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mm: use a folio in copy_present_pte() 

We still have to keep the page around because we need to know which page
in the folio we're copying, but we can replace five implict calls to
compound_head() with one.

Link: https://lkml.kernel.org/r/20230116191813.2145215-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-01-16 19:18:13 +00:00 committed by Andrew Morton
parent edf5047058
commit 14ddee4126
1 changed files with 9 additions and 6 deletions
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15
mm/memory.c
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@ -906,25 +906,28 @@ copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
unsigned long vm_flags = src_vma->vm_flags;
pte_t pte = *src_pte;
struct page *page;
struct folio *folio;
page = vm_normal_page(src_vma, addr, pte);
if (page && PageAnon(page)) {
if (page)
folio = page_folio(page);
if (page && folio_test_anon(folio)) {
/*
* If this page may have been pinned by the parent process,
* copy the page immediately for the child so that we'll always
* guarantee the pinned page won't be randomly replaced in the
* future.
*/
get_page(page);
folio_get(folio);
if (unlikely(page_try_dup_anon_rmap(page, false, src_vma))) {
/* Page maybe pinned, we have to copy. */
put_page(page);
/* Page may be pinned, we have to copy. */
folio_put(folio);
return copy_present_page(dst_vma, src_vma, dst_pte, src_pte,
addr, rss, prealloc, page);
}
rss[MM_ANONPAGES]++;
} else if (page) {
get_page(page);
folio_get(folio);
page_dup_file_rmap(page, false);
rss[mm_counter_file(page)]++;
}
@ -937,7 +940,7 @@ copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
ptep_set_wrprotect(src_mm, addr, src_pte);
pte = pte_wrprotect(pte);
}
VM_BUG_ON(page && PageAnon(page) && PageAnonExclusive(page));
VM_BUG_ON(page && folio_test_anon(folio) && PageAnonExclusive(page));
/*
* If it's a shared mapping, mark it clean in