On 6/15/26 13:06, Harry Yoo (Oracle) wrote: > struct rcu_head is overkill for kfree_rcu() because the callback > function is always kfree() and thus there is no need for a function > pointer. > > It is enough to implement a linked list using a single pointer. > Introduce a new struct called kfree_rcu_head (the name was suggested > by Vlastimil Babka), which is similar to struct rcu_head but is only > a single pointer. Use it only in kfree_rcu_nolock() for now. > > It is intended that in most cases, kfree_rcu_nolock() goes through > sheaves path and the field is not used at all. However, in the worst > case where trylock fails or no empty sheaves are available, maintain > a global list of objects that will later be freed after > synchronize_rcu() in a workqueue. Since the fallback is intended to be > the last resort, it focuses on minimizing complexity and memory usage. > > To avoid crashing the kernel in a theoretical case where fallback path > is taken before kmem_cache_init_late(), do not queue the work until > the workqueue is actually allocated. > > Factor out the logic that calculates object start address into > object_start_address() from kvfree_rcu_cb() to avoid duplicating it. > > Suggested-by: Alexei Starovoitov <[email protected]> > Signed-off-by: Harry Yoo (Oracle) <[email protected]>
Looks reasonable, if it works fast enough in practice. Acked-by: Vlastimil Babka (SUSE) <[email protected]>
