KCSAN: data-race in fsnotify / fsnotify_put_mark

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bb5baaa9 Merge tag 'arm64-fixes' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1540038a900000
kernel config: https://syzkaller.appspot.com/x/.config?x=eb948cec8745bdce
dashboard link: https://syzkaller.appspot.com/bug?extid=68fa3855e60a3d51a81d
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project.git ca2dcbd030eadbf0aa9b660efe864ff08af6e18b)
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.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+68fa38...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in fsnotify / fsnotify_put_mark

write to 0xffff888129ff894c of 4 bytes by task 11332 on cpu 0:
fsnotify_detach_connector_from_object fs/notify/mark.c:184 [inline]
fsnotify_put_mark+0x269/0x5e0 fs/notify/mark.c:250
__do_sys_inotify_rm_watch fs/notify/inotify/inotify_user.c:790 [inline]
__se_sys_inotify_rm_watch+0xff/0x170 fs/notify/inotify/inotify_user.c:764
__x64_sys_inotify_rm_watch+0x2d/0x40 fs/notify/inotify/inotify_user.c:764
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888129ff894c of 4 bytes by task 5076 on cpu 1:
fsnotify+0x171/0xe50 fs/notify/fsnotify.c:468
__fsnotify_parent+0x3e3/0x470 fs/notify/fsnotify.c:223
fsnotify_parent include/linux/fsnotify.h:68 [inline]
fsnotify_file include/linux/fsnotify.h:90 [inline]
fsnotify_open include/linux/fsnotify.h:268 [inline]
do_sys_openat2+0x492/0x500 fs/open.c:1179
do_sys_open fs/open.c:1190 [inline]
__do_sys_open fs/open.c:1198 [inline]
__se_sys_open fs/open.c:1194 [inline]
__x64_sys_open+0xe2/0x110 fs/open.c:1194
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5076 Comm: systemd-udevd Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 5076 Comm: systemd-udevd Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x10f/0x19d lib/dump_stack.c:118
panic+0x207/0x64a kernel/panic.c:231
kcsan_report+0x684/0x690 kernel/kcsan/report.c:630
kcsan_setup_watchpoint+0x41e/0x4a0 kernel/kcsan/core.c:540
fsnotify+0x171/0xe50 fs/notify/fsnotify.c:468
__fsnotify_parent+0x3e3/0x470 fs/notify/fsnotify.c:223
fsnotify_parent include/linux/fsnotify.h:68 [inline]
fsnotify_file include/linux/fsnotify.h:90 [inline]
fsnotify_open include/linux/fsnotify.h:268 [inline]
do_sys_openat2+0x492/0x500 fs/open.c:1179
do_sys_open fs/open.c:1190 [inline]
__do_sys_open fs/open.c:1198 [inline]
__se_sys_open fs/open.c:1194 [inline]
__x64_sys_open+0xe2/0x110 fs/open.c:1194
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f110836e840
Code: 73 01 c3 48 8b 0d 68 77 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 89 bb 20 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 1e f6 ff ff 48 89 04 24
RSP: 002b:00007ffd1297bfc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007ffd1297c090 RCX: 00007f110836e840
RDX: 00005590a5607fe3 RSI: 00000000000a0800 RDI: 00005590a5fe1530
RBP: 00007ffd1297c500 R08: 00005590a5607670 R09: 0000000000000010
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd1297c170
R13: 00005590a5fca010 R14: 00005590a5fd8670 R15: 00007ffd1297c040
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[syzbot]

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