Hi, one bit from LSF/MM discussions is that there might be call_rcu users with a callback that only does a kmem_cache_free() to a specific cache. Since SLOB was removed, it's always ok to use kfree() and thus also kfree_rcu() on allocations from kmem_cache_alloc() in addition to kmalloc(). Thus, such call_rcu() users might be simplified to kfree_rcu(). I found some cases semi-manually, but I'd expect coccinelle could help here so if anyone wants to take this task, feel free to.
Vlastimil
