->_mapcount of all sub-pages in order to have race-free detection of
last unmap of subpages.
-PageDoubleMap() indicates that the page is *possibly* mapped with PTEs.
-
-For anonymous pages, PageDoubleMap() also indicates ->_mapcount in all
-subpages is offset up by one. This additional reference is required to
-get race-free detection of unmap of subpages when we have them mapped with
-both PMDs and PTEs.
-
-This optimization is required to lower the overhead of per-subpage mapcount
-tracking. The alternative is to alter ->_mapcount in all subpages on each
-map/unmap of the whole compound page.
-
-For anonymous pages, we set PG_double_map when a PMD of the page is split
-for the first time, but still have a PMD mapping. The additional references
-go away with the last compound_mapcount.
-
-File pages get PG_double_map set on the first map of the page with PTE and
-goes away when the page gets evicted from the page cache.
-
split_huge_page internally has to distribute the refcounts in the head
page to the tail pages before clearing all PG_head/tail bits from the page
structures. It can be done easily for refcounts taken by page table
/*
* How many times the entire folio is mapped as a single unit (eg by a
* PMD or PUD entry). This is probably not what you want, except for
- * debugging purposes; look at folio_mapcount() or page_mapcount()
- * instead.
+ * debugging purposes - it does not include PTE-mapped sub-pages; look
+ * at folio_mapcount() or page_mapcount() or total_mapcount() instead.
*/
static inline int folio_entire_mapcount(struct folio *folio)
{
/*
* Mapcount of compound page as a whole, does not include mapped sub-pages.
- *
- * Must be called only for compound pages.
+ * Must be called only on head of compound page.
*/
-static inline int compound_mapcount(struct page *page)
+static inline int head_compound_mapcount(struct page *head)
{
- return folio_entire_mapcount(page_folio(page));
+ return atomic_read(compound_mapcount_ptr(head)) + 1;
+}
+
+/*
+ * Sum of mapcounts of sub-pages, does not include compound mapcount.
+ * Must be called only on head of compound page.
+ */
+static inline int head_subpages_mapcount(struct page *head)
+{
+ return atomic_read(subpages_mapcount_ptr(head));
}
/*
atomic_set(&(page)->_mapcount, -1);
}
-int __page_mapcount(struct page *page);
-
/*
* Mapcount of 0-order page; when compound sub-page, includes
- * compound_mapcount().
+ * compound_mapcount of compound_head of page.
*
* Result is undefined for pages which cannot be mapped into userspace.
* For example SLAB or special types of pages. See function page_has_type().
*/
static inline int page_mapcount(struct page *page)
{
- if (unlikely(PageCompound(page)))
- return __page_mapcount(page);
- return atomic_read(&page->_mapcount) + 1;
-}
+ int mapcount = atomic_read(&page->_mapcount) + 1;
-int folio_mapcount(struct folio *folio);
+ if (likely(!PageCompound(page)))
+ return mapcount;
+ page = compound_head(page);
+ return head_compound_mapcount(page) + mapcount;
+}
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline int total_mapcount(struct page *page)
{
- return folio_mapcount(page_folio(page));
+ if (likely(!PageCompound(page)))
+ return atomic_read(&page->_mapcount) + 1;
+ page = compound_head(page);
+ return head_compound_mapcount(page) + head_subpages_mapcount(page);
}
-#else
-static inline int total_mapcount(struct page *page)
+/*
+ * Return true if this page is mapped into pagetables.
+ * For compound page it returns true if any subpage of compound page is mapped,
+ * even if this particular subpage is not itself mapped by any PTE or PMD.
+ */
+static inline bool page_mapped(struct page *page)
{
- return page_mapcount(page);
+ return total_mapcount(page) > 0;
+}
+
+/**
+ * folio_mapcount() - Calculate the number of mappings of this folio.
+ * @folio: The folio.
+ *
+ * A large folio tracks both how many times the entire folio is mapped,
+ * and how many times each individual page in the folio is mapped.
+ * This function calculates the total number of times the folio is
+ * mapped.
+ *
+ * Return: The number of times this folio is mapped.
+ */
+static inline int folio_mapcount(struct folio *folio)
+{
+ if (likely(!folio_test_large(folio)))
+ return atomic_read(&folio->_mapcount) + 1;
+ return atomic_read(folio_mapcount_ptr(folio)) + 1 +
+ atomic_read(folio_subpages_mapcount_ptr(folio));
+}
+
+/**
+ * folio_mapped - Is this folio mapped into userspace?
+ * @folio: The folio.
+ *
+ * Return: True if any page in this folio is referenced by user page tables.
+ */
+static inline bool folio_mapped(struct folio *folio)
+{
+ return folio_mapcount(folio) > 0;
}
-#endif
static inline struct page *virt_to_head_page(const void *x)
{
return page->index;
}
-bool page_mapped(struct page *page);
-bool folio_mapped(struct folio *folio);
-
/*
* Return true only if the page has been allocated with
* ALLOC_NO_WATERMARKS and the low watermark was not
unsigned char compound_dtor;
unsigned char compound_order;
atomic_t compound_mapcount;
+ atomic_t subpages_mapcount;
atomic_t compound_pincount;
#ifdef CONFIG_64BIT
unsigned int compound_nr; /* 1 << compound_order */
* @_head_1: Points to the folio. Do not use.
* @_folio_dtor: Which destructor to use for this folio.
* @_folio_order: Do not use directly, call folio_order().
- * @_total_mapcount: Do not use directly, call folio_entire_mapcount().
+ * @_compound_mapcount: Do not use directly, call folio_entire_mapcount().
+ * @_subpages_mapcount: Do not use directly, call folio_mapcount().
* @_pincount: Do not use directly, call folio_maybe_dma_pinned().
* @_folio_nr_pages: Do not use directly, call folio_nr_pages().
* @_flags_2: For alignment. Do not use.
unsigned long _head_1;
unsigned char _folio_dtor;
unsigned char _folio_order;
- atomic_t _total_mapcount;
+ atomic_t _compound_mapcount;
+ atomic_t _subpages_mapcount;
atomic_t _pincount;
#ifdef CONFIG_64BIT
unsigned int _folio_nr_pages;
FOLIO_MATCH(compound_head, _head_1);
FOLIO_MATCH(compound_dtor, _folio_dtor);
FOLIO_MATCH(compound_order, _folio_order);
-FOLIO_MATCH(compound_mapcount, _total_mapcount);
+FOLIO_MATCH(compound_mapcount, _compound_mapcount);
+FOLIO_MATCH(subpages_mapcount, _subpages_mapcount);
FOLIO_MATCH(compound_pincount, _pincount);
#ifdef CONFIG_64BIT
FOLIO_MATCH(compound_nr, _folio_nr_pages);
return &tail->compound_mapcount;
}
+static inline atomic_t *folio_subpages_mapcount_ptr(struct folio *folio)
+{
+ struct page *tail = &folio->page + 1;
+ return &tail->subpages_mapcount;
+}
+
static inline atomic_t *compound_mapcount_ptr(struct page *page)
{
return &page[1].compound_mapcount;
}
+static inline atomic_t *subpages_mapcount_ptr(struct page *page)
+{
+ return &page[1].subpages_mapcount;
+}
+
static inline atomic_t *compound_pincount_ptr(struct page *page)
{
return &page[1].compound_pincount;
/* SLOB */
PG_slob_free = PG_private,
- /* Compound pages. Stored in first tail page's flags */
- PG_double_map = PG_workingset,
-
#ifdef CONFIG_MEMORY_FAILURE
/*
* Compound pages. Stored in first tail page's flags.
{
return PageTail(page);
}
-
-/*
- * PageDoubleMap indicates that the compound page is mapped with PTEs as well
- * as PMDs.
- *
- * This is required for optimization of rmap operations for THP: we can postpone
- * per small page mapcount accounting (and its overhead from atomic operations)
- * until the first PMD split.
- *
- * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
- * by one. This reference will go away with last compound_mapcount.
- *
- * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
- */
-PAGEFLAG(DoubleMap, double_map, PF_SECOND)
- TESTSCFLAG(DoubleMap, double_map, PF_SECOND)
#else
TESTPAGEFLAG_FALSE(TransHuge, transhuge)
TESTPAGEFLAG_FALSE(TransCompound, transcompound)
TESTPAGEFLAG_FALSE(TransCompoundMap, transcompoundmap)
TESTPAGEFLAG_FALSE(TransTail, transtail)
-PAGEFLAG_FALSE(DoubleMap, double_map)
- TESTSCFLAG_FALSE(DoubleMap, double_map)
#endif
#if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
static inline void __page_dup_rmap(struct page *page, bool compound)
{
+ if (!compound && PageCompound(page))
+ atomic_inc(subpages_mapcount_ptr(compound_head(page)));
atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount);
}
page, page_ref_count(head), mapcount, mapping,
page_to_pgoff(page), page_to_pfn(page));
if (compound) {
- pr_warn("head:%p order:%u compound_mapcount:%d compound_pincount:%d\n",
+ pr_warn("head:%p order:%u compound_mapcount:%d subpages_mapcount:%d compound_pincount:%d\n",
head, compound_order(head),
- folio_entire_mapcount(folio),
+ head_compound_mapcount(head),
+ head_subpages_mapcount(head),
head_compound_pincount(head));
}
}
EXPORT_SYMBOL_GPL(wait_for_stable_page);
-bool page_mapped(struct page *page)
-{
- return folio_mapped(page_folio(page));
-}
-EXPORT_SYMBOL(page_mapped);
-
void mark_page_accessed(struct page *page)
{
folio_mark_accessed(page_folio(page));
VM_BUG_ON_PAGE(!page_count(page), page);
page_ref_add(page, HPAGE_PMD_NR - 1);
+ atomic_add(HPAGE_PMD_NR, subpages_mapcount_ptr(page));
/*
* Without "freeze", we'll simply split the PMD, propagating the
pte_unmap(pte);
}
- if (!pmd_migration) {
- /*
- * Set PG_double_map before dropping compound_mapcount to avoid
- * false-negative page_mapped().
- */
- if (compound_mapcount(page) > 1 &&
- !TestSetPageDoubleMap(page)) {
- for (i = 0; i < HPAGE_PMD_NR; i++)
- atomic_inc(&page[i]._mapcount);
- }
-
- lock_page_memcg(page);
- if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
- /* Last compound_mapcount is gone. */
- __mod_lruvec_page_state(page, NR_ANON_THPS,
- -HPAGE_PMD_NR);
- if (TestClearPageDoubleMap(page)) {
- /* No need in mapcount reference anymore */
- for (i = 0; i < HPAGE_PMD_NR; i++)
- atomic_dec(&page[i]._mapcount);
- }
- }
- unlock_page_memcg(page);
-
- /* Above is effectively page_remove_rmap(page, vma, true) */
- munlock_vma_page(page, vma, true);
- }
+ if (!pmd_migration)
+ page_remove_rmap(page, vma, true);
smp_wmb(); /* make pte visible before pmd */
pmd_populate(mm, pmd, pgtable);
(1L << PG_dirty) |
LRU_GEN_MASK | LRU_REFS_MASK));
- /* ->mapping in first tail page is compound_mapcount */
+ /* ->mapping in first and second tail page is replaced by other uses */
VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
page_tail);
page_tail->mapping = head->mapping;
* page->private should not be set in tail pages with the exception
* of swap cache pages that store the swp_entry_t in tail pages.
* Fix up and warn once if private is unexpectedly set.
+ *
+ * What of 32-bit systems, on which head[1].compound_pincount overlays
+ * head[1].private? No problem: THP_SWAP is not enabled on 32-bit, and
+ * compound_pincount must be 0 for folio_ref_freeze() to have succeeded.
*/
if (!folio_test_swapcache(page_folio(head))) {
VM_WARN_ON_ONCE_PAGE(page_tail->private != 0, page_tail);
struct page *p;
atomic_set(compound_mapcount_ptr(page), 0);
+ atomic_set(subpages_mapcount_ptr(page), 0);
atomic_set(compound_pincount_ptr(page), 0);
for (i = 1; i < nr_pages; i++) {
set_compound_head(p, page);
}
atomic_set(compound_mapcount_ptr(page), -1);
+ atomic_set(subpages_mapcount_ptr(page), 0);
atomic_set(compound_pincount_ptr(page), 0);
return true;
/*
* Check if the page has any GUP (or other external) pins.
*
- * Here the check is racy it may see total_mapcount > refcount
- * in some cases.
- * For example, one process with one forked child process.
- * The parent has the PMD split due to MADV_DONTNEED, then
- * the child is trying unmap the whole PMD, but khugepaged
- * may be scanning the parent between the child has
- * PageDoubleMap flag cleared and dec the mapcount. So
- * khugepaged may see total_mapcount > refcount.
- *
+ * Here the check may be racy:
+ * it may see total_mapcount > refcount in some cases?
* But such case is ephemeral we could always retry collapse
* later. However it may report false positive if the page
* has excessive GUP pins (i.e. 512). Anyway the same check
set_compound_page_dtor(page, COMPOUND_PAGE_DTOR);
set_compound_order(page, order);
atomic_set(compound_mapcount_ptr(page), -1);
+ atomic_set(subpages_mapcount_ptr(page), 0);
atomic_set(compound_pincount_ptr(page), 0);
}
}
switch (page - head_page) {
case 1:
- /* the first tail page: ->mapping may be compound_mapcount() */
- if (unlikely(compound_mapcount(page))) {
+ /* the first tail page: these may be in place of ->mapping */
+ if (unlikely(head_compound_mapcount(head_page))) {
bad_page(page, "nonzero compound_mapcount");
goto out;
}
+ if (unlikely(head_subpages_mapcount(head_page))) {
+ bad_page(page, "nonzero subpages_mapcount");
+ goto out;
+ }
+ if (unlikely(head_compound_pincount(head_page))) {
+ bad_page(page, "nonzero compound_pincount");
+ goto out;
+ }
break;
case 2:
/*
VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
- if (compound) {
- ClearPageDoubleMap(page);
+ if (compound)
ClearPageHasHWPoisoned(page);
- }
for (i = 1; i < (1 << order); i++) {
if (compound)
bad += free_tail_pages_check(page, page + i);
set_page_count(page, 0);
/*
- * The first tail page stores compound_mapcount_ptr() and
- * compound_order() and the second tail page stores
- * compound_pincount_ptr(). Call prep_compound_head() after
- * the first and second tail pages have been initialized to
- * not have the data overwritten.
+ * The first tail page stores important compound page info.
+ * Call prep_compound_head() after the first tail page has
+ * been initialized, to not have the data overwritten.
*/
- if (pfn == head_pfn + 2)
+ if (pfn == head_pfn + 1)
prep_compound_head(head, order);
}
}
return page_vma_mkclean_one(&pvmw);
}
+/*
+ * When mapping a THP's first pmd, or unmapping its last pmd, if that THP
+ * also has pte mappings, then those must be discounted: in order to maintain
+ * NR_ANON_MAPPED and NR_FILE_MAPPED statistics exactly, without any drift,
+ * and to decide when an anon THP should be put on the deferred split queue.
+ */
+static int nr_subpages_unmapped(struct page *head, int nr_subpages)
+{
+ int nr = nr_subpages;
+ int i;
+
+ /* Discount those subpages mapped by pte */
+ for (i = 0; i < nr_subpages; i++)
+ if (atomic_read(&head[i]._mapcount) >= 0)
+ nr--;
+ return nr;
+}
+
/**
* page_move_anon_rmap - move a page to our anon_vma
* @page: the page to move to our anon_vma
void page_add_anon_rmap(struct page *page,
struct vm_area_struct *vma, unsigned long address, rmap_t flags)
{
+ int nr, nr_pages;
bool compound = flags & RMAP_COMPOUND;
bool first;
else
VM_BUG_ON_PAGE(!PageLocked(page), page);
- if (compound) {
+ if (compound && PageTransHuge(page)) {
atomic_t *mapcount;
VM_BUG_ON_PAGE(!PageLocked(page), page);
- VM_BUG_ON_PAGE(!PageTransHuge(page), page);
mapcount = compound_mapcount_ptr(page);
first = atomic_inc_and_test(mapcount);
+
+ nr = nr_pages = thp_nr_pages(page);
+ if (first && head_subpages_mapcount(page))
+ nr = nr_subpages_unmapped(page, nr_pages);
} else {
+ nr = 1;
+ if (PageTransCompound(page)) {
+ struct page *head = compound_head(page);
+
+ atomic_inc(subpages_mapcount_ptr(head));
+ nr = !head_compound_mapcount(head);
+ }
first = atomic_inc_and_test(&page->_mapcount);
}
+
VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page);
VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page);
if (first) {
- int nr = compound ? thp_nr_pages(page) : 1;
- /*
- * We use the irq-unsafe __{inc|mod}_zone_page_stat because
- * these counters are not modified in interrupt context, and
- * pte lock(a spinlock) is held, which implies preemption
- * disabled.
- */
if (compound)
- __mod_lruvec_page_state(page, NR_ANON_THPS, nr);
+ __mod_lruvec_page_state(page, NR_ANON_THPS, nr_pages);
__mod_lruvec_page_state(page, NR_ANON_MAPPED, nr);
}
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
/* increment count (starts at -1) */
atomic_set(compound_mapcount_ptr(page), 0);
- atomic_set(compound_pincount_ptr(page), 0);
-
__mod_lruvec_page_state(page, NR_ANON_THPS, nr);
} else {
/* increment count (starts at -1) */
void page_add_file_rmap(struct page *page,
struct vm_area_struct *vma, bool compound)
{
- int i, nr = 0;
+ int nr = 0;
VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
lock_page_memcg(page);
if (compound && PageTransHuge(page)) {
- int nr_pages = thp_nr_pages(page);
+ int nr_pages;
- for (i = 0; i < nr_pages; i++) {
- if (atomic_inc_and_test(&page[i]._mapcount))
- nr++;
- }
if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
goto out;
- /*
- * It is racy to ClearPageDoubleMap in page_remove_file_rmap();
- * but page lock is held by all page_add_file_rmap() compound
- * callers, and SetPageDoubleMap below warns if !PageLocked:
- * so here is a place that DoubleMap can be safely cleared.
- */
- VM_WARN_ON_ONCE(!PageLocked(page));
- if (nr == nr_pages && PageDoubleMap(page))
- ClearPageDoubleMap(page);
+ nr = nr_pages = thp_nr_pages(page);
+ if (head_subpages_mapcount(page))
+ nr = nr_subpages_unmapped(page, nr_pages);
if (PageSwapBacked(page))
__mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED,
__mod_lruvec_page_state(page, NR_FILE_PMDMAPPED,
nr_pages);
} else {
- if (PageTransCompound(page) && page_mapping(page)) {
- VM_WARN_ON_ONCE(!PageLocked(page));
- SetPageDoubleMap(compound_head(page));
+ bool pmd_mapped = false;
+
+ if (PageTransCompound(page)) {
+ struct page *head = compound_head(page);
+
+ atomic_inc(subpages_mapcount_ptr(head));
+ pmd_mapped = head_compound_mapcount(head);
}
- if (atomic_inc_and_test(&page->_mapcount))
+ if (atomic_inc_and_test(&page->_mapcount) && !pmd_mapped)
nr++;
}
out:
static void page_remove_file_rmap(struct page *page, bool compound)
{
- int i, nr = 0;
+ int nr = 0;
VM_BUG_ON_PAGE(compound && !PageHead(page), page);
/* page still mapped by someone else? */
if (compound && PageTransHuge(page)) {
- int nr_pages = thp_nr_pages(page);
+ int nr_pages;
- for (i = 0; i < nr_pages; i++) {
- if (atomic_add_negative(-1, &page[i]._mapcount))
- nr++;
- }
if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
- goto out;
+ return;
+
+ nr = nr_pages = thp_nr_pages(page);
+ if (head_subpages_mapcount(page))
+ nr = nr_subpages_unmapped(page, nr_pages);
+
if (PageSwapBacked(page))
__mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED,
-nr_pages);
__mod_lruvec_page_state(page, NR_FILE_PMDMAPPED,
-nr_pages);
} else {
- if (atomic_add_negative(-1, &page->_mapcount))
+ bool pmd_mapped = false;
+
+ if (PageTransCompound(page)) {
+ struct page *head = compound_head(page);
+
+ atomic_dec(subpages_mapcount_ptr(head));
+ pmd_mapped = head_compound_mapcount(head);
+ }
+ if (atomic_add_negative(-1, &page->_mapcount) && !pmd_mapped)
nr++;
}
-out:
+
if (nr)
__mod_lruvec_page_state(page, NR_FILE_MAPPED, -nr);
}
static void page_remove_anon_compound_rmap(struct page *page)
{
- int i, nr;
+ int nr, nr_pages;
if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
return;
if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
return;
- __mod_lruvec_page_state(page, NR_ANON_THPS, -thp_nr_pages(page));
+ nr = nr_pages = thp_nr_pages(page);
+ __mod_lruvec_page_state(page, NR_ANON_THPS, -nr);
- if (TestClearPageDoubleMap(page)) {
- /*
- * Subpages can be mapped with PTEs too. Check how many of
- * them are still mapped.
- */
- for (i = 0, nr = 0; i < thp_nr_pages(page); i++) {
- if (atomic_add_negative(-1, &page[i]._mapcount))
- nr++;
- }
+ if (head_subpages_mapcount(page)) {
+ nr = nr_subpages_unmapped(page, nr_pages);
/*
* Queue the page for deferred split if at least one small
* page of the compound page is unmapped, but at least one
* small page is still mapped.
*/
- if (nr && nr < thp_nr_pages(page))
+ if (nr && nr < nr_pages)
deferred_split_huge_page(page);
- } else {
- nr = thp_nr_pages(page);
}
if (nr)
void page_remove_rmap(struct page *page,
struct vm_area_struct *vma, bool compound)
{
+ bool pmd_mapped = false;
+
lock_page_memcg(page);
if (!PageAnon(page)) {
goto out;
}
+ if (PageTransCompound(page)) {
+ struct page *head = compound_head(page);
+
+ atomic_dec(subpages_mapcount_ptr(head));
+ pmd_mapped = head_compound_mapcount(head);
+ }
+
/* page still mapped by someone else? */
- if (!atomic_add_negative(-1, &page->_mapcount))
+ if (!atomic_add_negative(-1, &page->_mapcount) || pmd_mapped)
goto out;
- /*
- * We use the irq-unsafe __{inc|mod}_zone_page_stat because
- * these counters are not modified in interrupt context, and
- * pte lock(a spinlock) is held, which implies preemption disabled.
- */
__dec_lruvec_page_state(page, NR_ANON_MAPPED);
if (PageTransCompound(page))
struct vm_area_struct *vma, unsigned long address)
{
BUG_ON(address < vma->vm_start || address >= vma->vm_end);
+ /* increment count (starts at -1) */
atomic_set(compound_mapcount_ptr(page), 0);
- atomic_set(compound_pincount_ptr(page), 0);
ClearHPageRestoreReserve(page);
__page_set_anon_rmap(page, vma, address, 1);
}
return folio_raw_mapping(page_folio(page));
}
-/**
- * folio_mapped - Is this folio mapped into userspace?
- * @folio: The folio.
- *
- * Return: True if any page in this folio is referenced by user page tables.
- */
-bool folio_mapped(struct folio *folio)
-{
- long i, nr;
-
- if (!folio_test_large(folio))
- return atomic_read(&folio->_mapcount) >= 0;
- if (atomic_read(folio_mapcount_ptr(folio)) >= 0)
- return true;
- if (folio_test_hugetlb(folio))
- return false;
-
- nr = folio_nr_pages(folio);
- for (i = 0; i < nr; i++) {
- if (atomic_read(&folio_page(folio, i)->_mapcount) >= 0)
- return true;
- }
- return false;
-}
-EXPORT_SYMBOL(folio_mapped);
-
struct anon_vma *folio_anon_vma(struct folio *folio)
{
unsigned long mapping = (unsigned long)folio->mapping;
}
EXPORT_SYMBOL(folio_mapping);
-/* Slow path of page_mapcount() for compound pages */
-int __page_mapcount(struct page *page)
-{
- int ret;
-
- ret = atomic_read(&page->_mapcount) + 1;
- /*
- * For file THP page->_mapcount contains total number of mapping
- * of the page: no need to look into compound_mapcount.
- */
- if (!PageAnon(page) && !PageHuge(page))
- return ret;
- page = compound_head(page);
- ret += atomic_read(compound_mapcount_ptr(page)) + 1;
- if (PageDoubleMap(page))
- ret--;
- return ret;
-}
-EXPORT_SYMBOL_GPL(__page_mapcount);
-
-/**
- * folio_mapcount() - Calculate the number of mappings of this folio.
- * @folio: The folio.
- *
- * A large folio tracks both how many times the entire folio is mapped,
- * and how many times each individual page in the folio is mapped.
- * This function calculates the total number of times the folio is
- * mapped.
- *
- * Return: The number of times this folio is mapped.
- */
-int folio_mapcount(struct folio *folio)
-{
- int i, compound, nr, ret;
-
- if (likely(!folio_test_large(folio)))
- return atomic_read(&folio->_mapcount) + 1;
-
- compound = folio_entire_mapcount(folio);
- if (folio_test_hugetlb(folio))
- return compound;
- ret = compound;
- nr = folio_nr_pages(folio);
- for (i = 0; i < nr; i++)
- ret += atomic_read(&folio_page(folio, i)->_mapcount) + 1;
- /* File pages has compound_mapcount included in _mapcount */
- if (!folio_test_anon(folio))
- return ret - compound * nr;
- if (folio_test_double_map(folio))
- ret -= nr;
- return ret;
-}
-
/**
* folio_copy - Copy the contents of one folio to another.
* @dst: Folio to copy to.
projects / linux-2.6-block.git / commitdiff