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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bc3372351d0c Merge tag 'for-6.15-rc3-tag' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12cda63f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=85dd0f8b81b9d41f
dashboard link: https://syzkaller.appspot.com/bug?extid=c1135fc33b779acb2912
compiler: Debian clang version 15.0.6, Debian LLD 15.0.6
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/e34c7b45191d/disk-bc337235.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/20da91ffebb2/vmlinux-bc337235.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ffbfdf7d8b67/bzImage-bc337235.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c1135f...@syzkaller.appspotmail.com

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

read-write to 0xffff888106064cc0 of 4 bytes by task 3474 on cpu 1:
d_shrink_del fs/dcache.c:506 [inline]
shrink_dentry_list+0x226/0x3e0 fs/dcache.c:1124
shrink_dcache_sb+0x156/0x280 fs/dcache.c:1252
reconfigure_super+0x4c1/0x5b0 fs/super.c:1061
do_remount fs/namespace.c:3365 [inline]
path_mount+0x96a/0xb30 fs/namespace.c:4200
do_mount fs/namespace.c:4221 [inline]
__do_sys_mount fs/namespace.c:4432 [inline]
__se_sys_mount+0x28f/0x2e0 fs/namespace.c:4409
__x64_sys_mount+0x67/0x80 fs/namespace.c:4409
x64_sys_call+0xd11/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:166
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc9/0x1a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106064cc0 of 4 bytes by task 3296 on cpu 0:
__d_entry_type include/linux/dcache.h:409 [inline]
d_is_reg include/linux/dcache.h:444 [inline]
do_open fs/namei.c:3872 [inline]
path_openat+0x194f/0x2000 fs/namei.c:4039
do_filp_open+0x115/0x240 fs/namei.c:4066
do_sys_openat2+0xaa/0x110 fs/open.c:1429
do_sys_open fs/open.c:1444 [inline]
__do_sys_openat fs/open.c:1460 [inline]
__se_sys_openat fs/open.c:1455 [inline]
__x64_sys_openat+0xf8/0x120 fs/open.c:1455
x64_sys_call+0x1ac/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc9/0x1a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00240444 -> 0x00200044

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3296 Comm: udevd Not tainted 6.15.0-rc3-syzkaller-00019-gbc3372351d0c #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================


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[syzbot]

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