[moderation] [kernfs?] KCSAN: data-race in __kernfs_remove / cleanup_glue_dir (8)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 88035e5694a8 Merge tag 'hid-for-linus-2023121201' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13df70aee80000
kernel config: https://syzkaller.appspot.com/x/.config?x=d6f4b50a94fc12a6
dashboard link: https://syzkaller.appspot.com/bug?extid=7466867e5f72e66f1880
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [gre...@linuxfoundation.org linux-...@vger.kernel.org linux-...@vger.kernel.org t...@kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bcfa87ceea25/disk-88035e56.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5e39c99719af/vmlinux-88035e56.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b47f2fa75492/bzImage-88035e56.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+746686...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __kernfs_remove / cleanup_glue_dir

read-write to 0xffff8881016ff3c0 of 8 bytes by task 5411 on cpu 0:
kernfs_unlink_sibling fs/kernfs/dir.c:415 [inline]
__kernfs_remove+0x2ff/0x480 fs/kernfs/dir.c:1471
kernfs_remove+0x4e/0x70 fs/kernfs/dir.c:1507
sysfs_remove_dir+0x7e/0xa0 fs/sysfs/dir.c:101
__kobject_del+0x8c/0x190 lib/kobject.c:601
kobject_del+0x2e/0x50 lib/kobject.c:624
device_add+0x5e5/0x8b0 drivers/base/core.c:3674
device_create_groups_vargs drivers/base/core.c:4312 [inline]
device_create+0x181/0x1d0 drivers/base/core.c:4351
bdi_register_va+0x70/0x420 mm/backing-dev.c:1005
super_setup_bdi_name+0x97/0x140 fs/super.c:1830
super_setup_bdi+0x47/0x50 fs/super.c:1852
v9fs_fill_super fs/9p/vfs_super.c:75 [inline]
v9fs_mount+0x270/0x630 fs/9p/vfs_super.c:134
legacy_get_tree+0x74/0xd0 fs/fs_context.c:662
vfs_get_tree+0x51/0x1b0 fs/super.c:1771
do_new_mount+0x203/0x660 fs/namespace.c:3337
path_mount+0x496/0xb30 fs/namespace.c:3664
do_mount fs/namespace.c:3677 [inline]
__do_sys_mount fs/namespace.c:3886 [inline]
__se_sys_mount+0x27f/0x2d0 fs/namespace.c:3863
__x64_sys_mount+0x67/0x80 fs/namespace.c:3863
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881016ff3c0 of 8 bytes by task 5429 on cpu 1:
kobject_has_children drivers/base/core.c:3283 [inline]
cleanup_glue_dir+0xe5/0x160 drivers/base/core.c:3349
device_del+0x73a/0x7a0 drivers/base/core.c:3835
device_unregister+0x15/0x30 drivers/base/core.c:3855
bdi_unregister+0x307/0x390 mm/backing-dev.c:1081
generic_shutdown_super+0x1a1/0x210 fs/super.c:730
kill_anon_super+0x2b/0x130 fs/super.c:1295
v9fs_kill_super+0x2f/0x60 fs/9p/vfs_super.c:220
deactivate_locked_super+0x7a/0x1c0 fs/super.c:484
v9fs_mount+0x4b5/0x630 fs/9p/vfs_super.c:204
legacy_get_tree+0x74/0xd0 fs/fs_context.c:662
vfs_get_tree+0x51/0x1b0 fs/super.c:1771
do_new_mount+0x203/0x660 fs/namespace.c:3337
path_mount+0x496/0xb30 fs/namespace.c:3664
do_mount fs/namespace.c:3677 [inline]
__do_sys_mount fs/namespace.c:3886 [inline]
__se_sys_mount+0x27f/0x2d0 fs/namespace.c:3863
__x64_sys_mount+0x67/0x80 fs/namespace.c:3863
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x000000000000000a -> 0x0000000000000009

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5429 Comm: syz-executor.3 Not tainted 6.7.0-rc5-syzkaller-00042-g88035e5694a8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================


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[syzbot]

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