Commit 5e014966 authored by David Hildenbrand's avatar David Hildenbrand Committed by Kefeng Wang
Browse files

mm/memory: factor out copying the actual PTE in copy_present_pte() 

mainline inclusion
from mainline-v6.9-rc1
commit 23ed190868a65525b8941370630fbb215f12ebe8
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I9CHB4
CVE: NA

-------------------------------------------------

Let's prepare for further changes.

Link: https://lkml.kernel.org/r/20240129124649.189745-12-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarRyan Roberts <ryan.roberts@arm.com>
Reviewed-by: default avatarMike Rapoport (IBM) <rppt@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Russell King (Oracle) <linux@armlinux.org.uk>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
(cherry picked from commit 23ed190868a65525b8941370630fbb215f12ebe8)
Signed-off-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
parent cd35f40b

mm/memory.c

+33 −30
Original line number Diff line number Diff line
@@ -935,6 +935,29 @@ copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma 
	return 0;

}



static inline void __copy_present_pte(struct vm_area_struct *dst_vma,

		struct vm_area_struct *src_vma, pte_t *dst_pte, pte_t *src_pte,

		pte_t pte, unsigned long addr)

{

	struct mm_struct *src_mm = src_vma->vm_mm;



	/* If it's a COW mapping, write protect it both processes. */

	if (is_cow_mapping(src_vma->vm_flags) && pte_write(pte)) {

		ptep_set_wrprotect(src_mm, addr, src_pte);

		pte = pte_wrprotect(pte);

	}



	/* If it's a shared mapping, mark it clean in the child. */

	if (src_vma->vm_flags & VM_SHARED)

		pte = pte_mkclean(pte);

	pte = pte_mkold(pte);



	if (!userfaultfd_wp(dst_vma))

		pte = pte_clear_uffd_wp(pte);



	set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);

}



/*

 * Copy one pte.  Returns 0 if succeeded, or -EAGAIN if one preallocated page

 * is required to copy this pte.
@@ -944,23 +967,23 @@ copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, 
		 pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,

		 struct folio **prealloc)

{

	struct mm_struct *src_mm = src_vma->vm_mm;

	unsigned long vm_flags = src_vma->vm_flags;

	pte_t pte = ptep_get(src_pte);

	struct page *page;

	struct folio *folio;



	page = vm_normal_page(src_vma, addr, pte);

	if (page)

	if (unlikely(!page))

		goto copy_pte;



	folio = page_folio(page);

	if (page && folio_test_anon(folio)) {

	folio_get(folio);

	if (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.

		 */

		folio_get(folio);

		if (unlikely(folio_try_dup_anon_rmap_pte(folio, page, src_vma))) {

			/* Page may be pinned, we have to copy. */

			folio_put(folio);
@@ -968,35 +991,15 @@ copy_present_pte(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, 
						 addr, rss, prealloc, page);

		}

		rss[MM_ANONPAGES]++;

	} else if (page) {

		folio_get(folio);

		VM_WARN_ON_FOLIO(PageAnonExclusive(page), folio);

	} else {

		folio_dup_file_rmap_pte(folio, page);

		rss[mm_counter_file(folio)]++;

		add_reliable_folio_counter(folio, dst_vma->vm_mm, 1);

	}



	/*

	 * If it's a COW mapping, write protect it both

	 * in the parent and the child

	 */

	if (is_cow_mapping(vm_flags) && pte_write(pte)) {

		ptep_set_wrprotect(src_mm, addr, src_pte);

		pte = pte_wrprotect(pte);

	}

	VM_BUG_ON(page && folio_test_anon(folio) && PageAnonExclusive(page));



	/*

	 * If it's a shared mapping, mark it clean in

	 * the child

	 */

	if (vm_flags & VM_SHARED)

		pte = pte_mkclean(pte);

	pte = pte_mkold(pte);



	if (!userfaultfd_wp(dst_vma))

		pte = pte_clear_uffd_wp(pte);



	set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);

copy_pte:

	__copy_present_pte(dst_vma, src_vma, dst_pte, src_pte, pte, addr);

	return 0;

}