rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P27490/3:b..l
rcu: (detected by 0, t=10502 jiffies, g=316225, q=795 ncpus=2)
task:kworker/u8:9 state:R running task stack:25800 pid:27490 tgid:27490 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: krds_cp_wq#6/5 rds_send_worker
Call Trace:
context_switch kernel/sched/core.c:5388 [inline]
__schedule+0x1295/0x67a0 kernel/sched/core.c:7189
preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7370
preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
__local_bh_enable_ip+0xff/0x120 kernel/softirq.c:457
local_bh_enable include/linux/bottom_half.h:33 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:912 [inline]
__dev_queue_xmit+0xa04/0x4950 net/core/dev.c:4905
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
neigh_resolve_output net/core/neighbour.c:1619 [inline]
neigh_resolve_output+0x51f/0x8f0 net/core/neighbour.c:1599
neigh_output include/net/neighbour.h:560 [inline]
ip6_finish_output2+0xb0f/0x1ce0 net/ipv6/ip6_output.c:136
__ip6_finish_output+0x357/0xdf0 net/ipv6/ip6_output.c:208
ip6_finish_output net/ipv6/ip6_output.c:219 [inline]
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x2aa/0xa60 net/ipv6/ip6_output.c:246
dst_output include/net/dst.h:470 [inline]
NF_HOOK include/linux/netfilter.h:318 [inline]
NF_HOOK include/linux/netfilter.h:312 [inline]
ip6_xmit+0x1006/0x24a0 net/ipv6/ip6_output.c:379
inet6_csk_xmit+0x387/0x760 net/ipv6/inet6_connection_sock.c:115
__tcp_transmit_skb+0x1fab/0x4f10 net/ipv4/tcp_output.c:1715
__tcp_send_ack.part.0+0x4db/0x940 net/ipv4/tcp_output.c:4500
__tcp_send_ack net/ipv4/tcp_output.c:4506 [inline]
tcp_send_ack+0x84/0xa0 net/ipv4/tcp_output.c:4506
tcp_validate_incoming+0x1513/0x2530 net/ipv4/tcp_input.c:6347
tcp_rcv_established+0x628/0x3910 net/ipv4/tcp_input.c:6639
tcp_v6_do_rcv+0x1129/0x1ff0 net/ipv6/tcp_ipv6.c:1610
sk_backlog_rcv include/net/sock.h:1190 [inline]
__release_sock+0x151/0x440 net/core/sock.c:3216
release_sock+0x1e5/0x280 net/core/sock.c:3815
rds_send_xmit+0x3bd/0x2950 net/rds/send.c:244
rds_send_worker+0x94/0x320 net/rds/threads.c:200
process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314
process_scheduled_works kernel/workqueue.c:3397 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478
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: rcu_preempt kthread starved for 7019 jiffies! g316225 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:27848 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5388 [inline]
__schedule+0x1295/0x67a0 kernel/sched/core.c:7189
__schedule_loop kernel/sched/core.c:7268 [inline]
schedule+0xdd/0x390 kernel/sched/core.c:7283
schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095
rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297
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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:rcu_is_watching+0x80/0xc0 kernel/rcu/tree.c:753
Code: 89 da 48 c1 ea 03 0f b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 24 8b 03 c1 e8 02 83 e0 01 65 ff 0d 00 fd 1c 12 <74> 07 5b 5d c3 cc cc cc cc e8 12 e7 88 ff 5b 5d e9 9b a9 9f 09 48
RSP: 0018:ffffc90000a08130 EFLAGS: 00000282
RAX: 0000000000000001 RBX: ffff8880b8533da8 RCX: 0000000000000003
RDX: 0000000000000000 RSI: ffffffff8c1c4400 RDI: ffffffff8e1c1928
RBP: 0000000000000001 R08: 000000005970cd9e R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000000000 R12: ffffffff81f2d470
R13: ffffc90000a081b8 R14: 0000000000000000 R15: ffff88801e2f2540
FS: 0000000000000000(0000) GS:ffff888124483000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fab1e2449e3 CR3: 000000007633d000 CR4: 00000000003526f0
Call Trace:
rcu_read_lock include/linux/rcupdate.h:839 [inline]
class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
unwind_next_frame+0x6fa/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:2689 [inline]
slab_free mm/slub.c:6251 [inline]
kmem_cache_free+0x127/0x6c0 mm/slub.c:6378
kfree_skbmem+0x19a/0x210 net/core/skbuff.c:1137
__kfree_skb net/core/skbuff.c:1204 [inline]
consume_skb net/core/skbuff.c:1436 [inline]
consume_skb+0xd1/0x110 net/core/skbuff.c:1430
nft_synproxy_eval_v6 net/netfilter/nft_synproxy.c:92 [inline]
nft_synproxy_do_eval+0x940/0xd50 net/netfilter/nft_synproxy.c:146
expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
nft_do_chain+0x2e5/0x1990 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]
ip6_input+0xe0/0x2f0 net/ipv6/ip6_input.c:545
dst_input include/net/dst.h:480 [inline]
ip6_rcv_finish net/ipv6/ip6_input.c:119 [inline]
NF_HOOK include/linux/netfilter.h:318 [inline]
NF_HOOK include/linux/netfilter.h:312 [inline]
ipv6_rcv+0x263/0x3d0 net/ipv6/ip6_input.c:351
__netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:6202
__netif_receive_skb+0x1f/0x120 net/core/dev.c:6315
process_backlog+0x37a/0x1580 net/core/dev.c:6666
__napi_poll.constprop.0+0xaf/0x450 net/core/dev.c:7733
napi_poll net/core/dev.c:7796 [inline]
net_rx_action+0xa40/0xf20 net/core/dev.c:7953
handle_softirqs+0x1ea/0xa00 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x162/0x210 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+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
Code: e5 92 02 c3 cc cc cc cc 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 83 41 22 00 fb f4 fc 43 03 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffc90000197df0 EFLAGS: 00000246
RAX: 0000000006cc1bcf RBX: ffff88801e2f2540 RCX: ffffffff8b895285
RDX: 0000000000000000 RSI: ffffffff8df0f560 RDI: ffffffff8c1c4480
RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed10170a67b5
R10: ffff8880b8533dab R11: 0000000000000000 R12: 0000000000000001
R13: ffffed1003c5e4a8 R14: 0000000000000001 R15: ffffffff90d70d50
arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline]
default_idle+0x9/0x10 arch/x86/kernel/process.c:767
default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:199 [inline]
do_idle+0x464/0x590 kernel/sched/idle.c:352
cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:451
start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312
common_startup_64+0x13e/0x148