[PATCH v5 8/8] mm/lru: debug checking for page memcg moving and lock_page_memcg

From: Alex Shi
Date: Tue Dec 10 2019 - 06:48:43 EST


The extra irq disable/enable and BUG_ON checking costs 5% readtwice
performance on a 2 socket * 26 cores * HT box.

Need to remove them later?

Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: cgroups@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
mm/compaction.c | 4 ++++
mm/memcontrol.c | 13 +++++++++++++
2 files changed, 17 insertions(+)

diff --git a/mm/compaction.c b/mm/compaction.c
index 0907eec3db84..7f750a9100af 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -972,6 +972,10 @@ static bool too_many_isolated(pg_data_t *pgdat)
compact_lock_irqsave(&lruvec->lru_lock, &flags, cc);
locked_lruvec = lruvec;

+#ifdef CONFIG_MEMCG
+ if (!mem_cgroup_disabled())
+ VM_BUG_ON_PAGE(lruvec_memcg(lruvec) != page->mem_cgroup, page);
+#endif
/* Try get exclusive access under lock */
if (!skip_updated) {
skip_updated = true;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4a92689c37d6..833df0ce1bc1 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1255,6 +1255,10 @@ struct lruvec *lock_page_lruvec_irq(struct page *page)
lruvec = mem_cgroup_lruvec(memcg, page_pgdat(page));
spin_lock_irq(&lruvec->lru_lock);

+#ifdef CONFIG_MEMCG
+ if (!mem_cgroup_disabled())
+ VM_BUG_ON_PAGE(lruvec_memcg(lruvec) != page->mem_cgroup, page);
+#endif
return lruvec;
}

@@ -1267,6 +1271,10 @@ struct lruvec *lock_page_lruvec_irqsave(struct page *page, unsigned long *flags)
lruvec = mem_cgroup_lruvec(memcg, page_pgdat(page));
spin_lock_irqsave(&lruvec->lru_lock, *flags);

+#ifdef CONFIG_MEMCG
+ if (!mem_cgroup_disabled())
+ VM_BUG_ON_PAGE(lruvec_memcg(lruvec) != page->mem_cgroup, page);
+#endif
return lruvec;
}

@@ -2015,6 +2023,11 @@ struct mem_cgroup *lock_page_memcg(struct page *page)
if (unlikely(!memcg))
return NULL;

+ /* temporary lockdep checking, need remove */
+ local_irq_save(flags);
+ might_lock(&memcg->move_lock);
+ local_irq_restore(flags);
+
if (atomic_read(&memcg->moving_account) <= 0)
return memcg;

--
1.8.3.1