rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=05ec/1/0x4000000000000000 softirq=26818/26818 fqs=4 rcu: (detected by 0, t=10502 jiffies, g=20549, q=1671 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6604 Comm: sed Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026 RIP: 0010:write_comp_data+0x90/0xa0 kernel/kcov.c:268 Code: 00 00 4a 8d 14 dd 28 00 00 00 48 39 d7 72 1b 48 83 c6 01 48 89 30 4c 89 44 10 e0 4c 89 4c 10 e8 4c 89 54 10 f0 4a 89 4c d8 20 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 RSP: 0000:ffffc90000a18e40 EFLAGS: 00000046 RAX: 0000000001000001 RBX: ffff88802dc99300 RCX: ffffffff81f794f1 RDX: 0000000001000001 RSI: 0000000000000000 RDI: ffff888038cf8000 RBP: ffff8880b8528640 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8880b8528500 R14: 0000000000000001 R15: 0000000000000000 FS: 00007f9b494ecc80(0000) GS:ffff888123c4e000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005645fd394c68 CR3: 0000000035bb4000 CR4: 00000000003526f0 Call Trace: __remove_hrtimer+0xc1/0x650 kernel/time/hrtimer.c:1174 __run_hrtimer kernel/time/hrtimer.c:2054 [inline] __hrtimer_run_queues+0x352/0x9c0 kernel/time/hrtimer.c:2131 hrtimer_interrupt+0x441/0xaa0 kernel/time/hrtimer.c:2250 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x109/0x470 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:unwind_get_return_address+0x78/0xa0 arch/x86/kernel/unwind_orc.c:386 Code: 75 36 48 8b 7b 48 e8 37 dd 18 00 85 c0 74 cf 48 b8 00 00 00 00 00 fc ff df 48 89 ea 48 c1 ea 03 80 3c 02 00 75 1c 48 8b 43 48 <5b> 5d c3 cc cc cc cc e8 2c 17 c6 00 eb a0 48 89 ef e8 52 17 c6 00 RSP: 0000:ffffc90003247270 EFLAGS: 00000246 RAX: ffffffff8264ca79 RBX: ffffc90003247288 RCX: ffffc900032471dc RDX: 1ffff92000648e5a RSI: ffffffff8e36911a RDI: ffffffff8264ca79 RBP: ffffc900032472d0 R08: 0000000000000001 R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000017ce7 R12: ffffffff81f61260 R13: ffffc90003247348 R14: 0000000000000000 R15: ffff888038cf8000 arch_stack_walk+0xa6/0xf0 arch/x86/kernel/stacktrace.c:26 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 save_stack+0x162/0x1e0 mm/page_owner.c:183 __set_page_owner+0x8c/0x540 mm/page_owner.c:359 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871 prep_new_page mm/page_alloc.c:1879 [inline] get_page_from_freelist+0x110d/0x35d0 mm/page_alloc.c:3943 __alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436 alloc_pages_mpol+0x201/0x550 mm/mempolicy.c:2486 folio_alloc_mpol_noprof+0x36/0x260 mm/mempolicy.c:2505 vma_alloc_folio_noprof+0xed/0x1d0 mm/mempolicy.c:2540 folio_prealloc mm/memory.c:1289 [inline] alloc_anon_folio mm/memory.c:5387 [inline] do_anonymous_page+0xac9/0x2050 mm/memory.c:5482 do_pte_missing mm/memory.c:4698 [inline] handle_pte_fault mm/memory.c:6558 [inline] __handle_mm_fault+0x1ff3/0x2f60 mm/memory.c:6707 handle_mm_fault+0x363/0xa20 mm/memory.c:6876 do_user_addr_fault+0x59c/0x12f0 arch/x86/mm/fault.c:1343 handle_page_fault arch/x86/mm/fault.c:1483 [inline] exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1536 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595 RIP: 0033:0x7f9b4964dd34 Code: 8d 34 19 49 39 d0 49 89 70 60 0f 95 c2 48 29 d8 48 83 c1 10 0f b6 d2 48 83 c8 01 48 c1 e2 02 48 09 da 48 83 ca 01 48 89 51 f8 <48> 89 46 08 48 89 cf 4c 89 e6 48 89 4c 24 08 e8 18 c7 ff ff 48 8b RSP: 002b:00007ffc149a9b30 EFLAGS: 00010206 RAX: 00000000000173a1 RBX: 0000000000001010 RCX: 00005645fd393c60 RDX: 0000000000001011 RSI: 00005645fd394c60 RDI: 0000000000000000 RBP: ffffffffffffffc0 R08: 00007f9b49786ac0 R09: 0000000000000000 R10: 0000000000000004 R11: 0000000000000297 R12: 0000000000001000 R13: 0000000000000000 R14: 00000000000000ff R15: 00007f9b49786b20 rcu: rcu_preempt kthread starved for 9078 jiffies! g20549 f0x0 RCU_GP_WAIT_FQS(5) ->state=R ->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:26728 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7284 __schedule_loop kernel/sched/core.c:7361 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7376 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x8f0 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x17a/0x220 kernel/rcu/tree.c:2330 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 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: 5950 Comm: syz-execprog Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026 RIP: 0010:csd_lock_wait kernel/smp.c:363 [inline] RIP: 0010:csd_lock kernel/smp.c:396 [inline] RIP: 0010:smp_call_function_many_cond+0x57c/0x18c0 kernel/smp.c:944 Code: 00 00 00 00 00 fc ff df 48 89 ea 49 89 ec 48 c1 ea 03 41 83 e4 07 4c 8d 2c 02 41 83 c4 03 e8 cb c7 0c 00 f3 90 41 0f b6 45 00 <41> 38 c4 7c 08 84 c0 0f 85 51 11 00 00 44 8b 73 08 31 ff 41 83 e6 RSP: 0018:ffffc90003207a38 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b8541900 RCX: 0000000000000001 RDX: ffff888032dfa580 RSI: ffffffff81ff8025 RDI: ffff888032dfa580 RBP: ffff8880b8541908 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000003 R13: ffffed10170a8321 R14: 0000000000000001 R15: 0000000000000001 FS: 00001d2b750e8890(0000) GS:ffff888123b4e000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f084b63ffdc CR3: 00000000355aa000 CR4: 00000000003526f0 Call Trace: __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x3c9/0x1360 arch/x86/mm/tlb.c:1435 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:509 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:499 [inline] tlb_flush_mmu mm/mmu_gather.c:423 [inline] tlb_finish_mmu+0x3fe/0x810 mm/mmu_gather.c:549 madvise_finish_tlb mm/madvise.c:1842 [inline] madvise_finish_tlb mm/madvise.c:1839 [inline] do_madvise+0x26e/0x290 mm/madvise.c:2015 __do_sys_madvise mm/madvise.c:2023 [inline] __se_sys_madvise mm/madvise.c:2021 [inline] __x64_sys_madvise+0xa9/0x110 mm/madvise.c:2021 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x493db7 Code: 10 5d c3 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 48 8b 7c 24 08 48 8b 74 24 10 8b 54 24 18 48 c7 c0 1c 00 00 00 0f 05 <89> 44 24 20 c3 cc cc cc cc 48 8b 7c 24 08 8b 74 24 10 8b 54 24 14 RSP: 002b:00001d2b75073ed8 EFLAGS: 00000246 ORIG_RAX: 000000000000001c RAX: ffffffffffffffda RBX: 0000000000010000 RCX: 0000000000493db7 RDX: 0000000000000004 RSI: 0000000000010000 RDI: 00001d2b7c670000 RBP: 00001d2b75073f00 R08: 00009d2b7c67ffff R09: 0000000000000fff R10: 00009d2b7c670000 R11: 0000000000000246 R12: 000000000306d3c0 R13: 0000000000000003 R14: 00001d2b750b5a40 R15: 000000000306d440