diff options
| author | Muchun Song <songmuchun@bytedance.com> | 2026-09-10 14:32:42 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-10-06 17:38:49 -0700 |
| commit | 89fb8ed75e3c4991dc596037b825041b91b4cfc5 (patch) | |
| tree | b9aeb9af4ab0df33549ed92f9990e630c8deb682 /include/linux | |
| parent | 5e72deef11ba2d9110e3e4f1d9b2edf9e46495bb (diff) | |
mm/mm_init: skip initializing shared vmemmap tail pages
memmap_init_range() initializes every struct page in the target range.
For compound pages with vmemmap optimization, the tail struct pages are
backed by a shared vmemmap page.
Initializing those tail struct pages would overwrite the shared vmemmap
page contents, requiring users such as HugeTLB to restore the metadata
afterwards.
Track the compound page order for HVO-backed sections and use that
metadata to detect struct pages that fall into the shared tail vmemmap
range. Skip those shared tail pages in memmap_init_range(), then
initialize pageblock migratetypes for the processed range with a helper
after the per-page initialization loop.
Keep direct mem_section access inside sparse helpers. Expose
pfn_to_section_compound_order() for callers that only need the order
associated with a PFN. This lets memmap_init_range() skip shared tail
vmemmap pages without exposing __pfn_to_section() to !SPARSEMEM builds.
This is a preparatory change for consolidating handling across users of
vmemmap optimization, and it also avoids redundant initialization of
shared tail vmemmap pages during early boot. That early-boot benefit
appears only once HugeTLB is switched to this common handling, since
HugeTLB is the early-boot user that creates those shared tail vmemmap
pages.
Link: https://lore.kernel.org/20260910063256.64386-4-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: David Laight <david.laight.linux@gmail.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/mmzone.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 5fb9b37819d5..738bf3d27256 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -2022,6 +2022,14 @@ struct mem_section { unsigned long section_mem_map; struct mem_section_usage *usage; +#ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP + /* + * Normally, sections hold regular (order-0) pages. However, for + * sections with HVO enabled, this tracks the compound page order + * to enable deduplication of redundant vmemmap pages. + */ + unsigned int compound_page_order; +#endif #ifdef CONFIG_PAGE_EXTENSION /* * If SPARSEMEM, pgdat doesn't have page_ext pointer. We use |