rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=2234/1/0x4000000000000000 softirq=204096/204099 fqs=5 rcu: (detected by 0, t=10502 jiffies, g=206957, q=397 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 5562 Comm: syz.2.9332 Not tainted 6.15.0-syzkaller-12331-gcfc4ca8986bb #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:__lock_is_held kernel/locking/lockdep.c:5604 [inline] RIP: 0010:lock_is_held_type+0xaa/0x190 kernel/locking/lockdep.c:5943 Code: 41 83 bd e8 0a 00 00 00 7e 48 4c 89 eb 48 81 c3 f0 0a 00 00 45 31 ff 49 83 ff 31 73 24 48 89 df 4c 89 f6 e8 78 02 00 00 85 c0 <75> 2a 49 ff c7 49 63 85 e8 0a 00 00 48 83 c3 28 49 39 c7 7c d8 eb RSP: 0018:ffffc90000a08c28 EFLAGS: 00000002 RAX: 0000000000000001 RBX: ffff88802b98e590 RCX: a8bb22024f176300 RDX: ffff88802b98da00 RSI: ffff88807a46b300 RDI: ffff88802b98e590 RBP: 00000000ffffffff R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff5200014117c R12: 0000000000000046 R13: ffff88802b98da00 R14: ffff88807a46b300 R15: 0000000000000004 FS: 0000000000000000(0000) GS:ffff888125d55000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b33c1eff8 CR3: 000000000df38000 CR4: 0000000000350ef0 Call Trace: lock_is_held include/linux/lockdep.h:249 [inline] advance_sched+0x1d2/0xc90 net/sched/sch_taprio.c:929 __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+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:lock_acquire+0x175/0x360 kernel/locking/lockdep.c:5875 Code: 00 00 00 00 9c 8f 44 24 30 f7 44 24 30 00 02 00 00 0f 85 cd 00 00 00 f7 44 24 08 00 02 00 00 74 01 fb 65 48 8b 05 3b 7a fe 10 <48> 3b 44 24 58 0f 85 f2 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e RSP: 0018:ffffc900036f74f0 EFLAGS: 00000206 RAX: a8bb22024f176300 RBX: 0000000000000000 RCX: a8bb22024f176300 RDX: 0000000000000000 RSI: ffffffff8db69626 RDI: ffffffff8be28340 RBP: ffffffff822eebf7 R08: 0000000000000000 R09: ffffffff822eebf7 R10: dffffc0000000000 R11: fffff9400036a851 R12: 0000000000000002 R13: ffffffff8e13f060 R14: 0000000000000000 R15: 0000000000000246 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:841 [inline] page_table_check_clear+0x1a4/0x700 mm/page_table_check.c:77 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: 0033:0x7fe198d8e929 Code: Unable to access opcode bytes at 0x7fe198d8e8ff. RSP: 002b:00007ffc1ef6e588 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe198d8e929 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007ffc1ef6e5ec R08: 000000041ef6e67f R09: 00000000000927c0 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000004 R13: 00000000000927c0 R14: 000000000028fe6f R15: 00007ffc1ef6e640 rcu: rcu_preempt kthread starved for 10492 jiffies! g206957 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:26400 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+0x711/0x8a0 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: 0 UID: 0 PID: 23458 Comm: kworker/u8:2 Not tainted 6.15.0-syzkaller-12331-gcfc4ca8986bb #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: events_unbound toggle_allocation_gate RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_many_cond+0xf6e/0x12d0 kernel/smp.c:885 Code: 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 00 eb e5 44 89 RSP: 0018:ffffc90003daf6a0 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b863cb40 RCX: ffff888027355a00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90003daf800 R08: ffffffff8fa100f7 R09: 1ffffffff1f4201e R10: dffffc0000000000 R11: fffffbfff1f4201f R12: 1ffff110170e828d R13: dffffc0000000000 R14: 0000000000000001 R15: ffff8880b8741468 FS: 0000000000000000(0000) GS:ffff888125c55000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000555c50ff0168 CR3: 000000000df38000 CR4: 0000000000350ef0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1052 on_each_cpu include/linux/smp.h:71 [inline] smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2660 [inline] smp_text_poke_batch_finish+0x5e0/0x1100 arch/x86/kernel/alternative.c:2870 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146 static_key_enable_cpuslocked+0x128/0x250 kernel/jump_label.c:210 static_key_enable+0x1a/0x20 kernel/jump_label.c:223 toggle_allocation_gate+0xad/0x240 mm/kfence/core.c:850 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402 kthread+0x711/0x8a0 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