Comment # 2 on bug 1193852 from Dirk Mueller

looks like none of the btrfs lzo fixes (including memory leak fixes) have been
added to 5.14. likely candidates to fix this are 

commit ccaa66c8dd277ac02f96914168bb7177f7ea8117
Author: David Sterba <dsterba@suse.com>
Date:   Wed Oct 27 10:44:21 2021 +0200

    Revert "btrfs: compression: drop kmap/kunmap from lzo"

    This reverts commit 8c945d32e60427cbc0859cf7045bbe6196bb03d8.

    The kmaps in compression code are still needed and cause crashes on
    32bit machines (ARM, x86). Reproducible eg. by running fstest btrfs/004
    with enabled LZO or ZSTD compression.


and the followon commits from Linus Torvals and Qu Wenruo