rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=8b44/1/0x4000000000000000 softirq=79658/79659 fqs=1 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5934/1:b..l rcu: (detected by 0, t=10506 jiffies, g=87893, q=580 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 15965 Comm: udevd Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:__raw_spin_unlock include/linux/spinlock_api_smp.h:169 [inline] RIP: 0010:_raw_spin_unlock+0x23/0x50 kernel/locking/spinlock.c:190 Code: 90 90 90 90 90 90 90 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 7a 70 f7 f5 48 89 df e8 82 e5 f7 f5 bf 01 00 00 00 e8 67 e9 f5 65 8b 05 71 51 8e 07 85 c0 74 07 5b e9 42 e2 65 f5 RSP: 0018:ffffc90000a08d00 EFLAGS: 00000046 RAX: 0000000000000001 RBX: ffff888079d422a8 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000001 RBP: dffffc0000000000 R08: ffff888079d422ab R09: 1ffff1100f3a8455 R10: dffffc0000000000 R11: ffffed100f3a8456 R12: ffff88807d1c3000 R13: ffff888079d42000 R14: ffff88807d1c2000 R15: 18aa01920519c93a FS: 00007faf99802880(0000) GS:ffff888125395000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffcd65b3d1c CR3: 00000000977f3000 CR4: 0000000000350ef0 Call Trace: spin_unlock include/linux/spinlock.h:390 [inline] advance_sched+0x94f/0xc20 net/sched/sch_taprio.c:988 __run_hrtimer kernel/time/hrtimer.c:1930 [inline] __hrtimer_run_queues+0x3c0/0xa20 kernel/time/hrtimer.c:1994 hrtimer_interrupt+0x44b/0x950 kernel/time/hrtimer.c:2113 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1067 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1061 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:sock_sendmsg_nosec net/socket.c:787 [inline] RIP: 0010:__sock_sendmsg net/socket.c:802 [inline] RIP: 0010:sock_write_iter+0x304/0x4f0 net/socket.c:1254 Code: 38 00 74 08 48 89 df e8 1a 9e be f8 41 bf 90 00 00 00 4c 03 3b 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 <74> 08 4c 89 ff e8 f2 9d be f8 4d 8b 3f 49 81 ff 10 71 4f 8a 0f 85 RSP: 0018:ffffc900066ffb60 EFLAGS: 00000246 RAX: 1ffffffff19d879a RBX: ffff888035d37260 RCX: dffffc0000000000 RDX: ffff88801d7d9ec0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc900066ffc90 R08: ffff88801d7d9ec0 R09: 0000000000000003 R10: 000000000000000a R11: 0000000000000000 R12: 1ffff92000cdff70 R13: ffffc900066ffba0 R14: ffff888035d37240 R15: ffffffff8cec3cd0 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x61d/0xb90 fs/read_write.c:688 ksys_write+0x150/0x270 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7faf990a7407 Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff RSP: 002b:00007ffcd65b66f0 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007faf99802880 RCX: 00007faf990a7407 RDX: 0000000000000000 RSI: 00007ffcd65b6797 RDI: 000000000000000a RBP: 000000000000000a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007faf998026e8 R13: 0000000000000000 R14: 0000000000000000 R15: 0000560737195bb0 task:kworker/1:7 state:R running task stack:22560 pid:5934 tgid:5934 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: events_power_efficient gc_worker Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x17b4/0x5680 kernel/sched/core.c:7188 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7512 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline] irqentry_exit+0x14f/0x730 kernel/entry/common.c:164 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:seqcount_lockdep_reader_access+0xed/0x100 include/linux/seqlock.h:76 Code: 00 75 11 e8 45 27 fb f7 4d 85 f6 75 16 e8 3b 27 fb f7 eb 15 e8 34 27 fb f7 e8 9f 38 dd 01 4d 85 f6 74 ea e8 25 27 fb f7 fb 5b <41> 5e e9 77 c4 45 f7 cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 RSP: 0018:ffffc9000582f970 EFLAGS: 00000293 RAX: ffffffff89ca7c8b RBX: 0000000000000001 RCX: ffff888032ca8000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc9000582fad0 R08: ffffffff903096f7 R09: 1ffffffff20612de R10: dffffc0000000000 R11: fffffbfff20612df R12: dffffc0000000000 R13: ffffffff9a94a720 R14: 0000000000000200 R15: 000000000001c563 nf_conntrack_get_ht include/net/netfilter/nf_conntrack.h:343 [inline] gc_worker+0x304/0x1290 net/netfilter/nf_conntrack_core.c:1545 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466 kthread+0x388/0x470 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 10500 jiffies! g87893 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:27536 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x17b4/0x5680 kernel/sched/core.c:7188 __schedule_loop kernel/sched/core.c:7267 [inline] schedule+0x164/0x360 kernel/sched/core.c:7282 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297 kthread+0x388/0x470 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: 0 UID: 0 PID: 6830 Comm: syz-executor Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xfd4/0x13d0 kernel/smp.c:892 Code: 89 ee 83 e6 01 31 ff e8 fa fc 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 a5 f8 0b 00 eb 37 f3 90 43 0f b6 04 2c <84> c0 75 10 41 f7 06 01 00 00 00 74 1e e8 8a f8 0b 00 eb e5 44 89 RSP: 0018:ffffc90004587560 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b863c148 RCX: ffff888024fb3d80 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90004587688 R08: ffffffff903096f7 R09: 1ffffffff20612de R10: dffffc0000000000 R11: fffffbfff20612df R12: 1ffff110170e8169 R13: dffffc0000000000 R14: ffff8880b8740b48 R15: 0000000000000001 FS: 0000555595066500(0000) GS:ffff888125295000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000002 CR3: 0000000029be4000 CR4: 0000000000350ef0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057 __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+0x5c3/0x10b0 arch/x86/mm/tlb.c:1451 dup_mmap+0x17a2/0x1d90 mm/mmap.c:1905 dup_mm kernel/fork.c:1534 [inline] copy_mm+0x13b/0x4a0 kernel/fork.c:1586 copy_process+0x1f1c/0x4450 kernel/fork.c:2262 kernel_clone+0x284/0x8f0 kernel/fork.c:2723 __do_sys_clone kernel/fork.c:2864 [inline] __se_sys_clone kernel/fork.c:2848 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2848 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f90369c5852 Code: 89 e7 e8 71 8b f7 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 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffc6983b460 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffc6983b460 RCX: 00007f90369c5852 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffc6983b5ec R08: 0000000000000000 R09: 0000000000000001 R10: 00005555950667d0 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000000927c0 R14: 0000000000113011 R15: 00007ffc6983b640