[v2,08/10] hugetlb: add comment for subtle SetHPageVmemmapOptimized()

Commit Message

Miaohe Lin Sept. 1, 2022, noon UTC

The SetHPageVmemmapOptimized() called here seems unnecessary as it's
assumed to be set when calling this function. But it's indeed cleared
by above set_page_private(page, 0). Add a comment to avoid possible
future confusion.

Signed-off-by: Miaohe Lin <[e-mail]>
Reviewed-by: Muchun Song <[e-mail]>
---
 mm/hugetlb.c | 4 ++++
 1 file changed, 4 insertions(+)

Patch

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 26bcc85715eb..2ba45addcdeb 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1520,6 +1520,10 @@  static void add_hugetlb_page(struct hstate *h, struct page *page,
 
 	set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
 	set_page_private(page, 0);
+	/*
+	 * We have to set HPageVmemmapOptimized again as above
+	 * set_page_private(page, 0) cleared it.
+	 */
 	SetHPageVmemmapOptimized(page);
 
 	/*