syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=980c/1/0x4000000000000000 softirq=45634/45635 fqs=1
rcu: 	(detected by 0, t=10506 jiffies, g=53889, q=79 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5614 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:lockdep_enabled kernel/locking/lockdep.c:124 [inline]
RIP: 0010:lock_is_held_type+0x42/0x140 kernel/locking/lockdep.c:5933
Code: 8b 15 aa a6 80 08 85 d2 0f 85 de 00 00 00 41 57 41 56 41 55 41 54 55 53 48 83 ec 08 65 48 8b 2d 1c 5f 80 08 8b 95 8c 0b 00 00 <85> d2 0f 85 a7 00 00 00 48 89 fb 41 89 f4 9c 41 5d fa 48 c7 c7 5a
RSP: 0018:ffffc90000a08e48 EFLAGS: 00000096
RAX: 00000000ffffffff RBX: 0000000000000001 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffff8880b85284d8
RBP: ffff88802bef0000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff888037dd3300
R13: 0000000000000001 R14: dffffc0000000000 R15: 18b7f77c48396cf2
FS:  0000555583877500(0000) GS:ffff888124483000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4f65617dac CR3: 000000005c9cc000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 lock_is_held include/linux/lockdep.h:249 [inline]
 __run_hrtimer kernel/time/hrtimer.c:1896 [inline]
 __hrtimer_run_queues+0x7c3/0xa00 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
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872
Code: 05 3b 45 25 12 83 f8 07 0f 87 d9 02 00 00 48 0f a3 05 46 86 f2 0e 0f 82 a4 02 00 00 8b 35 ce b9 f2 0e 85 f6 0f 85 bf 00 00 00 <48> 8b 44 24 30 65 48 2b 05 dd 44 25 12 0f 85 ed 02 00 00 48 83 c4
RSP: 0018:ffffc900037d73d8 EFLAGS: 00000206
RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000007
RDX: 0000000000000000 RSI: ffffffff8deea396 RDI: ffffffff8c1c4680
RBP: ffffffff8e7e5560 R08: 000000007bf5c8e5 R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 rcu_read_lock include/linux/rcupdate.h:838 [inline]
 page_table_check_set+0x2b2/0x920 mm/page_table_check.c:112
 __page_table_check_ptes_set+0x27a/0x4e0 mm/page_table_check.c:212
 page_table_check_ptes_set include/linux/page_table_check.h:83 [inline]
 set_ptes include/linux/pgtable.h:413 [inline]
 __copy_present_ptes mm/memory.c:1118 [inline]
 copy_present_ptes mm/memory.c:1197 [inline]
 copy_pte_range mm/memory.c:1320 [inline]
 copy_pmd_range mm/memory.c:1408 [inline]
 copy_pud_range mm/memory.c:1445 [inline]
 copy_p4d_range mm/memory.c:1469 [inline]
 copy_page_range+0x2197/0x5b20 mm/memory.c:1555
 dup_mmap+0xd44/0x21b0 mm/mmap.c:1840
 dup_mm kernel/fork.c:1534 [inline]
 copy_mm kernel/fork.c:1586 [inline]
 copy_process+0x6c78/0x7ed0 kernel/fork.c:2264
 kernel_clone+0x176/0x9e0 kernel/fork.c:2722
 __do_sys_clone+0xd9/0x120 kernel/fork.c:2863
 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: 0033:0x7f7f62dc58d2
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:00007ffff868b810 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffff868b810 RCX: 00007f7f62dc58d2
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffff868b99c R08: 0000000000000000 R09: 0000000000000001
R10: 00005555838777d0 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000000927c0 R14: 00000000000587a6 R15: 00007ffff868b9f0
 </TASK>
rcu: rcu_preempt kthread starved for 10500 jiffies! g53889 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:27992 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 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
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 1111 Comm: kworker/u8:7 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:210
Code: f6 7f 5c 00 48 89 df 5b e9 dd 10 62 00 be 03 00 00 00 5b e9 b2 ab f0 02 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 65 8b 05 65 20 01 12 48 8b 34 24 65 48 8b 15 41 20 01
RSP: 0018:ffffc900054e7868 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81fc2c4d
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff888029342540
RBP: ffff8880b8540f80 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: ffffed10170a81f1 R14: 0000000000000001 R15: ffff8880b843c600
FS:  0000000000000000(0000) GS:ffff888124383000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4f6544f156 CR3: 000000000e596000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 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
 on_each_cpu include/linux/smp.h:72 [inline]
 smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2773 [inline]
 smp_text_poke_batch_finish+0x337/0xc60 arch/x86/kernel/alternative.c:2983
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 jump_label_update+0x37a/0x550 kernel/jump_label.c:910
 static_key_enable_cpuslocked+0x1bc/0x270 kernel/jump_label.c:210
 static_key_enable+0x1a/0x20 kernel/jump_label.c:223
 toggle_allocation_gate mm/kfence/core.c:906 [inline]
 toggle_allocation_gate+0xfe/0x2d0 mm/kfence/core.c:898
 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314
 process_scheduled_works kernel/workqueue.c:3397 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478
 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
 </TASK>