rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=8104/1/0x4000000000000000 softirq=75416/75418 fqs=1 rcu: (detected by 0, t=10502 jiffies, g=57189, q=200 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 15289 Comm: syz.0.4138 Not tainted 6.15.0-rc4-syzkaller-00189-g2bfcee565c3a #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x0/0x20 kernel/kcov.c:313 Code: 0c 24 0f b7 d6 0f b7 f7 bf 03 00 00 00 e9 58 fe ff ff 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 48 8b 0c 24 89 f2 89 fe bf 05 00 00 00 e9 2a fe ff ff RSP: 0018:ffffc90000a08d88 EFLAGS: 00000046 RAX: 0000000000000001 RBX: ffff88807e829340 RCX: ffffffff81985b5c RDX: 1ffff1100fd0525f RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000001 R08: 0000000000000001 R09: fffff520001411a4 R10: 0000000000000003 R11: 0000000000000000 R12: ffff8880b8527840 R13: 0000000000000000 R14: ffff88807e829340 R15: ffffffff898149d0 FS: 0000000000000000(0000) GS:ffff888124ae1000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3694d74f98 CR3: 000000006844a000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: advance_sched+0xe9/0xc80 net/sched/sch_taprio.c:925 __run_hrtimer kernel/time/hrtimer.c:1761 [inline] __hrtimer_run_queues+0x1ff/0xad0 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline] __sysvec_apic_timer_interrupt+0x108/0x3f0 arch/x86/kernel/apic/apic.c:1055 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:rcu_is_watching_curr_cpu include/linux/context_tracking.h:128 [inline] RIP: 0010:rcu_is_watching+0x41/0xc0 kernel/rcu/tree.c:736 Code: a5 93 89 c5 83 f8 07 0f 87 82 00 00 00 48 8d 3c ed 00 cd ce 8d 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 <75> 5c 48 03 1c ed 00 cd ce 8d 48 b8 00 00 00 00 00 fc ff df 48 89 RSP: 0018:ffffc90004cb74b8 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ffffffff93a51de8 RCX: 0000000000000002 RDX: 1ffffffff1b9d9a1 RSI: ffffffff8bf48120 RDI: ffffffff8dcecd08 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 R10: 000000000000000c R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 trace_lock_acquire include/trace/events/lock.h:24 [inline] lock_acquire+0x2cd/0x350 kernel/locking/lockdep.c:5829 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock_sched include/linux/rcupdate.h:932 [inline] pfn_valid include/linux/mmzone.h:2117 [inline] page_table_check_clear+0x115/0xb30 mm/page_table_check.c:70 __page_table_check_pte_clear+0xf1/0x100 mm/page_table_check.c:154 page_table_check_pte_clear include/linux/page_table_check.h:49 [inline] ptep_get_and_clear_full arch/x86/include/asm/pgtable.h:1337 [inline] get_and_clear_full_ptes include/linux/pgtable.h:714 [inline] zap_present_folio_ptes mm/memory.c:1501 [inline] zap_present_ptes mm/memory.c:1586 [inline] do_zap_pte_range mm/memory.c:1687 [inline] zap_pte_range mm/memory.c:1731 [inline] zap_pmd_range mm/memory.c:1823 [inline] zap_pud_range mm/memory.c:1852 [inline] zap_p4d_range mm/memory.c:1873 [inline] unmap_page_range+0x2383/0x4390 mm/memory.c:1894 unmap_single_vma+0x194/0x2a0 mm/memory.c:1940 unmap_vmas+0x22c/0x490 mm/memory.c:1984 exit_mmap+0x1b9/0xb90 mm/mmap.c:1284 __mmput+0x12a/0x410 kernel/fork.c:1379 mmput+0x62/0x70 kernel/fork.c:1401 exit_mm kernel/exit.c:589 [inline] do_exit+0x9d1/0x2c30 kernel/exit.c:940 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102 get_signal+0x2673/0x26d0 kernel/signal.c:3034 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218 do_syscall_64+0xda/0x260 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7faf8d18e969 Code: Unable to access opcode bytes at 0x7faf8d18e93f. RSP: 002b:00007faf8dff60e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007faf8d3b5fa8 RCX: 00007faf8d18e969 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007faf8d3b5fa8 RBP: 00007faf8d3b5fa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007faf8d3b5fac R13: 0000000000000000 R14: 00007ffeaf6e2410 R15: 00007ffeaf6e24f8 rcu: rcu_preempt kthread starved for 10500 jiffies! g57189 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:27704 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x116f/0x5de0 kernel/sched/core.c:6767 __schedule_loop kernel/sched/core.c:6845 [inline] schedule+0xe7/0x3a0 kernel/sched/core.c:6860 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2046 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2248 kthread+0x3c2/0x780 kernel/kthread.c:464 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153 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: 15291 Comm: syz.5.4140 Not tainted 6.15.0-rc4-syzkaller-00189-g2bfcee565c3a #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_many_cond+0x4a5/0x1290 kernel/smp.c:885 Code: 89 ee e8 be 12 0c 00 85 ed 74 48 48 8b 44 24 20 49 89 c4 83 e0 07 49 c1 ec 03 48 89 c5 4d 01 f4 83 c5 03 e8 5d 17 0c 00 f3 90 <41> 0f b6 04 24 40 38 c5 7c 08 84 c0 0f 85 de 0b 00 00 8b 43 08 31 RSP: 0018:ffffc90003e3f7c8 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b853f740 RCX: ffffffff81af1bb9 RDX: ffff888031ea2440 RSI: ffffffff81af1b93 RDI: 0000000000000005 RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffffed10170a7ee9 R13: 0000000000000001 R14: dffffc0000000000 R15: ffff8880b843b040 FS: 0000000000000000(0000) GS:ffff8881249e1000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2ed15ffc CR3: 0000000061d9f000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1052 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1275 [inline] flush_tlb_mm_range+0x322/0x1780 arch/x86/mm/tlb.c:1365 tlb_flush arch/x86/include/asm/tlb.h:23 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:480 [inline] tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:470 [inline] tlb_flush_mmu mm/mmu_gather.c:403 [inline] tlb_finish_mmu+0x3c9/0x7b0 mm/mmu_gather.c:496 exit_mmap+0x403/0xb90 mm/mmap.c:1297 __mmput+0x12a/0x410 kernel/fork.c:1379 mmput+0x62/0x70 kernel/fork.c:1401 exit_mm kernel/exit.c:589 [inline] do_exit+0x9d1/0x2c30 kernel/exit.c:940 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102 get_signal+0x2673/0x26d0 kernel/signal.c:3034 arch_do_signal_or_restart+0x8f/0x7d0 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218 do_syscall_64+0xda/0x260 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff3c5d8e969 Code: Unable to access opcode bytes at 0x7ff3c5d8e93f. RSP: 002b:00007ff3c6b160e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 00007ff3c5fb5fa8 RCX: 00007ff3c5d8e969 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007ff3c5fb5fac RBP: 00007ff3c5fb5fa0 R08: 00007ff3c6b17000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff3c5fb5fac R13: 0000000000000000 R14: 00007ffd9f497590 R15: 00007ffd9f497678