[moderation] [fs?] KCSAN: data-race in dentry_unlink_inode / step_into

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6feb57c2fd7c Merge tag 'kbuild-v6.2' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12a1a04f880000
kernel config: https://syzkaller.appspot.com/x/.config?x=636e09e08afda718
dashboard link: https://syzkaller.appspot.com/bug?extid=10935029822fbc89bbfa
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1442914f880000
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fd871ab7a8c2/disk-6feb57c2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a5d644541dd0/vmlinux-6feb57c2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b02a70523453/bzImage-6feb57c2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+109350...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in dentry_unlink_inode / step_into

write to 0xffff88810acf5930 of 8 bytes by task 3114 on cpu 1:
__d_clear_type_and_inode fs/dcache.c:358 [inline]
dentry_unlink_inode+0x65/0x240 fs/dcache.c:391
d_delete+0x70/0xa0 fs/dcache.c:2565
d_delete_notify+0x30/0xe0 include/linux/fsnotify.h:259
vfs_unlink+0x306/0x3e0 fs/namei.c:4267
do_unlinkat+0x258/0x510 fs/namei.c:4320
__do_sys_unlink fs/namei.c:4368 [inline]
__se_sys_unlink fs/namei.c:4366 [inline]
__x64_sys_unlink+0x2c/0x30 fs/namei.c:4366
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88810acf5930 of 8 bytes by task 2737 on cpu 0:
step_into+0x115/0x7d0 fs/namei.c:1835
walk_component+0x164/0x230 fs/namei.c:1999
lookup_last fs/namei.c:2450 [inline]
path_lookupat+0x11d/0x2b0 fs/namei.c:2474
filename_lookup+0x133/0x310 fs/namei.c:2503
user_path_at_empty+0x3e/0x110 fs/namei.c:2876
do_readlinkat+0x98/0x210 fs/stat.c:471
__do_sys_readlink fs/stat.c:504 [inline]
__se_sys_readlink fs/stat.c:501 [inline]
__x64_sys_readlink+0x43/0x50 fs/stat.c:501
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0xffff88810bc26a58 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2737 Comm: udevd Not tainted 6.1.0-syzkaller-13822-g6feb57c2fd7c-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
==================================================================


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