On Mon, Apr 28, 2025 at 12:01 AM Vlastimil Babka <vba...@suse.cz> wrote:
>
> On 4/25/25 19:31, Christoph Lameter (Ampere) wrote:
> > On Fri, 25 Apr 2025, Vlastimil Babka wrote:
> >
> >> @@ -4195,7 +4793,11 @@ static __fastpath_inline void
> >> *slab_alloc_node(struct kmem_cache *s, struct list
> >> if (unlikely(object))
> >> goto out;
> >>
> >> - object = __slab_alloc_node(s, gfpflags, node, addr, orig_size);
> >> + if (s->cpu_sheaves && node == NUMA_NO_NODE)
> >> + object = alloc_from_pcs(s, gfpflags);
> >
> > The node to use is determined in __slab_alloc_node() only based on the
> > memory policy etc. NUMA_NO_NODE allocations can be redirected by memory
> > policies and this check disables it.
>
> To handle that, alloc_from_pcs() contains this:
>
> #ifdef CONFIG_NUMA
> if (static_branch_unlikely(&strict_numa)) {
> if (current->mempolicy)
> return NULL;
> }
> #endif
>
> And so there will be a fallback. It doesn't (currently) try to evaluate if
> the local node is compatible as this is before taking the local lock (and
> thus preventing migration).
>
>
> >> @@ -4653,7 +5483,10 @@ void slab_free(struct kmem_cache *s, struct slab
> >> *slab, void *object,
> >> memcg_slab_free_hook(s, slab, &object, 1);
> >> alloc_tagging_slab_free_hook(s, slab, &object, 1);
> >>
> >> - if (likely(slab_free_hook(s, object, slab_want_init_on_free(s),
> >> false)))
> >> + if (unlikely(!slab_free_hook(s, object, slab_want_init_on_free(s),
> >> false)))
> >> + return;
> >> +
> >> + if (!s->cpu_sheaves || !free_to_pcs(s, object))
> >> do_slab_free(s, slab, object, object, 1, addr);
> >> }
> >
> > We free to pcs even if the object is remote?
Overall the patch LGTM but I would like to hear the answer to this
question too, please.
> >
>
