rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=8754/1/0x4000000000000000 softirq=31057/31063 fqs=1 rcu: (detected by 1, t=10505 jiffies, g=25537, q=1184 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 5827 Comm: syz-executor Not tainted 6.15.0-next-20250604-syzkaller #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:write_comp_data kernel/kcov.c:246 [inline] RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x18/0x90 kernel/kcov.c:321 Code: 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 65 48 8b 0c 25 08 30 9d 92 65 8b 15 98 cc dc 10 <81> e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 57 83 b9 3c 16 00 00 RSP: 0018:ffffc90000007c68 EFLAGS: 00000802 RAX: ffffffff8986777a RBX: ffff88802e47f928 RCX: ffff88802a733c00 RDX: 0000000000010002 RSI: 0000000000000000 RDI: 0000000000000010 RBP: 0000000000000001 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000000f7c R12: dffffc0000000000 R13: ffff88802e47d0c0 R14: ffff88802e47d140 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888125c4d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000000df38000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: advance_sched+0x51a/0xc90 net/sched/sch_taprio.c:961 __run_hrtimer kernel/time/hrtimer.c:1761 [inline] __hrtimer_run_queues+0x52c/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+0x108/0x410 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:folio_remove_rmap_ptes+0x6ec/0xaf0 mm/rmap.c:1805 Code: 75 00 4c 89 f6 48 81 e6 00 20 00 00 31 ff e8 2b 98 ae ff 49 81 e6 00 20 00 00 0f 85 13 01 00 00 e8 39 93 ae ff 48 83 c4 58 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 20 93 ae ff e9 fe RSP: 0018:ffffc9000438f370 EFLAGS: 00000282 RAX: ffffffff8211cb67 RBX: ffff888066b5bb00 RCX: ffff88802a733c00 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffffea00019611f3 R09: 1ffffd400032c23e R10: dffffc0000000000 R11: fffff9400032c23f R12: ffffea00019611c0 R13: ffff8880331d4a20 R14: 0000000000000000 R15: dffffc0000000000 zap_present_folio_ptes mm/memory.c:1529 [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+0x1e59/0x41c0 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 get_signal+0x1286/0x1340 kernel/signal.c:3034 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:111 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline] do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7eff3c384b53 Code: Unable to access opcode bytes at 0x7eff3c384b29. RSP: 002b:00007ffe8cccc958 EFLAGS: 00000202 ORIG_RAX: 000000000000003d RAX: fffffffffffffe00 RBX: 00000000000016ca RCX: 00007eff3c384b53 RDX: 0000000040000000 RSI: 00007ffe8cccc96c RDI: 00000000ffffffff RBP: 00007ffe8cccc96c R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000008 R13: 0000000000000003 R14: 0000000000000009 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 10500 jiffies! g25537 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+0x16f5/0x4d00 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: 5500 Comm: dhcpcd Not tainted 6.15.0-next-20250604-syzkaller #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 60 78 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 0b 74 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 f0 73 0b RSP: 0018:ffffc90003c7f560 EFLAGS: 00000293 RAX: ffffffff81b4eab0 RBX: ffff8880b873cb40 RCX: ffff88802f2f5a00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90003c7f6c0 R08: ffffffff8fa123f7 R09: 1ffffffff1f4247e R10: dffffc0000000000 R11: fffffbfff1f4247f R12: 1ffff110170c86b5 R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8880b86435a8 FS: 00007fb5a7f65740(0000) GS:ffff888125d4d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007eff3c57fab8 CR3: 00000000788ec000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 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+0x21e/0x870 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: 0033:0x7fb5a8039636 Code: 89 df e8 6d e8 f6 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 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffd1da79e40 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffd1da79e48 RCX: 00007fb5a8039636 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffd1da9a390 R08: 0000000000000000 R09: 0000000000000001 R10: 00007fb5a7f65a10 R11: 0000000000000246 R12: 00007ffd1da79f80 R13: 0000000000000000 R14: 0000000000000000 R15: 000056047e3f7ac0