syzbot

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BUG: KCSAN: data-race in set_nlink / set_nlink

read to 0xffff888106448518 of 4 bytes by task 3000 on cpu 0:
 set_nlink+0x2b/0xb0
 kernfs_refresh_inode fs/kernfs/inode.c:180 [inline]
 kernfs_iop_permission+0x1c8/0x210 fs/kernfs/inode.c:288
 do_inode_permission fs/namei.c:525 [inline]
 inode_permission+0x18c/0x300 fs/namei.c:592
 may_lookup fs/namei.c:1821 [inline]
 link_path_walk+0x13e/0x830 fs/namei.c:2427
 path_lookupat+0x72/0x2b0 fs/namei.c:2635
 filename_lookup+0x150/0x340 fs/namei.c:2665
 vfs_statx+0x9a/0x170 fs/stat.c:346
 vfs_fstatat fs/stat.c:368 [inline]
 __do_sys_newfstatat fs/stat.c:532 [inline]
 __se_sys_newfstatat+0xdc/0x300 fs/stat.c:526
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:526
 x64_sys_call+0x236d/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:263
 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 0xffff888106448518 of 4 bytes by task 7729 on cpu 1:
 set_nlink+0x98/0xb0 fs/inode.c:448
 kernfs_refresh_inode fs/kernfs/inode.c:180 [inline]
 kernfs_iop_permission+0x1c8/0x210 fs/kernfs/inode.c:288
 do_inode_permission fs/namei.c:525 [inline]
 inode_permission+0x18c/0x300 fs/namei.c:592
 may_lookup fs/namei.c:1821 [inline]
 link_path_walk+0x13e/0x830 fs/namei.c:2427
 path_openat+0x1af/0x1fc0 fs/namei.c:3985
 do_filp_open+0x107/0x230 fs/namei.c:4016
 do_sys_openat2+0xab/0x120 fs/open.c:1428
 do_sys_open fs/open.c:1443 [inline]
 __do_sys_openat fs/open.c:1459 [inline]
 __se_sys_openat fs/open.c:1454 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1454
 x64_sys_call+0x2b30/0x2dc0 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: 0x00000009 -> 0x00000008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 7729 Comm: udevd Tainted: G        W          6.14.0-rc2-syzkaller-00034-gfebbc555cf0f #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
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