Commit 14ddee41 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

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: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarZi Yan <ziy@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent edf50470

mm/memory.c

+9 −6
Original line number Diff line number Diff line
@@ -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 may be pinned, we have to copy. */

			put_page(page);

			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