[v10,07/11] mm/hugetlb: Flush work when dissolving hugetlb page

Commit Message

Muchun Song Dec. 17, 2020, 12:12 p.m. UTC

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 <[e-mail]>
---
 mm/hugetlb.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

Comments

Oscar Salvador Dec. 21, 2020, 10:40 a.m. UTC | #1

On Thu, Dec 17, 2020 at 08:12:59PM +0800, Muchun Song wrote:
> 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 <[e-mail]>

Reviewed-by: Oscar Salvador <[e-mail]>

Muchun Song Dec. 21, 2020, 11:07 a.m. UTC | #2

On Mon, Dec 21, 2020 at 6:40 PM Oscar Salvador <[e-mail]> wrote:
>
> On Thu, Dec 17, 2020 at 08:12:59PM +0800, Muchun Song wrote:
> > 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 <[e-mail]>
>
> Reviewed-by: Oscar Salvador <[e-mail]>

Thanks.
>
>
> --
> Oscar Salvador
> SUSE L3

Patch

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index f15aa9b19b6e..fea8a96dd718 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1326,6 +1326,12 @@  static void update_hpage_vmemmap_workfn(struct work_struct *work)
 }
 static DECLARE_WORK(hpage_update_work, update_hpage_vmemmap_workfn);
 
+static inline void flush_hpage_update_work(struct hstate *h)
+{
+	if (free_vmemmap_pages_per_hpage(h))
+		flush_work(&hpage_update_work);
+}
+
 static inline void __update_and_free_page(struct hstate *h, struct page *page)
 {
 	/* No need to allocate vmemmap pages */
@@ -1864,6 +1870,7 @@  static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
 int dissolve_free_huge_page(struct page *page)
 {
 	int rc = -EBUSY;
+	struct hstate *h = NULL;
 
 	/* Not to disrupt normal path by vainly holding hugetlb_lock */
 	if (!PageHuge(page))
@@ -1877,8 +1884,9 @@  int dissolve_free_huge_page(struct page *page)
 
 	if (!page_count(page)) {
 		struct page *head = compound_head(page);
-		struct hstate *h = page_hstate(head);
 		int nid = page_to_nid(head);
+
+		h = page_hstate(head);
 		if (h->free_huge_pages - h->resv_huge_pages == 0)
 			goto out;
 
@@ -1892,6 +1900,14 @@  int dissolve_free_huge_page(struct page *page)
 	}
 out:
 	spin_unlock(&hugetlb_lock);
+
+	/*
+	 * We should flush work before return to make sure that
+	 * the HugeTLB page is freed to the buddy.
+	 */
+	if (!rc && h)
+		flush_hpage_update_work(h);
+
 	return rc;
 }