rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=ea4c/1/0x4000000000000000 softirq=18707/18708 fqs=2 rcu: (detected by 0, t=10506 jiffies, g=17469, q=500 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6490 Comm: syz.0.185 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:__remove_hrtimer+0xde/0x440 kernel/time/hrtimer.c:1151 Code: b6 73 38 31 ff 44 89 f6 e8 0f 2a 14 00 45 84 f6 75 18 e8 b5 2f 14 00 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 9d 2f 14 00 48 8d 7b 18 44 88 7b 38 48 b8 00 00 00 00 00 fc ff RSP: 0018:ffffc90000a08e40 EFLAGS: 00000002 RAX: 0000000080010002 RBX: ffff8880256ec300 RCX: ffffffff81f45be1 RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff888078b3a500 RBP: ffff8880b8528600 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000 R13: ffff8880b85284c0 R14: 0000000000000001 R15: 0000000000000000 FS: 00007f9906e666c0(0000) GS:ffff888124476000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9906e65ff8 CR3: 000000002ce03000 CR4: 00000000003526f0 Call Trace: __run_hrtimer kernel/time/hrtimer.c:1910 [inline] __hrtimer_run_queues+0x359/0xa00 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:check_kcov_mode kernel/kcov.c:185 [inline] RIP: 0010:write_comp_data+0x3a/0x90 kernel/kcov.c:246 Code: 65 48 8b 3d 70 1b 02 12 a9 00 01 ff 00 74 1b f6 c4 01 74 07 a9 00 00 ff 00 74 05 c3 cc cc cc cc 8b 87 cc 16 00 00 85 c0 74 f1 <8b> 87 a8 16 00 00 83 f8 03 75 e6 48 8b 87 b0 16 00 00 8b bf ac 16 RSP: 0018:ffffc9000d9afc10 EFLAGS: 00000246 RAX: 0000000080000001 RBX: ffffc900077a7b48 RCX: ffffffff81fae313 RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff888078b3a500 RBP: ffff888067e820c8 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffffc900077a7b78 R13: 0000000000000001 R14: ffffc9000d9afcc0 R15: 00007f9906216000 __futex_unqueue+0xb3/0x1a0 kernel/futex/core.c:858 __futex_wake_mark kernel/futex/waitwake.c:115 [inline] __futex_wake_mark kernel/futex/waitwake.c:110 [inline] futex_wake_mark+0x15e/0x250 kernel/futex/waitwake.c:140 futex_wake+0x428/0x530 kernel/futex/waitwake.c:191 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+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f9905f9cdd9 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:00007f9906e660e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: ffffffffffffffda RBX: 00007f9906216188 RCX: 00007f9905f9cdd9 RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f990621618c RBP: 00007f9906216180 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f9906216218 R14: 00007ffd1e138f90 R15: 00007ffd1e139078 rcu: rcu_preempt kthread starved for 10495 jiffies! g17469 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:27848 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5387 [inline] __schedule+0x10e9/0x6820 kernel/sched/core.c:7188 __schedule_loop kernel/sched/core.c:7267 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7282 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: 0 UID: 0 PID: 5611 Comm: syz-executor 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:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0x5ad/0x1700 kernel/smp.c:892 Code: 89 7c 0c 00 f3 90 41 0f b6 45 00 41 38 c4 7c 08 84 c0 0f 85 63 0f 00 00 8b 45 08 31 ff 83 e0 01 41 89 c6 89 c6 e8 13 77 0c 00 <45> 85 f6 75 d0 e8 59 7c 0c 00 e8 54 7c 0c 00 83 c3 01 bf 07 00 00 RSP: 0018:ffffc9000422f620 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81fc0f3d RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff88807cbda500 RBP: ffff8880b8540f40 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003 R13: ffffed10170a81e9 R14: 0000000000000001 R15: ffff8880b843c5c0 FS: 0000555575397500(0000) GS:ffff888124376000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff76ad456b8 CR3: 000000005b951000 CR4: 00000000003526f0 Call Trace: 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 dup_mmap+0x12e8/0x2180 mm/mmap.c:1905 dup_mm kernel/fork.c:1534 [inline] copy_mm kernel/fork.c:1586 [inline] copy_process+0x7b37/0x7fa0 kernel/fork.c:2262 kernel_clone+0x12e/0x9c0 kernel/fork.c:2723 __do_sys_clone+0xd9/0x120 kernel/fork.c:2864 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff769fc5852 Code: 89 e7 e8 71 8b f7 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffc4800f520 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffc4800f520 RCX: 00007ff769fc5852 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffc4800f6ac R08: 0000000000000000 R09: 0000000000000001 R10: 00005555753977d0 R11: 0000000000000246 R12: 0000000000000001 R13: 00000000000927c0 R14: 000000000001e434 R15: 00007ffc4800f700