From: David Hildenbrand <david@redhat.com>
To: Mike Kravetz <mike.kravetz@oracle.com>,
Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <songmuchun@bytedance.com>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/2] mm,page_alloc: Make alloc_contig_range handle in-use hugetlb pages
Date: Thu, 11 Feb 2021 11:40:13 +0100 [thread overview]
Message-ID: <007046e9-4655-42d1-0422-6a210f726eff@redhat.com> (raw)
In-Reply-To: <6783e871-e981-c845-16c3-c5ff3e6502ed@oracle.com>
On 11.02.21 01:56, Mike Kravetz wrote:
> On 2/8/21 2:38 AM, Oscar Salvador wrote:
>> alloc_contig_range is not prepared to handle hugetlb pages and will
>> fail if it ever sees one, but since they can be migrated as any other
>> page (LRU and Movable), it makes sense to also handle them.
>>
>> For now, do it only when coming from alloc_contig_range.
>>
>> Signed-off-by: Oscar Salvador <osalvador@suse.de>
>> ---
>> mm/compaction.c | 17 +++++++++++++++++
>> mm/vmscan.c | 5 +++--
>> 2 files changed, 20 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/compaction.c b/mm/compaction.c
>> index e5acb9714436..89cd2e60da29 100644
>> --- a/mm/compaction.c
>> +++ b/mm/compaction.c
>> @@ -940,6 +940,22 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
>> goto isolate_fail;
>> }
>>
>> + /*
>> + * Handle hugetlb pages only when coming from alloc_contig
>> + */
>> + if (PageHuge(page) && cc->alloc_contig) {
>> + if (page_count(page)) {
>
> Thanks for doing this!
>
> I agree with everything in the discussion you and David had. This code
> is racy, but since we are scanning lockless there is no way to eliminate
> them all. Best to just minimize the windows and document.
>
Agreed - and make sure that we don't have strange side. (e.g., in the
next patch, allocate a new page, try to dissolve. Dissolving fails, what
happens to the just-allocated page?)
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-02-11 10:40 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-08 10:38 [RFC PATCH 0/2] Make alloc_contig_range handle Hugetlb pages Oscar Salvador
2021-02-08 10:38 ` [RFC PATCH 1/2] mm,page_alloc: Make alloc_contig_range handle in-use hugetlb pages Oscar Salvador
2021-02-10 8:56 ` David Hildenbrand
2021-02-10 14:09 ` Oscar Salvador
2021-02-10 14:11 ` David Hildenbrand
2021-02-10 14:14 ` Oscar Salvador
2021-02-10 14:22 ` David Hildenbrand
2021-02-11 0:56 ` Mike Kravetz
2021-02-11 10:40 ` David Hildenbrand [this message]
2021-02-08 10:38 ` [RFC PATCH 2/2] mm,page_alloc: Make alloc_contig_range handle free " Oscar Salvador
2021-02-10 8:23 ` David Hildenbrand
2021-02-10 14:24 ` Oscar Salvador
2021-02-10 14:36 ` David Hildenbrand
2021-02-25 21:43 ` Mike Kravetz
2021-02-25 22:15 ` David Hildenbrand
2021-02-11 1:16 ` Mike Kravetz
2021-02-11 21:38 ` Oscar Salvador
2021-02-08 10:39 ` [RFC PATCH 0/2] Make alloc_contig_range handle Hugetlb pages Oscar Salvador
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