rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5839/1:b..l rcu: (detected by 1, t=10502 jiffies, g=29973, q=770 ncpus=2) task:syz-executor state:R running task stack:21592 pid:5839 tgid:5839 ppid:5818 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5260 [inline] __schedule+0x149b/0x4fd0 kernel/sched/core.c:6867 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:7051 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] copy_pte_range mm/memory.c:1331 [inline] copy_pmd_range+0x74f2/0x7e00 mm/memory.c:1392 copy_pud_range mm/memory.c:1429 [inline] copy_p4d_range mm/memory.c:1453 [inline] copy_page_range+0xb88/0x11d0 mm/memory.c:1535 dup_mmap+0xf4a/0x1b80 mm/mmap.c:1827 dup_mm kernel/fork.c:1529 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1581 copy_process+0x165d/0x3950 kernel/fork.c:2221 kernel_clone+0x21e/0x820 kernel/fork.c:2651 __do_sys_clone kernel/fork.c:2792 [inline] __se_sys_clone kernel/fork.c:2776 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2776 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: 0033:0x7fc55fd85e93 RSP: 002b:00007fff9432d808 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc55fd85e93 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 0000555575c967d0 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000000927c0 R14: 000000000004fb44 R15: 00007fff9432d9a0 rcu: rcu_preempt kthread starved for 1883 jiffies! g29973 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:27568 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5260 [inline] __schedule+0x149b/0x4fd0 kernel/sched/core.c:6867 __schedule_loop kernel/sched/core.c:6949 [inline] schedule+0x165/0x360 kernel/sched/core.c:6964 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 8802 Comm: syz.9.545 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:37 [inline] RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:139 [inline] RIP: 0010:wrmsrq arch/x86/include/asm/msr.h:199 [inline] RIP: 0010:native_apic_msr_write+0x39/0x50 arch/x86/include/asm/apic.h:212 Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 e9 7b c2 9d ff cc f3 0f 1e fa 89 f6 31 d2 e9 c2 53 55 03 66 RSP: 0018:ffffc90000007e50 EFLAGS: 00000046 RAX: 000000000000ef49 RBX: ffff8880b8623e40 RCX: 0000000000000838 RDX: 0000000000000000 RSI: 000000000000ef49 RDI: 0000000000000838 RBP: 0000000000000000 R08: ffffffff81aecf75 R09: ffffffff998fd508 R10: 0000000000000003 R11: ffffffff81715640 R12: 000000000ffffe52 R13: dffffc0000000000 R14: 000000000000ef49 R15: 0000000000000020 FS: 00007f460e6476c0(0000) GS:ffff888125e1b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000031be5000 CR4: 0000000000350ef0 Call Trace: apic_write arch/x86/include/asm/apic.h:409 [inline] lapic_next_event+0x11/0x20 arch/x86/kernel/apic/apic.c:418 clockevents_program_event+0x1c9/0x350 kernel/time/clockevents.c:334 hrtimer_interrupt+0x620/0xaa0 kernel/time/hrtimer.c:1916 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:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:194 Code: f7 e8 0d c0 41 f6 f7 c3 00 02 00 00 74 05 e8 b0 ee 6b f6 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 74 c5 33 f6 65 8b 05 0d 68 23 07 85 c0 74 18 5b 41 5e e9 dc 58 RSP: 0018:ffffc90003197828 EFLAGS: 00000206 RAX: 0000000000000002 RBX: 0000000000000286 RCX: 0000000080000001 RDX: 0000000000000000 RSI: ffffffff8d79361f RDI: 0000000000000001 RBP: ffffffff99bb1570 R08: ffffffff8f822e77 R09: 1ffffffff1f045ce R10: dffffc0000000000 R11: fffffbfff1f045cf R12: ffff888030a9e440 R13: ffff888030a9e428 R14: ffffffff99bb1578 R15: dffffc0000000000 debug_object_assert_init+0x20e/0x380 lib/debugobjects.c:1009 debug_timer_assert_init kernel/time/timer.c:803 [inline] debug_assert_init kernel/time/timer.c:848 [inline] __mod_timer+0x4a/0xf30 kernel/time/timer.c:1025 schedule_timeout+0x126/0x270 kernel/time/sleep_timeout.c:98 snd_rawmidi_write+0x3a8/0xbc0 sound/core/rawmidi.c:1616 do_loop_readv_writev fs/read_write.c:850 [inline] vfs_writev+0x4b6/0x960 fs/read_write.c:1059 do_writev+0x14d/0x2d0 fs/read_write.c:1103 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: 0033:0x7f460d78f749 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:00007f460e647038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007f460d9e5fa0 RCX: 00007f460d78f749 RDX: 0000000000000002 RSI: 0000200000000840 RDI: 0000000000000007 RBP: 00007f460d813f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f460d9e6038 R14: 00007f460d9e5fa0 R15: 00007ffd8a911cd8