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BUG: KCSAN: data-race in kernfs_iop_permission / kernfs_link_sibling

read-write to 0xffff88810038e6c0 of 8 bytes by task 3076 on cpu 1:
 kernfs_link_sibling+0x1e7/0x230 fs/kernfs/dir.c:387
 kernfs_add_one+0x260/0x390 fs/kernfs/dir.c:768
 kernfs_create_dir_ns+0x100/0x150 fs/kernfs/dir.c:1044
 kernfs_create_dir include/linux/kernfs.h:610 [inline]
 cgroup_create kernel/cgroup/cgroup.c:5605 [inline]
 cgroup_mkdir+0x24e/0xd10 kernel/cgroup/cgroup.c:5738
 kernfs_iop_mkdir+0x12b/0x1e0 fs/kernfs/dir.c:1219
 vfs_mkdir+0x1ac/0x2b0 fs/namei.c:4115
 do_mkdirat+0xf9/0x260 fs/namei.c:4138
 __do_sys_mkdirat fs/namei.c:4153 [inline]
 __se_sys_mkdirat fs/namei.c:4151 [inline]
 __x64_sys_mkdirat+0x50/0x60 fs/namei.c:4151
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88810038e6c0 of 8 bytes by task 3079 on cpu 0:
 kernfs_refresh_inode fs/kernfs/inode.c:181 [inline]
 kernfs_iop_permission+0x165/0x1b0 fs/kernfs/inode.c:289
 do_inode_permission fs/namei.c:461 [inline]
 inode_permission+0x184/0x300 fs/namei.c:528
 may_lookup fs/namei.c:1720 [inline]
 link_path_walk+0x19e/0x7e0 fs/namei.c:2267
 path_openat+0x19b/0x1d00 fs/namei.c:3787
 do_filp_open+0xf6/0x200 fs/namei.c:3818
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1356
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000005 -> 0x0000000000000006

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3079 Comm: syz-executor.2 Not tainted 6.4.0-rc4-syzkaller-00078-g929ed21dfdb6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
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EXT4-fs (loop2): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop2): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop2): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop2): unmounting filesystem 00000000-0000-0000-0000-000000000000.