Merge branch 'for-4.18/dax' into libnvdimm-for-next

1 files changed, 26 insertions, 10 deletions

diff --git a/mm/gup.c b/mm/gup.c
index 541904a7c60f..3d8472d48a0b 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1459,32 +1459,48 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
 	return 1;
 }
 
-static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr,
+static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 		unsigned long end, struct page **pages, int *nr)
 {
 	unsigned long fault_pfn;
+	int nr_start = *nr;
+
+	fault_pfn = pmd_pfn(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+	if (!__gup_device_huge(fault_pfn, addr, end, pages, nr))
+		return 0;
 
-	fault_pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	return __gup_device_huge(fault_pfn, addr, end, pages, nr);
+	if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) {
+		undo_dev_pagemap(nr, nr_start, pages);
+		return 0;
+	}
+	return 1;
 }
 
-static int __gup_device_huge_pud(pud_t pud, unsigned long addr,
+static int __gup_device_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
 		unsigned long end, struct page **pages, int *nr)
 {
 	unsigned long fault_pfn;
+	int nr_start = *nr;
+
+	fault_pfn = pud_pfn(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
+	if (!__gup_device_huge(fault_pfn, addr, end, pages, nr))
+		return 0;
 
-	fault_pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-	return __gup_device_huge(fault_pfn, addr, end, pages, nr);
+	if (unlikely(pud_val(orig) != pud_val(*pudp))) {
+		undo_dev_pagemap(nr, nr_start, pages);
+		return 0;
+	}
+	return 1;
 }
 #else
-static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr,
+static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 		unsigned long end, struct page **pages, int *nr)
 {
 	BUILD_BUG();
 	return 0;
 }
 
-static int __gup_device_huge_pud(pud_t pud, unsigned long addr,
+static int __gup_device_huge_pud(pud_t pud, pud_t *pudp, unsigned long addr,
 		unsigned long end, struct page **pages, int *nr)
 {
 	BUILD_BUG();
@@ -1502,7 +1518,7 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
 		return 0;
 
 	if (pmd_devmap(orig))
-		return __gup_device_huge_pmd(orig, addr, end, pages, nr);
+		return __gup_device_huge_pmd(orig, pmdp, addr, end, pages, nr);
 
 	refs = 0;
 	page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
@@ -1540,7 +1556,7 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
 		return 0;
 
 	if (pud_devmap(orig))
-		return __gup_device_huge_pud(orig, addr, end, pages, nr);
+		return __gup_device_huge_pud(orig, pudp, addr, end, pages, nr);
 
 	refs = 0;
 	page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);