rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=7784/1/0x4000000000000000 softirq=43426/43427 fqs=0 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P9658/1:b..l P6165/1:b..l rcu: (detected by 1, t=10506 jiffies, g=31357, q=240 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 9684 Comm: Ã Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:lock_acquire+0x0/0x330 kernel/locking/lockdep.c:5828 Code: 7e 18 12 00 00 00 00 eb c3 e8 dc 68 dd 09 eb c3 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 0f 1e fa 41 57 4d 89 cf 41 56 41 89 f6 41 55 41 89 d5 41 54 45 RSP: 0018:ffffc90000007d80 EFLAGS: 00000046 RAX: ffffffff89802848 RBX: ffff88802af70300 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e3c9620 RBP: ffff88805576d400 R08: 0000000000000000 R09: 0000000000000000 R10: ffff88802af702ab R11: ffff88801e74aff0 R12: 1884e8e6ee0b2908 R13: 1884e8e6ee0b2908 R14: 0000000000000002 R15: ffff888052535010 FS: 00007f00f45816c0(0000) GS:ffff8881248fd000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000003000 CR3: 0000000047a52000 CR4: 00000000003526f0 Call Trace: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:867 [inline] advance_sched+0x699/0xc80 net/sched/sch_taprio.c:991 __run_hrtimer kernel/time/hrtimer.c:1777 [inline] __hrtimer_run_queues+0x202/0xc40 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x10b/0x3c0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline] RIP: 0010:raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline] RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] RIP: 0010:rcu_is_watching+0x69/0xc0 kernel/rcu/tree.c:751 Code: 02 00 75 5c 48 03 1c ed 20 8f d7 8d 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 0f b6 14 02 48 89 d8 83 e0 07 83 c0 03 <38> d0 7c 04 84 d2 75 24 8b 03 c1 e8 02 83 e0 01 65 ff 0d 80 20 0f RSP: 0018:ffffc90004a1f328 EFLAGS: 00000206 RAX: 0000000000000003 RBX: ffff8880b84339e8 RCX: 000000002ba72b25 RDX: 0000000000000000 RSI: ffffffff8bf2a500 RDI: ffffffff8dd78f20 RBP: 0000000000000000 R08: 00000000bf5e8c5b R09: 00000000bbf5e8c5 R10: 0000000000000002 R11: ffff88801e74aff0 R12: ffffffff81a894e8 R13: ffffc90004a1f4a8 R14: 0000000000000000 R15: ffff88801e74a4c0 trace_lock_release include/trace/events/lock.h:69 [inline] lock_release+0x201/0x2d0 kernel/locking/lockdep.c:5879 rcu_lock_release include/linux/rcupdate.h:341 [inline] rcu_read_unlock include/linux/rcupdate.h:897 [inline] class_rcu_destructor include/linux/rcupdate.h:1195 [inline] is_module_text_address+0x14d/0x220 kernel/module/main.c:3856 kernel_text_address kernel/extable.c:119 [inline] kernel_text_address+0x81/0x100 kernel/extable.c:94 __kernel_text_address+0xd/0x40 kernel/extable.c:79 unwind_get_return_address+0x59/0xa0 arch/x86/kernel/unwind_orc.c:369 arch_stack_walk+0xa6/0x100 arch/x86/kernel/stacktrace.c:26 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56 kasan_save_track+0x14/0x30 mm/kasan/common.c:77 unpoison_slab_object mm/kasan/common.c:339 [inline] __kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:365 kasan_slab_alloc include/linux/kasan.h:252 [inline] slab_post_alloc_hook mm/slub.c:4953 [inline] slab_alloc_node mm/slub.c:5263 [inline] kmem_cache_alloc_lru_noprof+0x262/0x770 mm/slub.c:5282 __d_alloc+0x35/0xa80 fs/dcache.c:1730 d_alloc+0x4a/0x1e0 fs/dcache.c:1809 lookup_one_qstr_excl+0x175/0x250 fs/namei.c:1743 __start_dirop fs/namei.c:2866 [inline] start_dirop+0x59/0xb0 fs/namei.c:2875 simple_start_creating+0xf4/0x100 fs/libfs.c:2338 debugfs_start_creating.part.0+0x86/0x1c0 fs/debugfs/inode.c:394 debugfs_start_creating fs/debugfs/inode.c:371 [inline] debugfs_create_dir+0x72/0x470 fs/debugfs/inode.c:572 bdi_debug_register mm/backing-dev.c:235 [inline] bdi_register_va+0x2c0/0x7f0 mm/backing-dev.c:1106 super_setup_bdi_name+0xff/0x250 fs/super.c:1810 fuse_bdi_init fs/fuse/inode.c:1592 [inline] fuse_fill_super_common+0x5e5/0x10d0 fs/fuse/inode.c:1868 fuse_fill_super+0x1f2/0x2e0 fs/fuse/inode.c:1949 vfs_get_super fs/super.c:1324 [inline] get_tree_nodev+0xdd/0x190 fs/super.c:1343 fuse_get_tree+0x271/0x650 fs/fuse/inode.c:2026 vfs_get_tree+0x8e/0x330 fs/super.c:1751 fc_mount fs/namespace.c:1199 [inline] do_new_mount_fc fs/namespace.c:3636 [inline] do_new_mount fs/namespace.c:3712 [inline] path_mount+0x7bf/0x23a0 fs/namespace.c:4022 do_mount fs/namespace.c:4035 [inline] __do_sys_mount fs/namespace.c:4224 [inline] __se_sys_mount fs/namespace.c:4201 [inline] __x64_sys_mount+0x293/0x310 fs/namespace.c:4201 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f00f378f749 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:00007f00f4581038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f00f39e5fa0 RCX: 00007f00f378f749 RDX: 0000200000000140 RSI: 0000200000000000 RDI: 0000000000000000 RBP: 00007f00f3813f91 R08: 0000200000002280 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f00f39e6038 R14: 00007f00f39e5fa0 R15: 00007fffaf39b088 task:kworker/u8:19 state:R running task stack:24712 pid:6165 tgid:6165 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: iou_exit io_ring_exit_work Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190 irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:220 [inline] RIP: 0010:unwind_next_frame+0x2a0/0x20a0 arch/x86/kernel/unwind_orc.c:494 Code: 28 89 74 24 20 44 89 5c 24 18 e8 1b f9 bb 00 48 8b 54 24 30 8b 4c 24 28 8b 74 24 20 44 8b 5c 24 18 89 cf 8b 14 95 e8 4c dc 91 <48> 8d 04 7f 48 8d 84 00 0c 67 1a 91 83 c2 01 48 3d e8 4c dc 91 0f RSP: 0018:ffffc9000512f470 EFLAGS: 00000246 RAX: 0000000000000007 RBX: 0000000000000001 RCX: 00000000000acdfb RDX: 00000000000ace03 RSI: 00000000000a7b75 RDI: 00000000000acdfb RBP: ffffc9000512f528 R08: 0000000000000000 R09: 00000000af9f8a00 R10: 0000000000000002 R11: 000000000003a150 R12: ffffc9000512f530 R13: ffffc9000512f4e0 R14: ffffc9000512f515 R15: ffffffff84a1508f arch_stack_walk+0x94/0x100 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56 kasan_save_track+0x14/0x30 mm/kasan/common.c:77 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:252 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284 kasan_slab_free include/linux/kasan.h:234 [inline] slab_free_hook mm/slub.c:2540 [inline] slab_free mm/slub.c:6668 [inline] kfree+0x2f8/0x6e0 mm/slub.c:6876 io_remove_buffers_legacy+0x1f0/0x360 io_uring/kbuf.c:422 io_put_bl io_uring/kbuf.c:433 [inline] io_destroy_buffers+0x23c/0x280 io_uring/kbuf.c:452 io_ring_ctx_free io_uring/io_uring.c:2849 [inline] io_ring_exit_work+0x7f0/0x1130 io_uring/io_uring.c:3073 process_one_work+0x9ba/0x1b20 kernel/workqueue.c:3257 process_scheduled_works kernel/workqueue.c:3340 [inline] worker_thread+0x6c8/0xf10 kernel/workqueue.c:3421 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 task:syz.0.958 state:R running task stack:25800 pid:9658 tgid:9657 ppid:5806 task_flags:0x400040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:7190 irqentry_exit+0x1d8/0x8c0 kernel/entry/common.c:216 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_release+0x183/0x2d0 kernel/locking/lockdep.c:5893 Code: 0f c1 05 58 83 18 12 83 f8 01 0f 85 03 01 00 00 9c 58 f6 c4 02 0f 85 ee 00 00 00 41 f7 c5 00 02 00 00 74 01 fb 48 8b 44 24 10 <65> 48 2b 05 ed 3b 18 12 0f 85 32 01 00 00 48 83 c4 18 5b 41 5c 41 RSP: 0018:ffffc90006a579e8 EFLAGS: 00000206 RAX: 02b3ace2b6638300 RBX: ffffffff8e3c9620 RCX: ffffc90006a579f4 RDX: 0000000000000001 RSI: ffffffff8daa563c RDI: ffffffff8bf2a580 RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: ffff88806c5d0b30 R12: ffffffff820a376b R13: 0000000000000206 R14: ffff88806c5d0000 R15: 0000000000000002 rcu_lock_release include/linux/rcupdate.h:341 [inline] rcu_read_unlock include/linux/rcupdate.h:897 [inline] pte_unmap include/linux/pgtable.h:136 [inline] follow_page_pte+0x900/0x1390 mm/gup.c:889 follow_pmd_mask mm/gup.c:928 [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+0x918/0x3590 mm/gup.c:1426 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1860 __mm_populate+0x1d8/0x380 mm/gup.c:1963 mm_populate include/linux/mm.h:3701 [inline] vm_mmap_pgoff+0x37f/0x470 mm/util.c:586 ksys_mmap_pgoff+0x7d/0x5c0 mm/mmap.c:604 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f310918f749 RSP: 002b:00007f310a089038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f31093e5fa0 RCX: 00007f310918f749 RDX: 000000000100000e RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007f3109213f91 R08: ffffffffffffffff R09: 0000000000000000 R10: 20c44fb6edc09a38 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f31093e6038 R14: 00007f31093e5fa0 R15: 00007ffcdd0c8018 rcu: rcu_preempt kthread starved for 10506 jiffies! g31357 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:28216 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x1139/0x6150 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6960 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xaf0 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x26d/0x380 kernel/rcu/tree.c:2285 kthread+0x3c5/0x780 kernel/kthread.c:463 ret_from_fork+0x983/0xb10 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 UID: 0 PID: 9683 Comm: syz.5.965 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:native_pause arch/x86/include/asm/vdso/processor.h:13 [inline] RIP: 0010:cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline] RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xdfb/0x15e0 kernel/smp.c:877 Code: ed 74 57 48 8b 54 24 10 4c 89 74 24 10 49 89 d5 48 89 d5 48 89 54 24 18 49 c1 ed 03 83 e5 07 4d 01 e5 83 c5 03 e8 b5 5a 0c 00 90 41 0f b6 45 00 40 38 c5 7c 08 84 c0 0f 85 b6 05 00 00 8b 43 RSP: 0000:ffffc9000be578a8 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b84431e0 RCX: ffffffff81b28931 RDX: ffff88807f7ba4c0 RSI: ffffffff81b2890b RDI: 0000000000000005 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: ffff88807f7baff0 R12: dffffc0000000000 R13: ffffed101708863d R14: 0000000000000001 R15: 0000000000000000 FS: 0000555582e86500(0000) GS:ffff8881249fd000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fffaf399020 CR3: 0000000047a52000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1043 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1382 [inline] flush_tlb_mm_range+0x2f0/0x12c0 arch/x86/mm/tlb.c:1472 flush_tlb_page arch/x86/include/asm/tlbflush.h:324 [inline] ptep_clear_flush+0x136/0x180 mm/pgtable-generic.c:103 wp_page_copy mm/memory.c:3785 [inline] do_wp_page+0x171f/0x5010 mm/memory.c:4180 handle_pte_fault mm/memory.c:6289 [inline] __handle_mm_fault+0x1bd2/0x2bb0 mm/memory.c:6411 handle_mm_fault+0x3fe/0xad0 mm/memory.c:6580 do_user_addr_fault+0x60c/0x1370 arch/x86/mm/fault.c:1336 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x64/0xc0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 RIP: 0033:0x7f00f373cc6b Code: 01 00 00 c7 87 c0 00 00 00 ff ff ff ff 48 8d 84 24 20 21 00 00 48 8d 7c 24 20 0f 29 44 24 40 49 89 e4 48 89 44 24 50 8b 43 74 <48> 89 9c 24 00 01 00 00 89 84 24 94 00 00 00 48 8d 05 1f f0 27 00 RSP: 002b:00007fffaf398f20 EFLAGS: 00010246 RAX: 0000000000000080 RBX: 00007f00f39ba640 RCX: 0000000000000000 RDX: 00007fffaf39b088 RSI: 00007f00f3814d18 RDI: 00007fffaf398f40 RBP: 000000000000006e R08: 00007f00f39e5fa0 R09: 000000000000000f R10: 0000000000000001 R11: 0000000000000006 R12: 00007fffaf398f20 R13: 00007f00f39e6720 R14: 00000000000013c4 R15: 0000000000000004