Re: [PATCH 6/6] mm/page_alloc.c: avoid allocating highmem pages via alloc_pages_exact_nid()

[Matthew Wilcox]

On Mon, Aug 30, 2021 at 10:10:51PM +0800, Miaohe Lin wrote:
> Don't use with __GFP_HIGHMEM because page_address() cannot represent
> highmem pages without kmap(). Newly allocated pages would leak as
> page_address() will return NULL for highmem pages here. But It works
> now because the only caller does not specify __GFP_HIGHMEM now.

This is a misunderstanding of how alloc_pages_exact() /
alloc_pages_exact_nid() work.  You simply can't call them with
GFP_HIGHMEM.

If you really must change anything here,
s/__GFP_COMP/(__GFP_COMP|__GFP_HIGHMEM)/g throughout both
alloc_pages_exact() and alloc_pages_exact_nid().