syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5870/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=22885, q=367 ncpus=2)
task:kworker/0:6     state:R  running task     stack:23608 pid:5870  tgid:5870  ppid:2      task_flags:0x4288060 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5367 [inline]
 __schedule+0x112e/0x5b80 kernel/sched/core.c:6748
 preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:6927
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0x61/0x80 kernel/locking/spinlock.c:194
 sock_def_readable+0x15f/0x610 net/core/sock.c:3493
 __netlink_sendskb net/netlink/af_netlink.c:1258 [inline]
 netlink_broadcast_deliver net/netlink/af_netlink.c:1389 [inline]
 do_one_broadcast net/netlink/af_netlink.c:1476 [inline]
 netlink_broadcast_filtered+0x96a/0xef0 net/netlink/af_netlink.c:1521
 netlink_broadcast+0x39/0x50 net/netlink/af_netlink.c:1545
 uevent_net_broadcast_untagged lib/kobject_uevent.c:331 [inline]
 kobject_uevent_net_broadcast lib/kobject_uevent.c:410 [inline]
 kobject_uevent_env+0xc69/0x1870 lib/kobject_uevent.c:608
 device_del+0x623/0x9f0 drivers/base/core.c:3873
 usb_disable_device+0x36c/0x7f0 drivers/usb/core/message.c:1418
 usb_disconnect+0x2e1/0x920 drivers/usb/core/hub.c:2316
 hub_port_connect drivers/usb/core/hub.c:5373 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5673 [inline]
 port_event drivers/usb/core/hub.c:5833 [inline]
 hub_event+0x1c51/0x4f80 drivers/usb/core/hub.c:5915
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3400
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10500 jiffies! g22885 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=17471
rcu: rcu_preempt kthread starved for 10501 jiffies! g22885 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:26856 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5367 [inline]
 __schedule+0x112e/0x5b80 kernel/sched/core.c:6748
 __schedule_loop kernel/sched/core.c:6825 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6840
 schedule_timeout+0x124/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1eb/0xb00 kernel/rcu/tree.c:2046
 rcu_gp_kthread+0x271/0x380 kernel/rcu/tree.c:2248
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </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: 9201 Comm: syz.2.691 Not tainted 6.14.0-syzkaller-00826-g327ecdbc0fda #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:__sanitizer_cov_trace_pc+0x66/0x70 kernel/kcov.c:235
Code: 82 10 16 00 00 83 f8 02 75 20 48 8b 8a 18 16 00 00 8b 92 14 16 00 00 48 8b 01 48 83 c0 01 48 39 d0 73 07 48 89 01 48 89 34 c1 <c3> cc cc cc cc 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90000007df8 EFLAGS: 00000046
RAX: 0000000080010001 RBX: ffff8880b8628900 RCX: ffffffff81a7a10d
RDX: ffff88802affa440 RSI: ffffffff81a7a11c RDI: 0000000000000005
RBP: ffff88805c0ba340 R08: 0000000000000005 R09: 0000000000000007
R10: 0000000000000000 R11: 0000000000000002 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8880b8628800 R15: ffffffff896bf3a0
FS:  00007f75f76a56c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555570abc608 CR3: 0000000021310000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 cpumask_test_cpu include/linux/cpumask.h:587 [inline]
 cpu_online include/linux/cpumask.h:1143 [inline]
 trace_hrtimer_start include/trace/events/timer.h:222 [inline]
 debug_activate kernel/time/hrtimer.c:497 [inline]
 enqueue_hrtimer+0x5c/0x3c0 kernel/time/hrtimer.c:1100
 __run_hrtimer kernel/time/hrtimer.c:1818 [inline]
 __hrtimer_run_queues+0x903/0xae0 kernel/time/hrtimer.c:1865
 hrtimer_interrupt+0x392/0x8e0 kernel/time/hrtimer.c:1927
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x10f/0x400 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__sanitizer_cov_trace_const_cmp1+0x8/0x20 kernel/kcov.c:300
Code: bf 06 00 00 00 e9 b8 fe ff ff 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 0c 24 <40> 0f b6 d6 40 0f b6 f7 bf 01 00 00 00 e9 86 fe ff ff 66 0f 1f 44
RSP: 0018:ffffc9000f8d73c0 EFLAGS: 00000202
RAX: dffffc0000000000 RBX: ffffea00016bc480 RCX: ffffffff81fb1717
RDX: 1ffffd40002d7890 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: fffff940002d7890
R10: ffffea00016bc487 R11: 0000000000000001 R12: ffff888069cf3e68
R13: 0000000000000129 R14: 0000000000000001 R15: 0000000000000000
 shmem_add_to_page_cache+0x517/0x9b0 mm/shmem.c:878
 shmem_alloc_and_add_folio+0x662/0xc10 mm/shmem.c:1928
 shmem_get_folio_gfp+0x689/0x1530 mm/shmem.c:2545
 shmem_fault+0x200/0xaf0 mm/shmem.c:2746
 __do_fault+0x10a/0x490 mm/memory.c:4989
 do_read_fault mm/memory.c:5409 [inline]
 do_fault mm/memory.c:5543 [inline]
 do_pte_missing+0xecf/0x3e10 mm/memory.c:4059
 handle_pte_fault mm/memory.c:5888 [inline]
 __handle_mm_fault+0x103c/0x2a40 mm/memory.c:6031
 handle_mm_fault+0x3fa/0xaa0 mm/memory.c:6200
 faultin_page mm/gup.c:1196 [inline]
 __get_user_pages+0x773/0x36f0 mm/gup.c:1491
 populate_vma_page_range+0x27f/0x3a0 mm/gup.c:1929
 __mm_populate+0x1d6/0x380 mm/gup.c:2032
 mm_populate include/linux/mm.h:3392 [inline]
 vm_mmap_pgoff+0x352/0x440 mm/util.c:583
 ksys_mmap_pgoff+0x7d/0x5c0 mm/mmap.c:607
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f75f678d169
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:00007f75f76a5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f75f69a5fa0 RCX: 00007f75f678d169
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f75f680e2a0 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f75f69a5fa0 R15: 00007ffeabea1678
 </TASK>