kern/kmem: reduce fragmentation

This reverts a change brought when reworking slab lists handling that made
the allocator store slabs in LIFO order, whatever their reference count.
While it's fine for free slabs, it actually increased fragmentation for
partial slabs.

1 files changed, 5 insertions, 2 deletions

diff --git a/kern/kmem.c b/kern/kmem.c
index 46c9c10b..09870574 100644
--- a/kern/kmem.c
+++ b/kern/kmem.c
@@ -686,9 +686,12 @@ kmem_cache_alloc_from_slab(struct kmem_cache *cache)
         if (slab->nr_refs == 1)
             cache->nr_free_slabs--;
     } else if (slab->nr_refs == 1) {
-        /* The slab has become partial */
+        /*
+         * The slab has become partial. Insert the new slab at the end of
+         * the list to reduce fragmentation.
+         */
         list_remove(&slab->node);
-        list_insert_head(&cache->partial_slabs, &slab->node);
+        list_insert_tail(&cache->partial_slabs, &slab->node);
         cache->nr_free_slabs--;
     }