rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=c72c/1/0x4000000000000000 softirq=126348/126349 fqs=1 rcu: (detected by 0, t=10505 jiffies, g=125553, q=256 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 12641 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:__run_hrtimer kernel/time/hrtimer.c:1792 [inline] RIP: 0010:__hrtimer_run_queues+0x642/0xc60 kernel/time/hrtimer.c:1841 Code: 00 42 0f b6 04 28 84 c0 4c 8b 74 24 58 0f 85 43 02 00 00 48 8b 44 24 28 0f b6 18 89 de 83 e6 01 31 ff e8 71 5d 12 00 83 e3 01 <75> 20 e8 67 5a 12 00 4c 89 e7 4c 89 fe 31 d2 e8 6a 2d 00 00 eb 11 RSP: 0018:ffffc90000a08d40 EFLAGS: 00000046 RAX: ffffffff81ada94f RBX: 0000000000000000 RCX: 0000000000010000 RDX: ffff88802e1ebc80 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000a08e90 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000141184 R12: ffff888051de1340 R13: dffffc0000000000 R14: ffff8880b8927d18 R15: ffff8880b8927cc0 FS: 0000555589ba5500(0000) GS:ffff888126239000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000240 CR3: 000000007d277000 CR4: 0000000000350ef0 Call Trace: hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline] __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1058 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:trace_lock_acquire include/trace/events/lock.h:24 [inline] RIP: 0010:lock_acquire+0x58/0x360 kernel/locking/lockdep.c:5831 Code: 8b 05 9c 1e d1 10 48 89 44 24 58 0f 1f 44 00 00 65 8b 05 9f 1e d1 10 83 f8 08 0f 83 b8 01 00 00 89 c0 48 0f a3 05 c8 9d df 0d <73> 16 e8 61 fd 08 00 84 c0 75 0d f6 05 10 a9 c9 0d 01 0f 84 d7 01 RSP: 0018:ffffc9001a1372a8 EFLAGS: 00000297 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8df3d6e0 RBP: ffffffff8230eaad R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: fffff9400035af91 R12: 0000000000000002 R13: ffffffff8df3d6e0 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:867 [inline] page_table_check_set+0x1aa/0x730 mm/page_table_check.c:112 page_table_check_ptes_set include/linux/page_table_check.h:76 [inline] set_ptes include/linux/pgtable.h:292 [inline] __copy_present_ptes mm/memory.c:1101 [inline] copy_present_ptes mm/memory.c:1180 [inline] copy_pte_range mm/memory.c:1303 [inline] copy_pmd_range+0x4b9b/0x7f00 mm/memory.c:1390 copy_pud_range mm/memory.c:1427 [inline] copy_p4d_range mm/memory.c:1451 [inline] copy_page_range+0xc14/0x1270 mm/memory.c:1539 dup_mmap+0xf4c/0x1b10 mm/mmap.c:1834 dup_mm kernel/fork.c:1489 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1541 copy_process+0x1706/0x3c00 kernel/fork.c:2181 kernel_clone+0x21e/0x840 kernel/fork.c:2609 __do_sys_clone kernel/fork.c:2750 [inline] __se_sys_clone kernel/fork.c:2734 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2734 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f64cad85e93 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:00007ffd96f41568 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f64cad85e93 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 0000555589ba57d0 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000000927c0 R14: 00000000000da09c R15: 00007ffd96f41700 rcu: rcu_preempt kthread starved for 10500 jiffies! g125553 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:27224 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5325 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 __schedule_loop kernel/sched/core.c:7011 [inline] schedule+0x165/0x360 kernel/sched/core.c:7026 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+0x4bc/0x870 arch/x86/kernel/process.c:158 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: 25647 Comm: syz.2.7237 Not tainted syzkaller #0 PREEMPT(full) 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+0xd38/0x12d0 kernel/smp.c:877 Code: 89 ee 83 e6 01 31 ff e8 e6 73 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 91 6f 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 75 6f 0b 00 eb e4 44 RSP: 0018:ffffc9000cbc7480 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 1ffff11017127ffd RCX: ffff8880508abc80 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000cbc7600 R08: ffffffff8f7cef77 R09: 1ffffffff1ef9dee R10: dffffc0000000000 R11: fffffbfff1ef9def R12: ffff8880b893ffe8 R13: dffffc0000000000 R14: ffff8880b883b240 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff888126139000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b30d22ff8 CR3: 0000000063bc8000 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:1381 [inline] flush_tlb_mm_range+0x6b1/0x12d0 arch/x86/mm/tlb.c:1471 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:490 [inline] tlb_flush_mmu+0x1a7/0x680 mm/mmu_gather.c:403 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:497 exit_mmap+0x444/0xb40 mm/mmap.c:1293 __mmput+0x118/0x430 kernel/fork.c:1133 exit_mm+0x1da/0x2c0 kernel/exit.c:582 do_exit+0x648/0x2300 kernel/exit.c:954 do_group_exit+0x21c/0x2d0 kernel/exit.c:1107 get_signal+0x1285/0x1340 kernel/signal.c:3034 arch_do_signal_or_restart+0xa0/0x790 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x72/0x130 kernel/entry/common.c:40 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fdbc3f8f749 Code: Unable to access opcode bytes at 0x7fdbc3f8f71f. RSP: 002b:00007fdbc4e690e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007fdbc41e6098 RCX: 00007fdbc3f8f749 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fdbc41e6098 RBP: 00007fdbc41e6090 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fdbc41e6128 R14: 00007ffec04df480 R15: 00007ffec04df568