linux-kernel - [PATCH v2 15/19] mm/hugetlb: Flush work when dissolving hugetlb page

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Message-Id: <20201026145114.59424-16-songmuchun@bytedance.com>
Date:   Mon, 26 Oct 2020 22:51:10 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     corbet@....net, mike.kravetz@...cle.com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, x86@...nel.org, hpa@...or.com,
        dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        viro@...iv.linux.org.uk, akpm@...ux-foundation.org,
        paulmck@...nel.org, mchehab+huawei@...nel.org,
        pawan.kumar.gupta@...ux.intel.com, rdunlap@...radead.org,
        oneukum@...e.com, anshuman.khandual@....com, jroedel@...e.de,
        almasrymina@...gle.com, rientjes@...gle.com, willy@...radead.org
Cc:     duanxiongchun@...edance.com, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>
Subject: [PATCH v2 15/19] mm/hugetlb: Flush work when dissolving hugetlb page

We should flush work when dissolving a hugetlb page to make sure that
the hugetlb page is freed to the buddy.

Signed-off-by: Muchun Song <songmuchun@...edance.com>
---
 mm/hugetlb.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7198bd9bdce5..509de0732d9f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1807,6 +1807,11 @@ static inline void free_gigantic_page_comm(struct hstate *h, struct page *page)
 	free_gigantic_page(page, huge_page_order(h));
 }
 
+static inline void flush_free_huge_page_work(void)
+{
+	flush_work(&hpage_update_work);
+}
+
 static inline bool subpage_hwpoison(struct page *head, struct page *page)
 {
 	return page_private(head + 4) == page - head;
@@ -1869,6 +1874,10 @@ static inline void free_gigantic_page_comm(struct hstate *h, struct page *page)
 	spin_lock(&hugetlb_lock);
 }
 
+static inline void flush_free_huge_page_work(void)
+{
+}
+
 static inline bool subpage_hwpoison(struct page *head, struct page *page)
 {
 	return true;
@@ -2443,6 +2452,7 @@ static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
 int dissolve_free_huge_page(struct page *page)
 {
 	int rc = -EBUSY;
+	bool need_flush = false;
 
 	/* Not to disrupt normal path by vainly holding hugetlb_lock */
 	if (!PageHuge(page))
@@ -2474,10 +2484,19 @@ int dissolve_free_huge_page(struct page *page)
 		h->free_huge_pages_node[nid]--;
 		h->max_huge_pages--;
 		update_and_free_page(h, head);
+		need_flush = true;
 		rc = 0;
 	}
 out:
 	spin_unlock(&hugetlb_lock);
+
+	/*
+	 * We should flush work before return to make sure that
+	 * the hugetlb page is freed to the buddy.
+	 */
+	if (need_flush)
+		flush_free_huge_page_work();
+
 	return rc;
 }
 
-- 
2.20.1