[moderation] [fs?] KCSAN: data-race in __fsnotify_parent / d_make_discardable (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4a50a141f05a Merge tag 'bootconfig-fixes-v7.2-rc1' of git:..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13f0711c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=84b3039e8461eef5
dashboard link: https://syzkaller.appspot.com/bug?extid=41ff5addc0df59ff3f75
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [amir...@gmail.com ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/188bad4d8701/disk-4a50a141.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3ab9f679852f/vmlinux-4a50a141.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a98087016602/bzImage-4a50a141.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+41ff5a...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __fsnotify_parent / d_make_discardable

write to 0xffff88811ad726c0 of 4 bytes by task 5266 on cpu 1:
d_make_discardable+0x4f/0x90 fs/dcache.c:1050
simple_unlink+0x68/0x80 fs/libfs.c:808
shmem_unlink+0x12d/0x140 mm/shmem.c:3917
shmem_rename2+0x185/0x310 mm/shmem.c:3998
vfs_rename+0x963/0xac0 fs/namei.c:6070
filename_renameat2+0x3a4/0x6a0 fs/namei.c:6188
__do_sys_rename fs/namei.c:6232 [inline]
__se_sys_rename+0x4a/0x1c0 fs/namei.c:6228
__x64_sys_rename+0x31/0x40 fs/namei.c:6228
x64_sys_call+0x2b3/0x3020 arch/x86/include/generated/asm/syscalls_64.h:83
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811ad726c0 of 4 bytes by task 7603 on cpu 0:
__fsnotify_parent+0xbc/0x3a0 fs/notify/fsnotify.c:192
fsnotify_parent include/linux/fsnotify.h:96 [inline]
fsnotify_path include/linux/fsnotify.h:113 [inline]
fsnotify_file include/linux/fsnotify.h:127 [inline]
fsnotify_open include/linux/fsnotify.h:450 [inline]
vfs_open+0x19c/0x1e0 fs/open.c:1059
do_open fs/namei.c:4700 [inline]
path_openat+0x1b39/0x2000 fs/namei.c:4859
do_file_open+0x16c/0x290 fs/namei.c:4888
do_sys_openat2+0xa0/0x130 fs/open.c:1368
do_sys_open fs/open.c:1374 [inline]
__do_sys_openat fs/open.c:1390 [inline]
__se_sys_openat fs/open.c:1385 [inline]
__x64_sys_openat+0xf2/0x120 fs/open.c:1385
x64_sys_call+0x1e39/0x3020 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x08200080 -> 0x00200180

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 7603 Comm: udevd Tainted: G W syzkaller #0 PREEMPT(lazy)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================


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