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BUG: KCSAN: data-race in rwsem_down_write_slowpath / rwsem_down_write_slowpath

write to 0xffffc90001b8fbf8 of 1 bytes by task 5453 on cpu 0:
 rwsem_try_write_lock kernel/locking/rwsem.c:676 [inline]
 rwsem_down_write_slowpath+0x3eb/0xab0 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:1632
 kernfs_activate+0x50/0x220 fs/kernfs/dir.c:1462
 kernfs_add_one+0x208/0x290 fs/kernfs/dir.c:868
 __kernfs_create_file+0x145/0x180 fs/kernfs/file.c:1079
 sysfs_add_file_mode_ns+0x132/0x1b0 fs/sysfs/file.c:316
 create_files fs/sysfs/group.c:82 [inline]
 internal_create_group+0x43e/0x9e0 fs/sysfs/group.c:189
 internal_create_groups fs/sysfs/group.c:229 [inline]
 sysfs_create_groups+0x3f/0xf0 fs/sysfs/group.c:255
 device_add_groups drivers/base/core.c:2907 [inline]
 device_add_attrs+0x64/0x3f0 drivers/base/core.c:2971
 device_add+0x37a/0x790 drivers/base/core.c:3711
 netdev_register_kobject+0x108/0x220 net/core/net-sysfs.c:2337
 register_netdevice+0xaf7/0x11a0 net/core/dev.c:11439
 __ip_tunnel_create+0x31d/0x420 net/ipv4/ip_tunnel.c:268
 ip_tunnel_init_net+0x20a/0x480 net/ipv4/ip_tunnel.c:1150
 erspan_init_net+0x35/0x40 net/ipv4/ip_gre.c:1780
 ops_init+0x22a/0x2e0 net/core/net_namespace.c:137
 setup_net+0x9f/0x230 net/core/net_namespace.c:446
 copy_net_ns+0x31a/0x460 net/core/net_namespace.c:579
 create_new_namespaces+0x1f6/0x420 kernel/nsproxy.c:132
 unshare_nsproxy_namespaces+0x115/0x150 kernel/nsproxy.c:234
 ksys_unshare+0x411/0x760 kernel/fork.c:3267
 __do_sys_unshare kernel/fork.c:3341 [inline]
 __se_sys_unshare kernel/fork.c:3339 [inline]
 __x64_sys_unshare+0x1f/0x30 kernel/fork.c:3339
 x64_sys_call+0x1cef/0x3020 arch/x86/include/generated/asm/syscalls_64.h:273
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffc90001b8fbf8 of 1 bytes by task 5459 on cpu 1:
 rwsem_down_write_slowpath+0x462/0xab0 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:1632
 kernfs_remove_by_name_ns+0x6b/0x110 fs/kernfs/dir.c:1792
 kernfs_remove_by_name include/linux/kernfs.h:644 [inline]
 sysfs_unmerge_group+0x80/0xb0 fs/sysfs/group.c:408
 rpm_sysfs_remove drivers/base/power/sysfs.c:823 [inline]
 dpm_sysfs_remove+0x63/0x90 drivers/base/power/sysfs.c:832
 device_del+0x13d/0x790 drivers/base/core.c:3936
 nfc_remove_device+0x91/0xb0 net/nfc/core.c:1197
 nci_unregister_device+0x15b/0x170 net/nfc/nci/core.c:1341
 virtual_ncidev_close+0x2a/0x50 drivers/nfc/virtual_ncidev.c:168
 __fput+0x29e/0x630 fs/file_table.c:512
 ____fput+0x1c/0x30 fs/file_table.c:540
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
 exit_to_user_mode_loop+0x1e4/0x8c0 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x23c/0x3c0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5459 Comm: syz.1.496 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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