syzbot

loop2: detected capacity change from 0 to 4
==================================================================
BUG: KCSAN: data-race in ext4_handle_error / mnt_want_write

write to 0xffff888101564050 of 8 bytes by task 21486 on cpu 0:
 ext4_handle_error+0x492/0x4d0 fs/ext4/super.c:689
 __ext4_error+0xd7/0x1f0 fs/ext4/super.c:755
 ext4_remount+0x64f/0x1840 fs/ext4/super.c:5934
 legacy_reconfigure+0x8e/0xa0 fs/fs_context.c:615
 reconfigure_super+0x2d3/0x4f0 fs/super.c:906
 do_remount fs/namespace.c:2639 [inline]
 path_mount+0x1442/0x1ce0 fs/namespace.c:3227
 do_mount fs/namespace.c:3248 [inline]
 __do_sys_mount fs/namespace.c:3456 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3433
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3433
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888101564050 of 8 bytes by task 21491 on cpu 1:
 sb_rdonly include/linux/fs.h:2221 [inline]
 __mnt_is_readonly fs/namespace.c:269 [inline]
 mnt_is_readonly fs/namespace.c:313 [inline]
 __mnt_want_write fs/namespace.c:353 [inline]
 mnt_want_write+0x13e/0x220 fs/namespace.c:376
 filename_create+0x92/0x3c0 fs/namei.c:3587
 user_path_create fs/namei.c:3650 [inline]
 do_mkdirat+0x59/0x200 fs/namei.c:3828
 __do_sys_mkdir fs/namei.c:3856 [inline]
 __se_sys_mkdir fs/namei.c:3854 [inline]
 __x64_sys_mkdir+0x32/0x40 fs/namei.c:3854
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 21491 Comm: syz-executor.2 Not tainted 5.13.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
EXT4-fs (loop2): Invalid log cluster size: 2424834
loop2: detected capacity change from 0 to 4
EXT4-fs (loop2): Invalid log cluster size: 2424834