linux-kernel - [PATCH] mm/hugetlb: add mis_resv_equal

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Date:   Fri, 16 Sep 2022 14:35:50 +0800
From:   Xin Hao <xhao@...ux.alibaba.com>
To:     mike.kravetz@...cle.com
Cc:     songmuchun@...edance.com, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        xhao@...ux.alibaba.com
Subject: [PATCH] mm/hugetlb: add mis_resv_equal_free() func

In hugetlb.c file, there are several places to compare the values of
'h->free_huge_pages' and 'h->resv_huge_pages', it looks a bit messy, so
there add a new mis_resv_equal_free() func to do these.

Signed-off-by: Xin Hao <xhao@...ux.alibaba.com>
---
 mm/hugetlb.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 66496fc424f4..db6f63fb083f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1191,6 +1191,11 @@ static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask,
 	return NULL;
 }
 
+static inline bool is_resv_equal_free(struct hstate *h)
+{
+	return (h->free_huge_pages - h->resv_huge_pages == 0) ? true : false;
+}
+
 static struct page *dequeue_huge_page_vma(struct hstate *h,
 				struct vm_area_struct *vma,
 				unsigned long address, int avoid_reserve,
@@ -1207,12 +1212,11 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
 	 * have no page reserves. This check ensures that reservations are
 	 * not "stolen". The child may still get SIGKILLed
 	 */
-	if (!vma_has_reserves(vma, chg) &&
-			h->free_huge_pages - h->resv_huge_pages == 0)
+	if (!vma_has_reserves(vma, chg) && is_resv_equal_free(h))
 		goto err;
 
 	/* If reserves cannot be used, ensure enough pages are in the pool */
-	if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
+	if (avoid_reserve && is_resv_equal_free(h))
 		goto err;
 
 	gfp_mask = htlb_alloc_mask(h);
@@ -2105,7 +2109,7 @@ int dissolve_free_huge_page(struct page *page)
 	if (!page_count(page)) {
 		struct page *head = compound_head(page);
 		struct hstate *h = page_hstate(head);
-		if (h->free_huge_pages - h->resv_huge_pages == 0)
+		if (is_resv_equal_free(h))
 			goto out;
 
 		/*
@@ -2315,7 +2319,7 @@ struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
 		nodemask_t *nmask, gfp_t gfp_mask)
 {
 	spin_lock_irq(&hugetlb_lock);
-	if (h->free_huge_pages - h->resv_huge_pages > 0) {
+	if (!is_resv_equal_free(h)) {
 		struct page *page;
 
 		page = dequeue_huge_page_nodemask(h, gfp_mask, preferred_nid, nmask);
-- 
2.31.0