syzbot

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BUG: KCSAN: data-race in set_nlink / set_nlink

read to 0xffff8881064822b0 of 4 bytes by task 3261 on cpu 1:
 set_nlink+0x2b/0xb0
 kernfs_refresh_inode fs/kernfs/inode.c:180 [inline]
 kernfs_iop_permission+0x1d5/0x220 fs/kernfs/inode.c:288
 do_inode_permission fs/namei.c:468 [inline]
 inode_permission+0x18c/0x300 fs/namei.c:535
 may_lookup fs/namei.c:1761 [inline]
 link_path_walk+0x5f3/0x820 fs/namei.c:2352
 path_parentat fs/namei.c:2613 [inline]
 __filename_parentat+0x13c/0x3c0 fs/namei.c:2637
 filename_parentat fs/namei.c:2655 [inline]
 filename_create+0x77/0x2b0 fs/namei.c:3960
 do_mkdirat+0x63/0x2a0 fs/namei.c:4225
 __do_sys_mkdirat fs/namei.c:4248 [inline]
 __se_sys_mkdirat fs/namei.c:4246 [inline]
 __x64_sys_mkdirat+0x4e/0x60 fs/namei.c:4246
 x64_sys_call+0x2cd3/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:259
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff8881064822b0 of 4 bytes by task 3265 on cpu 0:
 set_nlink+0x98/0xb0 fs/inode.c:375
 kernfs_refresh_inode fs/kernfs/inode.c:180 [inline]
 kernfs_iop_permission+0x1d5/0x220 fs/kernfs/inode.c:288
 do_inode_permission fs/namei.c:468 [inline]
 inode_permission+0x18c/0x300 fs/namei.c:535
 may_lookup fs/namei.c:1761 [inline]
 link_path_walk+0x5f3/0x820 fs/namei.c:2352
 path_openat+0x1aa/0x1f10 fs/namei.c:3882
 do_filp_open+0xf7/0x200 fs/namei.c:3913
 do_sys_openat2+0xab/0x120 fs/open.c:1416
 do_sys_open fs/open.c:1431 [inline]
 __do_sys_openat fs/open.c:1447 [inline]
 __se_sys_openat fs/open.c:1442 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1442
 x64_sys_call+0x1025/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000004 -> 0x00000005

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3265 Comm: syz-executor Not tainted 6.11.0-rc5-syzkaller-00219-g1934261d8974 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
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