linux-kernel - [PATCH v10 4/7] mm,hugetlb: Split prep_new_huge

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Date:   Mon, 19 Apr 2021 09:54:10 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Mike Kravetz <mike.kravetz@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        David Hildenbrand <david@...hat.com>,
        Michal Hocko <mhocko@...nel.org>,
        Muchun Song <songmuchun@...edance.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Oscar Salvador <osalvador@...e.de>
Subject: [PATCH v10 4/7] mm,hugetlb: Split prep_new_huge_page functionality

Currently, prep_new_huge_page() performs two functions.
It sets the right state for a new hugetlb, and increases the hstate's
counters to account for the new page.

Let us split its functionality into two separate functions, decoupling
the handling of the counters from initializing a hugepage.
The outcome is having __prep_new_huge_page(), which only
initializes the page , and __prep_account_new_huge_page(), which adds
the new page to the hstate's counters.

This allows us to be able to set a hugetlb without having to worry
about the counter/locking. It will prove useful in the next patch.
prep_new_huge_page() still calls both functions.

Signed-off-by: Oscar Salvador <osalvador@...e.de>
Acked-by: Michal Hocko <mhocko@...e.com>
Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>
Reviewed-by: David Hildenbrand <david@...hat.com>
---
 mm/hugetlb.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2cb9fa79cbaa..6f39ec79face 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1483,16 +1483,30 @@ void free_huge_page(struct page *page)
 	}
 }
 
-static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
+/*
+ * Must be called with the hugetlb lock held
+ */
+static void __prep_account_new_huge_page(struct hstate *h, int nid)
+{
+	lockdep_assert_held(&hugetlb_lock);
+	h->nr_huge_pages++;
+	h->nr_huge_pages_node[nid]++;
+}
+
+static void __prep_new_huge_page(struct page *page)
 {
 	INIT_LIST_HEAD(&page->lru);
 	set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
 	hugetlb_set_page_subpool(page, NULL);
 	set_hugetlb_cgroup(page, NULL);
 	set_hugetlb_cgroup_rsvd(page, NULL);
+}
+
+static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
+{
+	__prep_new_huge_page(page);
 	spin_lock_irq(&hugetlb_lock);
-	h->nr_huge_pages++;
-	h->nr_huge_pages_node[nid]++;
+	__prep_account_new_huge_page(h, nid);
 	spin_unlock_irq(&hugetlb_lock);
 }
 
-- 
2.16.3