Re: [PATCH 1/4] x86/mm: fix missing pgtable destructor for vmemmap tables

[Dave Hansen]

On 10/8/26 00:30, Muchun Song wrote:
> Since commit 49f599666420 ("mm: call ctor/dtor for kernel PTEs"),
> pte_alloc_one_kernel() runs the page-table constructor for kernel PTE
> tables.
> 
> HugeTLB vmemmap optimization uses pte_alloc_one_kernel() when splitting
> a PMD. Restoring the vmemmap backing pages does not collapse the PTE
> table, so a later memory hot-remove eventually frees that table through
> free_pagetable(). That path currently calls pagetable_free() directly
> without decrementing NR_PAGETABLE.
> 
> Use PageTable() to identify constructor-backed tables and run the
> matching destructor before freeing them. Keep reserved and
> constructor-free tables on their existing paths. This also prepares
> vmemmap teardown for generic runtime allocations through the normal
> pgalloc helpers.

Could you please take some time and trim the bits out of this changelog
that the LLM inserted but that are not super relevant? For instance, I'm
not sure what the first paragraph is trying to say. It is apparently
missing some context.

FWIW, I really don't like the LLM changelogs on their own. They almost
inevitably need human editing to make them usable. I really, really
expect humans that are sending x86 patches to spend some human
brainpower on them. In fact, I expect folks with:

	Assisted-by: LLM

to be sending _impeccable_ changelogs in v1 because their LLM saved them
so much time that they can spend gobs on their changelogs. More than
ever. ;)

Oh, and it's an x86 crime that we have:

	free_pagetable()
and
	pagetable_free()

Any work that makes that coherent would be much appreciated.