rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P7654/1:b..l
rcu: (detected by 0, t=10503 jiffies, g=35253, q=1499 ncpus=2)
task:syz.4.455 state:R running task stack:24912 pid:7654 tgid:7641 ppid:5646 task_flags:0x400040 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5388 [inline]
__schedule+0x1840/0x57a0 kernel/sched/core.c:7189
preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7370
preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
__local_bh_enable_ip+0xe1/0x130 kernel/softirq.c:457
local_bh_enable include/linux/bottom_half.h:33 [inline]
ipt_do_table+0x137f/0x15d0 net/ipv4/netfilter/ip_tables.c:357
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
__ip_local_out+0x558/0x6a0 net/ipv4/ip_output.c:120
ip_local_out+0x2a/0x190 net/ipv4/ip_output.c:129
ip_send_skb+0x45/0xc0 net/ipv4/ip_output.c:1510
udp_send_skb+0x7f7/0xfb0 net/ipv4/udp.c:1161
udp_sendmsg+0x1971/0x2140 net/ipv4/udp.c:1443
sock_sendmsg_nosec net/socket.c:788 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x853/0xa20 net/socket.c:2699
___sys_sendmsg+0x2a5/0x360 net/socket.c:2753
__sys_sendmmsg+0x27c/0x4e0 net/socket.c:2842
__do_sys_sendmmsg net/socket.c:2869 [inline]
__se_sys_sendmmsg net/socket.c:2866 [inline]
__x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2866
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: 0033:0x7f5a3659ce59
RSP: 002b:00007f5a37395028 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f5a36816270 RCX: 00007f5a3659ce59
RDX: 000000000800001d RSI: 0000200000007fc0 RDI: 0000000000000003
RBP: 00007f5a36632d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000300 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5a36816308 R14: 00007f5a36816270 R15: 00007f5a3693fa48
rcu: rcu_preempt kthread starved for 805 jiffies! g35253 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
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:5388 [inline]
__schedule+0x1840/0x57a0 kernel/sched/core.c:7189
__schedule_loop kernel/sched/core.c:7268 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7283
schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2095
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297
kthread+0x389/0x470 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 2 Comm: kthreadd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:kmem_cache_alloc_node_noprof+0x38/0x680 mm/slub.c:-1
Code: 48 83 ec 40 89 d3 89 f5 49 89 fe 65 48 8b 05 2f 92 11 11 48 89 44 24 38 48 8b 44 24 70 48 89 44 24 20 8b 47 1c 48 89 44 24 18 <44> 8b 3d 81 b1 0a 0e 41 21 f7 44 89 ff e8 76 81 fd ff 44 89 ff e8
RSP: 0018:ffffc90000a081e0 EFLAGS: 00000282
RAX: 00000000000002c0 RBX: 00000000ffffffff RCX: 0000000000000100
RDX: 00000000ffffffff RSI: 0000000000082820 RDI: ffff888140ec0a00
RBP: 0000000000082820 R08: ffff8880920e3707 R09: 0000000000000000
R10: ffff8880920e36c0 R11: ffffed101241c6e1 R12: 0000000000000180
R13: 0000000000000000 R14: ffff888140ec0a00 R15: 00000000ffffffff
FS: 0000000000000000(0000) GS:ffff8881253b9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000001aa030 CR3: 0000000025a1c000 CR4: 00000000003526f0
Call Trace:
kmalloc_reserve net/core/skbuff.c:613 [inline]
__alloc_skb+0x276/0x7a0 net/core/skbuff.c:713
alloc_skb include/linux/skbuff.h:1385 [inline]
synproxy_send_client_synack_ipv6+0x16e/0xcd0 net/netfilter/nf_synproxy_core.c:883
nft_synproxy_eval_v6+0x37b/0x530 net/netfilter/nft_synproxy.c:91
nft_synproxy_do_eval+0x3d1/0x550 net/netfilter/nft_synproxy.c:146
expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
nft_do_chain+0x48d/0x1ad0 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
ip6_input+0x16a/0x270 net/ipv6/ip6_input.c:545
NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318
__netif_receive_skb_one_core net/core/dev.c:6202 [inline]
__netif_receive_skb net/core/dev.c:6315 [inline]
process_backlog+0x774/0x1860 net/core/dev.c:6666
__napi_poll+0xaa/0x330 net/core/dev.c:7733
napi_poll net/core/dev.c:7796 [inline]
net_rx_action+0x61d/0xf50 net/core/dev.c:7953
handle_softirqs+0x225/0x840 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:arch_try_cmpxchg128 arch/x86/include/asm/cmpxchg_64.h:83 [inline]
RIP: 0010:__update_freelist_fast mm/slub.c:641 [inline]
RIP: 0010:slab_update_freelist mm/slub.c:707 [inline]
RIP: 0010:__slab_free+0xbd/0x2c0 mm/slub.c:5564
Code: 44 24 04 74 45 85 c0 74 41 45 31 e4 41 f6 46 0a 20 74 66 48 8b 44 24 40 48 8b 54 24 48 48 89 de 48 8b 5c 24 30 48 8b 4c 24 38 48 0f c7 4e 20 48 89 f3 0f 84 e8 00 00 00 48 89 44 24 40 48 89
RSP: 0018:ffffc90000077770 EFLAGS: 00000202
RAX: ffff888093c8a3c0 RBX: ffff888093c8a080 RCX: 000000080013000a
RDX: 000000080013000b RSI: ffffea00024f2200 RDI: ffff888140ec0a00
RBP: ffffc900000777f8 R08: 0000000000000000 R09: ffffffff82308fce
R10: dffffc0000000000 R11: ffffed10170e81f1 R12: 0000000000000000
R13: ffff888093c8a3c0 R14: ffff888140ec0a00 R15: 0000000000000000
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4570 [inline]
slab_alloc_node mm/slub.c:4899 [inline]
kmem_cache_alloc_noprof+0x2b8/0x650 mm/slub.c:4906
copy_sighand+0x50/0x220 kernel/fork.c:1655
copy_process+0x1d0d/0x4380 kernel/fork.c:2258
kernel_clone+0x2d7/0x940 kernel/fork.c:2722
kernel_thread+0x13f/0x1b0 kernel/fork.c:2783
create_kthread kernel/kthread.c:459 [inline]
kthreadd+0x4ec/0x6e0 kernel/kthread.c:817
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245