[moderation] [fs?] KCSAN: data-race in __d_lookup_rcu / shrink_dentry_list (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 50768a425b46 Merge tag 'linux-kselftest-fixes-6.6-rc4' of ..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1049e322680000
kernel config: https://syzkaller.appspot.com/x/.config?x=a4bf49462978a33a
dashboard link: https://syzkaller.appspot.com/bug?extid=5ba3af2320dde0017662
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/446d959d5f5c/disk-50768a42.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9ff7679f62dd/vmlinux-50768a42.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7de7006b295d/bzImage-50768a42.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5ba3af...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __d_lookup_rcu / shrink_dentry_list

read-write to 0xffff88813c30c9c0 of 4 bytes by task 26853 on cpu 1:
d_shrink_del fs/dcache.c:448 [inline]
shrink_dentry_list+0x1c7/0x380 fs/dcache.c:1188
shrink_dcache_sb+0x165/0x290 fs/dcache.c:1321
reconfigure_super+0x3ef/0x580 fs/super.c:1118
do_remount fs/namespace.c:2882 [inline]
path_mount+0x969/0xb30 fs/namespace.c:3654
do_mount fs/namespace.c:3675 [inline]
__do_sys_mount fs/namespace.c:3884 [inline]
__se_sys_mount+0x27f/0x2d0 fs/namespace.c:3861
__x64_sys_mount+0x67/0x80 fs/namespace.c:3861
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88813c30c9c0 of 4 bytes by task 3107 on cpu 0:
__d_lookup_rcu+0x42/0x290 fs/dcache.c:2360
lookup_fast+0x8e/0x290 fs/namei.c:1628
walk_component+0x3f/0x230 fs/namei.c:1997
lookup_last fs/namei.c:2458 [inline]
path_lookupat+0x10a/0x2a0 fs/namei.c:2482
filename_lookup+0x126/0x300 fs/namei.c:2511
vfs_statx+0xa2/0x430 fs/stat.c:240
vfs_fstatat+0xcd/0x100 fs/stat.c:295
__do_sys_newfstatat fs/stat.c:459 [inline]
__se_sys_newfstatat+0x58/0x260 fs/stat.c:453
__x64_sys_newfstatat+0x55/0x60 fs/stat.c:453
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00280400 -> 0x00200000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3107 Comm: syz-executor.3 Tainted: G W 6.6.0-rc3-syzkaller-00025-g50768a425b46 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
==================================================================


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[syzbot]

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