syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P10/1:b..l P6748/1:b..l
rcu: 	(detected by 1, t=10506 jiffies, g=15937, q=437 ncpus=2)
task:syz.5.148       state:R  running task     stack:25304 pid:6748  tgid:6747  ppid:6088   task_flags:0x400040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5282 [inline]
 __schedule+0x14ed/0x5040 kernel/sched/core.c:6894
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7221
 irqentry_exit+0x5e3/0x670 kernel/entry/common.c:216
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x222/0x340 kernel/locking/lockdep.c:5872
Code: ff ff ff e8 60 9c bf 09 f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 7a 9a 03 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 97 ad 07
RSP: 0018:ffffc900033f70e0 EFLAGS: 00000282
RAX: 1a88dacc6b862b00 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 000000007f360bd7 RSI: ffffffff8db845c0 RDI: ffffffff8be08c60
RBP: ffffffff81ab29fd R08: ffffffff81ab29fd R09: ffffffff8e13efa0
R10: ffffc900033f71f8 R11: ffffffff81acb2b0 R12: 0000000000000002
R13: ffffffff8e13efa0 R14: 0000000000000000 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 rcu_read_lock include/linux/rcupdate.h:850 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1193 [inline]
 is_module_text_address+0x39/0x1e0 kernel/module/main.c:3856
 kernel_text_address+0x94/0xe0 kernel/extable.c:119
 __kernel_text_address+0xd/0x40 kernel/extable.c:79
 unwind_get_return_address+0x4d/0x90 arch/x86/kernel/unwind_orc.c:385
 arch_stack_walk+0xfc/0x150 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 save_stack+0xf5/0x1f0 mm/page_owner.c:165
 __set_page_owner+0x8d/0x4c0 mm/page_owner.c:341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x23d/0x2a0 mm/page_alloc.c:1887
 prep_new_page mm/page_alloc.c:1895 [inline]
 get_page_from_freelist+0x23a5/0x2440 mm/page_alloc.c:3948
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5257
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
 folio_alloc_mpol_noprof+0x39/0x70 mm/mempolicy.c:2505
 shmem_alloc_folio mm/shmem.c:1902 [inline]
 shmem_alloc_and_add_folio+0x423/0xf40 mm/shmem.c:1944
 shmem_get_folio_gfp+0x59d/0x1660 mm/shmem.c:2539
 shmem_get_folio mm/shmem.c:2645 [inline]
 shmem_write_begin+0x16c/0x330 mm/shmem.c:3298
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4314
 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3473
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5c9/0xb30 fs/read_write.c:686
 ksys_write+0x145/0x250 fs/read_write.c:738
 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: 0033:0x7feaa2b8e1ff
RSP: 002b:00007feaa3b0edf0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000001000000 RCX: 00007feaa2b8e1ff
RDX: 0000000001000000 RSI: 00007fea98800000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000009687
R10: 000020000001c302 R11: 0000000000000293 R12: 0000000000000003
R13: 00007feaa3b0eef0 R14: 00007feaa3b0eeb0 R15: 00007fea98800000
 </TASK>
task:kworker/0:1     state:R  running task     stack:22304 pid:10    tgid:10    ppid:2      task_flags:0x4288060 flags:0x00080000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5282 [inline]
 __schedule+0x14ed/0x5040 kernel/sched/core.c:6894
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7221
 irqentry_exit+0x5e3/0x670 kernel/entry/common.c:216
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x11/0x70 kernel/kcov.c:217
Code: 5b e9 23 84 5b 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 65 48 8b 0c 25 08 90 a1 92 <65> 8b 15 58 d5 e0 10 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75
RSP: 0018:ffffc900000f7448 EFLAGS: 00000202
RAX: ffffffff8263fd9e RBX: ffffffff8263fd5c RCX: ffff88801d681e40
RDX: ffff88801d681e40 RSI: ffffffff8be08c40 RDI: ffffffff8be08c00
RBP: 0000000000000001 R08: ffffffff8263fd5c R09: ffffffff8e13efa0
R10: dffffc0000000000 R11: ffffed10039de025 R12: ffff88807941cc30
R13: 0000000000000001 R14: ffff88807941cc30 R15: ffff88807941c6d0
 rcu_read_lock include/linux/rcupdate.h:851 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1193 [inline]
 kernfs_root+0x5e/0x230 fs/kernfs/kernfs-internal.h:75
 kernfs_find_ns+0xa2/0x320 fs/kernfs/dir.c:865
 kernfs_remove_by_name_ns+0x4b/0x130 fs/kernfs/dir.c:1719
 kernfs_remove_by_name include/linux/kernfs.h:633 [inline]
 remove_files fs/sysfs/group.c:28 [inline]
 sysfs_remove_group+0xfc/0x2f0 fs/sysfs/group.c:328
 sysfs_remove_groups+0x54/0xb0 fs/sysfs/group.c:352
 device_remove_groups drivers/base/core.c:2843 [inline]
 device_remove_attrs+0x1aa/0x260 drivers/base/core.c:2973
 device_del+0x509/0x8e0 drivers/base/core.c:3877
 device_unregister+0x21/0x100 drivers/base/core.c:3919
 usb_remove_ep_devs+0x50/0x80 drivers/usb/core/endpoint.c:189
 remove_intf_ep_devs drivers/usb/core/message.c:1266 [inline]
 usb_disable_device+0x357/0x8e0 drivers/usb/core/message.c:1417
 usb_disconnect+0x32f/0x990 drivers/usb/core/hub.c:2345
 hub_port_connect drivers/usb/core/hub.c:5407 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 port_event drivers/usb/core/hub.c:5871 [inline]
 hub_event+0x1ca9/0x4ef0 drivers/usb/core/hub.c:5953
 process_one_work+0x93a/0x15a0 kernel/workqueue.c:3279
 process_scheduled_works kernel/workqueue.c:3362 [inline]
 worker_thread+0x9f5/0xee0 kernel/workqueue.c:3443
 kthread+0x389/0x480 kernel/kthread.c:467
 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 timer wakeup didn't happen for 10505 jiffies! g15937 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=6427
rcu: rcu_preempt kthread starved for 10506 jiffies! g15937 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:28032 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5282 [inline]
 __schedule+0x14ed/0x5040 kernel/sched/core.c:6894
 __schedule_loop kernel/sched/core.c:6976 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6991
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x11b0 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x9b/0x2d0 kernel/rcu/tree.c:2297
 kthread+0x389/0x480 kernel/kthread.c:467
 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:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 6766 Comm: syz.4.149 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:debug_spin_unlock kernel/locking/spinlock_debug.c:102 [inline]
RIP: 0010:do_raw_spin_unlock+0x6a/0x240 kernel/locking/spinlock_debug.c:141
Code: 48 89 df be 04 00 00 00 e8 63 f5 88 00 48 89 d8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 74 01 00 00 83 3b 00 0f 84 ea 00 00 00 <4c> 8d 73 10 4d 89 f5 49 c1 ed 03 43 80 7c 25 00 00 74 08 4c 89 f7
RSP: 0018:ffffc90000007cc8 EFLAGS: 00000002
RAX: 0000000000000000 RBX: ffffffff99db5a98 RCX: ffffffff819e989d
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff99db5a98
RBP: ffffc90000007e90 R08: ffffffff99db5a9b R09: 1ffffffff33b6b53
R10: dffffc0000000000 R11: fffffbfff33b6b54 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff99db5a9c R15: ffff8880b8628380
FS:  00007f1af29f66c0(0000) GS:ffff888125c07000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30620ff8 CR3: 000000007f7d0000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:177 [inline]
 _raw_spin_unlock_irqrestore+0x23/0x80 kernel/locking/spinlock.c:194
 debug_hrtimer_deactivate kernel/time/hrtimer.c:443 [inline]
 debug_deactivate+0x1d/0x1e0 kernel/time/hrtimer.c:483
 __run_hrtimer kernel/time/hrtimer.c:1745 [inline]
 __hrtimer_run_queues+0x2b0/0xc30 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903
 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
 </IRQ>
 <TASK>
 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:179 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:194
Code: f7 e8 2d 70 3e f6 f7 c3 00 02 00 00 74 05 e8 30 5d 68 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> 04 8b 30 f6 65 8b 05 dd 67 41 07 85 c0 74 18 5b 41 5e e9 01 48
RSP: 0018:ffffc90003367be8 EFLAGS: 00000206
RAX: 0000000000000006 RBX: 0000000000000a02 RCX: 0000000080000002
RDX: 0000000000000000 RSI: ffffffff8d9a0b7f RDI: 0000000000000001
RBP: ffffc90003367db0 R08: ffffffff8fa25d77 R09: 1ffffffff1f44bae
R10: dffffc0000000000 R11: fffffbfff1f44baf R12: 0000000000000001
R13: dffffc0000000000 R14: ffff888079098a28 R15: ffff8880b863b9d8
 task_rq_unlock kernel/sched/sched.h:1871 [inline]
 __sched_setscheduler+0x15f1/0x1ab0 kernel/sched/syscalls.c:702
 _sched_setscheduler kernel/sched/syscalls.c:742 [inline]
 sched_setscheduler kernel/sched/syscalls.c:759 [inline]
 do_sched_setscheduler+0x19b/0x270 kernel/sched/syscalls.c:864
 __do_sys_sched_setscheduler kernel/sched/syscalls.c:937 [inline]
 __se_sys_sched_setscheduler kernel/sched/syscalls.c:932 [inline]
 __x64_sys_sched_setscheduler+0x79/0x90 kernel/sched/syscalls.c:932
 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: 0033:0x7f1af478f749
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:00007f1af29f6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000090
RAX: ffffffffffffffda RBX: 00007f1af49e5fa0 RCX: 00007f1af478f749
RDX: 0000200000000200 RSI: 0000000000000002 RDI: 000000000000007b
RBP: 00007f1af4813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1af49e6038 R14: 00007f1af49e5fa0 R15: 00007ffdf8a39368
 </TASK>