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From: Mike Kravetz <mike.kravetz@oracle.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: David Hildenbrand <david@redhat.com>,
	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>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mike Kravetz <mike.kravetz@oracle.com>
Subject: [PATCH 4/8] hugetlb: add hugetlb demote page support
Date: Wed, 21 Jul 2021 16:05:07 -0700	[thread overview]
Message-ID: <20210721230511.201823-5-mike.kravetz@oracle.com> (raw)
In-Reply-To: <20210721230511.201823-1-mike.kravetz@oracle.com>

Demote page functionality will split a huge page into a number of huge
pages of a smaller size.  For example, on x86 a 1GB huge page can be
demoted into 512 2M huge pages.  Demotion is done 'in place' by simply
splitting the huge page.

Added '*_for_demote' wrappers for remove_hugetlb_page,
destroy_compound_gigantic_page and prep_compound_gigantic_page for use
by demote code.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 mm/hugetlb.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 73 insertions(+), 3 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 0ad75e7775dd..9bbfeba3e1ae 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1279,6 +1279,12 @@ static void destroy_compound_gigantic_page(struct page *page,
 	__destroy_compound_gigantic_page(page, order, false);
 }
 
+static void destroy_compound_gigantic_page_for_demote(struct page *page,
+					unsigned int order)
+{
+	__destroy_compound_gigantic_page(page, order, true);
+}
+
 static void free_gigantic_page(struct page *page, unsigned int order)
 {
 #ifdef CONFIG_CMA
@@ -1418,6 +1424,12 @@ static void remove_hugetlb_page(struct hstate *h, struct page *page,
 	__remove_hugetlb_page(h, page, adjust_surplus, false);
 }
 
+static void remove_hugetlb_page_for_demote(struct hstate *h, struct page *page,
+							bool adjust_surplus)
+{
+	__remove_hugetlb_page(h, page, adjust_surplus, true);
+}
+
 static void add_hugetlb_page(struct hstate *h, struct page *page,
 			     bool adjust_surplus)
 {
@@ -1764,6 +1776,12 @@ static bool prep_compound_gigantic_page(struct page *page, unsigned int order)
 	return __prep_compound_gigantic_page(page, order, false);
 }
 
+static bool prep_compound_gigantic_page_for_demote(struct page *page,
+							unsigned int order)
+{
+	return __prep_compound_gigantic_page(page, order, true);
+}
+
 /*
  * PageHuge() only returns true for hugetlbfs pages, but not for normal or
  * transparent huge pages.  See the PageTransHuge() documentation for more
@@ -3271,9 +3289,55 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
 	return 0;
 }
 
+static int demote_free_huge_page(struct hstate *h, struct page *page)
+{
+	int i, nid = page_to_nid(page);
+	struct hstate *target_hstate;
+	bool cma_page = HPageCma(page);
+
+	target_hstate = size_to_hstate(PAGE_SIZE << h->demote_order);
+
+	remove_hugetlb_page_for_demote(h, page, false);
+	spin_unlock_irq(&hugetlb_lock);
+
+	if (alloc_huge_page_vmemmap(h, page)) {
+		/* Allocation of vmemmmap failed, we can not demote page */
+		spin_lock_irq(&hugetlb_lock);
+		set_page_refcounted(page);
+		add_hugetlb_page(h, page, false);
+		return 1;
+	}
+
+	/*
+	 * Use destroy_compound_gigantic_page_for_demote for all huge page
+	 * sizes as it will not ref count pages.
+	 */
+	destroy_compound_gigantic_page_for_demote(page, huge_page_order(h));
+
+	for (i = 0; i < pages_per_huge_page(h);
+				i += pages_per_huge_page(target_hstate)) {
+		if (hstate_is_gigantic(target_hstate))
+			prep_compound_gigantic_page_for_demote(page + i,
+							target_hstate->order);
+		else
+			prep_compound_page(page + i, target_hstate->order);
+		set_page_private(page + i, 0);
+		set_page_refcounted(page + i);
+		prep_new_huge_page(target_hstate, page + i, nid);
+		if (cma_page)
+			SetHPageCma(page + i);
+		put_page(page + i);
+	}
+
+	spin_lock_irq(&hugetlb_lock);
+	return 0;
+}
+
 static int demote_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
 	__must_hold(&hugetlb_lock)
 {
+	int nr_nodes, node;
+	struct page *page;
 	int rc = 0;
 
 	lockdep_assert_held(&hugetlb_lock);
@@ -3289,9 +3353,15 @@ static int demote_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
 		return 1;
 	}
 
-	/*
-	 * TODO - demote fucntionality will be added in subsequent patch
-	 */
+	for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) {
+		if (!list_empty(&h->hugepage_freelists[node])) {
+			page = list_entry(h->hugepage_freelists[node].next,
+					struct page, lru);
+			rc = !demote_free_huge_page(h, page);
+			break;
+		}
+	}
+
 	return rc;
 }
 
-- 
2.31.1


  parent reply	other threads:[~2021-07-21 23:06 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-21 23:05 [PATCH 0/8] hugetlb: add demote/split page functionality Mike Kravetz
2021-07-21 23:05 ` [PATCH 1/8] hugetlb: add demote hugetlb page sysfs interfaces Mike Kravetz
2021-07-21 23:05 ` [PATCH 2/8] hugetlb: add HPageCma flag and code to free non-gigantic pages in CMA Mike Kravetz
2021-07-21 23:05 ` [PATCH 3/8] hugetlb: add demote bool to gigantic page routines Mike Kravetz
2021-07-21 23:05 ` Mike Kravetz [this message]
2021-07-21 23:05 ` [PATCH 5/8] hugetlb: document the demote sysfs interfaces Mike Kravetz
2021-07-21 23:05 ` [PATCH 6/8] hugetlb: vmemmap optimizations when demoting hugetlb pages Mike Kravetz
2021-07-21 23:05 ` [PATCH 7/8] hugetlb: prepare destroy and prep routines for vmemmap optimized pages Mike Kravetz
2021-07-21 23:05 ` [PATCH 8/8] hugetlb: Optimized demote vmemmap optimizatized pages Mike Kravetz
2021-08-16 22:49 [PATCH RESEND 0/8] hugetlb: add demote/split page functionality Mike Kravetz
2021-08-16 22:49 ` [PATCH 4/8] hugetlb: add hugetlb demote page support Mike Kravetz

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