[moderation] [fs?] KCSAN: data-race in lookup_fast / shrink_dentry_list (10)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9d1694dc91ce Merge tag 'for-6.8/block-2024-01-18' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17d54993e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=afe76ef1b82444cf
dashboard link: https://syzkaller.appspot.com/bug?extid=577b1d046f4e5d6e7ca7
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz 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/ca73a5ac6e74/disk-9d1694dc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d599970abc9b/vmlinux-9d1694dc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ed9beb079aaf/bzImage-9d1694dc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+577b1d...@syzkaller.appspotmail.com

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

read-write to 0xffff888106e69300 of 4 bytes by task 9141 on cpu 0:
d_shrink_del fs/dcache.c:449 [inline]
shrink_dentry_list+0x19f/0x3d0 fs/dcache.c:1074
shrink_dcache_sb+0x165/0x290 fs/dcache.c:1195
reconfigure_super+0x3ef/0x580 fs/super.c:1054
do_remount fs/namespace.c:2892 [inline]
path_mount+0x969/0xb30 fs/namespace.c:3671
do_mount fs/namespace.c:3692 [inline]
__do_sys_mount fs/namespace.c:3898 [inline]
__se_sys_mount+0x27f/0x2d0 fs/namespace.c:3875
__x64_sys_mount+0x67/0x80 fs/namespace.c:3875
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888106e69300 of 4 bytes by task 9143 on cpu 1:
d_revalidate fs/namei.c:861 [inline]
lookup_fast+0xd9/0x290 fs/namei.c:1642
walk_component fs/namei.c:1997 [inline]
link_path_walk+0x3f4/0x7e0 fs/namei.c:2328
path_lookupat+0x72/0x2a0 fs/namei.c:2481
filename_lookup+0x126/0x300 fs/namei.c:2511
vfs_statx+0xa2/0x320 fs/stat.c:244
vfs_fstatat+0xcd/0x100 fs/stat.c:304
__do_sys_newfstatat fs/stat.c:468 [inline]
__se_sys_newfstatat+0x58/0x260 fs/stat.c:462
__x64_sys_newfstatat+0x55/0x60 fs/stat.c:462
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x59/0x120 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00680400 -> 0x00008000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9143 Comm: modprobe Not tainted 6.7.0-syzkaller-12377-g9d1694dc91ce #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.