[moderation] [fs?] KCSAN: data-race in shrink_dentry_list / step_into (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cd2286fc5775 Merge tag 'xfs-6.8-fixes-1' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17df3cf3e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bd33f45956bbc2
dashboard link: https://syzkaller.appspot.com/bug?extid=d7455a83ef563674225f
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/8d1d5b187557/disk-cd2286fc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b8f7a5eaec2e/vmlinux-cd2286fc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5e98a9942012/bzImage-cd2286fc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d7455a...@syzkaller.appspotmail.com

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

read-write to 0xffff8881006c8a80 of 4 bytes by task 5152 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 0xffff8881006c8a80 of 4 bytes by task 5153 on cpu 1:
__follow_mount_rcu fs/namei.c:1486 [inline]
handle_mounts fs/namei.c:1537 [inline]
step_into+0xe7/0x800 fs/namei.c:1839
walk_component fs/namei.c:2007 [inline]
link_path_walk+0x4d8/0x7e0 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: 0x00680440 -> 0x00008040

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5153 Comm: modprobe Not tainted 6.8.0-rc1-syzkaller-00331-gcd2286fc5775 #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.