rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 1, t=10502 jiffies, g=14217, q=812446 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 9150 (4294961694-4294952544), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 9151 jiffies! g14217 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:27304 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x16e2/0x4cd0 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0x165/0x360 kernel/sched/core.c:6860 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2046 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2248 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x4b/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: 1 UID: 0 PID: 55 Comm: kworker/u9:0 Not tainted 6.15.0-rc4-syzkaller-00802-g075001c9eb41 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025 Workqueue: hci4 hci_conn_timeout RIP: 0010:__read_once_word_nocheck+0x3/0x10 include/asm-generic/rwonce.h:67 Code: af 00 48 ba 00 00 00 00 00 fc ff df e9 88 fc ff ff 66 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 48 8b 07 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc90000a07cf8 EFLAGS: 00000202 RAX: ffffc9000121fd10 RBX: ffffc90001218000 RCX: 0000000000000001 RDX: ffffc90000a07e68 RSI: dffffc0000000000 RDI: ffffc9000121fb10 RBP: 1ffff92000140fc5 R08: ffffc9000121fb10 R09: 0000000000000000 R10: ffffc90000a07e78 R11: fffff52000140fd1 R12: 1ffff92000140fc6 R13: 1ffff92000140fc7 R14: ffffc90001220000 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8881261c1000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffda0e8f87c CR3: 000000007e086000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: deref_stack_reg+0x19f/0x230 arch/x86/kernel/unwind_orc.c:406 unwind_next_frame+0x17c4/0x2390 arch/x86/kernel/unwind_orc.c:-1 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2398 [inline] slab_free mm/slub.c:4656 [inline] kmem_cache_free+0x192/0x3f0 mm/slub.c:4758 nft_synproxy_eval_v4+0x376/0x560 net/netfilter/nft_synproxy.c:60 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:154 [inline] nf_hook_slow+0xc2/0x220 net/netfilter/core.c:626 nf_hook include/linux/netfilter.h:269 [inline] NF_HOOK+0x206/0x3a0 include/linux/netfilter.h:312 NF_HOOK+0x309/0x3a0 include/linux/netfilter.h:314 __netif_receive_skb_one_core net/core/dev.c:5941 [inline] __netif_receive_skb+0x143/0x380 net/core/dev.c:6054 process_backlog+0x60e/0x14f0 net/core/dev.c:6406 __napi_poll+0xc4/0x480 net/core/dev.c:7378 napi_poll net/core/dev.c:7442 [inline] net_rx_action+0x6ea/0xdf0 net/core/dev.c:7564 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: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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0xa8/0x110 kernel/locking/spinlock.c:194 Code: 74 05 e8 0b b3 6d f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 f3 34 37 f6 65 8b 05 5c 65 1c 07 85 c0 74 40 48 c7 04 24 0e 36 RSP: 0018:ffffc9000121f7a0 EFLAGS: 00000206 RAX: 35614412ba8c7c00 RBX: 0000000000000a02 RCX: 35614412ba8c7c00 RDX: 0000000000000007 RSI: ffffffff8d74f6c2 RDI: 0000000000000001 RBP: ffffc9000121f820 R08: ffffffff8f7f2c77 R09: 1ffffffff1efe58e R10: dffffc0000000000 R11: fffffbfff1efe58f R12: dffffc0000000000 R13: ffff88807fd58000 R14: ffffffff99acd4c8 R15: 1ffff92000243ef4 __debug_check_no_obj_freed lib/debugobjects.c:1108 [inline] debug_check_no_obj_freed+0x451/0x470 lib/debugobjects.c:1129 free_pages_prepare mm/page_alloc.c:1265 [inline] __free_frozen_pages+0x403/0xce0 mm/page_alloc.c:2721 __slab_free+0x326/0x400 mm/slub.c:4567 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:329 kasan_slab_alloc include/linux/kasan.h:250 [inline] slab_post_alloc_hook mm/slub.c:4161 [inline] slab_alloc_node mm/slub.c:4210 [inline] __kmalloc_cache_noprof+0x1be/0x3d0 mm/slub.c:4367 kmalloc_noprof include/linux/slab.h:905 [inline] hci_cmd_sync_submit+0xcb/0x2b0 net/bluetooth/hci_sync.c:714 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xadb/0x17a0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245