syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9499/1:b.el
rcu: 	(detected by 0, t=10502 jiffies, g=142033, q=865 ncpus=2)
task:kworker/0:15    state:R  running task     stack:21728 pid:9499  tgid:9499  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x149b/0x4fd0 kernel/sched/core.c:6863
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7190
 irqentry_exit+0x5d8/0x660 kernel/entry/common.c:216
 asm_sysvec_call_function_single+0x1a/0x20 arch/x86/include/asm/idtentry.h:704
RIP: 0010:lookup_page_ext mm/page_ext.c:252 [inline]
RIP: 0010:page_ext_lookup+0xd5/0x180 mm/page_ext.c:509
Code: 83 e3 7f c1 e3 05 49 01 de eb 0f e8 e5 61 8e ff eb 05 e8 de 61 8e ff 45 31 f6 49 83 c6 10 4c 89 f0 48 c1 e8 03 42 80 3c 28 00 <74> 08 4c 89 f7 e8 f1 81 f4 ff 49 8b 1e e8 49 3b 73 ff 89 c5 31 ff
RSP: 0018:ffffc9000cf7f200 EFLAGS: 00000246
RAX: 1ffff11027fff4ae RBX: 0000000000000160 RCX: 0000000000100000
RDX: ffffc90012ab0000 RSI: 000000000000fc80 RDI: 000000000000fc81
RBP: 0000000000000003 R08: ffffffff8230e85e R09: ffffffff8df41aa0
R10: 0000000000000010 R11: ffffffff81acf3d0 R12: 000000000005d930
R13: dffffc0000000000 R14: ffff88813fffa570 R15: 0000000000001000
 page_ext_iter_begin include/linux/page_ext.h:132 [inline]
 __update_page_owner_free_handle+0x103/0x470 mm/page_owner.c:284
 __reset_page_owner+0x85/0x1f0 mm/page_owner.c:321
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0xbc8/0xd30 mm/page_alloc.c:2943
 discard_slab mm/slub.c:3346 [inline]
 __put_partials+0x146/0x170 mm/slub.c:3886
 __slab_free+0x294/0x320 mm/slub.c:5952
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_kmalloc+0x22/0xb0 mm/kasan/common.c:406
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5657 [inline]
 __kmalloc_noprof+0x41d/0x800 mm/slub.c:5669
 kmalloc_noprof include/linux/slab.h:961 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 rh_call_control drivers/usb/core/hcd.c:491 [inline]
 rh_urb_enqueue drivers/usb/core/hcd.c:821 [inline]
 usb_hcd_submit_urb+0x790/0x1b80 drivers/usb/core/hcd.c:1542
 usb_start_wait_urb+0x115/0x4f0 drivers/usb/core/message.c:59
 usb_internal_control_msg drivers/usb/core/message.c:103 [inline]
 usb_control_msg+0x232/0x3e0 drivers/usb/core/message.c:154
 usb_clear_port_feature drivers/usb/core/hub.c:456 [inline]
 port_event drivers/usb/core/hub.c:5765 [inline]
 hub_event+0x82a/0x4ef0 drivers/usb/core/hub.c:5953
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
 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
 </TASK>
rcu: rcu_preempt kthread starved for 2240 jiffies! g142033 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    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5256 [inline]
 __schedule+0x149b/0x4fd0 kernel/sched/core.c:6863
 __schedule_loop kernel/sched/core.c:6945 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6960
 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
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 25300 Comm: kworker/0:0H Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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 6b 42 f6 f7 c3 00 02 00 00 74 05 e8 60 97 6c f6 9c 58 a9 00 02 00 00 75 27 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 44 85 34 f6 65 8b 05 4d c8 23 07 85 c0 74 18 5b 41 5e e9 1c 19
RSP: 0018:ffffc90000007aa8 EFLAGS: 00000206
RAX: 0000000000000002 RBX: 0000000000000246 RCX: 0000000000000102
RDX: 0000000000000002 RSI: ffffffff8d791f69 RDI: 0000000000000001
RBP: ffffc90000007d90 R08: ffffffff8f822177 R09: 1ffffffff1f0442e
R10: dffffc0000000000 R11: fffffbfff1f0442f R12: dffffc0000000000
R13: 000000000000d000 R14: ffff888028b54000 R15: ffff888143bba470
FS:  0000000000000000(0000) GS:ffff888125e21000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055720033e008 CR3: 0000000063edc000 CR4: 0000000000350ef0
Call Trace:
 <IRQ>
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 dummy_timer+0x447c/0x45b0 drivers/usb/gadget/udc/dummy_hcd.c:-1
 __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
 __hrtimer_run_queues+0x51c/0xc30 kernel/time/hrtimer.c:1841
 hrtimer_run_softirq+0x187/0x2b0 kernel/time/hrtimer.c:1858
 handle_softirqs+0x22b/0x7c0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x60/0x150 kernel/softirq.c:723
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_release+0x2d8/0x3b0 kernel/locking/lockdep.c:5893
Code: 14 e2 10 00 00 00 00 eb b5 e8 64 6f bb 09 f7 c3 00 02 00 00 74 b9 65 48 8b 05 74 ce e1 10 48 3b 44 24 28 75 44 fb 48 83 c4 30 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 44 1f 72 ff cc 48 8d 3d 11 48 e7
RSP: 0018:ffffc90003257400 EFLAGS: 00000286
RAX: 130cc5112050ac00 RBX: 0000000000000202 RCX: 0000000000000001
RDX: 0000000000000001 RSI: ffffffff8d975e82 RDI: ffffffff8bc083e0
RBP: ffff88807c314858 R08: ffffc90003257d58 R09: ffffc90003257558
R10: dffffc0000000000 R11: fffff5200064aead R12: 0000000000000001
R13: 0000000000000001 R14: ffffffff8df41aa0 R15: ffff88807c313d00
 rcu_lock_release include/linux/rcupdate.h:341 [inline]
 rcu_read_unlock include/linux/rcupdate.h:897 [inline]
 class_rcu_destructor include/linux/rcupdate.h:1195 [inline]
 unwind_next_frame+0x1ab1/0x23d0 arch/x86/kernel/unwind_orc.c:695
 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 __call_rcu_common kernel/rcu/tree.c:3119 [inline]
 call_rcu+0xee/0x890 kernel/rcu/tree.c:3239
 radix_tree_node_free lib/radix-tree.c:310 [inline]
 delete_node+0x1b6/0xa50 lib/radix-tree.c:573
 radix_tree_delete_item+0x2b6/0x400 lib/radix-tree.c:1430
 free_pid+0x246/0x380 kernel/pid.c:142
 free_pids+0xb6/0x100 kernel/pid.c:159
 release_task+0x11ee/0x16c0 kernel/exit.c:295
 exit_notify kernel/exit.c:777 [inline]
 do_exit+0x15e3/0x22f0 kernel/exit.c:983
 kthread_exit+0x22c/0x280 kernel/kthread.c:336
 kthread+0x72f/0x8a0 kernel/kthread.c:465
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>