GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=8324/1/0x4000000000000000 softirq=73615/73616 fqs=0 rcu: (detected by 1, t=10506 jiffies, g=76117, q=359 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 13564 Comm: syz.3.1879 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:its_return_thunk+0x0/0x10 arch/x86/lib/retpoline.S:417 Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 e9 db 3d e9 f5 cc RSP: 0018:ffffc90000007e18 EFLAGS: 00000046 RAX: 0000000080010001 RBX: 0000000000000000 RCX: 0000000000000001 RDX: ffff888020baca80 RSI: ffffffff8b84c19a RDI: ffff8880263f8300 RBP: ffff8880b8428658 R08: 0000000000000005 R09: 000000000000001f R10: 0000000000000001 R11: 0000000000000001 R12: ffff8880263f8300 R13: ffff8880263f8318 R14: ffff8880b8428608 R15: ffff8880b8428658 FS: 00007f5eaa4a06c0(0000) GS:ffff888124386000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c33c2e5 CR3: 000000002638f000 CR4: 00000000003526f0 Call Trace: rb_add_linked include/linux/rbtree.h:283 [inline] timerqueue_linked_add+0x27a/0x430 lib/timerqueue.c:96 enqueue_hrtimer+0x1ad/0x2f0 kernel/time/hrtimer.c:1117 __run_hrtimer kernel/time/hrtimer.c:1946 [inline] __hrtimer_run_queues+0x73d/0xa00 kernel/time/hrtimer.c:1994 hrtimer_interrupt+0x3e5/0x940 kernel/time/hrtimer.c:2113 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] __sysvec_apic_timer_interrupt+0x10b/0x460 arch/x86/kernel/apic/apic.c:1067 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline] sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1061 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:jhash2 include/linux/jhash.h:137 [inline] RIP: 0010:__futex_hash_private kernel/futex/core.c:194 [inline] RIP: 0010:__futex_hash+0x2dd/0x810 kernel/futex/core.c:423 Code: 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 f2 04 00 00 41 8b 46 04 <48> 8d 7b 0c 48 89 fa 89 44 24 04 48 c1 ea 03 48 b8 00 00 00 00 00 RSP: 0018:ffffc9000f357bf0 EFLAGS: 00000246 RAX: 000000000000000f RBX: ffffc9000f357ce0 RCX: ffffc9000e329000 RDX: 0000000000000000 RSI: ffffffff81fa88cb RDI: ffff88804db3e004 RBP: 00000000ffffffff R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffffc9000f357cf0 R13: 0000000000000fac R14: ffff88804db3e000 R15: 0000000000000000 futex_hash+0x3d/0x370 kernel/futex/core.c:309 class_hb_constructor kernel/futex/futex.h:240 [inline] futex_wake+0x141/0x530 kernel/futex/waitwake.c:172 do_futex+0x32b/0x350 kernel/futex/syscalls.c:135 __do_sys_futex kernel/futex/syscalls.c:207 [inline] __se_sys_futex kernel/futex/syscalls.c:188 [inline] __x64_sys_futex+0x34f/0x4d0 kernel/futex/syscalls.c:188 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5ea959ce59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5eaa4a00e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: ffffffffffffffda RBX: 00007f5ea9815fa8 RCX: 00007f5ea959ce59 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f5ea9815fac RBP: 00007f5ea9815fa0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f5ea9816038 R14: 00007ffc7a42e680 R15: 00007ffc7a42e768 rcu: rcu_preempt kthread starved for 10506 jiffies! g76117 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:27848 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5388 [inline] __schedule+0x1295/0x67a0 kernel/sched/core.c:7189 __schedule_loop kernel/sched/core.c:7268 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7283 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 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: 13562 Comm: syz.5.1875 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:210 Code: f6 7f 5c 00 48 89 df 5b e9 bd 10 62 00 be 03 00 00 00 5b e9 12 9e f0 02 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 65 8b 05 05 0f 01 12 48 8b 34 24 65 48 8b 15 e1 0e 01 RSP: 0018:ffffc9000e887648 EFLAGS: 00000202 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81fc0d0d RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff88807c9e0000 RBP: ffff8880b8443360 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003 R13: ffffed101708866d R14: 0000000000000001 R15: ffff8880b853c600 FS: 0000000000000000(0000) GS:ffff888124486000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5eaa34da08 CR3: 000000001c337000 CR4: 00000000003526f0 Call Trace: native_pause arch/x86/include/asm/vdso/processor.h:13 [inline] cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline] csd_lock_wait kernel/smp.c:342 [inline] smp_call_function_many_cond+0x587/0x1700 kernel/smp.c:892 on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1057 __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+0x45f/0x16f0 arch/x86/mm/tlb.c:1451 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 exit_mmap+0x454/0xa10 mm/mmap.c:1313 __mmput+0x12a/0x410 kernel/fork.c:1178 mmput+0x67/0x80 kernel/fork.c:1201 exit_mm kernel/exit.c:582 [inline] do_exit+0x8b2/0x2af0 kernel/exit.c:964 do_group_exit+0xd5/0x2a0 kernel/exit.c:1119 get_signal+0x20ff/0x2210 kernel/signal.c:3037 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] exit_to_user_mode_loop+0x98/0x670 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f811019ce59 Code: Unable to access opcode bytes at 0x7f811019ce2f. RSP: 002b:00007f8110fad0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f8110416188 RCX: 00007f811019ce59 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f8110416188 RBP: 00007f8110416180 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f8110416218 R14: 00007ffd667e1d60 R15: 00007ffd667e1e48