X-Git-Url: http://git.monstr.eu/?a=blobdiff_plain;f=mm%2Fkhugepaged.c;h=99d77ffb79c2b39b2cd1cc4dfd72c4bf1684f3d6;hb=2d3008f658d32d82324717f44432bd4e8dc14c15;hp=3afc1e2d7a55d89a1df729fda47409b13c4a33bd;hpb=9de4f22a60f731943f050f4448bf2933ed3fa70b;p=linux-2.6-microblaze.git

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 3afc1e2d7a55..99d77ffb79c2 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -29,6 +29,7 @@ enum scan_result {
 	SCAN_PMD_NULL,
 	SCAN_EXCEED_NONE_PTE,
 	SCAN_PTE_NON_PRESENT,
+	SCAN_PTE_UFFD_WP,
 	SCAN_PAGE_RO,
 	SCAN_LACK_REFERENCED_PAGE,
 	SCAN_PAGE_NULL,
@@ -1137,6 +1138,15 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
 		pte_t pteval = *_pte;
 		if (is_swap_pte(pteval)) {
 			if (++unmapped <= khugepaged_max_ptes_swap) {
+				/*
+				 * Always be strict with uffd-wp
+				 * enabled swap entries.  Please see
+				 * comment below for pte_uffd_wp().
+				 */
+				if (pte_swp_uffd_wp(pteval)) {
+					result = SCAN_PTE_UFFD_WP;
+					goto out_unmap;
+				}
 				continue;
 			} else {
 				result = SCAN_EXCEED_SWAP_PTE;
@@ -1156,6 +1166,19 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
 			result = SCAN_PTE_NON_PRESENT;
 			goto out_unmap;
 		}
+		if (pte_uffd_wp(pteval)) {
+			/*
+			 * Don't collapse the page if any of the small
+			 * PTEs are armed with uffd write protection.
+			 * Here we can also mark the new huge pmd as
+			 * write protected if any of the small ones is
+			 * marked but that could bring uknown
+			 * userfault messages that falls outside of
+			 * the registered range.  So, just be simple.
+			 */
+			result = SCAN_PTE_UFFD_WP;
+			goto out_unmap;
+		}
 		if (pte_write(pteval))
 			writable = true;