==================================================================
BUG: KCSAN: data-race in __mnt_want_write / ext4_remount

read to 0xffff888218410850 of 8 bytes by task 8052 on cpu 1:
 __mnt_is_readonly fs/namespace.c:248 [inline]
 mnt_is_readonly fs/namespace.c:292 [inline]
 __mnt_want_write+0x172/0x1a0 fs/namespace.c:332
 mnt_want_write+0x41/0x90 fs/namespace.c:355
 do_rmdir+0x16a/0x300 fs/namei.c:3928
 __do_sys_rmdir fs/namei.c:3962 [inline]
 __se_sys_rmdir fs/namei.c:3960 [inline]
 __x64_sys_rmdir+0x2f/0x40 fs/namei.c:3960
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff888218410850 of 8 bytes by task 18820 on cpu 0:
 ext4_remount+0x685/0x13a0 fs/ext4/super.c:5361
 legacy_reconfigure+0x9a/0xc0 fs/fs_context.c:670
 reconfigure_super+0x36a/0x570 fs/super.c:955
 do_remount fs/namespace.c:2553 [inline]
 do_mount+0x1136/0x14f0 fs/namespace.c:3133
 ksys_mount+0xe8/0x160 fs/namespace.c:3351
 __do_sys_mount fs/namespace.c:3365 [inline]
 __se_sys_mount fs/namespace.c:3362 [inline]
 __x64_sys_mount+0x70/0x90 fs/namespace.c:3362
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18820 Comm: syz-executor.5 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================