The patch titled
Subject: mm: convert page_remove_rmap() to use a folio internally
has been added to the -mm mm-unstable branch. Its filename is
mm-convert-page_remove_rmap-to-use-a-folio-internally.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-convert-page_remove_rmap-to-use-a-folio-internally.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: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: convert page_remove_rmap() to use a folio internally
Date: Wed, 11 Jan 2023 14:28:51 +0000
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@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/rmap.c | 47 ++++++++++++++++++++++++++---------------------
1 file changed, 26 insertions(+), 21 deletions(-)
--- a/mm/rmap.c~mm-convert-page_remove_rmap-to-use-a-folio-internally
+++ a/mm/rmap.c
@@ -1365,19 +1365,21 @@ void page_add_file_rmap(struct page *pag
*
* 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);
}
/*
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
buffer-add-b_folio-as-an-alias-of-b_page.patch
buffer-replace-obvious-uses-of-b_page-with-b_folio.patch
buffer-use-b_folio-in-touch_buffer.patch
buffer-use-b_folio-in-end_buffer_async_read.patch
buffer-use-b_folio-in-end_buffer_async_write.patch
page_io-remove-buffer_head-include.patch
buffer-use-b_folio-in-mark_buffer_dirty.patch
gfs2-replace-obvious-uses-of-b_page-with-b_folio.patch
jbd2-replace-obvious-uses-of-b_page-with-b_folio.patch
nilfs2-replace-obvious-uses-of-b_page-with-b_folio.patch
reiserfs-replace-obvious-uses-of-b_page-with-b_folio.patch
mpage-use-b_folio-in-do_mpage_readpage.patch
mm-memcg-add-folio_memcg_check.patch
mm-remove-folio_pincount_ptr-and-head_compound_pincount.patch
mm-convert-head_subpages_mapcount-into-folio_nr_pages_mapped.patch
doc-clarify-refcount-section-by-referring-to-folios-pages.patch
mm-convert-total_compound_mapcount-to-folio_total_mapcount.patch
mm-convert-page_remove_rmap-to-use-a-folio-internally.patch
mm-convert-page_add_anon_rmap-to-use-a-folio-internally.patch
mm-convert-page_add_file_rmap-to-use-a-folio-internally.patch
mm-add-folio_add_new_anon_rmap.patch
page_alloc-use-folio-fields-directly.patch
mm-use-a-folio-in-hugepage_add_anon_rmap-and-hugepage_add_new_anon_rmap.patch
mm-use-entire_mapcount-in-__page_dup_rmap.patch
mm-debug-remove-call-to-head_compound_mapcount.patch
hugetlb-remove-uses-of-folio_mapcount_ptr.patch
mm-convert-page_mapcount-to-use-folio_entire_mapcount.patch
mm-remove-head_compound_mapcount-and-_ptr-functions.patch
mm-reimplement-compound_order.patch
mm-reimplement-compound_nr.patch
mm-convert-set_compound_page_dtor-and-set_compound_order-to-folios.patch
mm-convert-is_transparent_hugepage-to-use-a-folio.patch
mm-convert-destroy_large_folio-to-use-folio_dtor.patch
hugetlb-remove-uses-of-compound_dtor-and-compound_nr.patch
mm-remove-first-tail-page-members-from-struct-page.patch
doc-correct-struct-folio-kernel-doc.patch
mm-move-page-deferred_list-to-folio-_deferred_list.patch
mm-huge_memory-remove-page_deferred_list.patch
mm-huge_memory-convert-get_deferred_split_queue-to-take-a-folio.patch
mm-convert-deferred_split_huge_page-to-deferred_split_folio.patch
