rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (2 GPs behind) idle=09fc/1/0x4000000000000000 softirq=14136/14137 fqs=0 rcu: (detected by 1, t=10502 jiffies, g=11097, q=1074 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 6053 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:check_preemption_disabled+0x22/0xe0 lib/smp_processor_id.c:53 Code: 90 90 90 90 90 90 90 90 55 41 57 41 56 53 65 8b 05 57 73 6d 07 65 8b 0d 4c 73 6d 07 f7 c1 ff ff ff 7f 74 0c 5b 41 5e 41 5f 5d cc cc cc cc cc 9c 59 f7 c1 00 02 00 00 74 ea 65 4c 8b 3d fe 72 RSP: 0018:ffffc90000007d18 EFLAGS: 00000002 RAX: 0000000000000000 RBX: ffff88802f086338 RCX: 0000000000010002 RDX: ffff8880283bdb80 RSI: ffffffff8c27c8e0 RDI: ffffffff8c27c8a0 RBP: ffffc90000007e88 R08: ffffffff9011a7b7 R09: 1ffffffff20234f6 R10: dffffc0000000000 R11: fffffbfff20234f7 R12: ffff88802f086300 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff88812545d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055f9e5226660 CR3: 000000000e54c000 CR4: 00000000003526f0 Call Trace: rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] rcu_is_watching+0x15/0xb0 kernel/rcu/tree.c:752 trace_hrtimer_expire_exit include/trace/events/timer.h:306 [inline] __run_hrtimer kernel/time/hrtimer.c:1788 [inline] __hrtimer_run_queues+0x5c7/0xcc0 kernel/time/hrtimer.c:1849 hrtimer_interrupt+0x42b/0x1010 kernel/time/hrtimer.c:1911 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x102/0x460 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_acquire+0x20b/0x2e0 kernel/locking/lockdep.c:5872 Code: e9 30 ff ff ff e8 75 16 0d 0a f7 c3 00 02 00 00 0f 84 38 ff ff ff 65 48 8b 05 f1 a3 7a 11 48 3b 44 24 30 75 33 fb 48 83 c4 38 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 56 fc 0f 0a cc 48 8d 3d 2e 6f 73 RSP: 0018:ffffc9000488f550 EFLAGS: 00000296 RAX: ed67e50e744c4200 RBX: 0000000000000246 RCX: 0000000080000001 RDX: 00000000747a73c7 RSI: ffffffff8e168ad5 RDI: ffffffff8c27c900 RBP: 0000000000000000 R08: ffffffff823c1fa4 R09: ffffffff8e75e520 R10: dffffc0000000000 R11: fffff94000094fe9 R12: 0000000000000002 R13: ffffffff8e75e520 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:312 [inline] rcu_read_lock include/linux/rcupdate.h:850 [inline] page_table_check_clear+0x164/0x5f0 mm/page_table_check.c:77 ptep_get_and_clear_full arch/x86/include/asm/jump_label.h:-1 [inline] clear_full_ptes include/linux/pgtable.h:906 [inline] zap_present_folio_ptes mm/memory.c:1656 [inline] zap_present_ptes mm/memory.c:1725 [inline] do_zap_pte_range mm/memory.c:1827 [inline] zap_pte_range mm/memory.c:1929 [inline] zap_pmd_range mm/memory.c:2021 [inline] zap_pud_range mm/memory.c:2049 [inline] zap_p4d_range mm/memory.c:2070 [inline] unmap_page_range+0x33d9/0x48f0 mm/memory.c:2091 unmap_single_vma mm/memory.c:2133 [inline] unmap_vmas+0x48f/0x6a0 mm/memory.c:2171 exit_mmap+0x280/0xa10 mm/mmap.c:1302 __mmput+0x118/0x430 kernel/fork.c:1175 exit_mm+0x168/0x220 kernel/exit.c:581 do_exit+0x6a2/0x23c0 kernel/exit.c:964 do_group_exit+0x21b/0x2d0 kernel/exit.c:1118 __do_sys_exit_group kernel/exit.c:1129 [inline] __se_sys_exit_group kernel/exit.c:1127 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1127 x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f076131d6c5 Code: Unable to access opcode bytes at 0x7f076131d69b. RSP: 002b:00007ffc5e39fdd8 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f076131d6c5 RDX: 00000000000000e7 RSI: ffffffffffffff88 RDI: 0000000000000001 RBP: 00007ffc5e3a03e8 R08: 000055f9f7c5b2c0 R09: 0000000000000002 R10: 00000000000000e0 R11: 0000000000000206 R12: 00007ffc5e39fe20 R13: 000055f9f7c5c8a0 R14: 00007ffc5e3a0060 R15: 00007ffc5e39fe10 rcu: rcu_preempt kthread starved for 10502 jiffies! g11097 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:27656 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0x15dd/0x52d0 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] schedule+0x164/0x360 kernel/sched/core.c:7008 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 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: 1 UID: 0 PID: 6014 Comm: syz-executor.0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:check_kcov_mode kernel/kcov.c:185 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x30/0x70 kernel/kcov.c:217 Code: 04 24 65 48 8b 0d f8 8e 56 11 65 8b 15 19 8f 56 11 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 a4 16 00 00 00 74 2c <8b> 91 80 16 00 00 83 fa 02 75 21 48 8b 91 88 16 00 00 48 8b 32 48 RSP: 0018:ffffc9000457f578 EFLAGS: 00000246 RAX: ffffffff81b9bebd RBX: 1ffff110170c8515 RCX: ffff88801cf35b80 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000457f6a8 R08: ffffffff9011a7b7 R09: 1ffffffff20234f6 R10: dffffc0000000000 R11: fffffbfff20234f7 R12: ffff8880b86428a8 R13: dffffc0000000000 R14: ffff8880b873bf80 R15: 0000000000000000 FS: 0000000006d604c0(0000) GS:ffff88812555d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000a83b72 CR3: 000000007f4a0000 CR4: 00000000003526f0 Call Trace: csd_lock_wait kernel/smp.c:342 [inline] smp_call_function_many_cond+0xcfd/0x12c0 kernel/smp.c:877 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043 __flush_tlb_multi arch/x86/include/asm/paravirt.h:57 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1382 [inline] flush_tlb_mm_range+0x5c3/0x10c0 arch/x86/mm/tlb.c:1472 dup_mmap+0x17a2/0x1d90 mm/mmap.c:1906 dup_mm kernel/fork.c:1531 [inline] copy_mm+0x13b/0x4a0 kernel/fork.c:1583 copy_process+0x18b6/0x3cd0 kernel/fork.c:2223 kernel_clone+0x248/0x8e0 kernel/fork.c:2653 __do_sys_clone kernel/fork.c:2794 [inline] __se_sys_clone kernel/fork.c:2778 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2778 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x4701e2 Code: 89 e7 e8 51 55 fa ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 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 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffc73068e30 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffc73068e30 RCX: 00000000004701e2 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000006d60790 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffc73069030