From 23ec6c42c22a7bfd4494b15abc9c3303018dec85 Mon Sep 17 00:00:00 2001
From: Jordan Rife <jrife0@gmail.com>
Date: Sat, 16 Sep 2023 18:10:00 +0000
Subject: [PATCH] Handle kmem.limit_in_bytes removal

kmem.limit_in_bytes has been removed in upstream linux and this patch
is queued to be backported to linux 6.1 stable:

- https://lore.kernel.org/linux-mm/20230705134434.GA156754@cmpxchg.org/T/
- https://www.spinics.net/lists/stable-commits/msg316619.html

Without this change to libcontainerd, GetStats() will return an error
on the latest kernel(s). A downstream effect is that Kubernetes's
kubelet does not start up. This fix was tested by ensuring that it
unblocks kubelet startup when running on the latest kernel.

Signed-off-by: Jordan Rife <jrife0@gmail.com>
---
 libcontainer/cgroups/fs/memory.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libcontainer/cgroups/fs/memory.go b/libcontainer/cgroups/fs/memory.go
index b7c75f94..a0e78074 100644
--- a/libcontainer/cgroups/fs/memory.go
+++ b/libcontainer/cgroups/fs/memory.go
@@ -234,6 +234,12 @@ func getMemoryData(path, name string) (cgroups.MemoryData, error) {
 	memoryData.Failcnt = value
 	value, err = fscommon.GetCgroupParamUint(path, limit)
 	if err != nil {
+		if name == "kmem" && os.IsNotExist(err) {
+			// Ignore ENOENT as kmem.limit_in_bytes has
+			// been removed in newer kernels.
+			return memoryData, nil
+		}
+
 		return cgroups.MemoryData{}, err
 	}
 	memoryData.Limit = value
-- 
2.33.0

