From: Qi Zheng <qi.zheng@linux.dev>
To: Muchun Song <songmuchun@bytedance.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Oscar Salvador <osalvador@suse.de>,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Jonathan Corbet <corbet@lwn.net>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org,
Muchun Song <muchun.song@linux.dev>,
Lorenzo Stoakes <ljs@kernel.org>, Mike Rapoport <rppt@kernel.org>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <chleroy@kernel.org>,
Randy Dunlap <rdunlap@infradead.org>
Subject: Re: [PATCH v2 07/11] mm/sparse-vmemmap: move HVO helpers to a public header
Date: Tue, 8 Sep 2026 16:19:55 +0800 [thread overview]
Message-ID: <99aac41d-a68f-451b-ae10-f7132bb7a291@linux.dev> (raw)
In-Reply-To: <20260908030335.96549-8-songmuchun@bytedance.com>
On 9/8/26 11:03 AM, Muchun Song wrote:
> The vmemmap optimization helpers currently live in mm/sparse.h,
> which is an internal MM header. That works for MM code, but
> prevents powerpc from using the same interfaces without including a
> private header.
>
> Move the declarations and inline helpers to
> include/linux/vmemmap-optimization.h. This is a preparatory change for
> powerpc, which has its own vmemmap optimization implementation and
> needs to use the HVO interfaces from architecture code.
Make sense.
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Thanks,
Qi
>
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---
> v2:
> - Fix missing header dependencies.
> ---
> MAINTAINERS | 1 +
> include/linux/vmemmap-optimization.h | 91 ++++++++++++++++++++++++++++
> mm/hugetlb.c | 2 +-
> mm/hugetlb_vmemmap.c | 2 +-
> mm/memory_hotplug.c | 1 +
> mm/sparse.h | 73 +---------------------
> 6 files changed, 96 insertions(+), 74 deletions(-)
> create mode 100644 include/linux/vmemmap-optimization.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c7aaa2e4790e..2985286cbbbf 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -12096,6 +12096,7 @@ F: Documentation/mm/hugetlbfs_reserv.rst
> F: Documentation/mm/vmemmap_dedup.rst
> F: fs/hugetlbfs/
> F: include/linux/hugetlb.h
> +F: include/linux/vmemmap-optimization.h
> F: include/trace/events/hugetlbfs.h
> F: mm/hugetlb.c
> F: mm/hugetlb_cgroup.c
> diff --git a/include/linux/vmemmap-optimization.h b/include/linux/vmemmap-optimization.h
> new file mode 100644
> index 000000000000..492dc662aae7
> --- /dev/null
> +++ b/include/linux/vmemmap-optimization.h
> @@ -0,0 +1,91 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * vmemmap-optimization.h
> + *
> + * Generic vmemmap optimization declarations.
> + *
> + * Author: Muchun Song <songmuchun@bytedance.com>
> + */
> +#ifndef _LINUX_VMEMMAP_OPTIMIZATION_H
> +#define _LINUX_VMEMMAP_OPTIMIZATION_H
> +
> +#include <linux/align.h>
> +#include <linux/log2.h>
> +#include <linux/mmdebug.h>
> +#include <linux/mmzone.h>
> +
> +#ifdef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION
> +static inline unsigned int section_order(const struct mem_section *section)
> +{
> + return section->order;
> +}
> +
> +static inline void section_set_order(struct mem_section *section, unsigned int order)
> +{
> + VM_WARN_ON(section_order(section) && order && section_order(section) != order);
> + section->order = order;
> +}
> +
> +static inline void section_set_order_range(unsigned long pfn, unsigned long nr_pages,
> + unsigned int order)
> +{
> + unsigned long section_nr = pfn_to_section_nr(pfn);
> +
> + if (!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION))
> + return;
> +
> + for (unsigned long i = 0; i < nr_pages / PAGES_PER_SECTION; i++)
> + section_set_order(__nr_to_section(section_nr + i), order);
> +}
> +
> +static inline unsigned int pfn_to_section_order(unsigned long pfn)
> +{
> + return section_order(__pfn_to_section(pfn));
> +}
> +#else
> +static inline unsigned int section_order(const struct mem_section *section)
> +{
> + return 0;
> +}
> +
> +static inline void section_set_order(struct mem_section *section, unsigned int order)
> +{
> +}
> +
> +static inline void section_set_order_range(unsigned long pfn, unsigned long nr_pages,
> + unsigned int order)
> +{
> +}
> +
> +static inline unsigned int pfn_to_section_order(unsigned long pfn)
> +{
> + return 0;
> +}
> +#endif /* CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION */
> +
> +static inline bool vmemmap_optimizable_pfn(unsigned long pfn)
> +{
> + const unsigned int order = pfn_to_section_order(pfn);
> + const unsigned long nr_pages = 1UL << order;
> +
> + if (!is_power_of_2(sizeof(struct page)))
> + return false;
> +
> + return (pfn & (nr_pages - 1)) >= VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES;
> +}
> +
> +static inline bool vmemmap_optimizable_order(unsigned int order)
> +{
> + if (!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION))
> + return false;
> +
> + if (!is_power_of_2(sizeof(struct page)))
> + return false;
> +
> + return order >= VMEMMAP_OPTIMIZATION_MIN_ORDER;
> +}
> +
> +#ifdef CONFIG_SPARSEMEM_VMEMMAP
> +struct page *vmemmap_shared_tail_page(unsigned int order, struct zone *zone);
> +#endif /* CONFIG_SPARSEMEM_VMEMMAP */
> +#endif /* _LINUX_VMEMMAP_OPTIMIZATION_H */
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index fda525bccf50..dff915e6c48b 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -38,6 +38,7 @@
> #include <linux/mm_inline.h>
> #include <linux/padata.h>
> #include <linux/pgalloc.h>
> +#include <linux/vmemmap-optimization.h>
>
> #include <asm/page.h>
> #include <asm/tlb.h>
> @@ -52,7 +53,6 @@
> #include "hugetlb_cma.h"
> #include "hugetlb_internal.h"
> #include "mm_init.h"
> -#include "sparse.h"
> #include <linux/page-isolation.h>
>
> #define HUGE_BOOTMEM_ZONES_VALID BIT(0)
> diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
> index 4a57e6c3352c..25c4e7d2664c 100644
> --- a/mm/hugetlb_vmemmap.c
> +++ b/mm/hugetlb_vmemmap.c
> @@ -15,10 +15,10 @@
> #include <linux/mmdebug.h>
> #include <linux/pagewalk.h>
> #include <linux/pgalloc.h>
> +#include <linux/vmemmap-optimization.h>
>
> #include <asm/tlbflush.h>
> #include "hugetlb_vmemmap.h"
> -#include "sparse.h"
> #include "internal.h"
>
> /**
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 0db0379826df..d7a59167bec4 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -43,6 +43,7 @@
> #include "mm_init.h"
> #include "page_alloc.h"
> #include "shuffle.h"
> +#include "sparse.h"
>
> enum {
> MEMMAP_ON_MEMORY_DISABLE = 0,
> diff --git a/mm/sparse.h b/mm/sparse.h
> index 59b825df83b9..e511d99fc26b 100644
> --- a/mm/sparse.h
> +++ b/mm/sparse.h
> @@ -9,77 +9,7 @@
> #define __MM_SPARSE_H
>
> #include <linux/mmzone.h>
> -
> -#ifdef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION
> -static inline unsigned int section_order(const struct mem_section *section)
> -{
> - return section->order;
> -}
> -
> -static inline void section_set_order(struct mem_section *section, unsigned int order)
> -{
> - VM_WARN_ON(section_order(section) && order && section_order(section) != order);
> - section->order = order;
> -}
> -
> -static inline void section_set_order_range(unsigned long pfn, unsigned long nr_pages,
> - unsigned int order)
> -{
> - unsigned long section_nr = pfn_to_section_nr(pfn);
> -
> - if (!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION))
> - return;
> -
> - for (unsigned long i = 0; i < nr_pages / PAGES_PER_SECTION; i++)
> - section_set_order(__nr_to_section(section_nr + i), order);
> -}
> -
> -static inline unsigned int pfn_to_section_order(unsigned long pfn)
> -{
> - return section_order(__pfn_to_section(pfn));
> -}
> -#else
> -static inline unsigned int section_order(const struct mem_section *section)
> -{
> - return 0;
> -}
> -
> -static inline void section_set_order(struct mem_section *section, unsigned int order)
> -{
> -}
> -
> -static inline void section_set_order_range(unsigned long pfn, unsigned long nr_pages,
> - unsigned int order)
> -{
> -}
> -
> -static inline unsigned int pfn_to_section_order(unsigned long pfn)
> -{
> - return 0;
> -}
> -#endif
> -
> -static inline bool vmemmap_optimizable_pfn(unsigned long pfn)
> -{
> - const unsigned int order = pfn_to_section_order(pfn);
> - const unsigned long nr_pages = 1UL << order;
> -
> - if (!is_power_of_2(sizeof(struct page)))
> - return false;
> -
> - return (pfn & (nr_pages - 1)) >= VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES;
> -}
> -
> -static inline bool vmemmap_optimizable_order(unsigned int order)
> -{
> - if (!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION))
> - return false;
> -
> - if (!is_power_of_2(sizeof(struct page)))
> - return false;
> -
> - return order >= VMEMMAP_OPTIMIZATION_MIN_ORDER;
> -}
> +#include <linux/vmemmap-optimization.h>
>
> /*
> * mm/sparse.c
> @@ -139,7 +69,6 @@ static inline void sparse_sections_init(void) {}
> * mm/sparse-vmemmap.c
> */
> #ifdef CONFIG_SPARSEMEM_VMEMMAP
> -struct page *vmemmap_shared_tail_page(unsigned int order, struct zone *zone);
> void sparse_init_subsection_map(void);
> int section_nr_vmemmap_pages(unsigned long pfn, unsigned long nr_pages,
> struct vmem_altmap *altmap, struct dev_pagemap *pgmap);
next prev parent reply other threads:[~2026-09-08 8:20 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-08 3:03 [PATCH v2 00/11] mm: Switch device DAX to section-based vmemmap optimization Muchun Song
2026-09-08 3:03 ` [PATCH v2 01/11] mm/sparse-vmemmap: introduce CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION Muchun Song
2026-09-08 3:03 ` [PATCH v2 02/11] mm/sparse-vmemmap: factor out shared vmemmap tail page allocation Muchun Song
2026-09-08 3:03 ` [PATCH v2 03/11] mm/sparse-vmemmap: open-code init_compound_tail() Muchun Song
2026-09-10 7:50 ` David Hildenbrand (Arm)
2026-09-08 3:03 ` [PATCH v2 04/11] mm/sparse-vmemmap: prepare DAX vmemmap population for section orders Muchun Song
2026-09-08 3:03 ` [PATCH v2 05/11] mm/sparse-vmemmap: set section order for device DAX Muchun Song
2026-09-08 3:03 ` [PATCH v2 06/11] mm/sparse-vmemmap: switch device DAX to shared tail vmemmap pages Muchun Song
2026-09-08 4:09 ` Muchun Song
2026-09-08 7:46 ` Qi Zheng
2026-09-08 8:34 ` Muchun Song
2026-09-08 3:03 ` [PATCH v2 07/11] mm/sparse-vmemmap: move HVO helpers to a public header Muchun Song
2026-09-08 8:19 ` Qi Zheng [this message]
2026-09-08 3:03 ` [PATCH v2 08/11] powerpc/mm: switch device DAX to shared tail vmemmap pages Muchun Song
2026-09-08 3:03 ` [PATCH v2 09/11] mm/sparse-vmemmap: drop the extra tail page from device DAX reservation Muchun Song
2026-09-08 9:09 ` Qi Zheng
2026-09-08 9:12 ` Muchun Song
2026-09-08 3:03 ` [PATCH v2 10/11] mm/sparse-vmemmap: drop unused section_nr_vmemmap_pages() arguments Muchun Song
2026-09-08 9:23 ` Qi Zheng
2026-09-08 3:03 ` [PATCH v2 11/11] Documentation/mm: update DAX vmemmap deduplication docs Muchun Song
2026-09-08 9:29 ` Qi Zheng
2026-09-09 1:45 ` [PATCH v2 00/11] mm: Switch device DAX to section-based vmemmap optimization Andrew Morton
2026-09-10 6:48 ` Muchun Song
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