syzbot

==================================================================
BUG: KCSAN: data-race in rwsem_down_write_slowpath / rwsem_down_write_slowpath

write to 0xffffc900001c3ae0 of 1 bytes by task 5862 on cpu 1:
 rwsem_try_write_lock kernel/locking/rwsem.c:676 [inline]
 rwsem_down_write_slowpath+0x3dd/0xac0 kernel/locking/rwsem.c:1189
 __down_write_common kernel/locking/rwsem.c:1347 [inline]
 __down_write kernel/locking/rwsem.c:1356 [inline]
 down_write+0xab/0xc0 kernel/locking/rwsem.c:1626
 kernfs_activate+0x50/0x220 fs/kernfs/dir.c:1463
 kernfs_add_one+0x212/0x280 fs/kernfs/dir.c:869
 __kernfs_create_file+0x145/0x180 fs/kernfs/file.c:1086
 sysfs_add_file_mode_ns+0x132/0x1b0 fs/sysfs/file.c:313
 sysfs_merge_group+0xed/0x1c0 fs/sysfs/group.c:382
 dpm_sysfs_add+0xaf/0x1e0 drivers/base/power/sysfs.c:704
 device_add+0x3bc/0x790 drivers/base/core.c:3651
 netdev_register_kobject+0x109/0x230 net/core/net-sysfs.c:2343
 register_netdevice+0xaaf/0x1160 net/core/dev.c:11423
 __ip_tunnel_create+0x31d/0x430 net/ipv4/ip_tunnel.c:268
 ip_tunnel_init_net+0x210/0x490 net/ipv4/ip_tunnel.c:1147
 ipgre_tap_init_net+0x35/0x40 net/ipv4/ip_gre.c:1762
 ops_init+0x22a/0x2e0 net/core/net_namespace.c:137
 setup_net+0x9f/0x230 net/core/net_namespace.c:446
 copy_net_ns+0x310/0x450 net/core/net_namespace.c:579
 create_new_namespaces+0x20e/0x440 kernel/nsproxy.c:132
 copy_namespaces+0x1ad/0x210 kernel/nsproxy.c:195
 copy_process+0x10b1/0x2370 kernel/fork.c:2267
 kernel_clone+0x1a5/0x5e0 kernel/fork.c:2721
 __do_sys_clone3 kernel/fork.c:3025 [inline]
 __se_sys_clone3+0x1f5/0x230 kernel/fork.c:3004
 __x64_sys_clone3+0x31/0x40 kernel/fork.c:3004
 x64_sys_call+0x580/0x3020 arch/x86/include/generated/asm/syscalls_64.h:436
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffc900001c3ae0 of 1 bytes by task 62 on cpu 0:
 rwsem_down_write_slowpath+0x44f/0xac0 kernel/locking/rwsem.c:1207
 __down_write_common kernel/locking/rwsem.c:1347 [inline]
 __down_write kernel/locking/rwsem.c:1356 [inline]
 down_write+0xab/0xc0 kernel/locking/rwsem.c:1626
 kernfs_remove_by_name_ns+0x6b/0x110 fs/kernfs/dir.c:1793
 kernfs_remove_by_name include/linux/kernfs.h:639 [inline]
 remove_files fs/sysfs/group.c:28 [inline]
 sysfs_remove_group+0xa5/0x170 fs/sysfs/group.c:328
 sysfs_remove_groups+0x3a/0x80 fs/sysfs/group.c:352
 destroy_gid_attrs drivers/infiniband/core/sysfs.c:1138 [inline]
 ib_free_port_attrs+0x8e/0x250 drivers/infiniband/core/sysfs.c:1362
 remove_one_compat_dev drivers/infiniband/core/device.c:1011 [inline]
 rdma_dev_exit_net+0x1aa/0x290 drivers/infiniband/core/device.c:1149
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x285/0x420 net/core/net_namespace.c:252
 cleanup_net+0x37c/0x5b0 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3397
 worker_thread+0x58a/0x780 kernel/workqueue.c:3478
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 62 Comm: kworker/u8:5 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: netns cleanup_net
==================================================================