rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=09fc/1/0x4000000000000000 softirq=105624/105625 fqs=0 rcu: (detected by 1, t=10502 jiffies, g=96817, q=180 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 19600 Comm: syz.8.3658 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:__lock_acquire+0x2fc/0x2cf0 kernel/locking/lockdep.c:5174 Code: 94 24 20 01 00 00 49 89 54 c7 18 65 8b 15 78 4d 04 11 31 f6 85 d2 40 0f 95 c6 31 d2 41 83 be ec 0a 00 00 00 0f 95 c2 c1 e2 0d e6 0e 09 d6 8b 54 24 20 c1 e2 0f 0f b7 d2 09 f2 41 83 e5 03 41 RSP: 0018:ffffc90000007b48 EFLAGS: 00000046 RAX: 0000000000000005 RBX: 0000000000000000 RCX: 0000000000000073 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000001 R08: ffffffff81ae9342 R09: ffff8880b8628298 R10: dffffc0000000000 R11: fffffbfff1f45b3f R12: 0000000000000000 R13: 0000000000000000 R14: ffff888021bd5ac0 R15: ffff888021bd65c8 FS: 00007f2dc28506c0(0000) GS:ffff888125bf9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c373e6d CR3: 0000000030074000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock_irq+0x3d/0x50 kernel/locking/spinlock.c:170 __run_hrtimer kernel/time/hrtimer.c:1789 [inline] __hrtimer_run_queues+0x5e2/0xc30 kernel/time/hrtimer.c:1849 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1911 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x102/0x3e0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_acquire+0x222/0x340 kernel/locking/lockdep.c:5872 Code: ff ff ff e8 f0 41 c0 09 f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 0a 10 04 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d a7 bf 07 RSP: 0018:ffffc90003e97c80 EFLAGS: 00000282 RAX: 87f7cbd1d1314700 RBX: 0000000000000000 RCX: 0000000000000046 RDX: 00000000ddd44900 RSI: ffffffff8db8bddd RDI: ffffffff8be09760 RBP: ffffffff820b4e8f R08: ffffffff820b4e8f R09: ffff88807d745900 R10: dffffc0000000000 R11: ffffed100fae8b13 R12: 0000000000000001 R13: ffff88807d745900 R14: 0000000000000001 R15: 0000000000000246 down_read+0x47/0x2e0 kernel/locking/rwsem.c:1537 mmap_read_lock include/linux/mmap_lock.h:396 [inline] __mm_populate+0x16f/0x380 mm/gup.c:1942 mm_populate include/linux/mm.h:3680 [inline] vm_mmap_pgoff+0x387/0x4d0 mm/util.c:586 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2dc198f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f2dc2850038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f2dc1be5fa0 RCX: 00007f2dc198f749 RDX: b635773f06ebbee2 RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007f2dc1a13f91 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f2dc1be6038 R14: 00007f2dc1be5fa0 R15: 00007ffcd9e32d68 rcu: rcu_preempt kthread starved for 10502 jiffies! g96817 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:27488 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5290 [inline] __schedule+0x14db/0x5030 kernel/sched/core.c:6902 __schedule_loop kernel/sched/core.c:6984 [inline] schedule+0x165/0x360 kernel/sched/core.c:6999 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x11b0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9b/0x2d0 kernel/rcu/tree.c:2297 kthread+0x389/0x480 kernel/kthread.c:467 ret_from_fork+0x510/0xa50 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: 1 UID: 0 PID: 19591 Comm: syz.7.3654 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0xcc5/0x1260 kernel/smp.c:877 Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 b4 9a 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 5f 96 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 43 96 RSP: 0018:ffffc90003d0f5a0 EFLAGS: 00000246 RAX: ffffffff81b5835d RBX: 1ffff110170c85c1 RCX: 0000000000080000 RDX: ffffc90011031000 RSI: 000000000007ffff RDI: 0000000000080000 RBP: ffffc90003d0f6c8 R08: ffffffff8fa2d9f7 R09: 1ffffffff1f45b3e R10: dffffc0000000000 R11: fffffbfff1f45b3f R12: ffff8880b8642e08 R13: dffffc0000000000 R14: ffff8880b873bd80 R15: 0000000000000000 FS: 00007f2b0e9b56c0(0000) GS:ffff888125cf9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c2cfeb7 CR3: 00000000b3936000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043 __flush_tlb_multi arch/x86/include/asm/paravirt.h:57 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1382 [inline] flush_tlb_mm_range+0x5db/0x1100 arch/x86/mm/tlb.c:1472 dup_mmap+0x15fa/0x1b80 mm/mmap.c:1866 dup_mm kernel/fork.c:1529 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1581 copy_process+0x1812/0x3ba0 kernel/fork.c:2218 kernel_clone+0x21e/0x820 kernel/fork.c:2648 __do_sys_clone3 kernel/fork.c:2950 [inline] __se_sys_clone3+0x256/0x2d0 kernel/fork.c:2929 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2b0db8f749 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f2b0e9b4f08 EFLAGS: 00000246 ORIG_RAX: 00000000000001b3 RAX: ffffffffffffffda RBX: 0000000000000058 RCX: 00007f2b0db8f749 RDX: 00007f2b0e9b4f20 RSI: 0000000000000058 RDI: 00007f2b0e9b4f20 RBP: 00007f2b0dc13f91 R08: 0000000000000000 R09: 0000000000000058 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f2b0dde6038 R14: 00007f2b0dde5fa0 R15: 00007fffb4aa1d98