rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (6 ticks this GP) idle=6aa4/1/0x4000000000000000 softirq=18150/18150 fqs=8 rcu: (detected by 0, t=10502 jiffies, g=13113, q=500 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6315 Comm: syz.4.110 Not tainted 6.15.0-rc2-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 RIP: 0010:__raw_callee_save___pv_queued_spin_unlock+0x10/0x18 Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 52 b8 01 00 00 00 31 d2 f0 0f b0 17 <75> 06 5a c3 cc cc cc cc 56 0f b6 f0 e8 9f ff ff ff 5e 5a c3 cc cc RSP: 0018:ffffc90000a08b10 EFLAGS: 00000046 RAX: 0000000000000001 RBX: 1ffffffff3532226 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff9a991128 RBP: dffffc0000000000 R08: ffffffff9a99112b R09: 1ffffffff3532225 R10: dffffc0000000000 R11: fffffbfff3532226 R12: 1ffffffff3532227 R13: ffffffff9a991138 R14: ffffffff9a991130 R15: ffffffff9a991128 FS: 00007f78c29f76c0(0000) GS:ffff8881250c9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f78c2d9b218 CR3: 0000000033ea0000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: pv_queued_spin_unlock arch/x86/include/asm/paravirt.h:577 [inline] queued_spin_unlock arch/x86/include/asm/qspinlock.h:57 [inline] do_raw_spin_unlock+0x13c/0x8b0 kernel/locking/spinlock_debug.c:142 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:150 [inline] _raw_spin_unlock_irqrestore+0x82/0x140 kernel/locking/spinlock.c:194 debug_object_deactivate+0x2e1/0x390 lib/debugobjects.c:888 debug_hrtimer_deactivate kernel/time/hrtimer.c:450 [inline] debug_deactivate+0x1b/0x220 kernel/time/hrtimer.c:490 __run_hrtimer kernel/time/hrtimer.c:1729 [inline] __hrtimer_run_queues+0x310/0xd40 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x403/0xa40 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline] __sysvec_apic_timer_interrupt+0x110/0x420 arch/x86/kernel/apic/apic.c:1055 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:is_vm_hugetlb_page include/linux/hugetlb_inline.h:11 [inline] RIP: 0010:vma_pgtable_walk_begin+0x37/0x80 mm/memory.c:7370 Code: 2f a8 b1 ff 49 8d 5e 20 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 48 89 df e8 9c 50 19 00 4c 8b 3b 00 00 40 00 be 00 00 40 00 4c 21 fe 31 ff e8 d5 ac b1 ff 4c 21 RSP: 0018:ffffc90004a97940 EFLAGS: 00000246 RAX: 1ffff11003d72cf4 RBX: ffff88801eb967a0 RCX: dffffc0000000000 RDX: ffffc9000c5a4000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: ffffc90004a97c10 R08: ffffffff820db707 R09: 1ffff11004455b40 R10: dffffc0000000000 R11: ffffed1004455b41 R12: dffffc0000000000 R13: 1ffff11003d72cf2 R14: ffff88801eb96780 R15: 00000000080000fe follow_page_mask mm/gup.c:1079 [inline] __get_user_pages+0x7a1/0x4180 mm/gup.c:1489 populate_vma_page_range+0x266/0x340 mm/gup.c:1929 __mm_populate+0x27d/0x460 mm/gup.c:2032 mm_populate include/linux/mm.h:3470 [inline] vm_mmap_pgoff+0x390/0x530 mm/util.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f78c2b8d169 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f78c29f7038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f78c2da5fa0 RCX: 00007f78c2b8d169 RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007f78c2c0e990 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f78c2da5fa0 R15: 00007ffc2fe55118 rcu: rcu_preempt kthread starved for 10486 jiffies! g13113 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:26688 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x1b33/0x51f0 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0x163/0x360 kernel/sched/core.c:6860 schedule_timeout+0x15b/0x2b0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x2e1/0x1340 kernel/rcu/tree.c:2046 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2248 kthread+0x7b7/0x940 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 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: 5964 Comm: kworker/u8:9 Not tainted 6.15.0-rc2-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_many_cond+0x1bac/0x2d40 kernel/smp.c:885 Code: 03 84 c0 75 7e 45 8b 65 00 44 89 e6 83 e6 01 31 ff e8 08 e3 0b 00 41 83 e4 01 4c 8b 64 24 68 75 07 e8 b8 de 0b 00 eb 41 f3 90 <48> b8 00 00 00 00 00 fc ff df 0f b6 04 03 84 c0 75 11 41 f7 45 00 RSP: 0018:ffffc900048cf640 EFLAGS: 00000293 RAX: ffffffff81b765dd RBX: 1ffff110170e7e61 RCX: ffff888027219e00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900048cf840 R08: ffffffff81b765a8 R09: 1ffffffff20bd6ee R10: dffffc0000000000 R11: fffffbfff20bd6ef R12: ffff8880b863ab88 R13: ffff8880b873f308 R14: ffff8880b863ab80 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888124fc9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f09e36dd75e CR3: 000000000eb38000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052 on_each_cpu include/linux/smp.h:71 [inline] text_poke_sync arch/x86/kernel/alternative.c:2455 [inline] text_poke_bp_batch+0x354/0xb30 arch/x86/kernel/alternative.c:2665 text_poke_flush arch/x86/kernel/alternative.c:2856 [inline] text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2863 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x136/0x260 kernel/jump_label.c:210 static_key_enable+0x1a/0x20 kernel/jump_label.c:223 toggle_allocation_gate+0xc0/0x250 mm/kfence/core.c:850 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319 worker_thread+0x870/0xd50 kernel/workqueue.c:3400 kthread+0x7b7/0x940 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245