rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5870/1:b..l
rcu: (detected by 0, t=10503 jiffies, g=63953, q=893472 ncpus=2)
task:syz-executor state:R running task stack:21832 pid:5870 tgid:5870 ppid:1 task_flags:0x40054c flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:5357 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7145
preempt_schedule+0xae/0xc0 kernel/sched/core.c:7169
preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
__raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:391 [inline]
zap_pte_range mm/memory.c:1756 [inline]
zap_pmd_range mm/memory.c:1818 [inline]
zap_pud_range mm/memory.c:1847 [inline]
zap_p4d_range mm/memory.c:1868 [inline]
unmap_page_range+0x3a79/0x4370 mm/memory.c:1889
unmap_single_vma mm/memory.c:1932 [inline]
unmap_vmas+0x399/0x580 mm/memory.c:1976
exit_mmap+0x248/0xb50 mm/mmap.c:1280
__mmput+0x118/0x420 kernel/fork.c:1130
exit_mm+0x1da/0x2c0 kernel/exit.c:582
do_exit+0x648/0x2300 kernel/exit.c:949
do_group_exit+0x21c/0x2d0 kernel/exit.c:1102
get_signal+0x1286/0x1340 kernel/signal.c:3034
arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:40
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd8c5fc14a5
RSP: 002b:00007ffc5f2ab4f0 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6
RAX: 0000000000000000 RBX: 00000000000003db RCX: 00007fd8c5fc14a5
RDX: 00007ffc5f2ab530 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffc5f2ab59c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 000000000000011e
R13: 0000000000000061 R14: 000000000008d52b R15: 00007ffc5f2ab5f0
rcu: rcu_preempt kthread starved for 3098 jiffies! g63953 f0x2 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:27224 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000
Call Trace:
context_switch kernel/sched/core.c:5357 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
__schedule_loop kernel/sched/core.c:7043 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7058
schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
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: 6192 Comm: kworker/u8:11 Not tainted 6.16.0-next-20250808-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:rcu_read_unlock include/linux/rcupdate.h:873 [inline]
RIP: 0010:class_rcu_destructor include/linux/rcupdate.h:1155 [inline]
RIP: 0010:unwind_next_frame+0x19a9/0x2390 arch/x86/kernel/unwind_orc.c:680
Code: 1a 0e 01 48 c7 c7 00 3f 88 8b be 66 03 00 00 48 c7 c2 a0 3f 88 8b e8 c6 ac 2a 00 48 c7 c7 e0 9e 13 8e 4c 89 fe e8 a7 92 2a 00 22 3d 34 00 89 d8 48 81 c4 98 00 00 00 5b 41 5c 41 5d 41 5e 41
RSP: 0018:ffffc90000a07118 EFLAGS: 00000282
RAX: ec4e18b985a83400 RBX: ffffffff90336301 RCX: ec4e18b985a83400
RDX: 000000000000000a RSI: ffffffff8dba97f4 RDI: ffffffff8be34700
RBP: dffffc0000000000 R08: ffffc90000a07238 R09: 0000000000000000
R10: ffffc90000a07298 R11: fffff52000140e55 R12: ffffc90000a07248
R13: ffffc90000a01000 R14: ffffc90000a07248 R15: ffffffff8172c195
FS: 0000000000000000(0000) GS:ffff888125d15000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc41bd3fd8 CR3: 000000000df36000 CR4: 00000000003526f0
Call Trace:
__unwind_start+0x5b9/0x760 arch/x86/kernel/unwind_orc.c:758
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0xe4/0x150 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:47
kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:548
__call_rcu_common kernel/rcu/tree.c:3123 [inline]
call_rcu+0x157/0x9c0 kernel/rcu/tree.c:3243
refdst_drop include/net/dst.h:263 [inline]
skb_dst_drop include/net/dst.h:275 [inline]
skb_release_head_state+0x71/0x250 net/core/skbuff.c:1135
skb_release_all net/core/skbuff.c:1149 [inline]
__kfree_skb net/core/skbuff.c:1165 [inline]
sk_skb_reason_drop+0xe9/0x170 net/core/skbuff.c:1203
kfree_skb_reason include/linux/skbuff.h:1275 [inline]
enqueue_to_backlog+0xbc/0xfa0 net/core/dev.c:5193
netif_rx_internal+0x130/0x560 net/core/dev.c:5491
__netif_rx+0x78/0xc0 net/core/dev.c:5511
loopback_xmit+0x47a/0x6f0 drivers/net/loopback.c:90
__netdev_start_xmit include/linux/netdevice.h:5219 [inline]
netdev_start_xmit include/linux/netdevice.h:5228 [inline]
xmit_one net/core/dev.c:3827 [inline]
dev_hard_start_xmit+0x2d4/0x830 net/core/dev.c:3843
sch_direct_xmit+0x241/0x4b0 net/sched/sch_generic.c:344
qdisc_restart net/sched/sch_generic.c:409 [inline]
__qdisc_run+0xb16/0x15f0 net/sched/sch_generic.c:417
__dev_xmit_skb net/core/dev.c:4171 [inline]
__dev_queue_xmit+0x1056/0x3b50 net/core/dev.c:4679
dev_queue_xmit include/linux/netdevice.h:3358 [inline]
neigh_hh_output include/net/neighbour.h:531 [inline]
neigh_output include/net/neighbour.h:545 [inline]
ip_finish_output2+0xd03/0x1160 net/ipv4/ip_output.c:235
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip_output+0x2a1/0x3c0 net/ipv4/ip_output.c:436
synproxy_send_client_synack+0x8bb/0xe20 net/netfilter/nf_synproxy_core.c:484
nft_synproxy_eval_v4+0x36e/0x560 net/netfilter/nft_synproxy.c:59
nft_synproxy_do_eval+0x345/0x570 net/netfilter/nft_synproxy.c:141
expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline]
nft_do_chain+0x409/0x1920 net/netfilter/nf_tables_core.c:285
nft_do_chain_inet+0x25d/0x340 net/netfilter/nft_chain_filter.c:161
nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
nf_hook_slow+0xc5/0x220 net/netfilter/core.c:623
nf_hook include/linux/netfilter.h:273 [inline]
NF_HOOK+0x206/0x3a0 include/linux/netfilter.h:316
NF_HOOK+0x309/0x3a0 include/linux/netfilter.h:318
__netif_receive_skb_one_core net/core/dev.c:5979 [inline]
__netif_receive_skb+0x143/0x380 net/core/dev.c:6092
process_backlog+0x60e/0x14f0 net/core/dev.c:6444
__napi_poll+0xc4/0x360 net/core/dev.c:7489
napi_poll net/core/dev.c:7552 [inline]
net_rx_action+0x707/0xe30 net/core/dev.c:7679
handle_softirqs+0x283/0x870 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1050
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xd33/0x12d0 kernel/smp.c:877
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 b6 62 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 61 5e 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 45 5e
RSP: 0018:ffffc9000afdf660 EFLAGS: 00000293
RAX: ffffffff81b4557b RBX: 1ffff110170c8341 RCX: ffff88801e379e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000afdf7e0 R08: ffffffff8fa39a37 R09: 1ffffffff1f47346
R10: dffffc0000000000 R11: fffffbfff1f47347 R12: ffff8880b8641a08
R13: dffffc0000000000 R14: ffff8880b873b1c0 R15: 0000000000000000
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1044
on_each_cpu include/linux/smp.h:71 [inline]
smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2653 [inline]
smp_text_poke_batch_finish+0x5f9/0x1130 arch/x86/kernel/alternative.c:2863
arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
static_key_enable_cpuslocked+0x128/0x250 kernel/jump_label.c:210
static_key_enable+0x1a/0x20 kernel/jump_label.c:223
toggle_allocation_gate+0xad/0x240 mm/kfence/core.c:850
process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245