rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=5b7c/1/0x4000000000000000 softirq=16191/16193 fqs=1 rcu: (detected by 0, t=10513 jiffies, g=8721, q=1532 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6044 Comm: kworker/1:6 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: events_power_efficient gc_worker RIP: 0010:lockdep_recursion_finish kernel/locking/lockdep.c:470 [inline] RIP: 0010:lock_is_held_type+0xdf/0x150 kernel/locking/lockdep.c:5941 Code: bd 01 00 00 00 41 83 fe ff 74 13 31 c0 f6 43 22 03 0f 95 c0 45 31 ed 44 39 f0 41 0f 94 c5 48 c7 c7 1d 8a aa 8d e8 91 18 00 00 ff ff ff ff 65 0f c1 05 5c b0 3a 08 83 f8 01 75 2d 9c 58 f6 c4 RSP: 0018:ffffc90000a08d50 EFLAGS: 00000096 RAX: 0000000000000001 RBX: ffff8880324c5528 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffffffff8daa8a1d RDI: ffffffff8bf2b480 RBP: ffff888027f572c0 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: ffff8880324c54b0 R12: ffff8880324c4980 R13: 0000000000000001 R14: 00000000ffffffff R15: 0000000000000003 FS: 0000000000000000(0000) GS:ffff8881249f4000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9c5ddb6000 CR3: 000000005a78a000 CR4: 00000000003526f0 Call Trace: lock_is_held include/linux/lockdep.h:249 [inline] advance_sched+0x7b1/0xc80 net/sched/sch_taprio.c:933 __run_hrtimer kernel/time/hrtimer.c:1777 [inline] __hrtimer_run_queues+0x202/0xc40 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x10b/0x3c0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:__seqprop_spinlock_sequence include/linux/seqlock.h:227 [inline] RIP: 0010:nf_conntrack_get_ht include/net/netfilter/nf_conntrack.h:342 [inline] RIP: 0010:gc_worker+0x2d5/0x16e0 net/netfilter/nf_conntrack_core.c:1548 Code: 00 00 48 c7 c7 a8 6a 89 90 e8 b7 c0 05 f8 9c 5b 81 e3 00 02 00 00 31 ff 48 89 de e8 85 b1 2a f8 58 48 85 db 0f 85 d4 0f 00 00 a6 b6 2a f8 8b 1d 70 25 f5 06 41 89 dc 31 ff 41 83 e4 01 44 89 RSP: 0018:ffffc90003147ad8 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff89945069 RDX: ffff8880324c4980 RSI: ffffffff89945078 RDI: 0000000000000007 RBP: ffffffff9b0a48ec R08: 0000000000000007 R09: 0000000000000000 R10: 0000000000000000 R11: ffff8880324c54b0 R12: ffff888031600000 R13: 0000000000040000 R14: dffffc0000000000 R15: 0000000000001770 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257 process_scheduled_works kernel/workqueue.c:3340 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: rcu_preempt kthread starved for 10455 jiffies! g8721 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 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:28552 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6960 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 6127 Comm: syz.3.20 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xe02/0x15e0 kernel/smp.c:877 Code: 10 4c 89 74 24 10 49 89 d5 48 89 d5 48 89 54 24 18 49 c1 ed 03 83 e5 07 4d 01 e5 83 c5 03 e8 45 5f 0c 00 f3 90 41 0f b6 45 00 <40> 38 c5 7c 08 84 c0 0f 85 b6 05 00 00 8b 43 08 31 ff 83 e0 01 41 RSP: 0018:ffffc90002e676d0 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b8540cc0 RCX: ffffffff81b29cb1 RDX: ffff8880258dc980 RSI: ffffffff81b29c8b RDI: 0000000000000005 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: ffff8880258dd4b0 R12: dffffc0000000000 R13: ffffed10170a8199 R14: 0000000000000001 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8881248f4000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f21901b7e68 CR3: 000000000e184000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1043 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1382 [inline] flush_tlb_mm_range+0x2f0/0x12c0 arch/x86/mm/tlb.c:1472 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:490 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:480 [inline] tlb_flush_mmu mm/mmu_gather.c:403 [inline] tlb_finish_mmu+0x3c9/0x7c0 mm/mmu_gather.c:497 exit_mmap+0x3f9/0xb60 mm/mmap.c:1290 __mmput+0x12a/0x410 kernel/fork.c:1173 mmput+0x62/0x70 kernel/fork.c:1196 exit_mm kernel/exit.c:581 [inline] do_exit+0x7d7/0x2bd0 kernel/exit.c:959 do_group_exit+0xd3/0x2a0 kernel/exit.c:1112 get_signal+0x2671/0x26d0 kernel/signal.c:3034 arch_do_signal_or_restart+0x8f/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline] exit_to_user_mode_loop+0x8c/0x540 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x4ee/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fec75d8f749 Code: Unable to access opcode bytes at 0x7fec75d8f71f. RSP: 002b:00007ffd3eaa4268 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007fec75fe7da0 RCX: 00007fec75d8f749 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007fec75fe7da0 R08: 0000000000000000 R09: 000000043eaa455f R10: 000000000003fdc0 R11: 0000000000000246 R12: 000000000001b76e R13: 00007ffd3eaa4360 R14: ffffffffffffffff R15: 00007ffd3eaa4380