syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (0 ticks this GP) idle=367c/1/0x4000000000000000 softirq=21129/21129 fqs=5
	(detected by 0, t=10502 jiffies, g=28377, q=35 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 6788 Comm: syz.2.769 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:122 [inline]
RIP: 0010:lock_acquire+0x13f/0x490 kernel/locking/lockdep.c:5638
Code: 65 8b 05 c4 80 9f 7e 85 c0 0f 85 2f 01 00 00 65 4c 8b 35 74 76 9f 7e 49 81 c6 dc 0a 00 00 4c 89 f0 48 c1 e8 03 42 0f b6 04 38 <84> c0 0f 85 19 02 00 00 41 83 3e 00 0f 85 02 01 00 00 48 c7 84 24
RSP: 0018:ffffc900001e0b60 EFLAGS: 00000803
RAX: 0000000000000000 RBX: 0000000000000000 RCX: f6cf979a75faf800
RDX: 0000000000000000 RSI: ffffffff8adef740 RDI: ffffffff8adef700
RBP: ffffc900001e0c68 R08: dffffc0000000000 R09: fffffbfff1c3ed56
R10: fffffbfff1c3ed56 R11: 1ffffffff1c3ed55 R12: 0000000000000001
R13: 1ffff9200003c178 R14: ffff88802a78c65c R15: dffffc0000000000
FS:  00007feecdf9f6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2b834e CR3: 0000000056bb4000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 advance_sched+0x6e8/0x970 net/sched/sch_taprio.c:753
 __run_hrtimer kernel/time/hrtimer.c:1747 [inline]
 __hrtimer_run_queues+0x554/0xd60 kernel/time/hrtimer.c:1811
 hrtimer_interrupt+0x3c5/0x9c0 kernel/time/hrtimer.c:1873
 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:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:244 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp8+0x4/0x80 kernel/kcov.c:320
Code: 77 22 89 ff 89 f6 49 ff c0 4c 89 01 48 c7 44 11 08 05 00 00 00 48 89 7c 11 10 48 89 74 11 18 48 89 44 11 20 c3 90 48 8b 04 24 <65> 48 8b 0d f4 94 81 7e 65 8b 15 f5 94 81 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc900053efb10 EFLAGS: 00000202
RAX: ffffffff813a749f RBX: 0000000000000001 RCX: ffff88802a78bb80
RDX: 0000000000000002 RSI: 0000000000000001 RDI: 0000000000000001
RBP: ffff88807bbd9c01 R08: dffffc0000000000 R09: ffffed10054f1771
R10: ffffed10054f1771 R11: 1ffff110054f1770 R12: 1ffff1100f77b397
R13: dffffc0000000000 R14: 1ffff11005cfd000 R15: 00000000738f1067
 pud_huge+0x2f/0x40 arch/x86/mm/hugetlbpage.c:41
 follow_pud_mask mm/gup.c:803 [inline]
 follow_p4d_mask mm/gup.c:853 [inline]
 follow_page_mask+0x1c2/0x1320 mm/gup.c:917
 __get_user_pages+0x38b/0xeb0 mm/gup.c:1248
 populate_vma_page_range+0x214/0x2b0 mm/gup.c:1607
 __mm_populate+0x248/0x370 mm/gup.c:1721
 mm_populate include/linux/mm.h:2891 [inline]
 vm_mmap_pgoff+0x203/0x2b0 mm/util.c:525
 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: 0033:0x7feecd18f749
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:00007feecdf9f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007feecd3e5fa0 RCX: 00007feecd18f749
RDX: b635773f06ebbee2 RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007feecd213f91 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007feecd3e6038 R14: 00007feecd3e5fa0 R15: 00007ffe62ce8c68
 </TASK>
rcu: rcu_preempt kthread starved for 10492 jiffies! g28377 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:26880 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:2167
 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:
CPU: 0 PID: 4408 Comm: kworker/u4:9 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:424 [inline]
RIP: 0010:smp_call_function_many_cond+0xe7b/0x1270 kernel/smp.c:998
Code: 00 00 00 41 8b 1f 89 de 83 e6 01 31 ff e8 5d d9 0a 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 e9 d5 0a 00 eb 37 f3 90 <41> 0f b6 04 1c 84 c0 75 10 41 f7 07 01 00 00 00 74 1e e8 ce d5 0a
RSP: 0018:ffffc90004557800 EFLAGS: 00000293
RAX: ffffffff81760092 RBX: dffffc0000000000 RCX: ffff88807add9dc0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90004557960 R08: dffffc0000000000 R09: fffffbfff215c449
R10: fffffbfff215c449 R11: 1ffffffff215c448 R12: 1ffff110171e81c9
R13: ffff8880b8e3bb80 R14: 0000000000000001 R15: ffff8880b8f40e48
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcbd4b72a60 CR3: 000000000c88e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1165
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:1574 [inline]
 text_poke_bp_batch+0x2b0/0x7d0 arch/x86/kernel/alternative.c:1774
 text_poke_flush arch/x86/kernel/alternative.c:1965 [inline]
 text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1972
 arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x11f/0x240 kernel/jump_label.c:207
 static_key_enable+0x16/0x20 kernel/jump_label.c:220
 toggle_allocation_gate+0xb4/0x430 mm/kfence/core.c:805
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
vkms_vblank_simulate: vblank timer overrun