From: Roman Gushchin <guro@fb.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>, <linux-mm@kvack.org>,
<kernel-team@fb.com>, <linux-kernel@vger.kernel.org>,
Rik van Riel <riel@surriel.com>,
Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: [PATCH v2] mm: hugetlb: optionally allocate gigantic hugepages using cma
Date: Tue, 10 Mar 2020 10:30:56 -0700 [thread overview]
Message-ID: <20200310173056.GB85000@carbon.dhcp.thefacebook.com> (raw)
In-Reply-To: <20200310090121.GB8447@dhcp22.suse.cz>
On Tue, Mar 10, 2020 at 10:01:21AM +0100, Michal Hocko wrote:
> On Mon 09-03-20 17:25:24, Roman Gushchin wrote:
> [...]
> > 2) Run-time allocations of gigantic hugepages are performed using the
> > cma allocator and the dedicated cma area
>
> [...]
> > @@ -1237,6 +1246,23 @@ static struct page *alloc_gigantic_page(struct hstate *h, gfp_t gfp_mask,
> > {
> > unsigned long nr_pages = 1UL << huge_page_order(h);
> >
> > + if (IS_ENABLED(CONFIG_CMA) && hugetlb_cma[0]) {
> > + struct page *page;
> > + int nid;
> > +
> > + for_each_node_mask(nid, *nodemask) {
> > + if (!hugetlb_cma[nid])
> > + break;
> > +
> > + page = cma_alloc(hugetlb_cma[nid], nr_pages,
> > + huge_page_order(h), true);
> > + if (page)
> > + return page;
> > + }
> > +
> > + return NULL;
>
> Is there any strong reason why the alloaction annot fallback to non-CMA
> allocator when the cma is depleted?
The reason is that that gigantic pages allocated using cma require
a special handling on releasing. It's solvable by using an additional
page flag, but because the current code is usually not working except
a short time just after the system start, I don't think it's worth it.
But I do not have a strong opinion here.
Thanks!
next prev parent reply other threads:[~2020-03-10 17:31 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 0:25 [PATCH v2] mm: hugetlb: optionally allocate gigantic hugepages using cma Roman Gushchin
2020-03-10 0:30 ` Roman Gushchin
2020-03-10 8:45 ` Michal Hocko
2020-03-10 17:25 ` Roman Gushchin
2020-03-10 17:37 ` Michal Hocko
2020-03-16 1:08 ` Rik van Riel
2020-03-10 17:38 ` Mike Kravetz
2020-03-10 17:42 ` Michal Hocko
2020-03-10 9:01 ` Michal Hocko
2020-03-10 17:30 ` Roman Gushchin [this message]
2020-03-10 17:39 ` Michal Hocko
2020-03-10 17:58 ` Roman Gushchin
2020-03-10 17:27 ` Mike Kravetz
2020-03-10 18:05 ` Roman Gushchin
2020-03-10 18:22 ` Rik van Riel
2020-03-10 18:33 ` Mike Kravetz
2020-03-10 18:54 ` Andreas Schaufler
2020-03-10 18:56 ` Roman Gushchin
2020-03-10 19:00 ` Andreas Schaufler
2020-03-10 19:19 ` Roman Gushchin
2020-03-10 19:36 ` Michal Hocko
2020-03-10 19:46 ` Rik van Riel
2020-03-10 20:11 ` Mike Kravetz
2020-03-10 20:15 ` Rik van Riel
2020-03-10 20:29 ` Mike Kravetz
2020-03-10 20:38 ` Rik van Riel
2020-03-10 20:29 ` Roman Gushchin
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