Re: memcg memory accounting in vmalloc is broken

Michal Hocko
2021-10-07T10:08:37Z

On Thu 07-10-21 11:50:44, Vasily Averin wrote:
> On 10/7/21 11:16 AM, Michal Hocko wrote:
> > Cc Mel and Uladzislau
> >
> > On Thu 07-10-21 10:13:23, Michal Hocko wrote:
> >> On Thu 07-10-21 11:04:40, Vasily Averin wrote:
> >>> vmalloc was switched to __alloc_pages_bulk but it does not account the memory to memcg.
> >>>
> >>> Is it known issue perhaps?
> >>
> >> No, I think this was just overlooked. Definitely doesn't look
> >> intentional to me.
>
> I use following patch as a quick fix,
> it helps though it is far from ideal and can be optimized.
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index b37435c274cf..e6abe2cac159 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5290,6 +5290,12 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,
>
> page = __rmqueue_pcplist(zone, 0, ac.migratetype, alloc_flags,
> pcp, pcp_list);
> +
> + if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT) && page &&
> + unlikely(__memcg_kmem_charge_page(page, gfp, 0) != 0)) {
> + __free_pages(page, 0);
> + page = NULL;
> + }
> if (unlikely(!page)) {
> /* Try and get at least one page */
> if (!nr_populated)
> --
> 2.31.1

Yes, this makes sense to me.

--
Michal Hocko
SUSE Labs