[moderation] [fs?] KCSAN: data-race in link_path_walk / shrink_dentry_list (11)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 83a7eefedc9b Linux 6.10-rc3
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12651b5e980000
kernel config: https://syzkaller.appspot.com/x/.config?x=68336ea4b6f4fc09
dashboard link: https://syzkaller.appspot.com/bug?extid=084bdfde57f17b1d4722
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/dc4448d7f810/disk-83a7eefe.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1b7e727f29b/vmlinux-83a7eefe.xz
kernel image: https://storage.googleapis.com/syzbot-assets/470dd9374113/bzImage-83a7eefe.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+084bdf...@syzkaller.appspotmail.com

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

read-write to 0xffff888108aa6c00 of 4 bytes by task 4069 on cpu 0:
d_shrink_del fs/dcache.c:449 [inline]
shrink_dentry_list+0x226/0x3e0 fs/dcache.c:1067
shrink_dcache_sb+0x154/0x280 fs/dcache.c:1195
reconfigure_super+0x474/0x5b0 fs/super.c:1050
do_remount fs/namespace.c:2892 [inline]
path_mount+0x967/0xb30 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
x64_sys_call+0x25c9/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:166
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 0xffff888108aa6c00 of 4 bytes by task 4073 on cpu 1:
__d_entry_type include/linux/dcache.h:397 [inline]
d_can_lookup include/linux/dcache.h:412 [inline]
link_path_walk+0x4c1/0x810 fs/namei.c:2341
path_parentat fs/namei.c:2540 [inline]
__filename_parentat+0x13c/0x3c0 fs/namei.c:2564
filename_parentat fs/namei.c:2582 [inline]
filename_create+0x77/0x2b0 fs/namei.c:3881
do_symlinkat+0x84/0x350 fs/namei.c:4508
__do_sys_symlinkat fs/namei.c:4531 [inline]
__se_sys_symlinkat fs/namei.c:4528 [inline]
__x64_sys_symlinkat+0x62/0x70 fs/namei.c:4528
x64_sys_call+0x1e00/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:267
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: 0x00280400 -> 0x00200000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4073 Comm: syz-executor.4 Not tainted 6.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
==================================================================


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