rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 0, t=10504 jiffies, g=181073, q=228208 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4295103707-4295093205), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g181073 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:26376 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x1b88/0x5240 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0x163/0x360 kernel/sched/core.c:6860 schedule_timeout+0x15b/0x2b0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x2e1/0x1340 kernel/rcu/tree.c:2046 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2248 kthread+0x7b9/0x940 kernel/kthread.c:464 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:153 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: 16767 Comm: syz.0.10423 Not tainted 6.15.0-rc3-syzkaller-00032-ga79be02bba5c #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 RIP: 0010:srso_alias_safe_ret+0x0/0x7 arch/x86/lib/retpoline.S:171 Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc <48> 8d 64 24 08 c3 cc e8 f4 ff ff ff 0f 0b cc cc cc cc cc cc cc cc RSP: 0018:ffffc90000006eb0 EFLAGS: 00000246 RAX: 0000000000000100 RBX: 0000000000000000 RCX: 0000000000007001 RDX: ffff88801e7d5a00 RSI: 0000000000000000 RDI: 0000000000000514 RBP: ffffc90000006f90 R08: ffffffff8aa73eca R09: 1ffff11011ecb71c R10: dffffc0000000000 R11: ffffed1011ecb71d R12: ffff88808f65b214 R13: ffffc90000007020 R14: 1ffff92000000e04 R15: ffff88808f65b200 FS: 0000000000000000(0000) GS:ffff888124f9a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f45091eef47 CR3: 0000000027a48000 CR4: 0000000000350ef0 Call Trace: srso_alias_return_thunk+0x5/0xfbef5 arch/x86/lib/retpoline.S:181 __cookie_v4_init_sequence+0xda/0x520 net/ipv4/syncookies.c:161 synproxy_send_client_synack+0x553/0xf70 net/netfilter/nf_synproxy_core.c:472 nft_synproxy_eval_v4+0x3cc/0x610 net/netfilter/nft_synproxy.c:59 nft_synproxy_do_eval+0x36a/0xa90 net/netfilter/nft_synproxy.c:141 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x4b4/0x1db0 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x41f/0x6b0 net/netfilter/nft_chain_filter.c:161 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline] nf_hook_slow+0xca/0x220 net/netfilter/core.c:626 nf_hook include/linux/netfilter.h:269 [inline] NF_HOOK+0x29b/0x450 include/linux/netfilter.h:312 NF_HOOK+0x3a2/0x450 include/linux/netfilter.h:314 __netif_receive_skb_one_core net/core/dev.c:5887 [inline] __netif_receive_skb+0x2c9/0x670 net/core/dev.c:6000 process_backlog+0x664/0x15c0 net/core/dev.c:6352 __napi_poll+0xcd/0x480 net/core/dev.c:7324 napi_poll net/core/dev.c:7388 [inline] net_rx_action+0x89d/0x1240 net/core/dev.c:7510 handle_softirqs+0x2d8/0x9b0 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0xfb/0x220 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_many_cond+0x1bb6/0x2d40 kernel/smp.c:885 Code: 89 e6 83 e6 01 31 ff e8 88 dd 0b 00 41 83 e4 01 4c 8b 64 24 68 75 07 e8 38 d9 0b 00 eb 41 f3 90 48 b8 00 00 00 00 00 fc ff df <0f> b6 04 03 84 c0 75 11 41 f7 45 00 01 00 00 00 74 1e e8 13 d9 0b RSP: 0018:ffffc900045f7600 EFLAGS: 00000293 RAX: dffffc0000000000 RBX: 1ffff110170e7e91 RCX: ffff88801e7d5a00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900045f7800 R08: ffffffff81b6e3d8 R09: 1ffffffff20bfd0e R10: dffffc0000000000 R11: ffffffff816b0a80 R12: ffff8880b863ad08 R13: ffff8880b873f488 R14: ffff8880b863ad00 R15: 0000000000000001 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1275 [inline] flush_tlb_mm_range+0xb8d/0x13f0 arch/x86/mm/tlb.c:1365 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:480 [inline] tlb_flush_mmu+0x1aa/0x690 mm/mmu_gather.c:403 tlb_finish_mmu+0xd4/0x200 mm/mmu_gather.c:496 exit_mmap+0x5b1/0xde0 mm/mmap.c:1297 __mmput+0x115/0x420 kernel/fork.c:1379 exit_mm+0x221/0x310 kernel/exit.c:589 do_exit+0x994/0x27f0 kernel/exit.c:940 do_group_exit+0x207/0x2c0 kernel/exit.c:1102 __do_sys_exit_group kernel/exit.c:1113 [inline] __se_sys_exit_group kernel/exit.c:1111 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1111 x64_sys_call+0x26c3/0x26d0 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc79298e969 Code: Unable to access opcode bytes at 0x7fc79298e93f. RSP: 002b:00007ffd6cd9b8a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc79298e969 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007ffd6cd9b90c R08: 000000046cd9b99f R09: 00000000000927c0 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000786 R13: 00000000000927c0 R14: 000000000017cc01 R15: 00007ffd6cd9b960