syzbot

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BUG: KCSAN: data-race in set_nlink / set_nlink

read to 0xffff88810686bac0 of 4 bytes by task 3304 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:1819 [inline]
 link_path_walk+0x14b/0x820 fs/namei.c:2425
 path_openat+0x1af/0x1fa0 fs/namei.c:3983
 do_filp_open+0x107/0x230 fs/namei.c:4014
 do_sys_openat2+0xab/0x120 fs/open.c:1398
 do_sys_open fs/open.c:1413 [inline]
 __do_sys_openat fs/open.c:1429 [inline]
 __se_sys_openat fs/open.c:1424 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1424
 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

write to 0xffff88810686bac0 of 4 bytes by task 3016 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:1819 [inline]
 link_path_walk+0x14b/0x820 fs/namei.c:2425
 path_lookupat+0x72/0x2b0 fs/namei.c:2633
 filename_lookup+0x150/0x340 fs/namei.c:2663
 vfs_statx+0x9a/0x170 fs/stat.c:344
 vfs_fstatat fs/stat.c:366 [inline]
 __do_sys_newfstatat fs/stat.c:530 [inline]
 __se_sys_newfstatat+0xdc/0x300 fs/stat.c:524
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:524
 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

value changed: 0x00000008 -> 0x00000009

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3016 Comm: udevd Not tainted 6.12.0-syzkaller-01782-gbf9aa14fc523 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
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