On Mon, Jun 15, 2020 at 3:25 PM Joonsoo Kim <js1304@xxxxxxxxx> wrote:
>
> 2020년 6월 15일 (월) 오후 3:41, Muchun Song <songmuchun@xxxxxxxxxxxxx>님이 작성:
> >
> > On Mon, Jun 15, 2020 at 2:23 PM Joonsoo Kim <js1304@xxxxxxxxx> wrote:
> > >
> > > 2020년 6월 14일 (일) 오후 9:39, Muchun Song <songmuchun@xxxxxxxxxxxxx>님이 작성:
> > > >
> > > > The function of __kmem_cache_shutdown() is that release all resources
> > > > used by the slab cache, while currently it stop release resources when
> > > > the preceding node is not empty.
> > > >
> > > > Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> > > > ---
> > > > mm/slub.c | 7 ++++---
> > > > 1 file changed, 4 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/mm/slub.c b/mm/slub.c
> > > > index b73505df3de2..4e477ef0f2b9 100644
> > > > --- a/mm/slub.c
> > > > +++ b/mm/slub.c
> > > > @@ -3839,6 +3839,7 @@ bool __kmem_cache_empty(struct kmem_cache *s)
> > > > */
> > > > int __kmem_cache_shutdown(struct kmem_cache *s)
> > > > {
> > > > + int ret = 0;
> > > > int node;
> > > > struct kmem_cache_node *n;
> > > >
> > > > @@ -3846,11 +3847,11 @@ int __kmem_cache_shutdown(struct kmem_cache *s)
> > > > /* Attempt to free all objects */
> > > > for_each_kmem_cache_node(s, node, n) {
> > > > free_partial(s, n);
> > > > - if (node_nr_slabs(n))
> > > > - return 1;
> > > > + if (!ret && node_nr_slabs(n))
> > > > + ret = 1;
> > > > }
> > >
> > > I don't think that this is an improvement.
> > >
> > > If the shutdown condition isn't met, we don't need to process further.
> > > Just 'return 1' looks okay to me.
> > >
> > > And, with this change, sysfs_slab_remove() is called even if the
> > > shutdown is failed.
> > > It's better not to have side effects when failing.
> >
> > If someone calls __kmem_cache_shutdown, he may want to release
> > resources used by the slab cache as much as possible. If we continue,
> > we may release more pages. From this point, is it an improvement?
>
> My opinion is not strong but I still think that it's not useful enough
> to complicate
> the code.
>
> If shutdown is failed, it implies there are some bugs and someone should fix it.
Yeah, I agree with you.
> Releasing more resources would mitigate the resource problem but doesn't
> change the situation that someone should fix it soon.
>
> Anyway, I don't object more if you don't agree with my opinion. In that case,
> please fix not to call sysfs_slab_remove() when ret is 1.
>
Yeah, we should call sysfs_slab_remove only when ret is zero. Thanks very
much.
--
Yours,
Muchun
