[moderation] [fs?] KCSAN: data-race in d_lru_add / step_into (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a4aebe936554 posix-timers: Get rid of [COMPAT_]SYS_NI() uses
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=162979a5e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=989a728d0f884055
dashboard link: https://syzkaller.appspot.com/bug?extid=269e445f9ac92c4b8708
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org 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/5664a1a6a9c6/disk-a4aebe93.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9f158955737d/vmlinux-a4aebe93.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fd832a5634ea/bzImage-a4aebe93.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+269e44...@syzkaller.appspotmail.com

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

write to 0xffff888150b6e600 of 4 bytes by task 18596 on cpu 1:
d_lru_add+0x45/0xe0 fs/dcache.c:427
retain_dentry+0x157/0x190 fs/dcache.c:685
dput+0x108/0x1f0 fs/dcache.c:908
path_put fs/namei.c:562 [inline]
put_link fs/namei.c:1028 [inline]
pick_link+0x53b/0x7b0 fs/namei.c:1823
step_into+0x71b/0x800 fs/namei.c:1872
open_last_lookups fs/namei.c:3569 [inline]
path_openat+0x10da/0x1d70 fs/namei.c:3776
do_filp_open+0xf6/0x200 fs/namei.c:3809
do_sys_openat2+0xab/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+0xf3/0x120 fs/open.c:1463
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888150b6e600 of 4 bytes by task 18567 on cpu 0:
__d_entry_type include/linux/dcache.h:386 [inline]
d_is_symlink include/linux/dcache.h:416 [inline]
step_into+0x12f/0x800 fs/namei.c:1845
open_last_lookups fs/namei.c:3569 [inline]
path_openat+0x10da/0x1d70 fs/namei.c:3776
do_filp_open+0xf6/0x200 fs/namei.c:3809
do_sys_openat2+0xab/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+0xf3/0x120 fs/open.c:1463
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0060000c -> 0x0068004c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18567 Comm: syz-executor.2 Not tainted 6.7.0-rc6-syzkaller-00078-ga4aebe936554 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
==================================================================


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[syzbot]

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