rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (0 ticks this GP) idle=7a5c/1/0x4000000000000000 softirq=76097/76097 fqs=0 rcu: (detected by 0, t=10502 jiffies, g=65657, q=118 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 14053 Comm: syz.0.1821 Not tainted 6.16.0-rc5-syzkaller-00266-g3f31a806a62e #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:arch_atomic_try_cmpxchg arch/x86/include/asm/atomic.h:107 [inline] RIP: 0010:raw_atomic_try_cmpxchg_acquire include/linux/atomic/atomic-arch-fallback.h:2170 [inline] RIP: 0010:atomic_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1302 [inline] RIP: 0010:queued_spin_lock include/asm-generic/qspinlock.h:111 [inline] RIP: 0010:do_raw_spin_lock+0x125/0x290 kernel/locking/spinlock_debug.c:116 Code: 00 00 c7 44 24 40 00 00 00 00 48 89 df be 04 00 00 00 e8 ee aa 82 00 48 8d 7c 24 40 be 04 00 00 00 e8 df aa 82 00 8b 44 24 40 01 00 00 00 f0 0f b1 0b 0f 85 dd 00 00 00 65 8b 1d 99 30 fe 10 RSP: 0018:ffffc90000a08be0 EFLAGS: 00000097 RAX: 0000000000000000 RBX: ffff8880b8727ac0 RCX: ffffffff819edf81 RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc90000a08c20 RBP: ffffc90000a08c90 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000141184 R12: ffff8880b8727ad0 R13: ffff8880b8727ac8 R14: 1ffff110170e4f5a R15: 1ffff110170e4f59 FS: 00007f15553416c0(0000) GS:ffff888125d4f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c3efbd9 CR3: 00000000337da000 CR4: 00000000003526f0 Call Trace: __raw_spin_lock_irq include/linux/spinlock_api_smp.h:120 [inline] _raw_spin_lock_irq+0xae/0xf0 kernel/locking/spinlock.c:170 __run_hrtimer kernel/time/hrtimer.c:1765 [inline] __hrtimer_run_queues+0x602/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:rcu_read_lock_held_common kernel/rcu/update.c:105 [inline] RIP: 0010:rcu_read_lock_held+0x5/0x50 kernel/rcu/update.c:349 Code: c3 cc cc cc cc cc 66 66 66 66 66 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 53 46 42 c2 09 85 c0 74 26 31 db e8 fb 2d 01 00 84 c0 74 20 e8 b2 RSP: 0018:ffffc9000ddfeff8 EFLAGS: 00000246 RAX: 1ffff11027fff5a6 RBX: ffff88801bb80000 RCX: 0000000000080000 RDX: ffffc9000dea9000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff822c9b9a R10: dffffc0000000000 R11: ffffed100ae697f0 R12: 000000000006ab3f R13: dffffc0000000000 R14: ffff88813fffad30 R15: 0000000000001000 lookup_page_ext mm/page_ext.c:254 [inline] page_ext_lookup+0xe7/0x180 mm/page_ext.c:520 page_ext_iter_begin include/linux/page_ext.h:132 [inline] __page_table_check_zero+0x18f/0x530 mm/page_table_check.c:139 page_table_check_alloc include/linux/page_table_check.h:35 [inline] post_alloc_hook+0x253/0x2a0 mm/page_alloc.c:1705 prep_new_page mm/page_alloc.c:1712 [inline] get_page_from_freelist+0x21d5/0x22b0 mm/page_alloc.c:3669 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419 folio_alloc_mpol_noprof+0x39/0x70 mm/mempolicy.c:2438 shmem_alloc_folio mm/shmem.c:1851 [inline] shmem_alloc_and_add_folio+0x447/0xf60 mm/shmem.c:1890 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2536 shmem_fault+0x179/0x390 mm/shmem.c:2737 __do_fault+0x138/0x390 mm/memory.c:5169 do_read_fault mm/memory.c:5590 [inline] do_fault mm/memory.c:5724 [inline] do_pte_missing mm/memory.c:4251 [inline] handle_pte_fault mm/memory.c:6069 [inline] __handle_mm_fault+0x37ed/0x5620 mm/memory.c:6212 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6381 faultin_page mm/gup.c:1186 [inline] __get_user_pages+0x1af4/0x30b0 mm/gup.c:1488 populate_vma_page_range+0x26b/0x340 mm/gup.c:1926 __mm_populate+0x24c/0x380 mm/gup.c:2029 mm_populate include/linux/mm.h:3353 [inline] vm_mmap_pgoff+0x3f0/0x4c0 mm/util.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f155458e929 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:00007f1555341038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f15547b6080 RCX: 00007f155458e929 RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007f1554610b39 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f15547b6080 R15: 00007ffd5fac16b8 rcu: rcu_preempt kthread starved for 10502 jiffies! g65657 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:27128 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5397 [inline] __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6786 __schedule_loop kernel/sched/core.c:6864 [inline] schedule+0x165/0x360 kernel/sched/core.c:6879 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2054 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2256 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 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: 6135 Comm: kworker/u8:11 Not tainted 6.16.0-rc5-syzkaller-00266-g3f31a806a62e #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_many_cond+0xf6e/0x12d0 kernel/smp.c:885 Code: 89 ee 83 e6 01 31 ff e8 c0 78 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 6b 74 0b 00 eb 37 f3 90 43 0f b6 04 2c <84> c0 75 10 41 f7 07 01 00 00 00 74 1e e8 50 74 0b 00 eb e5 44 89 RSP: 0018:ffffc9000b5276a0 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b863b040 RCX: ffff88802ff73c00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000b527800 R08: ffffffff8fa0cbf7 R09: 1ffffffff1f4197e R10: dffffc0000000000 R11: fffffbfff1f4197f R12: 1ffff110170e7f2d R13: dffffc0000000000 R14: 0000000000000001 R15: ffff8880b873f968 FS: 0000000000000000(0000) GS:ffff888125c4f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b3361dff8 CR3: 000000000df38000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052 on_each_cpu include/linux/smp.h:71 [inline] smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2691 [inline] smp_text_poke_batch_finish+0x5e0/0x1100 arch/x86/kernel/alternative.c:2901 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x128/0x250 kernel/jump_label.c:210 static_key_enable+0x1a/0x20 kernel/jump_label.c:223 toggle_allocation_gate+0xad/0x240 mm/kfence/core.c:850 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245