On 2/12/26 12:23 AM, Hui Zhu wrote:
From: Hui Zhu <[email protected]>
When running tests on hosts with cgroup.memory=nokmem enabled for
performance reasons, test_kmem always gets a value of 0 for kmem
statistics.
Since BPF programs cannot easily determine whether kmem is enabled,
add a check in memcg_stat_item_valid() to return an error when
attempting to access MEMCG_KMEM statistics while kmem accounting
is disabled via cgroup_memory_nokmem.
This prevents BPF programs from silently receiving zero values and
allows them to properly handle the case where kmem accounting is
unavailable.
Signed-off-by: Hui Zhu <[email protected]>
---
mm/memcontrol.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 129eed3ff5bb..4d8419623d1c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -667,7 +667,8 @@ unsigned long memcg_page_state(struct mem_cgroup *memcg,
int idx)
bool memcg_stat_item_valid(int idx)
{
- if ((u32)idx >= MEMCG_NR_STAT)
+ if ((u32)idx >= MEMCG_NR_STAT ||
+ (cgroup_memory_nokmem && (u32)idx == MEMCG_KMEM))
return false;
It's still a valid stat though, right? When it's disabled the value will
just remain zero. I don't think this is necessary.
