[moderation] [fs?] KCSAN: data-race in d_lru_add / step_into (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6d280f4d760e Merge tag 'for-6.8-rc3-tag' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15f825b7e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=3cd0dc1b46a5bc5c
dashboard link: https://syzkaller.appspot.com/bug?extid=ad7ed898a6037cb45c06
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz 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/98f24bc563ab/disk-6d280f4d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9142703b73e2/vmlinux-6d280f4d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/aaa5c9990feb/bzImage-6d280f4d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ad7ed8...@syzkaller.appspotmail.com

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

write to 0xffff88811ce1f900 of 4 bytes by task 19180 on cpu 0:
d_lru_add+0x45/0xe0 fs/dcache.c:426
retain_dentry fs/dcache.c:712 [inline]
fast_dput+0x261/0x2b0 fs/dcache.c:799
dput+0x24/0xc0 fs/dcache.c:839
path_put fs/namei.c:562 [inline]
terminate_walk+0xf2/0x270 fs/namei.c:686
path_openat+0x1923/0x1d40 fs/namei.c:3799
do_filp_open+0xf6/0x200 fs/namei.c:3825
do_sys_openat2+0xab/0x110 fs/open.c:1404
do_sys_open fs/open.c:1419 [inline]
__do_sys_openat fs/open.c:1435 [inline]
__se_sys_openat fs/open.c:1430 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1430
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+0x63/0x6b

read to 0xffff88811ce1f900 of 4 bytes by task 19181 on cpu 1:
__follow_mount_rcu fs/namei.c:1486 [inline]
handle_mounts fs/namei.c:1537 [inline]
step_into+0xe7/0x800 fs/namei.c:1839
walk_component fs/namei.c:2007 [inline]
link_path_walk+0x4d8/0x7e0 fs/namei.c:2328
path_openat+0x1a0/0x1d40 fs/namei.c:3794
do_filp_open+0xf6/0x200 fs/namei.c:3825
do_sys_openat2+0xab/0x110 fs/open.c:1404
do_sys_open fs/open.c:1419 [inline]
__do_sys_openat fs/open.c:1435 [inline]
__se_sys_openat fs/open.c:1430 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1430
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+0x63/0x6b

value changed: 0x0020000c -> 0x0028004c

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19181 Comm: syz-executor.3 Not tainted 6.8.0-rc3-syzkaller-00010-g6d280f4d760e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================


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[syzbot]

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