From: Oscar Salvador <osalvador@suse.de>
To: Michal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
David Hildenbrand <david@redhat.com>,
Muchun Song <songmuchun@bytedance.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/2] mm: Make alloc_contig_range handle in-use hugetlb pages
Date: Fri, 26 Feb 2021 11:27:38 +0100 [thread overview]
Message-ID: <20210226102738.GB3557@linux> (raw)
In-Reply-To: <20210226102424.GA3557@linux>
On Fri, Feb 26, 2021 at 11:24:29AM +0100, Oscar Salvador wrote:
> On Fri, Feb 26, 2021 at 09:46:57AM +0100, Michal Hocko wrote:
> > On Mon 22-02-21 14:51:37, Oscar Salvador wrote:
> > [...]
> > > @@ -2394,9 +2397,19 @@ bool isolate_or_dissolve_huge_page(struct page *page)
> > > */
> > > if (hstate_is_gigantic(h))
> > > return ret;
> > > -
> > > - if (!page_count(head) && alloc_and_dissolve_huge_page(h, head))
> > > +retry:
> > > + if (page_count(head) && isolate_huge_page(head, list)) {
> > > ret = true;
> > > + } else if (!page_count(head)) {
> >
> > This is rather head spinning. Do we need to test page_count in the else
> > branch? Do you want to optimize for a case where the page cannot be
> > isolated because of page_huge_active?
>
> Well, I wanted to explictly call out both cases.
> We either 1) have an in-use page and we try to issolate it or 2) we have a free
> page (count == 0).
>
> If the page could not be dissolved due to page_huge_active, this would either
> mean that page is about to be freed, or that someone has already issolated the
> page.
> Being the former case, one could say that falling-through alloc_and_dissolve is
> ok.
>
> But no, I did not really want to optimize anything here, just wanted to be explicit
> about what we are checking and why.
Maybe I could add a comment to make it more explicit.
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2021-02-26 10:27 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 13:51 [PATCH v3 0/2] Make alloc_contig_range handle Hugetlb pages Oscar Salvador
2021-02-22 13:51 ` [PATCH v3 1/2] mm: Make alloc_contig_range handle free hugetlb pages Oscar Salvador
2021-02-25 20:03 ` Mike Kravetz
2021-02-26 9:48 ` Oscar Salvador
2021-02-26 8:35 ` Michal Hocko
2021-02-26 8:38 ` Michal Hocko
2021-02-26 9:25 ` David Hildenbrand
2021-02-26 9:47 ` Oscar Salvador
2021-02-26 9:45 ` Oscar Salvador
2021-02-26 9:51 ` Michal Hocko
2021-03-01 14:09 ` David Hildenbrand
2021-03-04 10:19 ` Oscar Salvador
2021-03-04 10:32 ` David Hildenbrand
2021-03-04 10:41 ` Oscar Salvador
2021-02-22 13:51 ` [PATCH v3 2/2] mm: Make alloc_contig_range handle in-use " Oscar Salvador
2021-02-25 23:05 ` Mike Kravetz
2021-02-26 8:46 ` Michal Hocko
2021-02-26 10:24 ` Oscar Salvador
2021-02-26 10:27 ` Oscar Salvador [this message]
2021-02-26 12:46 ` Michal Hocko
2021-02-28 13:43 ` Oscar Salvador
2021-03-05 17:30 ` David Hildenbrand
2021-03-01 12:43 ` [PATCH v3 0/2] Make alloc_contig_range handle Hugetlb pages David Hildenbrand
2021-03-01 12:57 ` Oscar Salvador
2021-03-01 12:59 ` David Hildenbrand
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