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mm/huge_memory: batch rmap operations in __split_huge_pmd_locked() 

Let's use folio_add_anon_rmap_ptes(), batching the rmap operations.

While at it, use more folio operations (but only in the code branch we're
touching), use VM_WARN_ON_FOLIO(), and pass RMAP_EXCLUSIVE instead of
manually setting PageAnonExclusive.

We should never see non-anon pages on that branch: otherwise, the existing
page_add_anon_rmap() call would have been flawed already.

Link: https://lkml.kernel.org/r/20231220224504.646757-16-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2023-12-20 23:44:39 +01:00 committed by Andrew Morton
parent 8bd5130070
commit 91b2978a34
1 changed files with 15 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
mm/huge_memory.c
View File

@ -2398,6 +2398,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long haddr, bool freeze)
{
struct mm_struct *mm = vma->vm_mm;
struct folio *folio;
struct page *page;
pgtable_t pgtable;
pmd_t old_pmd, _pmd;
@ -2493,16 +2494,18 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
uffd_wp = pmd_swp_uffd_wp(old_pmd);
} else {
page = pmd_page(old_pmd);
folio = page_folio(page);
if (pmd_dirty(old_pmd)) {
dirty = true;
SetPageDirty(page);
folio_set_dirty(folio);
}
write = pmd_write(old_pmd);
young = pmd_young(old_pmd);
soft_dirty = pmd_soft_dirty(old_pmd);
uffd_wp = pmd_uffd_wp(old_pmd);
VM_BUG_ON_PAGE(!page_count(page), page);
VM_WARN_ON_FOLIO(!folio_ref_count(folio), folio);
VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
/*
* Without "freeze", we'll simply split the PMD, propagating the
@ -2519,11 +2522,18 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
*
* See page_try_share_anon_rmap(): invalidate PMD first.
*/
anon_exclusive = PageAnon(page) && PageAnonExclusive(page);
anon_exclusive = PageAnonExclusive(page);
if (freeze && anon_exclusive && page_try_share_anon_rmap(page))
freeze = false;
if (!freeze)
page_ref_add(page, HPAGE_PMD_NR - 1);
if (!freeze) {
rmap_t rmap_flags = RMAP_NONE;
folio_ref_add(folio, HPAGE_PMD_NR - 1);
if (anon_exclusive)
rmap_flags |= RMAP_EXCLUSIVE;
folio_add_anon_rmap_ptes(folio, page, HPAGE_PMD_NR,
vma, haddr, rmap_flags);
}
}
/*
@ -2566,8 +2576,6 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
if (write)
entry = pte_mkwrite(entry, vma);
if (anon_exclusive)
SetPageAnonExclusive(page + i);
if (!young)
entry = pte_mkold(entry);
/* NOTE: this may set soft-dirty too on some archs */
@ -2577,7 +2585,6 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
entry = pte_mksoft_dirty(entry);
if (uffd_wp)
entry = pte_mkuffd_wp(entry);
page_add_anon_rmap(page + i, vma, addr, RMAP_NONE);
}
VM_BUG_ON(!pte_none(ptep_get(pte)));
set_pte_at(mm, addr, pte, entry);