rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=0cdc/1/0x4000000000000000 softirq=83086/83116 fqs=2 rcu: (detected by 0, t=10502 jiffies, g=103161, q=553 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 12414 Comm: syz.0.2048 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 RIP: 0010:kasan_check_range+0x7/0x2c0 mm/kasan/generic.c:199 Code: 48 c7 c6 5c 42 4b 8e e8 37 9e f3 fe 90 0f 0b cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 55 41 57 <41> 56 41 55 41 54 53 b0 01 48 85 f6 0f 84 ae 01 00 00 4c 8d 04 37 RSP: 0018:ffffc90000a08c90 EFLAGS: 00000082 RAX: ffff88807e5f0800 RBX: ffff88807e5f2d30 RCX: ffffffff89de2a85 RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff88807e5f0880 RBP: 000000007fffffff R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000141190 R12: 0000000000000000 R13: ffff88807e5f0800 R14: 0000000000000000 R15: ffff88807e5f0880 FS: 0000000000000000(0000) GS:ffff88812504e000(0000) knlGS:0000000000000000 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 00000000f7f355b8 CR3: 000000000e946000 CR4: 00000000003526f0 DR0: 0000000000007fff DR1: 0000000000000000 DR2: 0000000000000007 DR3: 0000000000000004 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: instrument_atomic_write include/linux/instrumented.h:97 [inline] atomic_set include/linux/atomic/atomic-instrumented.h:67 [inline] taprio_set_budgets+0x245/0x3a0 net/sched/sch_taprio.c:678 advance_sched+0x970/0xc80 net/sched/sch_taprio.c:984 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x3bc/0xa10 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215 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:deref_stack_reg+0x183/0x220 arch/x86/kernel/unwind_orc.c:422 Code: 39 c4 0f 96 c1 4d 39 c6 0f 97 c2 20 c2 20 ca 80 fa 01 75 46 49 8d 40 08 4c 39 e0 0f 97 c1 4c 39 f0 0f 96 c0 20 c8 3c 01 75 30 <4c> 89 c7 49 89 f7 e8 12 07 00 00 49 89 c6 48 8b 5c 24 08 48 89 d8 RSP: 0018:ffffc90003acf4d8 EFLAGS: 00000202 RAX: ffffc90003acfa01 RBX: 1ffff92000759eb9 RCX: 0000000000000001 RDX: ffffc90003acf608 RSI: dffffc0000000000 RDI: ffffc90003acf5d8 RBP: ffffc90003ac8000 R08: ffffc90003acfaf0 R09: 0000000000000000 R10: ffffc90003acf618 R11: fffff52000759ec5 R12: 1ffff92000759eba R13: 1ffff92000759ebb R14: ffffc90003ad0000 R15: ffffc90003acf5c8 unwind_next_frame+0x19bd/0x2550 arch/x86/kernel/unwind_orc.c:-1 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 save_stack+0x122/0x230 mm/page_owner.c:165 __reset_page_owner+0x71/0x1f0 mm/page_owner.c:320 reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1406 [inline] free_pages_prepare+0x960/0xa60 mm/page_alloc.c:1451 __free_contig_range_common+0x174/0x340 mm/page_alloc.c:6897 __free_contig_range mm/page_alloc.c:6942 [inline] free_pages_bulk+0x48/0x120 mm/page_alloc.c:5257 vm_area_free_pages mm/vmalloc.c:3439 [inline] vfree+0x224/0x4a0 mm/vmalloc.c:3488 kcov_put kernel/kcov.c:449 [inline] kcov_close+0x28/0x50 kernel/kcov.c:554 __fput+0x418/0xa50 fs/file_table.c:512 task_work_run+0x1d9/0x270 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x73a/0x2360 kernel/exit.c:1009 do_group_exit+0x22d/0x2f0 kernel/exit.c:1152 get_signal+0x121b/0x12c0 kernel/signal.c:3046 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x104/0x730 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_int80_emulation+0x31a/0x550 arch/x86/entry/syscall_32.c:175 asm_int80_emulation+0x1a/0x20 arch/x86/include/asm/idtentry.h:598 RIP: 0023:0xf71f72eb Code: Unable to access opcode bytes at 0xf71f72c1. RSP: 002b:00000000f54ad3ac EFLAGS: 00000246 ORIG_RAX: 000000000000010b RAX: fffffffffffffdfc RBX: 0000000000000000 RCX: 0000000000000000 RDX: 00000000f54ad444 RSI: 00000000f54ad43c RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 10498 jiffies! g103161 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:27736 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7326 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325 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: 8904 Comm: syz-executor Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0x11e6/0x15f0 kernel/smp.c:912 Code: c0 75 7a 41 8b 1e 89 de 83 e6 01 31 ff e8 e2 22 0c 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 8e 1e 0c 00 eb 37 f3 90 <41> 0f b6 04 1c 84 c0 75 10 41 f7 06 01 00 00 00 74 1e e8 73 1e 0c RSP: 0000:ffffc9001424f540 EFLAGS: 00000293 RAX: ffffffff81bae58d RBX: dffffc0000000000 RCX: ffff88802abc5d00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9001424f688 R08: ffffffff90579137 R09: 1ffffffff20af226 R10: dffffc0000000000 R11: fffffbfff20af227 R12: 1ffff110170e81d1 R13: ffff8880b863c448 R14: ffff8880b8740e88 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888124f4e000(0063) knlGS:00000000567a9480 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 00000000f7f855b8 CR3: 000000002132a000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1077 __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+0x5c4/0x1090 arch/x86/mm/tlb.c:1451 dup_mmap+0x1786/0x1d90 mm/mmap.c:1905 dup_mm kernel/fork.c:1543 [inline] copy_mm+0x11a/0x480 kernel/fork.c:1595 copy_process+0x1e3e/0x4390 kernel/fork.c:2289 kernel_clone+0x2d7/0x940 kernel/fork.c:2748 __do_compat_sys_ia32_clone arch/x86/kernel/sys_ia32.c:255 [inline] __se_compat_sys_ia32_clone arch/x86/kernel/sys_ia32.c:241 [inline] __ia32_compat_sys_ia32_clone+0x1b4/0x230 arch/x86/kernel/sys_ia32.c:241 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x23e/0x6f0 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf705f0ec Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8 RSP: 002b:00000000f757fc80 EFLAGS: 00000206 ORIG_RAX: 0000000000000078 RAX: ffffffffffffffda RBX: 0000000001200011 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000567a94e8 RBP: 00000000f757fcb4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000