syzbot

==================================================================
BUG: KCSAN: data-race in fsnotify_parent / vfs_unlink

write to 0xffff88811f1fd900 of 4 bytes by task 10866 on cpu 1:
 dont_mount include/linux/dcache.h:354 [inline]
 vfs_unlink+0x26e/0x3d0 fs/namei.c:3827
 do_unlinkat+0x28a/0x4d0 fs/namei.c:3889
 __do_sys_unlink fs/namei.c:3936 [inline]
 __se_sys_unlink fs/namei.c:3934 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:3934
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811f1fd900 of 4 bytes by task 10859 on cpu 0:
 fsnotify_parent+0x36/0x180 fs/notify/fsnotify.c:153
 fsnotify_file include/linux/fsnotify.h:74 [inline]
 fsnotify_modify include/linux/fsnotify.h:257 [inline]
 vfs_write+0x27c/0x690 fs/read_write.c:582
 ksys_write+0xce/0x180 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10859 Comm: syz-executor.3 Not tainted 5.8.0-rc5-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: 0 PID: 10859 Comm: syz-executor.3 Not tainted 5.8.0-rc5-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:626
 kcsan_setup_watchpoint+0x453/0x4d0 kernel/kcsan/core.c:519
 fsnotify_parent+0x36/0x180 fs/notify/fsnotify.c:153
 fsnotify_file include/linux/fsnotify.h:74 [inline]
 fsnotify_modify include/linux/fsnotify.h:257 [inline]
 vfs_write+0x27c/0x690 fs/read_write.c:582
 ksys_write+0xce/0x180 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c1d9
Code: Bad RIP value.
RSP: 002b:00007f958d0f4c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000036c40 RCX: 000000000045c1d9
RDX: 00000000fffffe58 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 000000000078bf40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007ffeda6245ff R14: 00007f958d0f59c0 R15: 000000000078bf0c
Kernel Offset: disabled
Rebooting in 86400 seconds..