[PATCH v8 4/7] mm,hugetlb: Split prep_new_huge_page functionality

From: Oscar Salvador
Date: Thu Apr 15 2021 - 06:36:05 EST


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@xxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
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