[fs?] KCSAN: data-race in __d_lookup_rcu / __d_rehash (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c0927a7a5391 Merge tag 'xfs-6.3-merge-4' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=122f6360c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=bfa8e7fa24e8342b
dashboard link: https://syzkaller.appspot.com/bug?extid=51e076f12e9009275f7e
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7342ffcaa33d/disk-c0927a7a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/215687b544d6/vmlinux-c0927a7a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f63840a989e/bzImage-c0927a7a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+51e076...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __d_lookup_rcu / __d_rehash

read to 0xffff888142420310 of 8 bytes by task 13653 on cpu 1:
hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
d_unhashed include/linux/dcache.h:335 [inline]
__d_lookup_rcu+0x120/0x290 fs/dcache.c:2400
lookup_fast+0x8e/0x290 fs/namei.c:1621
walk_component+0x3f/0x230 fs/namei.c:1990
lookup_last fs/namei.c:2451 [inline]
path_lookupat+0x10a/0x2a0 fs/namei.c:2475
filename_lookup+0x126/0x300 fs/namei.c:2504
user_path_at_empty+0x42/0x110 fs/namei.c:2877
user_path_at include/linux/namei.h:57 [inline]
__do_sys_chdir fs/open.c:551 [inline]
__se_sys_chdir+0x4f/0x140 fs/open.c:545
__x64_sys_chdir+0x1f/0x30 fs/open.c:545
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff888142420310 of 8 bytes by task 2744 on cpu 0:
hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
__d_rehash+0xc7/0x210 fs/dcache.c:2579
__d_add+0x367/0x490 fs/dcache.c:2794
d_add+0x45/0x50 fs/dcache.c:2817
simple_lookup+0x89/0xa0 fs/libfs.c:76
__lookup_hash+0xbc/0x180 fs/namei.c:1602
do_unlinkat+0x14c/0x4f0 fs/namei.c:4302
__do_sys_unlink fs/namei.c:4364 [inline]
__se_sys_unlink fs/namei.c:4362 [inline]
__x64_sys_unlink+0x30/0x40 fs/namei.c:4362
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2744 Comm: udevd Not tainted 6.2.0-syzkaller-12998-gc0927a7a5391-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.