rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (0 ticks this GP) idle=eb44/1/0x4000000000000000 softirq=129466/129466 fqs=1 rcu: (detected by 1, t=10502 jiffies, g=97401, q=262 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 17147 Comm: syz.1.3958 Not tainted 6.16.0-rc1-syzkaller-00203-g4774cfe3543a #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x20/0x70 kernel/kcov.c:217 Code: 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 65 48 8b 0c 25 08 a0 99 92 65 8b 15 d8 54 d9 10 81 e2 00 01 ff 00 74 11 <81> fa 00 01 00 00 75 35 83 b9 3c 16 00 00 00 74 2c 8b 91 18 16 00 RSP: 0018:ffffc90000007ce8 EFLAGS: 00000006 RAX: ffffffff8b5b367f RBX: 0000000000000000 RCX: ffff888029949e00 RDX: 0000000000010000 RSI: ffff88807c21f340 RDI: ffff88807c21f340 RBP: ffffc90000007e90 R08: ffffffff8f9fdef7 R09: 1ffffffff1f3fbde R10: dffffc0000000000 R11: fffffbfff1f3fbdf R12: ffff88807c21f340 R13: dffffc0000000000 R14: ffff8880b8627d10 R15: ffff88807c21f340 FS: 0000000000000000(0000) GS:ffff888125c86000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b30118ff8 CR3: 000000000df38000 CR4: 00000000003526f0 Call Trace: timerqueue_add+0x5f/0x200 lib/timerqueue.c:38 __run_hrtimer kernel/time/hrtimer.c:1778 [inline] __hrtimer_run_queues+0x656/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:preempt_count_add+0x0/0x1a0 kernel/sched/core.c:5861 Code: c1 7c 97 48 8b 3c 24 e8 5e d6 90 00 eb 8c e9 f1 fe ff ff 0f 1f 80 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 41 56 53 49 bf 00 00 00 00 00 fc ff df 48 c7 c0 RSP: 0018:ffffc90004b57550 EFLAGS: 00000282 RAX: ffffffff822ccb1f RBX: 0000000000000160 RCX: ffff888029949e00 RDX: 0000000000000000 RSI: 000000000005e8d6 RDI: 0000000000000001 RBP: ffffc90004b57890 R08: ffffea00017a3587 R09: 1ffffd40002f46b0 R10: dffffc0000000000 R11: fffff940002f46b1 R12: dffffc0000000000 R13: 1ffffd40002f46b3 R14: 000000000005e8d6 R15: ffff88813ffface0 rcu_read_lock_sched include/linux/rcupdate.h:930 [inline] pfn_valid+0xb3/0x490 include/linux/mmzone.h:2158 page_table_check_clear+0x21/0x700 mm/page_table_check.c:70 ptep_get_and_clear_full arch/x86/include/asm/jump_label.h:-1 [inline] get_and_clear_full_ptes include/linux/pgtable.h:714 [inline] zap_present_folio_ptes mm/memory.c:1505 [inline] zap_present_ptes mm/memory.c:1590 [inline] do_zap_pte_range mm/memory.c:1691 [inline] zap_pte_range mm/memory.c:1735 [inline] zap_pmd_range mm/memory.c:1827 [inline] zap_pud_range mm/memory.c:1856 [inline] zap_p4d_range mm/memory.c:1877 [inline] unmap_page_range+0x3249/0x41c0 mm/memory.c:1898 unmap_single_vma mm/memory.c:1941 [inline] unmap_vmas+0x399/0x580 mm/memory.c:1985 exit_mmap+0x248/0xb50 mm/mmap.c:1284 __mmput+0x118/0x420 kernel/fork.c:1121 exit_mm+0x1da/0x2c0 kernel/exit.c:581 do_exit+0x640/0x22e0 kernel/exit.c:943 do_group_exit+0x21c/0x2d0 kernel/exit.c:1104 __do_sys_exit_group kernel/exit.c:1115 [inline] __se_sys_exit_group kernel/exit.c:1113 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1113 x64_sys_call+0x21ba/0x21c0 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7efdc378e929 Code: Unable to access opcode bytes at 0x7efdc378e8ff. RSP: 002b:00007ffd77b0c1c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007efdc378e929 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007ffd77b0c22c R08: 0000000977b0c2bf R09: 00000000000927c0 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000414 R13: 00000000000927c0 R14: 000000000009abb1 R15: 00007ffd77b0c280 rcu: rcu_preempt kthread starved for 10500 jiffies! g97401 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:27128 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5396 [inline] __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6785 __schedule_loop kernel/sched/core.c:6863 [inline] schedule+0x165/0x360 kernel/sched/core.c:6878 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2054 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2256 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 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: 5840 Comm: syz-executor Not tainted 6.16.0-rc1-syzkaller-00203-g4774cfe3543a #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_many_cond+0xf69/0x12d0 kernel/smp.c:885 Code: 00 45 8b 2f 44 89 ee 83 e6 01 31 ff e8 50 78 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 fb 73 0b 00 eb 37 f3 90 <43> 0f b6 04 2c 84 c0 75 10 41 f7 07 01 00 00 00 74 1e e8 e0 73 0b RSP: 0018:ffffc9000453f580 EFLAGS: 00000293 RAX: ffffffff81b4d760 RBX: ffff8880b873c9c0 RCX: ffff888033ddda00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000453f6e0 R08: ffffffff8f9fdef7 R09: 1ffffffff1f3fbde R10: dffffc0000000000 R11: fffffbfff1f3fbdf R12: 1ffff110170c868d R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8880b8643468 FS: 00005555875a0500(0000) GS:ffff888125d86000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8655ce56c0 CR3: 0000000073ff4000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x6b1/0x12c0 arch/x86/mm/tlb.c:1451 dup_mmap+0x15a0/0x1ac0 mm/mmap.c:1877 dup_mm kernel/fork.c:1477 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1529 copy_process+0x1706/0x3c00 kernel/fork.c:2169 kernel_clone+0x224/0x7f0 kernel/fork.c:2599 __do_sys_clone kernel/fork.c:2742 [inline] __se_sys_clone kernel/fork.c:2726 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2726 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8654f85193 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:00007ffe70c45548 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f8654f85193 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 00005555875a07d0 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000000927c0 R14: 000000000009abfd R15: 00007ffe70c456e0