Other than the bug Song found in memfd_tag_pins(), I'd like to suggest two quick but pedantic changes to mm/filemap.c: Though not modified in this patch, in line 284, the parenthesis should be moved to after the period: * modified.) The function expects only THP head pages to be present in the > + * Move to the next page in the vector if this is a small page > + * or the index is of the last page in this compound page). A few lines later, there is an extraneous parenthesis, and the comment could be a bit clearer. Might I suggest: * Move to the next page in the vector if this is a PAGESIZE * page or if the index is of the last PAGESIZE page within * this compound page. You can say "base" instead of "PAGESIZE," but "small" seems open to interpretation. I haven't run across any problems and have been hammering the code for over five days without issue; all my testing was with transparent_hugepage/enabled set to "always." Tested-by: William Kucharski <william.kucharski@xxxxxxxxxx> Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx>