rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=84bc/1/0x4000000000000000 softirq=135292/135293 fqs=0 rcu: (detected by 0, t=10502 jiffies, g=127189, q=232 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 24783 Comm: syz.2.6543 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:__kasan_check_write+0xa/0x20 mm/kasan/shadow.c:37 Code: ff 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 89 f6 48 8b 0c 24 01 00 00 00 e9 bc e4 ff ff 66 66 66 2e 0f 1f 84 00 00 00 00 00 RSP: 0018:ffffc90000a08c78 EFLAGS: 00000056 RAX: 00000000ffffff01 RBX: ffff8880b8728240 RCX: ffffffff819e8f81 RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc90000a08cc0 RBP: ffffc90000a08d30 R08: ffff8880b8728243 R09: 1ffff110170e5048 R10: dffffc0000000000 R11: ffffed10170e5049 R12: ffff8880b8728250 R13: ffff8880b8728248 R14: 1ffff110170e504a R15: 1ffff110170e5049 FS: 0000000000000000(0000) GS:ffff888125f1f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000240 CR3: 0000000064c84000 CR4: 0000000000350ef0 Call Trace: instrument_read_write include/linux/instrumented.h:54 [inline] atomic_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1301 [inline] queued_spin_lock include/asm-generic/qspinlock.h:111 [inline] do_raw_spin_lock+0x121/0x290 kernel/locking/spinlock_debug.c:116 __run_hrtimer kernel/time/hrtimer.c:1781 [inline] __hrtimer_run_queues+0x5e2/0xc30 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x102/0x3e0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_is_held_type+0x5/0x150 kernel/locking/lockdep.c:5925 Code: 04 48 c7 c6 46 05 91 8d 67 48 0f b9 3a 90 eb ce 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 <41> 57 41 56 41 55 41 54 53 bb ff ff ff ff 83 3d 56 be 28 04 00 0f RSP: 0018:ffffc9000cf4f608 EFLAGS: 00000202 RAX: 1ffffffff1be8d01 RBX: ffff88801ae80000 RCX: 0000000080000002 RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffffffff8df41aa0 RBP: 0000000000000001 R08: ffffffff8232a2f4 R09: ffffffff8df41aa0 R10: dffffc0000000000 R11: fffff940001d4cb1 R12: 000000000003a996 R13: dffffc0000000000 R14: ffff88813fffa4f0 R15: 0000000000001000 lookup_page_ext mm/page_ext.c:254 [inline] page_ext_lookup+0xe7/0x180 mm/page_ext.c:509 page_ext_iter_begin include/linux/page_ext.h:132 [inline] page_table_check_clear+0x238/0x5f0 mm/page_table_check.c:78 ptep_get_and_clear_full arch/x86/include/asm/jump_label.h:-1 [inline] get_and_clear_full_ptes include/linux/pgtable.h:725 [inline] zap_present_folio_ptes mm/memory.c:1626 [inline] zap_present_ptes mm/memory.c:1708 [inline] do_zap_pte_range mm/memory.c:1810 [inline] zap_pte_range mm/memory.c:1854 [inline] zap_pmd_range mm/memory.c:1946 [inline] zap_pud_range mm/memory.c:1975 [inline] zap_p4d_range mm/memory.c:1996 [inline] unmap_page_range+0x3257/0x4170 mm/memory.c:2017 unmap_single_vma mm/memory.c:2059 [inline] unmap_vmas+0x399/0x580 mm/memory.c:2101 exit_mmap+0x239/0xb10 mm/mmap.c:1277 __mmput+0x118/0x430 kernel/fork.c:1173 exit_mm+0x169/0x230 kernel/exit.c:581 do_exit+0x627/0x22f0 kernel/exit.c:959 do_group_exit+0x21c/0x2d0 kernel/exit.c:1112 __do_sys_exit_group kernel/exit.c:1123 [inline] __se_sys_exit_group kernel/exit.c:1121 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1121 x64_sys_call+0x2210/0x2210 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fdcad18f749 Code: Unable to access opcode bytes at 0x7fdcad18f71f. RSP: 002b:00007ffd81e3f868 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdcad18f749 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007ffd81e3f8cc R08: 0000000581e3f95f R09: 00000000000927c0 R10: 0000000000000001 R11: 0000000000000246 R12: 00000000000003f5 R13: 00000000000927c0 R14: 00000000000ce2a2 R15: 00007ffd81e3f920 rcu: rcu_preempt kthread starved for 10502 jiffies! g127189 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:27544 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x149b/0x4fd0 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0x165/0x360 kernel/sched/core.c:6960 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x510/0xa50 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: 0 UID: 0 PID: 5831 Comm: syz-executor 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:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xcca/0x1260 kernel/smp.c:877 Code: 89 ee 83 e6 01 31 ff e8 d4 95 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 7f 91 0b 00 eb 38 f3 90 42 0f b6 04 2b <84> c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 63 91 0b 00 eb e4 44 RSP: 0018:ffffc90003abf640 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 1ffff110170e8129 RCX: ffff888076200000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90003abf768 R08: ffffffff8f822177 R09: 1ffffffff1f0442e R10: dffffc0000000000 R11: fffffbfff1f0442f R12: ffff8880b8740948 R13: dffffc0000000000 R14: ffff8880b863bb00 R15: 0000000000000001 FS: 000055556aedf500(0000) GS:ffff888125e1f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b3311fff8 CR3: 000000005bde0000 CR4: 0000000000350ef0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 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+0x60a/0x1170 arch/x86/mm/tlb.c:1472 dup_mmap+0x15fa/0x1b80 mm/mmap.c:1866 dup_mm kernel/fork.c:1529 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1581 copy_process+0x165d/0x3950 kernel/fork.c:2221 kernel_clone+0x21e/0x820 kernel/fork.c:2651 __do_sys_clone kernel/fork.c:2792 [inline] __se_sys_clone kernel/fork.c:2776 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2776 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3457985e93 Code: 1f 84 00 00 00 00 00 64 48 8b 04 25 10 00 00 00 45 31 c0 31 d2 31 f6 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 89 c2 85 c0 75 2c 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffc2e719608 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3457985e93 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 000055556aedf7d0 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000000927c0 R14: 00000000000ce276 R15: 00007ffc2e7197a0