Re: [PATCH for-next v3 5/9] mm/slab: extend deferred free mechanism to handle rcu sheaves

[Vlastimil Babka (SUSE)]

On 6/15/26 13:05, Harry Yoo (Oracle) wrote:
> __kfree_rcu_sheaf() cannot invoke call_rcu() when spinning is not
> allowed and IRQs are disabled. To relax the limitation, extend the
> deferred free fallback so that a full rcu sheaf can be submitted to
> call_rcu() via the existing IRQ work.
> 
> Since the deferred mechanism does more than deferred free of objects,
> rename the struct to deferred_percpu_work and adjust names accordingly.
> 
> When a sheaf is queued on an IRQ work, it is detached from
> pcs->rcu_free but call_rcu() is not invoked until the irq_work runs.
> To keep the kvfree_rcu barrier's promise, call irq_work_sync() on each
> CPU before calling rcu_barrier().
> 
> In the meantime, remove the TODO item as apparently there is no simple
> and effective way to achieve that.
> 
> Suggested-by: Alexei Starovoitov <ast@xxxxxxxxxx>
> Signed-off-by: Harry Yoo (Oracle) <harry@xxxxxxxxxx>

LGTM.
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@xxxxxxxxxx>