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mm: convert page_add_anon_rmap() to use a folio internally 

The API for page_add_anon_rmap() needs to be page-based, because we can
add mappings of individual pages.  But inside the function, we want to
only call compound_head() once and then use the folio APIs instead of the
page APIs that each call compound_head().

Link: https://lkml.kernel.org/r/20230111142915.1001531-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-01-11 14:28:52 +00:00 committed by Andrew Morton
parent 62beb906ef
commit ee0800c2f6
1 changed files with 11 additions and 12 deletions
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23
mm/rmap.c
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@ -1207,10 +1207,11 @@ static void __page_check_anon_rmap(struct page *page,
* and to ensure that PageAnon is not being upgraded racily to PageKsm
* (but PageKsm is never downgraded to PageAnon).
*/
void page_add_anon_rmap(struct page *page,
struct vm_area_struct *vma, unsigned long address, rmap_t flags)
void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
unsigned long address, rmap_t flags)
{
atomic_t *mapped;
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 = true;
@ -1219,20 +1220,18 @@ void page_add_anon_rmap(struct page *page,
if (likely(!compound)) {
first = atomic_inc_and_test(&page->_mapcount);
nr = first;
if (first && PageCompound(page)) {
mapped = subpages_mapcount_ptr(compound_head(page));
if (first && folio_test_large(folio)) {
nr = atomic_inc_return_relaxed(mapped);
nr = (nr < COMPOUND_MAPPED);
}
} else if (PageTransHuge(page)) {
} else if (folio_test_pmd_mappable(folio)) {
/* That test is redundant: it's for safety or to optimize out */
first = atomic_inc_and_test(compound_mapcount_ptr(page));
first = atomic_inc_and_test(&folio->_entire_mapcount);
if (first) {
mapped = subpages_mapcount_ptr(page);
nr = atomic_add_return_relaxed(COMPOUND_MAPPED, mapped);
if (likely(nr < COMPOUND_MAPPED + COMPOUND_MAPPED)) {
nr_pmdmapped = thp_nr_pages(page);
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))
@ -1248,11 +1247,11 @@ void page_add_anon_rmap(struct page *page,
VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page);
if (nr_pmdmapped)
__mod_lruvec_page_state(page, NR_ANON_THPS, nr_pmdmapped);
__lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr_pmdmapped);
if (nr)
__mod_lruvec_page_state(page, NR_ANON_MAPPED, nr);
__lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
if (likely(!PageKsm(page))) {
if (likely(!folio_test_ksm(folio))) {
/* address might be in next vma when migration races vma_adjust */
if (first)
__page_set_anon_rmap(page, vma, address,