From: David Hildenbrand <david@redhat.com>
To: Mike Kravetz <mike.kravetz@oracle.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Michal Hocko <mhocko@suse.com>,
Oscar Salvador <osalvador@suse.de>, Zi Yan <ziy@nvidia.com>,
Muchun Song <songmuchun@bytedance.com>,
Naoya Horiguchi <naoya.horiguchi@linux.dev>,
David Rientjes <rientjes@google.com>,
"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2 2/4] hugetlb: add HPageCma flag and code to free non-gigantic pages in CMA
Date: Fri, 24 Sep 2021 11:36:46 +0200 [thread overview]
Message-ID: <7ab7690d-aa21-0fd9-75f1-f3a23b892853@redhat.com> (raw)
In-Reply-To: <20210923175347.10727-3-mike.kravetz@oracle.com>
On 23.09.21 19:53, Mike Kravetz wrote:
> When huge page demotion is fully implemented, gigantic pages can be
> demoted to a smaller huge page size. For example, on x86 a 1G page
> can be demoted to 512 2M pages. However, gigantic pages can potentially
> be allocated from CMA. If a gigantic page which was allocated from CMA
> is demoted, the corresponding demoted pages needs to be returned to CMA.
>
> In order to track hugetlb pages that need to be returned to CMA, add the
> hugetlb specific flag HPageCma. Flag is set when a huge page is
> allocated from CMA and transferred to any demoted pages. Non-gigantic
> huge page freeing code checks for the flag and takes appropriate action.
Do we really need that flag or couldn't we simply always try
cma_release() and fallback to out ordinary freeing-path?
IIRC, cma knows exactly if something was allocated via a CMA are and can
be free via it. No need for additional tracking usually.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-09-24 9:36 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 17:53 [PATCH v2 0/4] hugetlb: add demote/split page functionality Mike Kravetz
2021-09-23 17:53 ` [PATCH v2 1/4] hugetlb: add demote hugetlb page sysfs interfaces Mike Kravetz
2021-09-23 21:24 ` Andrew Morton
2021-09-23 22:08 ` Mike Kravetz
2021-09-24 7:08 ` Aneesh Kumar K.V
2021-09-29 18:22 ` Mike Kravetz
2021-09-24 9:28 ` David Hildenbrand
2021-09-29 19:34 ` Mike Kravetz
2021-09-23 17:53 ` [PATCH v2 2/4] hugetlb: add HPageCma flag and code to free non-gigantic pages in CMA Mike Kravetz
2021-09-24 9:36 ` David Hildenbrand [this message]
2021-09-29 19:42 ` Mike Kravetz
2021-09-29 23:21 ` Mike Kravetz
2021-10-01 17:50 ` Mike Kravetz
2021-09-23 17:53 ` [PATCH v2 3/4] hugetlb: add demote bool to gigantic page routines Mike Kravetz
2021-09-23 17:53 ` [PATCH v2 4/4] hugetlb: add hugetlb demote page support Mike Kravetz
2021-09-24 9:44 ` David Hildenbrand
2021-09-29 19:54 ` Mike Kravetz
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