Re: [PATCH v8 1/4] mm: hugetlb_vmemmap: introduce CONFIG_HUGETLB_PAGE_HAS_OPTIMIZE_VMEMMAP

[Andrew Morton]

On Wed, 13 Apr 2022 22:47:45 +0800 Muchun Song <songmuchun@xxxxxxxxxxxxx> wrote:

> If the size of "struct page" is not the power of two but with the feature
> of minimizing overhead of struct page associated with each HugeTLB is
> enabled, then the vmemmap pages of HugeTLB will be corrupted after
> remapping (panic is about to happen in theory).  But this only exists when
> !CONFIG_MEMCG && !CONFIG_SLUB on x86_64.  However, it is not a conventional
> configuration nowadays.  So it is not a real word issue, just the result
> of a code review.

The patch does add a whole bunch of tricky junk to address something
which won't happen.  How about we simply disable
CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP if (!CONFIG_MEMCG &&
!CONFIG_SLUB)?