syzbot

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BUG: KCSAN: data-race in set_nlink / set_nlink

read to 0xffff888104e60518 of 4 bytes by task 4163 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:1760 [inline]
 link_path_walk+0x14b/0x820 fs/namei.c:2366
 path_lookupat+0x72/0x2b0 fs/namei.c:2579
 filename_lookup+0x127/0x300 fs/namei.c:2609
 vfs_statx+0xa1/0x2f0 fs/stat.c:312
 vfs_fstatat+0xec/0x110 fs/stat.c:341
 __do_sys_newfstatat fs/stat.c:505 [inline]
 __se_sys_newfstatat+0x58/0x260 fs/stat.c:499
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:499
 x64_sys_call+0x141f/0x2d60 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 0xffff888104e60518 of 4 bytes by task 2967 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:1760 [inline]
 link_path_walk+0x14b/0x820 fs/namei.c:2366
 path_openat+0x1af/0x1fa0 fs/namei.c:3929
 do_filp_open+0xf7/0x200 fs/namei.c:3960
 do_sys_openat2+0xab/0x120 fs/open.c:1415
 do_sys_open fs/open.c:1430 [inline]
 __do_sys_openat fs/open.c:1446 [inline]
 __se_sys_openat fs/open.c:1441 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1441
 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: 0x00000005 -> 0x00000006

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 2967 Comm: udevd Not tainted 6.12.0-rc2-syzkaller-00006-g87d6aab2389e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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