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Message-ID: <20231204142146.91437-15-david@redhat.com>
Date: Mon, 4 Dec 2023 15:21:21 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org, David Hildenbrand <david@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
"Matthew Wilcox (Oracle)" <willy@...radead.org>,
Hugh Dickins <hughd@...gle.com>,
Ryan Roberts <ryan.roberts@....com>,
Yin Fengwei <fengwei.yin@...el.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
Muchun Song <muchun.song@...ux.dev>,
Peter Xu <peterx@...hat.com>
Subject: [PATCH RFC 14/39] mm/rmap: introduce folio_add_anon_rmap_[pte|ptes|pmd]()
Let's mimic what we did with folio_add_file_rmap_*() so we can similarly
replace page_add_anon_rmap() next.
Make the compiler always special-case on the granularity by using
__always_inline.
Note that the new functions ignore the RMAP_COMPOUND flag, which we will
remove as soon as page_add_anon_rmap() is gone.
Signed-off-by: David Hildenbrand <david@...hat.com>
---
include/linux/rmap.h | 6 +++
mm/rmap.c | 115 +++++++++++++++++++++++++++++--------------
2 files changed, 85 insertions(+), 36 deletions(-)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 95f7b94a70295..9e1c197f50199 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -229,6 +229,12 @@ static inline void __folio_rmap_sanity_checks(struct folio *folio,
* rmap interfaces called when adding or removing pte of page
*/
void folio_move_anon_rmap(struct folio *, struct vm_area_struct *);
+void folio_add_anon_rmap_ptes(struct folio *, struct page *, unsigned int nr,
+ struct vm_area_struct *, unsigned long address, rmap_t flags);
+#define folio_add_anon_rmap_pte(folio, page, vma, address, flags) \
+ folio_add_anon_rmap_ptes(folio, page, 1, vma, address, flags)
+void folio_add_anon_rmap_pmd(struct folio *, struct page *,
+ struct vm_area_struct *, unsigned long address, rmap_t flags);
void page_add_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long address, rmap_t flags);
void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
diff --git a/mm/rmap.c b/mm/rmap.c
index c09b360402599..85bea11e9266b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1267,38 +1267,21 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
unsigned long address, rmap_t flags)
{
struct folio *folio = page_folio(page);
- atomic_t *mapped = &folio->_nr_pages_mapped;
- int nr = 0, nr_pmdmapped = 0;
- bool compound = flags & RMAP_COMPOUND;
- bool first;
- /* Is page being mapped by PTE? Is this its first map to be added? */
- if (likely(!compound)) {
- first = atomic_inc_and_test(&page->_mapcount);
- nr = first;
- if (first && folio_test_large(folio)) {
- nr = atomic_inc_return_relaxed(mapped);
- nr = (nr < COMPOUND_MAPPED);
- }
- } else if (folio_test_pmd_mappable(folio)) {
- /* That test is redundant: it's for safety or to optimize out */
+ if (likely(!(flags & RMAP_COMPOUND)))
+ folio_add_anon_rmap_pte(folio, page, vma, address, flags);
+ else
+ folio_add_anon_rmap_pmd(folio, page, vma, address, flags);
+}
- first = atomic_inc_and_test(&folio->_entire_mapcount);
- if (first) {
- nr = atomic_add_return_relaxed(COMPOUND_MAPPED, mapped);
- if (likely(nr < COMPOUND_MAPPED + COMPOUND_MAPPED)) {
- nr_pmdmapped = folio_nr_pages(folio);
- nr = nr_pmdmapped - (nr & FOLIO_PAGES_MAPPED);
- /* Raced ahead of a remove and another add? */
- if (unlikely(nr < 0))
- nr = 0;
- } else {
- /* Raced ahead of a remove of COMPOUND_MAPPED */
- nr = 0;
- }
- }
- }
+static __always_inline void __folio_add_anon_rmap(struct folio *folio,
+ struct page *page, unsigned int nr_pages,
+ struct vm_area_struct *vma, unsigned long address, rmap_t flags,
+ enum rmap_mode mode)
+{
+ unsigned int i, nr, nr_pmdmapped = 0;
+ nr = __folio_add_rmap(folio, page, nr_pages, mode, &nr_pmdmapped);
if (nr_pmdmapped)
__lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr_pmdmapped);
if (nr)
@@ -1312,18 +1295,30 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
* folio->index right when not given the address of the head
* page.
*/
- VM_WARN_ON_FOLIO(folio_test_large(folio) && !compound, folio);
+ VM_WARN_ON_FOLIO(folio_test_large(folio) &&
+ mode != RMAP_MODE_PMD, folio);
__folio_set_anon(folio, vma, address,
!!(flags & RMAP_EXCLUSIVE));
} else if (likely(!folio_test_ksm(folio))) {
__page_check_anon_rmap(folio, page, vma, address);
}
- if (flags & RMAP_EXCLUSIVE)
- SetPageAnonExclusive(page);
- /* While PTE-mapping a THP we have a PMD and a PTE mapping. */
- VM_WARN_ON_FOLIO((atomic_read(&page->_mapcount) > 0 ||
- (folio_test_large(folio) && folio_entire_mapcount(folio) > 1)) &&
- PageAnonExclusive(page), folio);
+
+ if (flags & RMAP_EXCLUSIVE) {
+ if (likely(nr_pages == 1 || mode != RMAP_MODE_PTE))
+ SetPageAnonExclusive(page);
+ else
+ for (i = 0; i < nr_pages; i++)
+ SetPageAnonExclusive(page + i);
+ }
+ for (i = 0; i < nr_pages; i++) {
+ struct page *cur_page = page + i;
+
+ /* While PTE-mapping a THP we have a PMD and a PTE mapping. */
+ VM_WARN_ON_FOLIO((atomic_read(&cur_page->_mapcount) > 0 ||
+ (folio_test_large(folio) &&
+ folio_entire_mapcount(folio) > 1)) &&
+ PageAnonExclusive(cur_page), folio);
+ }
/*
* For large folio, only mlock it if it's fully mapped to VMA. It's
@@ -1335,6 +1330,54 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
mlock_vma_folio(folio, vma);
}
+/**
+ * folio_add_anon_rmap_ptes - add PTE mappings to a page range of an anon folio
+ * @folio: The folio to add the mappings to
+ * @page: The first page to add
+ * @nr_pages: The number of pages which will be mapped
+ * @vma: The vm area in which the mappings are added
+ * @address: The user virtual address of the first page to map
+ * @flags: The rmap flags
+ *
+ * The page range of folio is defined by [first_page, first_page + nr_pages)
+ *
+ * The caller needs to hold the page table lock, and the page must be locked in
+ * the anon_vma case: to serialize mapping,index checking after setting,
+ * and to ensure that an anon folio is not being upgraded racily to a KSM folio
+ * (but KSM folios are never downgraded).
+ */
+void folio_add_anon_rmap_ptes(struct folio *folio, struct page *page,
+ unsigned int nr_pages, struct vm_area_struct *vma,
+ unsigned long address, rmap_t flags)
+{
+ __folio_add_anon_rmap(folio, page, nr_pages, vma, address, flags,
+ RMAP_MODE_PTE);
+}
+
+/**
+ * folio_add_anon_rmap_pmd - add a PMD mapping to a page range of an anon folio
+ * @folio: The folio to add the mapping to
+ * @page: The first page to add
+ * @vma: The vm area in which the mapping is added
+ * @address: The user virtual address of the first page to map
+ * @flags: The rmap flags
+ *
+ * The page range of folio is defined by [first_page, first_page + HPAGE_PMD_NR)
+ *
+ * The caller needs to hold the page table lock, and the page must be locked in
+ * the anon_vma case: to serialize mapping,index checking after setting.
+ */
+void folio_add_anon_rmap_pmd(struct folio *folio, struct page *page,
+ struct vm_area_struct *vma, unsigned long address, rmap_t flags)
+{
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ __folio_add_anon_rmap(folio, page, HPAGE_PMD_NR, vma, address, flags,
+ RMAP_MODE_PMD);
+#else
+ WARN_ON_ONCE(true);
+#endif
+}
+
/**
* folio_add_new_anon_rmap - Add mapping to a new anonymous folio.
* @folio: The folio to add the mapping to.
--
2.41.0
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