[moderation] [fs?] KCSAN: data-race in __fsnotify_parent / __fsnotify_recalc_mask (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 795c58e4c7fc Merge tag 'trace-v6.10-rc6' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16a6b6b9980000
kernel config: https://syzkaller.appspot.com/x/.config?x=5b9537cd00be479e
dashboard link: https://syzkaller.appspot.com/bug?extid=fe5e16cdc1d81cc8ace9
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/3d1d205c1fdf/disk-795c58e4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/641c78d42b7a/vmlinux-795c58e4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/45ecf25d8ba3/bzImage-795c58e4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fe5e16...@syzkaller.appspotmail.com

EXT4-fs (loop3): unmounting filesystem 00000000-0000-0000-0000-000000000000.
==================================================================
BUG: KCSAN: data-race in __fsnotify_parent / __fsnotify_recalc_mask

write to 0xffff8881001c9d44 of 4 bytes by task 6671 on cpu 1:
__fsnotify_recalc_mask+0x216/0x320 fs/notify/mark.c:248
fsnotify_recalc_mask fs/notify/mark.c:265 [inline]
fsnotify_add_mark_locked+0x703/0x870 fs/notify/mark.c:781
fsnotify_add_inode_mark_locked include/linux/fsnotify_backend.h:812 [inline]
inotify_new_watch fs/notify/inotify/inotify_user.c:620 [inline]
inotify_update_watch fs/notify/inotify/inotify_user.c:647 [inline]
__do_sys_inotify_add_watch fs/notify/inotify/inotify_user.c:786 [inline]
__se_sys_inotify_add_watch+0x66f/0x810 fs/notify/inotify/inotify_user.c:729
__x64_sys_inotify_add_watch+0x43/0x50 fs/notify/inotify/inotify_user.c:729
x64_sys_call+0x2af1/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:255
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 0xffff8881001c9d44 of 4 bytes by task 10004 on cpu 0:
fsnotify_object_watched fs/notify/fsnotify.c:187 [inline]
__fsnotify_parent+0xd4/0x370 fs/notify/fsnotify.c:217
fsnotify_parent include/linux/fsnotify.h:96 [inline]
fsnotify_file include/linux/fsnotify.h:131 [inline]
fsnotify_open include/linux/fsnotify.h:401 [inline]
vfs_open+0x1be/0x1f0 fs/open.c:1093
do_open fs/namei.c:3654 [inline]
path_openat+0x1ad9/0x1fa0 fs/namei.c:3813
do_filp_open+0xf7/0x200 fs/namei.c:3840
do_sys_openat2+0xab/0x120 fs/open.c:1413
do_sys_open fs/open.c:1428 [inline]
__do_sys_openat fs/open.c:1444 [inline]
__se_sys_openat fs/open.c:1439 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1439
x64_sys_call+0x1057/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:258
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: 0x00000000 -> 0x00002008

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10004 Comm: syz-executor Not tainted 6.10.0-rc6-syzkaller-00069-g795c58e4c7fc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================


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[Dmitry Vyukov]

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