rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P10720/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=423441, q=4488 ncpus=2)
task:syz.2.15601     state:R  running task     stack:25416 pid:10720 tgid:10719 ppid:6825   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1821/0x5740 kernel/sched/core.c:7189
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x14f/0x760 kernel/entry/common.c:164
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:lock_acquire+0x221/0x350 kernel/locking/lockdep.c:5872
Code: ff ff ff e8 f1 8d 07 0a f7 44 24 08 00 02 00 00 0f 84 3a ff ff ff 65 48 8b 05 db d8 97 11 48 3b 44 24 58 75 33 fb 48 83 c4 60 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 40 81 0a 0a cc 48 8d 3d 88 7a 92
RSP: 0018:ffffc90003f5f810 EFLAGS: 00000282
RAX: 085e437b1df67700 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 00000000e9a8190b RSI: ffffffff8e22036c RDI: ffffffff8c28b660
RBP: ffffffff826ff65c R08: ffffffff826ff65c R09: ffffffff8e95cca0
R10: dffffc0000000000 R11: ffffed10150158f1 R12: 0000000000000002
R13: ffffffff8e95cca0 R14: 0000000000000000 R15: 0000000000000246
 rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 rcu_read_lock include/linux/rcupdate.h:838 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
 kernfs_root+0x38/0x230 fs/kernfs/kernfs-internal.h:74
 kernfs_next_descendant_post+0x4e/0x310 fs/kernfs/dir.c:1411
 __kernfs_remove+0x277/0x8e0 fs/kernfs/dir.c:1561
 kernfs_remove_by_name_ns+0xc0/0x140 fs/kernfs/dir.c:1798
 kernfs_remove_by_name include/linux/kernfs.h:639 [inline]
 remove_files fs/sysfs/group.c:28 [inline]
 sysfs_remove_group+0xfc/0x2e0 fs/sysfs/group.c:328
 sysfs_remove_groups+0x54/0xb0 fs/sysfs/group.c:352
 destroy_port drivers/infiniband/core/sysfs.c:1233 [inline]
 ib_free_port_attrs+0x281/0x3b0 drivers/infiniband/core/sysfs.c:1363
 remove_one_compat_dev drivers/infiniband/core/device.c:1011 [inline]
 rdma_dev_exit_net+0x1de/0x350 drivers/infiniband/core/device.c:1149
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x49f/0x940 net/core/net_namespace.c:252
 setup_net+0x2f0/0x340 net/core/net_namespace.c:462
 copy_net_ns+0x50e/0x730 net/core/net_namespace.c:579
 create_new_namespaces+0x3e7/0x6a0 kernel/nsproxy.c:132
 unshare_nsproxy_namespaces+0x149/0x190 kernel/nsproxy.c:234
 ksys_unshare+0x57d/0x9f0 kernel/fork.c:3243
 __do_sys_unshare kernel/fork.c:3317 [inline]
 __se_sys_unshare kernel/fork.c:3315 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3315
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1ac1b9ce59
RSP: 002b:00007f1ac2afa028 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007f1ac1e15fa0 RCX: 00007f1ac1b9ce59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000064000600
RBP: 00007f1ac1c32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1ac1e16038 R14: 00007f1ac1e15fa0 R15: 00007ffd55461f38
 </TASK>