rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 0, t=10502 jiffies, g=7721, q=253 ncpus=2) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294957617-4294947114), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10504 jiffies! g7721 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:26888 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 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7288 irqentry_exit+0x6f/0x90 kernel/entry/common.c:197 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:100 Code: 18 af 81 31 d2 48 c7 c1 e0 f8 ac 8b 49 c7 c0 40 53 f5 99 e8 b7 76 25 f6 48 89 5c 24 30 4c 89 f7 e8 da 8a 25 f6 e8 25 a7 fe ff <4c> 89 f7 e8 4d 9a 25 f6 4c 89 f7 e8 b5 77 25 f6 43 80 7c 3d 00 00 RSP: 0018:ffffc90000157a40 EFLAGS: 00010246 RAX: 0000000000208040 RBX: 00000000ffffb12b RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8c04e5e0 RDI: 00000000ffffffff RBP: ffffc90000157b30 R08: ffffffff8fe52d37 R09: 1ffffffff1fca5a6 R10: dffffc0000000000 R11: fffffbfff1fca5a7 R12: 1ffff9200002af48 R13: 1ffffffff1c42240 R14: ffffc90000157a60 R15: dffffc0000000000 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+0x47c/0x820 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: 51 Comm: kworker/u9:0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Workqueue: hci0 hci_cmd_work RIP: 0010:sched_clock_cpu+0xac/0x430 kernel/sched/clock.c:412 Code: e0 45 4b c7 04 2f 00 00 00 00 65 48 8b 0d cc db 4a 11 48 3b 8c 24 80 00 00 00 75 14 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d cc cc cc cc cc e8 79 3c eb 09 f3 0f 1e fa 0f 1f 44 00 00 41 89 RSP: 0018:ffffc90000a08fb8 EFLAGS: 00000046 RAX: 0000002fcc807584 RBX: ffff8880b8723e58 RCX: a10d368a7f137500 RDX: 0000000000010000 RSI: 0000000000000000 RDI: 0000000000000002 RBP: 0000000000010000 R08: ffffffff8fe52d37 R09: 1ffffffff1fca5a6 R10: dffffc0000000000 R11: ffffc90000a08ff8 R12: dffffc0000000000 R13: 0000000000000000 R14: ffff88801a970000 R15: ffffffff8dec1dd8 FS: 0000000000000000(0000) GS:ffff8881258c4000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000058 CR3: 0000000028832000 CR4: 00000000003526f0 Call Trace: irqtime_account_irq+0x6e/0x1c0 kernel/sched/cputime.c:67 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0x99/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:finish_task_switch+0x26b/0x950 kernel/sched/core.c:5225 Code: 0f 84 3c 01 00 00 48 85 db 0f 85 63 01 00 00 0f 1f 44 00 00 4c 8b 75 d0 4c 89 e7 e8 0f 78 f6 09 e8 2a 3a 36 00 fb 4c 8b 65 c0 <49> 8d bc 24 18 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0 RSP: 0018:ffffc90000bb70f8 EFLAGS: 00000282 RAX: a10d368a7f137500 RBX: 0000000000000000 RCX: a10d368a7f137500 RDX: 0000000000000000 RSI: ffffffff8c04e5e0 RDI: ffffffff81923f56 RBP: ffffc90000bb7150 R08: ffffffff8fe52d37 R09: 1ffffffff1fca5a6 R10: dffffc0000000000 R11: fffffbfff1fca5a7 R12: ffff88801a970000 R13: dffffc0000000000 R14: ffff88803078da00 R15: ffff8880b873ab58 context_switch kernel/sched/core.c:5360 [inline] __schedule+0x17a0/0x4cc0 kernel/sched/core.c:6961 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7288 irqentry_exit+0x6f/0x90 kernel/entry/common.c:197 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:deref_stack_reg+0x3/0x230 arch/x86/kernel/unwind_orc.c:402 Code: e8 52 71 b0 00 48 8b 4c 24 18 e9 f2 fe ff ff 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 <41> 56 41 55 41 54 53 48 83 ec 20 48 89 54 24 18 49 89 f0 49 89 ff RSP: 0018:ffffc90000bb74e0 EFLAGS: 00000287 RAX: fffffffffffffff0 RBX: ffffffff9075dbc6 RCX: 0000000000000000 RDX: ffffc90000bb7668 RSI: ffffc90000bb7618 RDI: ffffc90000bb7628 RBP: dffffc0000000000 R08: ffffc90000bb7687 R09: 0000000000000000 R10: ffffc90000bb7678 R11: fffff52000176ed1 R12: ffffc90000bb7618 R13: ffffc90000bb7678 R14: ffffc90000bb7628 R15: 1ffffffff20ebb79 unwind_next_frame+0x17c4/0x2390 arch/x86/kernel/unwind_orc.c:-1 __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 mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587 kasan_save_free_info mm/kasan/kasan.h:406 [inline] poison_slab_object mm/kasan/common.c:252 [inline] __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:284 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2417 [inline] slab_free mm/slub.c:4680 [inline] kmem_cache_free+0x18f/0x400 mm/slub.c:4782 kfree_skb_reason include/linux/skbuff.h:1316 [inline] kfree_skb include/linux/skbuff.h:1325 [inline] hci_send_cmd_sync net/bluetooth/hci_core.c:4118 [inline] hci_cmd_work+0xd4/0x6e0 net/bluetooth/hci_core.c:4157 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245