The patch titled
Subject: mm/memory: factor out copying the actual PTE in copy_present_pte()
has been added to the -mm mm-unstable branch. Its filename is
mm-memory-factor-out-copying-the-actual-pte-in-copy_present_pte.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory-factor-out-copying-the-actual-pte-in-copy_present_pte.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: mm/memory: factor out copying the actual PTE in copy_present_pte()
Date: Mon, 29 Jan 2024 13:46:45 +0100
Let's prepare for further changes.
Link: https://lkml.kernel.org/r/20240129124649.189745-12-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Dinh Nguyen <dinguyen@xxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Russell King (Oracle) <linux@xxxxxxxxxxxxxxx>
Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 63 ++++++++++++++++++++++++++------------------------
1 file changed, 33 insertions(+), 30 deletions(-)
--- a/mm/memory.c~mm-memory-factor-out-copying-the-actual-pte-in-copy_present_pte
+++ a/mm/memory.c
@@ -930,6 +930,29 @@ copy_present_page(struct vm_area_struct
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.
@@ -939,23 +962,23 @@ copy_present_pte(struct vm_area_struct *
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)
- folio = page_folio(page);
- if (page && folio_test_anon(folio)) {
+ if (unlikely(!page))
+ goto copy_pte;
+
+ folio = page_folio(page);
+ 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);
@@ -963,34 +986,14 @@ copy_present_pte(struct vm_area_struct *
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)]++;
}
- /*
- * 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;
}
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
arm-pgtable-define-pfn_pte_shift.patch
nios2-pgtable-define-pfn_pte_shift.patch
powerpc-pgtable-define-pfn_pte_shift.patch
riscv-pgtable-define-pfn_pte_shift.patch
s390-pgtable-define-pfn_pte_shift.patch
sparc-pgtable-define-pfn_pte_shift.patch
mm-pgtable-make-pte_next_pfn-independent-of-set_ptes.patch
arm-mm-use-pte_next_pfn-in-set_ptes.patch
powerpc-mm-use-pte_next_pfn-in-set_ptes.patch
mm-memory-factor-out-copying-the-actual-pte-in-copy_present_pte.patch
mm-memory-pass-pte-to-copy_present_pte.patch
mm-memory-optimize-fork-with-pte-mapped-thp.patch
mm-memory-ignore-dirty-accessed-soft-dirty-bits-in-folio_pte_batch.patch
mm-memory-ignore-writable-bit-in-folio_pte_batch.patch
