rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=ae7/1/0x4000000000000000 softirq=8861/8862 fqs=466 (detected by 1, t=10502 jiffies, g=9981, q=323) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 4916 Comm: syz.0.17 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:enqueue_hrtimer+0x1a8/0x370 kernel/time/hrtimer.c:1077 Code: 04 20 84 c0 0f 85 ba 00 00 00 c6 43 38 01 49 83 c6 50 4c 89 f7 48 89 de e8 85 96 a2 02 0f b6 c0 5b 41 5c 41 5d 41 5e 41 5f 5d e8 e2 1b 10 00 0f 0b e9 4c ff ff ff e8 d6 1b 10 00 0f 0b e9 9d RSP: 0018:ffffc90000007d58 EFLAGS: 00000096 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000018 RSI: ffff8880b902a390 RDI: ffff888020578b40 RBP: ffffc90000007ec0 R08: ffff888020578b57 R09: ffff888020578b40 R10: dffffc0000000000 R11: ffffed10040af16b R12: ffff8880b902a340 R13: ffff888020578b40 R14: ffff8880b902a398 R15: dffffc0000000000 FS: 00007f2390dc86c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000600 CR3: 0000000074639000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __run_hrtimer kernel/time/hrtimer.c:1702 [inline] __hrtimer_run_queues+0x5ed/0xb60 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline] __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194 Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 1f c1 88 f7 65 8b 05 90 e8 38 76 85 c0 74 3c 48 c7 04 24 0e 36 RSP: 0018:ffffc900031bed40 EFLAGS: 00000206 RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 7e1f30b8f73f2e00 RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: 0000000000000001 RBP: ffffc900031bedd0 R08: ffffffff901ee18f R09: 1ffffffff203dc31 R10: dffffc0000000000 R11: fffffbfff203dc32 R12: dffffc0000000000 R13: 0000000000000000 R14: ffff888020578ae8 R15: 1ffff92000637da8 spin_unlock_irqrestore include/linux/spinlock.h:419 [inline] taprio_change+0x4398/0x52d0 net/sched/sch_taprio.c:1589 qdisc_create+0x7e4/0x11a0 net/sched/sch_api.c:1255 tc_modify_qdisc+0xae1/0x17d0 net/sched/sch_api.c:-1 rtnetlink_rcv_msg+0x7f1/0xf10 net/core/rtnetlink.c:5698 netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2519 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline] netlink_unicast+0x78f/0x940 net/netlink/af_netlink.c:1340 netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1919 sock_sendmsg_nosec net/socket.c:706 [inline] __sock_sendmsg net/socket.c:718 [inline] ____sys_sendmsg+0x5be/0x8f0 net/socket.c:2446 ___sys_sendmsg+0x236/0x2e0 net/socket.c:2500 __sys_sendmsg net/socket.c:2529 [inline] __do_sys_sendmsg net/socket.c:2538 [inline] __se_sys_sendmsg+0x1b7/0x2a0 net/socket.c:2536 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f2391764ef9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f2390dc8028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f23919cffa0 RCX: 00007f2391764ef9 RDX: 0000000000000000 RSI: 00002000000007c0 RDI: 0000000000000004 RBP: 00007f23917f9ee0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f23919d0038 R14: 00007f23919cffa0 R15: 00007fffafca2108 rcu: rcu_preempt kthread starved for 8170 jiffies! g9981 f0x0 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:27872 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11c3/0x4350 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117 rcu_gp_fqs_loop+0x2be/0x11f0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 1 CPU: 1 PID: 4309 Comm: kworker/u4:6 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Workqueue: writeback wb_workfn (flush-8:0) Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline] rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487 print_other_cpu_stall+0x1110/0x1270 kernel/rcu/tree_stall.h:592 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline] rcu_pending kernel/rcu/tree.c:3936 [inline] rcu_sched_clock_irq+0x845/0x1120 kernel/rcu/tree.c:2619 update_process_times+0x193/0x200 kernel/time/timer.c:2021 tick_sched_handle kernel/time/tick-sched.c:254 [inline] tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x4b0/0xb60 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline] __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline] RIP: 0010:smp_call_function_many_cond+0xba3/0xd80 kernel/smp.c:969 Code: 0f b6 44 05 00 84 c0 0f 85 9a 00 00 00 41 8b 1e 89 de 83 e6 01 31 ff e8 fb 73 0b 00 83 e3 01 75 07 e8 91 70 0b 00 eb 42 f3 90 <48> b8 00 00 00 00 00 fc ff df 41 0f b6 44 05 00 84 c0 75 10 41 f7 RSP: 0018:ffffc900031de8a0 EFLAGS: 00000293 RAX: ffffffff816d8c45 RBX: 0000000000000001 RCX: ffff888020efd940 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900031de9e0 R08: ffff8880b903b407 R09: 1ffff11017207680 R10: dffffc0000000000 R11: ffffed1017207681 R12: ffff8880b913b3c0 R13: 1ffff11017208509 R14: ffff8880b9042848 R15: 0000000000000000 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1134 __flush_tlb_multi arch/x86/include/asm/paravirt.h:87 [inline] flush_tlb_multi arch/x86/mm/tlb.c:946 [inline] flush_tlb_mm_range+0x363/0x570 arch/x86/mm/tlb.c:1034 flush_tlb_page arch/x86/include/asm/tlbflush.h:240 [inline] ptep_clear_flush+0x112/0x140 mm/pgtable-generic.c:97 page_mkclean_one+0x1eb/0x3e0 mm/rmap.c:938 rmap_walk_file+0x407/0x610 mm/rmap.c:2378 rmap_walk mm/rmap.c:2396 [inline] page_mkclean+0x2f5/0x400 mm/rmap.c:1006 clear_page_dirty_for_io+0x3f9/0x9f0 mm/page-writeback.c:2749 mpage_submit_page+0x8a/0x210 fs/ext4/inode.c:2095 mpage_map_and_submit_buffers fs/ext4/inode.c:2363 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2502 [inline] ext4_writepages+0x1970/0x2d40 fs/ext4/inode.c:2831 do_writepages+0x493/0x700 mm/page-writeback.c:2386 __writeback_single_inode+0x153/0xda0 fs/fs-writeback.c:1657 writeback_sb_inodes+0xaaa/0x1750 fs/fs-writeback.c:1940 __writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011 wb_writeback+0x45e/0xbc0 fs/fs-writeback.c:2116 wb_check_old_data_flush fs/fs-writeback.c:2216 [inline] wb_do_writeback fs/fs-writeback.c:2269 [inline] wb_workfn+0xb15/0xf20 fs/fs-writeback.c:2298 process_one_work+0x867/0xff0 kernel/workqueue.c:2310 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287