rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (2 GPs behind) idle=8d74/1/0x4000000000000000 softirq=81068/81088 fqs=63 rcu: (detected by 1, t=10506 jiffies, g=64145, q=1234 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 14462 Comm: syz.9.1458 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:advance_sched+0x3b4/0xc80 net/sched/sch_taprio.c:955 Code: 00 00 48 89 1c 24 31 ed 4d 85 ff 0f 85 ae fe ff ff e8 e0 e8 e9 f7 e9 3c 08 00 00 e8 d6 e8 e9 f7 48 b9 00 00 00 00 00 fc ff df <4c> 89 e0 48 c1 e8 03 80 3c 08 00 74 08 4c 89 e7 e8 87 73 57 f8 48 RSP: 0018:ffffc90000007d10 EFLAGS: 00000006 RAX: ffffffff89dc896a RBX: 0000000000000000 RCX: dffffc0000000000 RDX: 0000000000010000 RSI: 0000000000000000 RDI: 18bf96f5911b8c5c RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000000f90 R12: ffff888030cec510 R13: 0000000000000000 R14: 18bf96f5911b8c5c R15: ffff888030cec510 FS: 00007f62822436c0(0000) GS:ffff888124f59000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005569128d6950 CR3: 00000000484af000 CR4: 0000000000350ef0 Call Trace: __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:srso_alias_safe_ret+0x0/0x7 arch/x86/lib/retpoline.S:210 Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc <48> 8d 64 24 08 c3 cc e8 f4 ff ff ff 0f 0b cc cc cc cc cc cc cc cc RSP: 0018:ffffc90002d57938 EFLAGS: 00000292 RAX: ffff888075f5c510 RBX: ffff888034dd8008 RCX: 0000000000080000 RDX: ffffc900161c7000 RSI: 00000000000656cc RDI: 00000000000656cd RBP: ffffc90002d57ac0 R08: ffffffff821fcf99 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8eb59c60 R12: dffffc0000000000 R13: ffff888033d70150 R14: ffffc90002d57a40 R15: 00002000002a2000 srso_alias_return_thunk+0x5/0xfbef5 arch/x86/lib/retpoline.S:220 pte_offset_map_lock+0x46/0x210 mm/pgtable-generic.c:400 follow_page_pte+0xd1/0xe70 mm/gup.c:812 follow_pmd_mask mm/gup.c:-1 [inline] follow_pud_mask mm/gup.c:967 [inline] follow_p4d_mask mm/gup.c:984 [inline] follow_page_mask mm/gup.c:1023 [inline] __get_user_pages+0xa74/0x2720 mm/gup.c:1426 populate_vma_page_range+0x2be/0x3c0 mm/gup.c:1860 __mm_populate+0x25f/0x390 mm/gup.c:1963 mm_populate include/linux/mm.h:4171 [inline] vm_mmap_pgoff+0x353/0x4e0 mm/util.c:586 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f628139de59 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:00007f6282243028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f6281626090 RCX: 00007f628139de59 RDX: 0000000000000002 RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007f6281433e6f R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6281626128 R14: 00007f6281626090 R15: 00007ffcfea70478 rcu: rcu_preempt kthread starved for 10190 jiffies! g64145 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:26752 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: 1 UID: 0 PID: 7333 Comm: udevd Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:get_current arch/x86/include/asm/current.h:25 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:216 Code: 8b 3d 14 0e 89 0c 48 89 de 5b e9 c3 01 62 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d b8 fd a5 11 65 8b 15 d9 fd a5 11 81 e2 00 01 ff 00 74 RSP: 0000:ffffc90003a07838 EFLAGS: 00000202 RAX: ffffffff81ba57d7 RBX: dffffc0000000000 RCX: ffff88807f43be00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90003a07970 R08: ffffffff90576ff7 R09: 1ffffffff20aedfe R10: dffffc0000000000 R11: fffffbfff20aedff R12: 1ffff110170c85fd R13: ffff8880b873c448 R14: ffff8880b8642fe8 R15: 0000000000000000 FS: 00007f049df7a880(0000) GS:ffff888125059000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055ba5beff7c0 CR3: 0000000075bf9000 CR4: 0000000000350ef0 Call Trace: csd_lock_wait kernel/smp.c:342 [inline] smp_call_function_many_cond+0x10c7/0x14b0 kernel/smp.c:892 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+0x5c4/0x1090 arch/x86/mm/tlb.c:1451 flush_tlb_page arch/x86/include/asm/tlbflush.h:345 [inline] ptep_clear_flush+0x120/0x170 mm/pgtable-generic.c:104 wp_page_copy mm/memory.c:3941 [inline] do_wp_page+0x3d52/0x4c70 mm/memory.c:4336 handle_pte_fault mm/memory.c:6395 [inline] __handle_mm_fault mm/memory.c:6517 [inline] handle_mm_fault+0x1490/0x3080 mm/memory.c:6686 do_user_addr_fault+0xa4d/0x1340 arch/x86/mm/fault.c:1343 handle_page_fault arch/x86/mm/fault.c:1483 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595 RIP: 0033:0x7f049d8b5dda Code: f6 44 01 08 01 74 59 48 83 61 08 fe 48 3d ff 03 00 00 76 69 49 8b 55 70 49 8d 75 60 48 39 72 18 0f 85 ba 00 00 00 66 0f ef c0 <41> 0f 11 44 24 20 49 89 54 24 10 49 89 74 24 18 4c 89 66 10 4c 89 RSP: 002b:00007fffad8da050 EFLAGS: 00010246 RAX: 0000000000003500 RBX: 0000000000000da0 RCX: 000055ba5bf03c80 RDX: 000055ba5bed35b0 RSI: 00007f049d9f1b20 RDI: 000055ba5bf01f00 RBP: 00007f049d9f1ac0 R08: 0000000000000da0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 000055ba5beff7a0 R13: 00007f049d9f1ac0 R14: 0000000000000da0 R15: 00007f049d9f1ac0