kernel/git/next/linux-next.git/mm/sparse.c, branch master

mm/sparse: remove section_map_size()

2026-09-10T03:06:44+00:00

section_map_size() no longer provides any shared logic. After the sparse-vmemmap changes, its only remaining user is the !CONFIG_SPARSEMEM_VMEMMAP path in __populate_section_memmap(), which can compute the size inline with PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION). Remove section_map_size() and inline the remaining calculation. Link: https://lore.kernel.org/20260825084608.47437-14-songmuchun@bytedance.com Signed-off-by: Muchun Song Acked-by: Mike Rapoport (Microsoft) Acked-by: David Hildenbrand (Arm) Cc: David Laight Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Oscar Salvador Cc: Qi Zheng Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/sparse: inline usemap allocation into sparse_init_nid()

2026-09-10T03:06:43+00:00

After removing SPARSEMEM_VMEMMAP_PREINIT, sparse_init_nid() no longer needs the transient sparse_usagebuf state and its helper wrappers. Allocate the usemap buffer directly in sparse_init_nid(), pass it to sparse_init_one_section(), and drop sparse_usage_init(), sparse_usage_fini(), and sparse_init_early_section(). Link: https://lore.kernel.org/20260825084608.47437-13-songmuchun@bytedance.com Signed-off-by: Muchun Song Acked-by: Mike Rapoport (Microsoft) Acked-by: David Hildenbrand (Arm) Cc: David Laight Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Oscar Salvador Cc: Qi Zheng Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/sparse-vmemmap: remove SPARSEMEM_VMEMMAP_PREINIT support

2026-09-10T03:06:43+00:00

SPARSEMEM_VMEMMAP_PREINIT existed only to support HugeTLB's early vmemmap optimization setup. Now that HugeTLB bootmem vmemmap optimization uses the common section-based sparse-vmemmap path, the sparse initialization code no longer needs a separate pre-initialization mechanism for vmemmap population. Remove the related Kconfig symbols, section flag, and empty early hook, so present sections always go through the normal sparse setup path. Link: https://lore.kernel.org/20260825084608.47437-12-songmuchun@bytedance.com Signed-off-by: Muchun Song Acked-by: Mike Rapoport (Microsoft) Acked-by: Qi Zheng Acked-by: David Hildenbrand (Arm) Cc: David Laight Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Oscar Salvador Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/sparse: initialize memory sections earlier

2026-09-10T03:06:43+00:00

Upcoming HugeTLB bootmem changes need sparsemem section metadata before the HugeTLB bootmem allocation path runs. The memory sections are initialized from sparse_init(), which is called too late for that setup. Move the code that initializes sparsemem section metadata for memblock ranges into mm_core_init_early(), before free_area_init() and the HugeTLB bootmem setup. Rename the helper to sparse_sections_init() so the new caller describes the sparsemem-specific initialization step. This is a preparatory change. Link: https://lore.kernel.org/20260825084608.47437-10-songmuchun@bytedance.com Signed-off-by: Muchun Song Reviewed-by: Mike Rapoport (Microsoft) Acked-by: Qi Zheng Cc: David Hildenbrand Cc: David Laight Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Oscar Salvador Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/sparse-vmemmap: support section-based vmemmap optimization

2026-09-10T03:06:42+00:00

Teach sparse-vmemmap population code to use the compound page order when deciding whether a vmemmap page can be optimized. With this information, the common sparse-vmemmap population path can allocate or reuse shared tail vmemmap pages directly instead of relying on HugeTLB-specific handling. This centralizes vmemmap optimization logic in the sparse-vmemmap code, based on section metadata, and prepares for sharing the same mechanism across different users of vmemmap optimization, including HugeTLB and DAX. Link: https://lore.kernel.org/20260825084608.47437-9-songmuchun@bytedance.com Signed-off-by: Muchun Song Acked-by: Mike Rapoport (Microsoft) Acked-by: Qi Zheng Cc: David Hildenbrand Cc: David Laight Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Oscar Salvador Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/sparse: relax struct mem_section size constraints

2026-09-10T03:06:40+00:00

Patch series "mm: Introduce section-based vmemmap optimization for HugeTLB", v5. HugeTLB vmemmap optimization currently has its own early boot setup path. It pre-populates optimized vmemmap mappings before the normal sparse-vmemmap population code runs, and sparsemem carries SPARSEMEM_VMEMMAP_PREINIT only to support that special case. That makes the HugeTLB vmemmap optimization path harder to share with other users of sparse-vmemmap optimization and leaves a fair amount of HugeTLB-specific boot-time state in the generic memory initialization flow. This series introduces section-based vmemmap optimization support in the sparse-vmemmap code and switches HugeTLB bootmem pages over to it. Instead of having HugeTLB pre-populate optimized vmemmap mappings itself, HugeTLB now records the compound page order in the corresponding memory sections. The generic sparse-vmemmap population path can then allocate or reuse shared tail vmemmap pages based on section metadata. The patches are organized as follows: - patches 1-2 prepare sparsemem and vmemmap optimization metadata - patches 3-8 teach the common sparse-vmemmap paths to use that state - patches 9-10 switch HugeTLB bootmem optimization to the section-based path - patches 11-17 clean up sparsemem and HugeTLB bootmem code that is no longer needed after the conversion This is intended to be the second smaller step toward the broader HVO generalization [1]. The device DAX conversion and the wider HVO consolidation are left for follow-up series. This patch (of 17): struct mem_section is currently forced to a power-of-2 size so the section-to-root lookup can use a mask instead of a modulo. That requirement makes future extensions harder than necessary: adding a small field can require configuration-dependent padding or layout checks just to preserve the lookup scheme. Keep the lookup correct for any struct mem_section size by using a plain modulo instead. Do not leave the layout entirely unconstrained, though. Keep struct mem_section double-word aligned so modest size changes, such as adding another word-sized field on 64-bit systems, still keep a compact and efficient layout. If future fields grow the structure beyond that sweet spot, the lookup remains correct; only the exact layout efficiency changes. Link: https://lore.kernel.org/20260825084608.47437-1-songmuchun@bytedance.com Link: https://lore.kernel.org/20260825084608.47437-2-songmuchun@bytedance.com Link: https://lore.kernel.org/linux-mm/20260513130542.35604-1-songmuchun@bytedance.com/ [1] Signed-off-by: Muchun Song Acked-by: Mike Rapoport (Microsoft) Acked-by: David Hildenbrand (Arm) Cc: David Laight Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Oscar Salvador Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Qi Zheng Signed-off-by: Andrew Morton

mm/sparse: keep mem_section_usage_size() internal

2026-08-25T01:43:06+00:00

mem_section_usage_size() is only needed by sparsemem implementation code after commit ae751d567baa ("mm/bootmem_info: stop marking mem_section_usage as MIX_SECTION_INFO"), so keeping the declaration in mmzone.h now exposes the helper to all mmzone.h users for no reason. Move the helper to sparse.h so sparse.c and sparse-vmemmap.c can share it through the internal header. While doing so, calculate the allocation size with struct_size_t(), which ties the expression to the pageblock_flags trailing array instead of open-coding the struct header plus bitmap size. Link: https://lore.kernel.org/20260805022536.1206575-1-songmuchun@bytedance.com Signed-off-by: Muchun Song Acked-by: Mike Rapoport (Microsoft) Acked-by: David Hildenbrand (Arm) Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/sparse: correct init section annotations

2026-08-25T01:42:58+00:00

The !SPARSEMEM_EXTREME stub of sparse_index_init() has no annotation but the SPARSEMEM_EXTREME variant is __meminit. So mark the stub __meminit too. mminit_validate_memmodel_limits() is only called by memory_present(), which is __init. So mark it __init. sparse_usagebuf and sparse_usagebuf_end are only used by sparse_init_early_section(), sparse_usage_init() and sparse_usage_fini(), which are all __init. So mark them __initdata. Link: https://lore.kernel.org/20260731164758.1210668-1-ekffu200098@gmail.com Signed-off-by: Sang-Heon Jeon Reviewed-by: Andrew Morton Acked-by: David Hildenbrand (Arm) Acked-by: Mike Rapoport (Microsoft) Reviewed-by: Anshuman Khandual Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: split out sparse declarations from internal.h

2026-08-05T02:18:46+00:00

mm/internal.h becomes more and more bloated. Move declarations related to SPARSE and SPARSE_VMEMMAP memory models to a new mm/sparse.h header. No functional changes. Link: https://lore.kernel.org/20260709-internal-h-v2-2-695631425968@kernel.org Signed-off-by: Mike Rapoport (Microsoft) Acked-by: Muchun Song Acked-by: Vlastimil Babka (SUSE) Acked-by: David Hildenbrand (Arm) Acked-by: Lorenzo Stoakes Acked-by: Pratyush Yadav Acked-by: SJ Park Cc: Alexander Graf Cc: Alexander Potapenko Cc: Brendan Jackman Cc: Brendan Jackman Cc: Dennis Zhou Cc: Dmitry Vyukov Cc: Johannes Weiner Cc: Liam R. Howlett Cc: Marco Elver Cc: Michal Hocko Cc: Oscar Salvador Cc: Pasha Tatashin Cc: Suren Baghdasaryan Cc: Tejun Heo Cc: "Uladzislau Rezki (Sony)" Cc: Zi Yan Signed-off-by: Andrew Morton

mm: split out mm_init and memblock declarations from internal.h

2026-08-05T02:18:45+00:00

Patch series "mm: split a couple of headers from internal.h", v2. mm/internal.h becomes more and more bloated. Split declarations related to mm_init, memblock, vmalloc and sparse into new headers. This patch (of 3): mm/internal.h becomes more and more bloated. Move declarations for related to mm/mm_init.c and mm/memblock.c to a new mm/mm_init.h header. No functional changes. [rppt@kernel.org: split stubfs from internal.h to mm_init.h] Link: https://lore.kernel.org/alJd1BLypyK9Mpaw@kernel.org Link: https://lore.kernel.org/20260709-internal-h-v2-0-695631425968@kernel.org Link: https://lore.kernel.org/20260709-internal-h-v2-1-695631425968@kernel.org Signed-off-by: Mike Rapoport (Microsoft) Acked-by: Muchun Song Acked-by: Vlastimil Babka (SUSE) Acked-by: David Hildenbrand (Arm) Acked-by: Lorenzo Stoakes Acked-by: Pratyush Yadav Acked-by: SJ Park Cc: Alexander Graf Cc: Alexander Potapenko Cc: Brendan Jackman Cc: Brendan Jackman Cc: Dennis Zhou Cc: Dmitry Vyukov Cc: Johannes Weiner Cc: Liam R. Howlett Cc: Marco Elver Cc: Michal Hocko Cc: Oscar Salvador Cc: Pasha Tatashin Cc: Suren Baghdasaryan Cc: Tejun Heo Cc: "Uladzislau Rezki (Sony)" Cc: Zi Yan Signed-off-by: Andrew Morton