[PATCH 11/18] mm: memcontrol: switch to native NR_ANON_THPS counter

Johannes Weiner
2020-04-20T22:12:36Z

With rmap memcg locking already in place for NR_ANON_MAPPED, it's just
a small step to remove the MEMCG_RSS_HUGE wart and switch memcg to the
native NR_ANON_THPS accounting sites.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
include/linux/memcontrol.h | 3 +--
mm/huge_memory.c | 4 +++-
mm/memcontrol.c | 39 ++++++++++++++++----------------------
mm/rmap.c | 6 +++---
4 files changed, 23 insertions(+), 29 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index bfb1d961e346..9ac8122ec1cd 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -29,8 +29,7 @@ struct kmem_cache;

/* Cgroup-specific page state, on top of universal node page state */
enum memcg_stat_item {
- MEMCG_RSS_HUGE = NR_VM_NODE_STAT_ITEMS,
- MEMCG_SWAP,
+ MEMCG_SWAP = NR_VM_NODE_STAT_ITEMS,
MEMCG_SOCK,
/* XXX: why are these zone and not node counters? */
MEMCG_KERNEL_STACK_KB,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e9355a463e74..da6c413a75a5 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2359,15 +2359,17 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
atomic_inc(&page[i]._mapcount);
}

+ lock_page_memcg(page);
if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
/* Last compound_mapcount is gone. */
- __dec_node_page_state(page, NR_ANON_THPS);
+ __dec_lruvec_page_state(page, NR_ANON_THPS);
if (TestClearPageDoubleMap(page)) {
/* No need in mapcount reference anymore */
for (i = 0; i < HPAGE_PMD_NR; i++)
atomic_dec(&page[i]._mapcount);
}
}
+ unlock_page_memcg(page);

smp_wmb(); /* make pte visible before pmd */
pmd_populate(mm, pmd, pgtable);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c87178d6219f..7845a87b94d5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -836,11 +836,6 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
struct page *page,
int nr_pages)
{
- if (abs(nr_pages) > 1) {
- VM_BUG_ON_PAGE(!PageTransHuge(page), page);
- __mod_memcg_state(memcg, MEMCG_RSS_HUGE, nr_pages);
- }
-
/* pagein of a big page is an event. So, ignore page size */
if (nr_pages > 0)
__count_memcg_events(memcg, PGPGIN, 1);
@@ -1406,15 +1401,9 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
(u64)memcg_page_state(memcg, NR_WRITEBACK) *
PAGE_SIZE);

- /*
- * TODO: We should eventually replace our own MEMCG_RSS_HUGE counter
- * with the NR_ANON_THP vm counter, but right now it's a pain in the
- * arse because it requires migrating the work out of rmap to a place
- * where the page->mem_cgroup is set up and stable.
- */
seq_buf_printf(&s, "anon_thp %llu\n",
- (u64)memcg_page_state(memcg, MEMCG_RSS_HUGE) *
- PAGE_SIZE);
+ (u64)memcg_page_state(memcg, NR_ANON_THPS) *
+ HPAGE_PMD_NR * PAGE_SIZE);

for (i = 0; i < NR_LRU_LISTS; i++)
seq_buf_printf(&s, "%s %llu\n", lru_list_name(i),
@@ -3006,8 +2995,6 @@ void mem_cgroup_split_huge_fixup(struct page *head)

for (i = 1; i < HPAGE_PMD_NR; i++)
head[i].mem_cgroup = head->mem_cgroup;
-
- __mod_memcg_state(head->mem_cgroup, MEMCG_RSS_HUGE, -HPAGE_PMD_NR);
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

@@ -3762,7 +3749,7 @@ static int memcg_numa_stat_show(struct seq_file *m, void *v)
static const unsigned int memcg1_stats[] = {
NR_FILE_PAGES,
NR_ANON_MAPPED,
- MEMCG_RSS_HUGE,
+ NR_ANON_THPS,
NR_SHMEM,
NR_FILE_MAPPED,
NR_FILE_DIRTY,
@@ -3799,11 +3786,14 @@ static int memcg_stat_show(struct seq_file *m, void *v)
BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats));

for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
+ unsigned long nr;
+
if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
continue;
- seq_printf(m, "%s %lu\n", memcg1_stat_names[i],
- memcg_page_state_local(memcg, memcg1_stats[i]) *
- PAGE_SIZE);
+ nr = memcg_page_state_local(memcg, memcg1_stats[i]);
+ if (memcg1_stats[i] == NR_ANON_THPS)
+ nr *= HPAGE_PMD_NR;
+ seq_printf(m, "%s %lu\n", memcg1_stat_names[i], nr * PAGE_SIZE);
}

for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
@@ -5392,6 +5382,13 @@ static int mem_cgroup_move_account(struct page *page,
if (page_mapped(page)) {
__mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages);
__mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages);
+ if (PageTransHuge(page)) {
+ __mod_lruvec_state(from_vec, NR_ANON_THPS,
+ -nr_pages);
+ __mod_lruvec_state(to_vec, NR_ANON_THPS,
+ nr_pages);
+ }
+
}
} else {
__mod_lruvec_state(from_vec, NR_FILE_PAGES, -nr_pages);
@@ -6611,7 +6608,6 @@ struct uncharge_gather {
unsigned long nr_pages;
unsigned long pgpgout;
unsigned long nr_kmem;
- unsigned long nr_huge;
struct page *dummy_page;
};

@@ -6634,7 +6630,6 @@ static void uncharge_batch(const struct uncharge_gather *ug)
}

local_irq_save(flags);
- __mod_memcg_state(ug->memcg, MEMCG_RSS_HUGE, -ug->nr_huge);
__count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout);
__this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, ug->nr_pages);
memcg_check_events(ug->memcg, ug->dummy_page);
@@ -6673,8 +6668,6 @@ static void uncharge_page(struct page *page, struct uncharge_gather *ug)
ug->nr_pages += nr_pages;

if (!PageKmemcg(page)) {
- if (PageTransHuge(page))
- ug->nr_huge += nr_pages;
ug->pgpgout++;
} else {
ug->nr_kmem += nr_pages;
diff --git a/mm/rmap.c b/mm/rmap.c
index 150513d31efa..ad4a0fdcc94c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1138,7 +1138,7 @@ void do_page_add_anon_rmap(struct page *page,
* disabled.
*/
if (compound)
- __inc_node_page_state(page, NR_ANON_THPS);
+ __inc_lruvec_page_state(page, NR_ANON_THPS);
__mod_lruvec_page_state(page, NR_ANON_MAPPED, nr);
}

@@ -1180,7 +1180,7 @@ void page_add_new_anon_rmap(struct page *page,
if (hpage_pincount_available(page))
atomic_set(compound_pincount_ptr(page), 0);

- __inc_node_page_state(page, NR_ANON_THPS);
+ __inc_lruvec_page_state(page, NR_ANON_THPS);
} else {
/* Anon THP always mapped first with PMD */
VM_BUG_ON_PAGE(PageTransCompound(page), page);
@@ -1286,7 +1286,7 @@ static void page_remove_anon_compound_rmap(struct page *page)
if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
return;

- __dec_node_page_state(page, NR_ANON_THPS);
+ __dec_lruvec_page_state(page, NR_ANON_THPS);

if (TestClearPageDoubleMap(page)) {
/*
--
2.26.0