On 26/06/2024 04:06, Zi Yan wrote: > On Tue Jun 25, 2024 at 10:49 PM EDT, ran xiaokai wrote: >> From: Ran Xiaokai <ran.xiaokai@xxxxxxxxxx> >> >> KPF_COMPOUND_HEAD and KPF_COMPOUND_TAIL are set on "common" compound >> pages, which means of any order, but KPF_THP should only be set >> when the folio is a 2M pmd mappable THP. Why should KPF_THP only be set on 2M THP? What problem does it cause as it is currently configured? I would argue that mTHP is still THP so should still have the flag. And since these smaller mTHP sizes are disabled by default, only mTHP-aware user space will be enabling them, so I'll naively state that it should not cause compat issues as is. Also, the script at tools/mm/thpmaps relies on KPF_THP being set for all mTHP sizes to function correctly. So that would need to be reworked if making this change. Thanks, Ryan
