rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-....: (1 ticks this GP) idle=680c/1/0x4000000000000000 softirq=16723/16723 fqs=303 rcu: hardirqs softirqs csw/system rcu: number: 0 0 0 rcu: cputime: 0 0 0 ==> 39750(ms) rcu: (detected by 1, t=10506 jiffies, g=14769, q=1400 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 5748 Comm: kworker/0:5 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 Workqueue: events_power_efficient gc_worker RIP: 0010:check_wait_context kernel/locking/lockdep.c:4914 [inline] RIP: 0010:__lock_acquire+0x529/0x2de0 kernel/locking/lockdep.c:5238 Code: 45 89 e7 41 81 e7 ff ff ff 7f 83 f9 31 73 1d 4b 8d 0c bf 41 8b 8c ce d0 0b 00 00 31 c1 ff cb 49 ff cc f7 c1 00 60 00 00 74 cf 18 48 c7 c7 f0 ab c2 8e 4c 89 fe e8 96 49 79 03 48 8b 45 20 eb RSP: 0018:ffffc90000007bc8 EFLAGS: 00000006 RAX: 26000000000c4072 RBX: 0000000000000003 RCX: 00000000000e4075 RDX: 0000000000000002 RSI: 0000000000004000 RDI: 2600000000000000 RBP: ffff8880207f8c28 R08: ffffffff81b43696 R09: 0000000000000001 R10: dffffc0000000000 R11: fffffbfff20f4950 R12: 0000000000000001 R13: 0000000000000000 R14: ffff8880207f8000 R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffff888124cca000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00002000000012c0 CR3: 000000007080e000 CR4: 00000000003526f0 Call Trace: lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:165 [inline] _raw_spin_lock_irq+0x3d/0x50 kernel/locking/spinlock.c:189 __run_hrtimer kernel/time/hrtimer.c:2078 [inline] __hrtimer_run_queues+0x466/0xa10 kernel/time/hrtimer.c:2131 hrtimer_interrupt+0x4cd/0xaa0 kernel/time/hrtimer.c:2250 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_acquire+0x232/0x350 kernel/locking/lockdep.c:5947 Code: ff ff ff e8 50 15 43 0a f7 44 24 10 00 02 00 00 0f 84 38 ff ff ff 65 48 8b 05 a2 30 f2 11 48 3b 44 24 50 75 33 fb 48 83 c4 58 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 bf 19 46 0a cc 48 8d 3d 97 54 da RSP: 0018:ffffc90004547940 EFLAGS: 00000292 RAX: 395269ab2cf8bc00 RBX: 0000000000000000 RCX: 0000000000000046 RDX: 00000000d03bb34f RSI: ffffffff8e69c415 RDI: ffffffff8c6da080 RBP: ffff8880207f8000 R08: ffffffff8a01b494 R09: 0000000000000000 R10: dffffc0000000000 R11: fffffbfff20f4950 R12: ffffffff8ed5c8e0 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:309 [inline] rcu_read_lock include/linux/rcupdate.h:849 [inline] gc_worker+0x298/0x1890 net/netfilter/nf_conntrack_core.c:1532 process_one_work kernel/workqueue.c:3396 [inline] process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560 kthread+0x38b/0x480 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: rcu_preempt kthread starved for 3920 jiffies! g14769 f0x0 RCU_GP_WAIT_FQS(5) ->state=R ->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:27496 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x17db/0x58f0 kernel/sched/core.c:7277 __schedule_loop kernel/sched/core.c:7354 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7369 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2330 kthread+0x38b/0x480 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: CPU: 1 UID: 0 PID: 5279 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 RIP: 0010:csd_lock_wait kernel/smp.c:363 [inline] RIP: 0010:csd_lock kernel/smp.c:396 [inline] RIP: 0010:smp_call_function_many_cond+0x61e/0x1500 kernel/smp.c:944 Code: b6 04 04 84 c0 0f 85 d5 03 00 00 44 8b 3b 44 89 fe 83 e6 01 31 ff e8 31 56 0c 00 41 83 e7 01 75 07 e8 26 51 0c 00 eb 3f f3 90 <48> b8 00 00 00 00 00 fc ff df 41 0f b6 04 04 84 c0 75 0f f7 03 01 RSP: 0018:ffffc900034b7420 EFLAGS: 00000293 RAX: ffffffff81bb817e RBX: ffff8880b8643708 RCX: ffff88802f879f40 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900034b7570 R08: ffff88802f87b4df R09: 1ffff11005f0f69b R10: dffffc0000000000 R11: 0000000000000000 R12: 1ffff110170c86e1 R13: 0000000000000000 R14: ffff8880b8643700 R15: 0000000000000001 FS: 00007f541f243780(0000) GS:ffff888124dca000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4d93427da0 CR3: 00000000776fa000 CR4: 00000000003526f0 Call Trace: __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x8ff/0x1090 arch/x86/mm/tlb.c:1435 dup_mmap+0x1758/0x1dc0 mm/mmap.c:1884 dup_mm kernel/fork.c:1543 [inline] copy_mm+0x11a/0x480 kernel/fork.c:1595 copy_process+0x1e75/0x43e0 kernel/fork.c:2310 kernel_clone+0x2d7/0x940 kernel/fork.c:2769 __do_sys_clone kernel/fork.c:2911 [inline] __se_sys_clone kernel/fork.c:2895 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2895 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f541f317636 Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffe0233f720 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffe0233f728 RCX: 00007f541f317636 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffe0235fc70 R08: 0000000000000000 R09: 0000000000000001 R10: 00007f541f243a50 R11: 0000000000000246 R12: 00007ffe0233f860 R13: 0000000000000000 R14: 0000000000000000 R15: 000055fa18e9bac0