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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5254c0cbc92d Merge tag 'block-6.7-2023-12-22' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=137270cee80000
kernel config: https://syzkaller.appspot.com/x/.config?x=989a728d0f884055
dashboard link: https://syzkaller.appspot.com/bug?extid=9e6f5e2713e95f07da4d
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/a688ac746452/disk-5254c0cb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/87e0fe9c0d76/vmlinux-5254c0cb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7c03a8d415c8/bzImage-5254c0cb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9e6f5e...@syzkaller.appspotmail.com

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

write to 0xffff8881053ebc00 of 4 bytes by task 8540 on cpu 0:
d_lru_shrink_move fs/dcache.c:480 [inline]
dentry_lru_isolate_shrink+0x7f/0x100 fs/dcache.c:1300
__list_lru_walk_one+0x180/0x3b0 mm/list_lru.c:231
list_lru_walk_one mm/list_lru.c:276 [inline]
list_lru_walk_node+0x7f/0x1f0 mm/list_lru.c:304
list_lru_walk include/linux/list_lru.h:214 [inline]
shrink_dcache_sb+0xc5/0x290 fs/dcache.c:1319
reconfigure_super+0x3ef/0x580 fs/super.c:1121
do_remount fs/namespace.c:2884 [inline]
path_mount+0x969/0xb30 fs/namespace.c:3656
do_mount fs/namespace.c:3677 [inline]
__do_sys_mount fs/namespace.c:3886 [inline]
__se_sys_mount+0x27f/0x2d0 fs/namespace.c:3863
__x64_sys_mount+0x67/0x80 fs/namespace.c:3863
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 0xffff8881053ebc00 of 4 bytes by task 8544 on cpu 1:
__follow_mount_rcu fs/namei.c:1487 [inline]
handle_mounts fs/namei.c:1538 [inline]
step_into+0xe7/0x800 fs/namei.c:1840
walk_component fs/namei.c:2008 [inline]
link_path_walk+0x4d8/0x7e0 fs/namei.c:2329
path_openat+0x1a0/0x1d70 fs/namei.c:3775
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: 0x00680000 -> 0x00008000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8544 Comm: modprobe Not tainted 6.7.0-rc6-syzkaller-00248-g5254c0cbc92d #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.