rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (4 ticks this GP) idle=6db4/1/0x4000000000000000 softirq=31464/31467 fqs=3 rcu: (detected by 0, t=10506 jiffies, g=21369, q=811 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 9552 Comm: syz.5.578 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:__lock_is_held kernel/locking/lockdep.c:5596 [inline] RIP: 0010:lock_is_held_type+0xbd/0x1a0 kernel/locking/lockdep.c:5938 Code: e3 48 81 c3 f0 0a 00 00 31 ed 48 83 fd 31 73 25 48 89 df 4c 89 fe e8 82 02 00 00 85 c0 75 2b 48 ff c5 49 63 84 24 e8 0a 00 00 <48> 83 c3 28 48 39 c5 7c d7 eb 2e 48 c7 c7 90 f3 c0 8e 48 89 ee e8 RSP: 0018:ffffc90000a08cf8 EFLAGS: 00000002 RAX: 0000000000000003 RBX: ffff8880582028f0 RCX: ffff888058201e00 RDX: ffff888058201e00 RSI: ffff8880b87276d8 RDI: ffff8880582028f0 RBP: 0000000000000001 R08: ffffffff81b086c9 R09: 0000000000000000 R10: ffff88807b7ab340 R11: ffffed100f6f566b R12: ffff888058201e00 R13: 0000000000000046 R14: 00000000ffffffff R15: ffff8880b87276d8 FS: 00007fcf0dd726c0(0000) GS:ffff8881250c9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000005b628000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_is_held include/linux/lockdep.h:249 [inline] __run_hrtimer kernel/time/hrtimer.c:1727 [inline] __hrtimer_run_queues+0x2e4/0xd40 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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0xd9/0x140 kernel/locking/spinlock.c:194 Code: 9c 8f 44 24 20 42 80 3c 2b 00 74 08 4c 89 f7 e8 0d 5b ff f5 f6 44 24 21 02 75 55 41 f7 c7 00 02 00 00 74 01 fb bf 01 00 00 00 82 e7 64 f5 65 8b 05 1b de 39 07 85 c0 74 46 48 c7 04 24 0e 36 RSP: 0018:ffffc9000c2ae7c0 EFLAGS: 00000206 RAX: 2a89c0d88bebb400 RBX: 1ffff92001855cfc RCX: 0000000000000006 RDX: 0000000000000006 RSI: ffffffff8e687fbd RDI: 0000000000000001 RBP: ffffc9000c2ae850 R08: ffffffff905eb777 R09: 1ffffffff20bd6ee R10: dffffc0000000000 R11: fffffbfff20bd6ef R12: 1ffff92001855cf8 R13: dffffc0000000000 R14: ffffc9000c2ae7e0 R15: 0000000000000246 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] rmqueue_bulk mm/page_alloc.c:2340 [inline] __rmqueue_pcplist+0x209c/0x2a80 mm/page_alloc.c:3038 rmqueue_pcplist mm/page_alloc.c:3080 [inline] rmqueue mm/page_alloc.c:3111 [inline] get_page_from_freelist+0x941/0x36b0 mm/page_alloc.c:3649 __alloc_frozen_pages_noprof+0x211/0x5b0 mm/page_alloc.c:4934 alloc_pages_mpol+0x339/0x690 mm/mempolicy.c:2301 folio_alloc_mpol_noprof+0x36/0x70 mm/mempolicy.c:2320 shmem_alloc_folio mm/shmem.c:1854 [inline] shmem_alloc_and_add_folio+0x490/0x1070 mm/shmem.c:1893 shmem_get_folio_gfp+0x655/0x1800 mm/shmem.c:2533 shmem_fault+0x223/0x5c0 mm/shmem.c:2734 __do_fault+0x135/0x390 mm/memory.c:5098 do_read_fault mm/memory.c:5518 [inline] do_fault mm/memory.c:5652 [inline] do_pte_missing mm/memory.c:4160 [inline] handle_pte_fault+0x3f0c/0x61c0 mm/memory.c:5997 __handle_mm_fault mm/memory.c:6140 [inline] handle_mm_fault+0x1030/0x1aa0 mm/memory.c:6309 faultin_page mm/gup.c:1193 [inline] __get_user_pages+0x1adc/0x4180 mm/gup.c:1491 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: 0033:0x7fcf0cf8d169 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:00007fcf0dd72038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007fcf0d1a5fa0 RCX: 00007fcf0cf8d169 RDX: b635773f04ebbeeb RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007fcf0d00e990 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fcf0d1a5fa0 R15: 00007ffc555ce448 rcu: rcu_preempt kthread starved for 10495 jiffies! g21369 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:26576 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: 1138 Comm: kworker/u8:5 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+0x1bc6/0x2d40 kernel/smp.c:885 Code: 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 01 00 00 00 <74> 1e e8 93 de 0b 00 eb db 44 89 e9 80 e1 07 80 c1 03 38 c1 7c e2 RSP: 0018:ffffc90003d9f640 EFLAGS: 00000202 RAX: 0000000000000000 RBX: 1ffff110170e7e61 RCX: ffff8880278e5a00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90003d9f840 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: 00007f0db6513ba8 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