napi_poll net/core/dev.c:8029 [inline] net_rx_action+0x61d/0xf50 net/core/dev.c:8186 handle_softirqs+0x265/0x8d0 kernel/softirq.c:669 do_softirq+0x77/0xd0 kernel/softirq.c:569 __local_bh_enable_ip+0x100/0x140 kernel/softirq.c:473 spin_unlock_bh include/linux/spinlock.h:407 [inline] batadv_tt_local_purge+0x277/0x300 net/batman-adv/translation-table.c:1798 batadv_tt_purge+0x35/0xa40 net/batman-adv/translation-table.c:4269 process_one_work kernel/workqueue.c:3495 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578 rescuer_thread+0x84a/0x12a0 kernel/workqueue.c:3803 kthread+0x38b/0x480 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