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-rw-r--r--mm/slab.c1
-rw-r--r--mm/slub.c21
2 files changed, 18 insertions, 4 deletions
diff --git a/mm/slab.c b/mm/slab.c
index 4dcbf96a77b4..e7667a3584bc 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4099,6 +4099,7 @@ static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
if ((ret < 0) || !is_root_cache(cachep))
return ret;
+ VM_BUG_ON(!mutex_is_locked(&slab_mutex));
for_each_memcg_cache_index(i) {
c = cache_from_memcg(cachep, i);
if (c)
diff --git a/mm/slub.c b/mm/slub.c
index 21c94d9695ec..efe2cffc29b0 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5108,12 +5108,25 @@ static ssize_t slab_attr_store(struct kobject *kobj,
if (s->max_attr_size < len)
s->max_attr_size = len;
+ /*
+ * This is a best effort propagation, so this function's return
+ * value will be determined by the parent cache only. This is
+ * basically because not all attributes will have a well
+ * defined semantics for rollbacks - most of the actions will
+ * have permanent effects.
+ *
+ * Returning the error value of any of the children that fail
+ * is not 100 % defined, in the sense that users seeing the
+ * error code won't be able to know anything about the state of
+ * the cache.
+ *
+ * Only returning the error code for the parent cache at least
+ * has well defined semantics. The cache being written to
+ * directly either failed or succeeded, in which case we loop
+ * through the descendants with best-effort propagation.
+ */
for_each_memcg_cache_index(i) {
struct kmem_cache *c = cache_from_memcg(s, i);
- /*
- * This function's return value is determined by the
- * parent cache only
- */
if (c)
attribute->store(c, buf, len);
}