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mm: convert page_remove_rmap() to use a folio internally

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The API for page_remove_rmap() needs to be page-based, because we can
remove mappings of pages individually.  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/20230111142915.1001531-6-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 14:28:51 +00:00 committed by Andrew Morton
parent b14224fbea
commit 62beb906ef
1 changed files with 26 additions and 21 deletions
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47
mm/rmap.c
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@ -1365,19 +1365,21 @@ void page_add_file_rmap(struct page *page,
*
* The caller needs to hold the pte lock.
*/
void page_remove_rmap(struct page *page,
struct vm_area_struct *vma, bool compound)
void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
bool compound)
{
atomic_t *mapped;
struct folio *folio = page_folio(page);
atomic_t *mapped = &folio->_nr_pages_mapped;
int nr = 0, nr_pmdmapped = 0;
bool last;
enum node_stat_item idx;
VM_BUG_ON_PAGE(compound && !PageHead(page), page);
/* Hugetlb pages are not counted in NR_*MAPPED */
if (unlikely(PageHuge(page))) {
if (unlikely(folio_test_hugetlb(folio))) {
/* hugetlb pages are always mapped with pmds */
atomic_dec(compound_mapcount_ptr(page));
atomic_dec(&folio->_entire_mapcount);
return;
}
@ -1385,20 +1387,18 @@ void page_remove_rmap(struct page *page,
if (likely(!compound)) {
last = atomic_add_negative(-1, &page->_mapcount);
nr = last;
if (last && PageCompound(page)) {
mapped = subpages_mapcount_ptr(compound_head(page));
if (last && folio_test_large(folio)) {
nr = atomic_dec_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 */
last = atomic_add_negative(-1, compound_mapcount_ptr(page));
last = atomic_add_negative(-1, &folio->_entire_mapcount);
if (last) {
mapped = subpages_mapcount_ptr(page);
nr = atomic_sub_return_relaxed(COMPOUND_MAPPED, mapped);
if (likely(nr < COMPOUND_MAPPED)) {
nr_pmdmapped = thp_nr_pages(page);
nr_pmdmapped = folio_nr_pages(folio);
nr = nr_pmdmapped - (nr & FOLIO_PAGES_MAPPED);
/* Raced ahead of another remove and an add? */
if (unlikely(nr < 0))
@ -1411,21 +1411,26 @@ void page_remove_rmap(struct page *page,
}
if (nr_pmdmapped) {
__mod_lruvec_page_state(page, PageAnon(page) ? NR_ANON_THPS :
(PageSwapBacked(page) ? NR_SHMEM_PMDMAPPED :
NR_FILE_PMDMAPPED), -nr_pmdmapped);
if (folio_test_anon(folio))
idx = NR_ANON_THPS;
else if (folio_test_swapbacked(folio))
idx = NR_SHMEM_PMDMAPPED;
else
idx = NR_FILE_PMDMAPPED;
__lruvec_stat_mod_folio(folio, idx, -nr_pmdmapped);
}
if (nr) {
__mod_lruvec_page_state(page, PageAnon(page) ? NR_ANON_MAPPED :
NR_FILE_MAPPED, -nr);
idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED;
__lruvec_stat_mod_folio(folio, idx, -nr);
/*
* Queue anon THP for deferred split if at least one small
* page of the compound page is unmapped, but at least one
* small page is still mapped.
* Queue anon THP for deferred split if at least one
* page of the folio is unmapped and at least one page
* is still mapped.
*/
if (PageTransCompound(page) && PageAnon(page))
if (folio_test_pmd_mappable(folio) && folio_test_anon(folio))
if (!compound || nr < nr_pmdmapped)
deferred_split_huge_page(compound_head(page));
deferred_split_huge_page(&folio->page);
}
/*