[moderation] [fs?] KCSAN: data-race in d_alloc_parallel / d_set_d_op (11)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9b2ffa6148b1 Merge tag 'mtd/fixes-for-6.13-rc5' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15b39adf980000
kernel config: https://syzkaller.appspot.com/x/.config?x=87d3cfca6847d1fa
dashboard link: https://syzkaller.appspot.com/bug?extid=c14e4eb7c49e37e24c7a
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/8f3f5cceed80/disk-9b2ffa61.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1ba00b70d91e/vmlinux-9b2ffa61.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b99c1bb4d63f/bzImage-9b2ffa61.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c14e4e...@syzkaller.appspotmail.com

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

read-write to 0xffff88810636c480 of 4 bytes by task 24401 on cpu 0:
d_set_d_op+0xfb/0x1f0 fs/dcache.c:1814
proc_pident_instantiate+0x164/0x180 fs/proc/base.c:2710
proc_pident_lookup+0x112/0x190 fs/proc/base.c:2733
proc_tgid_base_lookup+0x2b/0x40 fs/proc/base.c:3445
__lookup_slow+0x184/0x250 fs/namei.c:1791
lookup_slow+0x3c/0x60 fs/namei.c:1808
walk_component fs/namei.c:2112 [inline]
link_path_walk+0x69e/0x820 fs/namei.c:2477
path_openat+0x1af/0x1fa0 fs/namei.c:3983
do_filp_open+0x107/0x230 fs/namei.c:4014
do_sys_openat2+0xab/0x120 fs/open.c:1402
do_sys_open fs/open.c:1417 [inline]
__do_sys_openat fs/open.c:1433 [inline]
__se_sys_openat fs/open.c:1428 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1428
x64_sys_call+0x2b30/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810636c480 of 4 bytes by task 24402 on cpu 1:
d_in_lookup include/linux/dcache.h:378 [inline]
d_wait_lookup fs/dcache.c:2471 [inline]
d_alloc_parallel+0x5fe/0xc60 fs/dcache.c:2559
__lookup_slow+0x8d/0x250 fs/namei.c:1776
lookup_slow+0x3c/0x60 fs/namei.c:1808
walk_component fs/namei.c:2112 [inline]
link_path_walk+0x69e/0x820 fs/namei.c:2477
path_openat+0x1af/0x1fa0 fs/namei.c:3983
do_filp_open+0x107/0x230 fs/namei.c:4014
do_sys_openat2+0xab/0x120 fs/open.c:1402
do_sys_open fs/open.c:1417 [inline]
__do_sys_openat fs/open.c:1433 [inline]
__se_sys_openat fs/open.c:1428 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1428
x64_sys_call+0x2b30/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x10000000 -> 0x1000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 24402 Comm: syz.6.5429 Tainted: G W 6.13.0-rc4-syzkaller-00012-g9b2ffa6148b1 #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


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[syzbot]

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