[moderation] [fs?] KCSAN: data-race in __fsnotify_parent / __fsnotify_recalc_mask (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 77fa2fbe87fc Merge tag 'for_linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1558cd60e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=f89e9ee49649fd75
dashboard link: https://syzkaller.appspot.com/bug?extid=237d89544930e1cab55e
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
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/6fc250f69bf4/disk-77fa2fbe.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/78d7961b496e/vmlinux-77fa2fbe.xz
kernel image: https://storage.googleapis.com/syzbot-assets/278c680fdcea/bzImage-77fa2fbe.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+237d89...@syzkaller.appspotmail.com

EXT4-fs (loop4): unmounting filesystem 00000000-0000-0000-0000-000000000000.
==================================================================
BUG: KCSAN: data-race in __fsnotify_parent / __fsnotify_recalc_mask

write to 0xffff8881001c4ba4 of 4 bytes by task 3086 on cpu 1:
__fsnotify_recalc_mask+0x204/0x300 fs/notify/mark.c:174
fsnotify_recalc_mask fs/notify/mark.c:191 [inline]
fsnotify_add_mark_locked+0x9c8/0xbd0 fs/notify/mark.c:730
fsnotify_add_inode_mark_locked include/linux/fsnotify_backend.h:784 [inline]
inotify_new_watch fs/notify/inotify/inotify_user.c:621 [inline]
inotify_update_watch fs/notify/inotify/inotify_user.c:648 [inline]
__do_sys_inotify_add_watch fs/notify/inotify/inotify_user.c:787 [inline]
__se_sys_inotify_add_watch+0x66b/0x820 fs/notify/inotify/inotify_user.c:730
__x64_sys_inotify_add_watch+0x43/0x50 fs/notify/inotify/inotify_user.c:730
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881001c4ba4 of 4 bytes by task 3123 on cpu 0:
fsnotify_event_needs_parent fs/notify/fsnotify.c:161 [inline]
__fsnotify_parent+0x128/0x480 fs/notify/fsnotify.c:202
fsnotify_parent include/linux/fsnotify.h:77 [inline]
fsnotify_file include/linux/fsnotify.h:100 [inline]
fsnotify_close include/linux/fsnotify.h:342 [inline]
__fput+0x1da/0x630 fs/file_table.c:380
__fput_sync+0x44/0x50 fs/file_table.c:475
__do_sys_close fs/open.c:1590 [inline]
__se_sys_close+0xfa/0x1a0 fs/open.c:1575
__x64_sys_close+0x1f/0x30 fs/open.c:1575
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000000 -> 0x00002008

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3123 Comm: syz-executor.4 Not tainted 6.6.0-syzkaller-14614-g77fa2fbe87fc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
==================================================================
EXT4-fs (loop4): unmounting filesystem 00000000-0000-0000-0000-000000000000.
EXT4-fs (loop4): unmounting filesystem 00000000-0000-0000-0000-000000000000.


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[syzbot]

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