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| author | Muchun Song <songmuchun@bytedance.com> | 2022-06-28 12:22:34 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-08-09 04:06:43 +0300 |
| commit | 838691a1c0ec44739db558834e6954d62577d6b8 (patch) | |
| tree | 948c5ec3500236cf7173ba940888b7c8650b8243 /include/linux/page-flags.h | |
| parent | 6213834c10de954470b7195cf0cdbda858edf0ee (diff) | |
| download | linux-838691a1c0ec44739db558834e6954d62577d6b8.tar.xz | |
mm: hugetlb_vmemmap: move code comments to vmemmap_dedup.rst
All the comments which explains how HVO works are moved to
vmemmap_dedup.rst since
commit 4917f55b4ef9 ("mm/sparse-vmemmap: improve memory savings for compound devmaps")
except some comments above page_fixed_fake_head(). This commit moves
those comments to vmemmap_dedup.rst and improve vmemmap_dedup.rst as well.
Link: https://lkml.kernel.org/r/20220628092235.91270-8-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Will Deacon <will@kernel.org>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux/page-flags.h')
| -rw-r--r-- | include/linux/page-flags.h | 15 |
1 files changed, 2 insertions, 13 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 78ed46ae6ee5..465ff35a8c00 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -208,19 +208,8 @@ enum pageflags { DECLARE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key); /* - * If HVO is enabled, the head vmemmap page frame is reused and all of the tail - * vmemmap addresses map to the head vmemmap page frame (furture details can - * refer to the figure at the head of the mm/hugetlb_vmemmap.c). In other - * words, there are more than one page struct with PG_head associated with each - * HugeTLB page. We __know__ that there is only one head page struct, the tail - * page structs with PG_head are fake head page structs. We need an approach - * to distinguish between those two different types of page structs so that - * compound_head() can return the real head page struct when the parameter is - * the tail page struct but with PG_head. - * - * The page_fixed_fake_head() returns the real head page struct if the @page is - * fake page head, otherwise, returns @page which can either be a true page - * head or tail. + * Return the real head page struct iff the @page is a fake head page, otherwise + * return the @page itself. See Documentation/mm/vmemmap_dedup.rst. */ static __always_inline const struct page *page_fixed_fake_head(const struct page *page) { |