A lot of intricacies go into updating the stats when adding or removing
mappings: which stat index to use and which function. Abstract this away
into a new static helper in rmap.c, __folio_mod_stat().
This adds an unnecessary call to folio_test_anon() in
__folio_add_anon_rmap() and __folio_add_file_rmap(). However, the folio
struct should already be in the cache at this point, so it shouldn't
cause any noticeable overhead.
No functional change intended.
Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
---
This applies on top of "mm: do not update memcg stats for
NR_{FILE/SHMEM}_PMDMAPPED":
https://lore.kernel.org/lkml/20240506192924.271999-1-yosryahmed@xxxxxxxxxx/
David, I was on the fence about adding a Suggested-by here. You did
suggest adding a helper, but the one with the extra folio_test_anon()
was my idea and I didn't want to blame it on you. So I'll leave this up
to you :)
---
mm/rmap.c | 56 ++++++++++++++++++++++++++++---------------------------
1 file changed, 29 insertions(+), 27 deletions(-)
diff --git a/mm/rmap.c b/mm/rmap.c
index ed7f820369864..9ed995da47099 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1269,6 +1269,28 @@ static void __page_check_anon_rmap(struct folio *folio, struct page *page,
page);
}
+static void __folio_mod_stat(struct folio *folio, int nr, int nr_pmdmapped)
+{
+ int idx;
+
+ if (nr) {
+ idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED;
+ __lruvec_stat_mod_folio(folio, idx, nr);
+ }
+ if (nr_pmdmapped) {
+ if (folio_test_anon(folio)) {
+ idx = NR_ANON_THPS;
+ __lruvec_stat_mod_folio(folio, idx, nr_pmdmapped);
+ } else {
+ /* NR_*_PMDMAPPED are not maintained per-memcg */
+ idx = folio_test_swapbacked(folio) ?
+ NR_SHMEM_PMDMAPPED : NR_FILE_PMDMAPPED;
+ __mod_node_page_state(folio_pgdat(folio), idx,
+ nr_pmdmapped);
+ }
+ }
+}
+
static __always_inline void __folio_add_anon_rmap(struct folio *folio,
struct page *page, int nr_pages, struct vm_area_struct *vma,
unsigned long address, rmap_t flags, enum rmap_level level)
@@ -1276,10 +1298,6 @@ static __always_inline void __folio_add_anon_rmap(struct folio *folio,
int i, nr, nr_pmdmapped = 0;
nr = __folio_add_rmap(folio, page, nr_pages, level, &nr_pmdmapped);
- if (nr_pmdmapped)
- __lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr_pmdmapped);
- if (nr)
- __lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
if (unlikely(!folio_test_anon(folio))) {
VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio);
@@ -1297,6 +1315,8 @@ static __always_inline void __folio_add_anon_rmap(struct folio *folio,
__page_check_anon_rmap(folio, page, vma, address);
}
+ __folio_mod_stat(folio, nr, nr_pmdmapped);
+
if (flags & RMAP_EXCLUSIVE) {
switch (level) {
case RMAP_LEVEL_PTE:
@@ -1393,6 +1413,7 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
unsigned long address)
{
int nr = folio_nr_pages(folio);
+ int nr_pmdmapped = 0;
VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
VM_BUG_ON_VMA(address < vma->vm_start ||
@@ -1425,27 +1446,22 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
atomic_set(&folio->_large_mapcount, 0);
atomic_set(&folio->_nr_pages_mapped, ENTIRELY_MAPPED);
SetPageAnonExclusive(&folio->page);
- __lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr);
+ nr_pmdmapped = nr;
}
- __lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
+ __folio_mod_stat(folio, nr, nr_pmdmapped);
}
static __always_inline void __folio_add_file_rmap(struct folio *folio,
struct page *page, int nr_pages, struct vm_area_struct *vma,
enum rmap_level level)
{
- pg_data_t *pgdat = folio_pgdat(folio);
int nr, nr_pmdmapped = 0;
VM_WARN_ON_FOLIO(folio_test_anon(folio), folio);
nr = __folio_add_rmap(folio, page, nr_pages, level, &nr_pmdmapped);
- if (nr_pmdmapped)
- __mod_node_page_state(pgdat, folio_test_swapbacked(folio) ?
- NR_SHMEM_PMDMAPPED : NR_FILE_PMDMAPPED, nr_pmdmapped);
- if (nr)
- __lruvec_stat_mod_folio(folio, NR_FILE_MAPPED, nr);
+ __folio_mod_stat(folio, nr, nr_pmdmapped);
/* See comments in folio_add_anon_rmap_*() */
if (!folio_test_large(folio))
@@ -1494,10 +1510,8 @@ static __always_inline void __folio_remove_rmap(struct folio *folio,
enum rmap_level level)
{
atomic_t *mapped = &folio->_nr_pages_mapped;
- pg_data_t *pgdat = folio_pgdat(folio);
int last, nr = 0, nr_pmdmapped = 0;
bool partially_mapped = false;
- enum node_stat_item idx;
__folio_rmap_sanity_checks(folio, page, nr_pages, level);
@@ -1541,20 +1555,7 @@ static __always_inline void __folio_remove_rmap(struct folio *folio,
break;
}
- if (nr_pmdmapped) {
- /* NR_{FILE/SHMEM}_PMDMAPPED are not maintained per-memcg */
- if (folio_test_anon(folio))
- __lruvec_stat_mod_folio(folio, NR_ANON_THPS, -nr_pmdmapped);
- else
- __mod_node_page_state(pgdat,
- folio_test_swapbacked(folio) ?
- NR_SHMEM_PMDMAPPED : NR_FILE_PMDMAPPED,
- -nr_pmdmapped);
- }
if (nr) {
- idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED;
- __lruvec_stat_mod_folio(folio, idx, -nr);
-
/*
* Queue anon large folio for deferred split if at least one
* page of the folio is unmapped and at least one page
@@ -1566,6 +1567,7 @@ static __always_inline void __folio_remove_rmap(struct folio *folio,
list_empty(&folio->_deferred_list))
deferred_split_folio(folio);
}
+ __folio_mod_stat(folio, nr, nr_pmdmapped);
/*
* It would be tidy to reset folio_test_anon mapping when fully
--
2.45.0.rc1.225.g2a3ae87e7f-goog
