EXT4-fs (loop0): Remounting filesystem read-only
EXT4-fs (loop0): 1 truncate cleaned up
EXT4-fs (loop0): pa ffff888105cf6230: logic 1, phys. 41, len 23
==================================================================
BUG: KCSAN: data-race in rwsem_down_write_slowpath / rwsem_down_write_slowpath

write to 0xffffc90000c1f858 of 1 bytes by task 4711 on cpu 1:
 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+0xad/0xc0 kernel/locking/rwsem.c:1632
 kernfs_add_one+0x5a/0x350 fs/kernfs/dir.c:825
 __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
 netdev_queue_add_kobject net/core/net-sysfs.c:1982 [inline]
 netdev_queue_update_kobjects+0x1e4/0x4b0 net/core/net-sysfs.c:2035
 register_queue_kobjects net/core/net-sysfs.c:2098 [inline]
 netdev_register_kobject+0x1cd/0x240 net/core/net-sysfs.c:2344
 register_netdevice+0xaf7/0x11a0 net/core/dev.c:11503
 tun_set_iff+0x5fe/0x870 drivers/net/tun.c:2956
 __tun_chr_ioctl+0x682/0x1550 drivers/net/tun.c:3239
 tun_chr_ioctl+0x27/0x40 drivers/net/tun.c:3488
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x239d/0x2550 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffc90000c1f858 of 1 bytes by task 4704 on cpu 0:
 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+0xad/0xc0 kernel/locking/rwsem.c:1632
 kernfs_add_one+0x5a/0x350 fs/kernfs/dir.c:825
 __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
 create_dir lib/kobject.c:78 [inline]
 kobject_add_internal+0x49d/0x770 lib/kobject.c:240
 kobject_add_varg lib/kobject.c:374 [inline]
 kobject_init_and_add+0x13c/0x1e0 lib/kobject.c:457
 ext4_register_sysfs+0xa5/0x270 fs/ext4/sysfs.c:617
 __ext4_fill_super fs/ext4/super.c:5764 [inline]
 ext4_fill_super+0x36d5/0x37b0 fs/ext4/super.c:5855
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1887
 get_tree_bdev+0x1f/0x30 fs/super.c:1910
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5887
 vfs_get_tree+0x57/0x1d0 fs/super.c:1947
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3772 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3848
 path_mount+0x4ad/0xb90 fs/namespace.c:4168
 do_mount fs/namespace.c:4181 [inline]
 __do_sys_mount fs/namespace.c:4397 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4374
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4374
 x64_sys_call+0xc3b/0x2550 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4704 Comm: syz.0.176 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 ro without journal. Quota mode: writeback.