[moderation] [fs?] KCSAN: data-race in d_alloc_parallel / d_set_d_op (8)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1b8af6552cb7 Merge tag 'powerpc-6.7-3' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=159d1f64e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=efc18f367a3f97fa
dashboard link: https://syzkaller.appspot.com/bug?extid=85840f7fd2dbe0a7309e
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2dbebc9ea594/disk-1b8af655.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/41592181ba2a/vmlinux-1b8af655.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b72b3a6a43ae/bzImage-1b8af655.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+85840f...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in d_alloc_parallel / d_set_d_op

read-write to 0xffff8881368c29c0 of 4 bytes by task 18418 on cpu 0:
d_set_d_op+0xf4/0x1e0 fs/dcache.c:1931
proc_ns_instantiate fs/proc/namespaces.c:114 [inline]
proc_ns_dir_lookup+0x180/0x220 fs/proc/namespaces.c:172
lookup_open fs/namei.c:3455 [inline]
open_last_lookups fs/namei.c:3546 [inline]
path_openat+0xc6f/0x1d70 fs/namei.c:3776
do_filp_open+0xf6/0x200 fs/namei.c:3809
do_sys_openat2+0xab/0x110 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_openat fs/open.c:1471 [inline]
__se_sys_openat fs/open.c:1466 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1466
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881368c29c0 of 4 bytes by task 18424 on cpu 1:
d_in_lookup include/linux/dcache.h:360 [inline]
d_wait_lookup fs/dcache.c:2618 [inline]
d_alloc_parallel+0x621/0xc90 fs/dcache.c:2706
lookup_open fs/namei.c:3402 [inline]
open_last_lookups fs/namei.c:3546 [inline]
path_openat+0x658/0x1d70 fs/namei.c:3776
do_filp_open+0xf6/0x200 fs/namei.c:3809
do_sys_openat2+0xab/0x110 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_openat fs/open.c:1471 [inline]
__se_sys_openat fs/open.c:1466 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1466
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x10000000 -> 0x1000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 18424 Comm: syz-executor.4 Not tainted 6.7.0-rc3-syzkaller-00298-g1b8af6552cb7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================


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[syzbot]

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