syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6421/1:b..l
	(detected by 0, t=10502 jiffies, g=28753, q=41 ncpus=2)
task:syz.7.357       state:R  running task     stack:26464 pid:6421  ppid:5928   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6730
 preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6754
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0xf6/0x100 kernel/locking/spinlock.c:194
 bpf_lru_pop_free+0x19a5/0x1c60 include/linux/list.h:-1
 prealloc_lru_pop kernel/bpf/hashtab.c:296 [inline]
 __htab_lru_percpu_map_update_elem+0x1ff/0x8c0 kernel/bpf/hashtab.c:1333
 bpf_percpu_hash_update+0x115/0x200 kernel/bpf/hashtab.c:2336
 bpf_map_update_value+0x310/0x670 kernel/bpf/syscall.c:202
 generic_map_update_batch+0x569/0x850 kernel/bpf/syscall.c:1709
 bpf_map_do_batch+0x466/0x600 kernel/bpf/syscall.c:-1
 __sys_bpf+0x65f/0x6d0 kernel/bpf/syscall.c:-1
 __do_sys_bpf kernel/bpf/syscall.c:5131 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5129 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5129
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9f10d8eba9
RSP: 002b:00007f9f11c8f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f9f10fd6090 RCX: 00007f9f10d8eba9
RDX: 0000000000000038 RSI: 0000200000000780 RDI: 000000000000001a
RBP: 00007f9f10e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9f10fd6128 R14: 00007f9f10fd6090 R15: 00007ffdaedbc198
 </TASK>
rcu: rcu_preempt kthread starved for 10510 jiffies! g28753 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:27200 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 7098 Comm: syz.0.483 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
RIP: 0010:static_key_false include/linux/jump_label.h:207 [inline]
RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:147 [inline]
RIP: 0010:wrmsr arch/x86/include/asm/msr.h:254 [inline]
RIP: 0010:native_apic_msr_write+0x35/0x50 arch/x86/include/asm/apic.h:206
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 c3 89 f6 31 d2 e9 ef c7 f7 02 66 2e 0f 1f 84 00 00 00 00 00
RSP: 0018:ffffc900001e0e38 EFLAGS: 00000046
RAX: 00000000000048bf RBX: 00000000000048bf RCX: 0000000000000838
RDX: 0000000000000000 RSI: 00000000000048bf RDI: 0000000000000838
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffffbfff1c3eea6
R10: fffffbfff1c3eea6 R11: 1ffffffff1c3eea5 R12: dffffc0000000000
R13: 0000000010005df3 R14: ffffffff8c5e4b40 R15: dffffc0000000000
FS:  00007feceef486c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000f7d000 CR3: 000000002e8d8000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 apic_write arch/x86/include/asm/apic.h:394 [inline]
 lapic_next_event+0x5b/0x70 arch/x86/kernel/apic/apic.c:478
 clockevents_program_event+0x1bc/0x310 kernel/time/clockevents.c:334
 hrtimer_interrupt+0x59d/0x9c0 kernel/time/hrtimer.c:1891
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x153/0x5a0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0018:ffffc9001fd7f9e0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 5b5a7f4a0918e200
RDX: 0000000000000000 RSI: ffffffff8a8c1680 RDI: ffffffff8adefca0
RBP: ffffc9001fd7faf0 R08: dffffc0000000000 R09: fffffbfff215c44f
R10: fffffbfff215c44f R11: 1ffffffff215c44e R12: 0000000000000001
R13: 1ffff92003faff48 R14: 0000000000000246 R15: dffffc0000000000
 __might_fault+0xc2/0x120 mm/memory.c:5852
 __copy_from_user include/linux/uaccess.h:75 [inline]
 check_xstate_in_sigframe arch/x86/kernel/fpu/signal.c:35 [inline]
 __fpu_restore_sig arch/x86/kernel/fpu/signal.c:348 [inline]
 fpu__restore_sig+0x203/0x1190 arch/x86/kernel/fpu/signal.c:493
 restore_sigcontext arch/x86/kernel/signal.c:140 [inline]
 __ia32_sys_rt_sigreturn+0x649/0x790 arch/x86/kernel/signal.c:675
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fecee18eba7
Code: ff ff 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
RSP: 002b:00007feceef48038 EFLAGS: 00000246
RAX: 000000000000002f RBX: 00007fecee3d5fa0 RCX: 00007fecee18eba9
RDX: 0000000000002020 RSI: 0000200000000480 RDI: 0000000000000008
RBP: 00007fecee211e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fecee3d6038 R14: 00007fecee3d5fa0 R15: 00007fffefc856e8
 </TASK>