syzbot

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BUG: KCSAN: data-race in set_nlink / set_nlink

read to 0xffff888106c069e8 of 4 bytes by task 2996 on cpu 0:
 set_nlink+0x29/0xb0 fs/inode.c:-1
 kernfs_refresh_inode fs/kernfs/inode.c:180 [inline]
 kernfs_iop_permission+0x1e2/0x220 fs/kernfs/inode.c:288
 do_inode_permission fs/namei.c:526 [inline]
 inode_permission+0x1c7/0x310 fs/namei.c:593
 may_lookup fs/namei.c:1845 [inline]
 link_path_walk+0x162/0x900 fs/namei.c:2454
 path_openat+0x1de/0x2170 fs/namei.c:4051
 do_filp_open+0x109/0x230 fs/namei.c:4082
 do_sys_openat2+0xa6/0x110 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_openat fs/open.c:1468 [inline]
 __se_sys_openat fs/open.c:1463 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1463
 x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff888106c069e8 of 4 bytes by task 3297 on cpu 1:
 set_nlink+0x99/0xb0 fs/inode.c:458
 kernfs_refresh_inode fs/kernfs/inode.c:180 [inline]
 kernfs_iop_permission+0x1e2/0x220 fs/kernfs/inode.c:288
 do_inode_permission fs/namei.c:526 [inline]
 inode_permission+0x1c7/0x310 fs/namei.c:593
 may_lookup fs/namei.c:1845 [inline]
 link_path_walk+0x162/0x900 fs/namei.c:2454
 path_openat+0x1de/0x2170 fs/namei.c:4051
 do_filp_open+0x109/0x230 fs/namei.c:4082
 do_sys_openat2+0xa6/0x110 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_openat fs/open.c:1468 [inline]
 __se_sys_openat fs/open.c:1463 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1463
 x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000010 -> 0x00000011

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3297 Comm: udevd Not tainted 6.16.0-rc5-syzkaller-00266-g3f31a806a62e #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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