syzbot

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BUG: KCSAN: data-race in set_nlink / set_nlink

read to 0xffff8881046d8a08 of 4 bytes by task 2826 on cpu 1:
 set_nlink+0x2b/0xb0
 kernfs_refresh_inode fs/kernfs/inode.c:180 [inline]
 kernfs_iop_permission+0x1dd/0x220 fs/kernfs/inode.c:288
 do_inode_permission fs/namei.c:461 [inline]
 inode_permission+0x18c/0x300 fs/namei.c:528
 may_lookup fs/namei.c:1726 [inline]
 link_path_walk+0x1b8/0x810 fs/namei.c:2273
 path_openat+0x1a1/0x1d80 fs/namei.c:3795
 do_filp_open+0xf7/0x200 fs/namei.c:3826
 do_sys_openat2+0xab/0x120 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_openat fs/open.c:1437 [inline]
 __se_sys_openat fs/open.c:1432 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1432
 x64_sys_call+0x2cad/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff8881046d8a08 of 4 bytes by task 2788 on cpu 0:
 set_nlink+0x98/0xb0 fs/inode.c:373
 kernfs_refresh_inode fs/kernfs/inode.c:180 [inline]
 kernfs_iop_permission+0x1dd/0x220 fs/kernfs/inode.c:288
 do_inode_permission fs/namei.c:461 [inline]
 inode_permission+0x18c/0x300 fs/namei.c:528
 may_lookup fs/namei.c:1726 [inline]
 link_path_walk+0x1b8/0x810 fs/namei.c:2273
 path_openat+0x1a1/0x1d80 fs/namei.c:3795
 do_filp_open+0xf7/0x200 fs/namei.c:3826
 do_sys_openat2+0xab/0x120 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_openat fs/open.c:1437 [inline]
 __se_sys_openat fs/open.c:1432 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1432
 x64_sys_call+0x2cad/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000018 -> 0x00000019

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2788 Comm: udevd Tainted: G        W          6.9.0-rc5-syzkaller-00042-ge88c4cfcb7b8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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