Move memcg check to mem_cgroup_page_lruvec() as there are callers which
may invoke this with !memcg in mem_cgroup_lruvec(), whereas they should
not in mem_cgroup_page_lruvec().
We expect that we have always charged a page to the memcg before
mem_cgroup_page_lruvec() is invoked, so add a warning to assert that this
is the case.
Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Reported-by: syzbot+ce635500093181f39c1c@xxxxxxxxxxxxxxxxxxxxxxxxx
---
include/linux/memcontrol.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 87ed56dc75f9..3e6a1df3bdb9 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -618,7 +618,6 @@ static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
goto out;
}
- VM_WARN_ON_ONCE(!memcg);
if (!memcg)
memcg = root_mem_cgroup;
@@ -645,7 +644,10 @@ static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
struct pglist_data *pgdat)
{
- return mem_cgroup_lruvec(page_memcg(page), pgdat);
+ struct mem_cgroup *memcg = page_memcg(page);
+
+ VM_WARN_ON_ONCE_PAGE(!memcg, page);
+ return mem_cgroup_lruvec(memcg, pgdat);
}
static inline bool lruvec_holds_page_lru_lock(struct page *page,
--
2.29.2
