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Message-ID: <20231124132626.235350-2-david@redhat.com>
Date: Fri, 24 Nov 2023 14:26:06 +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>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Ryan Roberts <ryan.roberts@....com>,
Matthew Wilcox <willy@...radead.org>,
Hugh Dickins <hughd@...gle.com>,
Yin Fengwei <fengwei.yin@...el.com>,
Yang Shi <shy828301@...il.com>,
Ying Huang <ying.huang@...el.com>, Zi Yan <ziy@...dia.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
Waiman Long <longman@...hat.com>,
"Paul E. McKenney" <paulmck@...nel.org>
Subject: [PATCH WIP v1 01/20] mm/rmap: factor out adding folio range into __folio_add_rmap_range()
Let's factor it out, optimize for small folios, and add some more sanity
checks.
Signed-off-by: David Hildenbrand <david@...hat.com>
---
mm/rmap.c | 119 ++++++++++++++++++++++++------------------------------
1 file changed, 53 insertions(+), 66 deletions(-)
diff --git a/mm/rmap.c b/mm/rmap.c
index 7a27a2b41802..afddf3d82a8f 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1127,6 +1127,54 @@ int folio_total_mapcount(struct folio *folio)
return mapcount;
}
+static unsigned int __folio_add_rmap_range(struct folio *folio,
+ struct page *page, unsigned int nr_pages, bool compound,
+ int *nr_pmdmapped)
+{
+ atomic_t *mapped = &folio->_nr_pages_mapped;
+ int first, nr = 0;
+
+ VM_WARN_ON_FOLIO(compound && page != &folio->page, folio);
+ VM_WARN_ON_FOLIO(compound && !folio_test_pmd_mappable(folio), folio);
+ VM_WARN_ON_FOLIO(compound && nr_pages != folio_nr_pages(folio), folio);
+ VM_WARN_ON_FOLIO(!folio_test_large(folio) && nr_pages != 1, folio);
+
+ if (likely(!folio_test_large(folio)))
+ return atomic_inc_and_test(&page->_mapcount);
+
+ /* Is page being mapped by PTE? Is this its first map to be added? */
+ if (!compound) {
+ do {
+ first = atomic_inc_and_test(&page->_mapcount);
+ if (first) {
+ first = atomic_inc_return_relaxed(mapped);
+ if (first < COMPOUND_MAPPED)
+ nr++;
+ }
+ } while (page++, --nr_pages > 0);
+ } else if (folio_test_pmd_mappable(folio)) {
+ /* That test is redundant: it's for safety or to optimize out */
+
+ 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;
+ }
+ }
+ } else {
+ VM_WARN_ON_ONCE_FOLIO(true, folio);
+ }
+ return nr;
+}
+
/**
* folio_move_anon_rmap - move a folio to our anon_vma
* @folio: The folio to move to our anon_vma
@@ -1227,38 +1275,10 @@ 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;
+ unsigned int nr, 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 */
-
- 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;
- }
- }
- }
+ nr = __folio_add_rmap_range(folio, page, 1, compound, &nr_pmdmapped);
if (nr_pmdmapped)
__lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr_pmdmapped);
if (nr)
@@ -1349,43 +1369,10 @@ void folio_add_file_rmap_range(struct folio *folio, struct page *page,
unsigned int nr_pages, struct vm_area_struct *vma,
bool compound)
{
- atomic_t *mapped = &folio->_nr_pages_mapped;
- unsigned int nr_pmdmapped = 0, first;
- int nr = 0;
-
- VM_WARN_ON_FOLIO(compound && !folio_test_pmd_mappable(folio), folio);
-
- /* Is page being mapped by PTE? Is this its first map to be added? */
- if (likely(!compound)) {
- do {
- first = atomic_inc_and_test(&page->_mapcount);
- if (first && folio_test_large(folio)) {
- first = atomic_inc_return_relaxed(mapped);
- first = (first < COMPOUND_MAPPED);
- }
-
- if (first)
- nr++;
- } while (page++, --nr_pages > 0);
- } else if (folio_test_pmd_mappable(folio)) {
- /* That test is redundant: it's for safety or to optimize out */
-
- 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;
- }
- }
- }
+ unsigned int nr, nr_pmdmapped = 0;
+ nr = __folio_add_rmap_range(folio, page, nr_pages, compound,
+ &nr_pmdmapped);
if (nr_pmdmapped)
__lruvec_stat_mod_folio(folio, folio_test_swapbacked(folio) ?
NR_SHMEM_PMDMAPPED : NR_FILE_PMDMAPPED, nr_pmdmapped);
--
2.41.0
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