diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 7d7856359920..7b5785032049 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -99,9 +99,9 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep);
struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
int write);
struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
- pmd_t *pmd, int write);
+ pmd_t *pmd, int flags);
struct page *follow_huge_pud(struct mm_struct *mm, unsigned long address,
- pud_t *pud, int write);
+ pud_t *pud, int flags);
int pmd_huge(pmd_t pmd);
int pud_huge(pud_t pmd);
unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
@@ -133,8 +133,8 @@ static inline void hugetlb_report_meminfo(struct seq_file *m)
static inline void hugetlb_show_meminfo(void)
{
}
-#define follow_huge_pmd(mm, addr, pmd, write) NULL
-#define follow_huge_pud(mm, addr, pud, write) NULL
+#define follow_huge_pmd(mm, addr, pmd, flags) NULL
+#define follow_huge_pud(mm, addr, pud, flags) NULL
#define prepare_hugepage_range(file, addr, len) (-EINVAL)
#define pmd_huge(x) 0
#define pud_huge(x) 0
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 50cbc876be56..831a3168ab35 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -135,6 +135,8 @@ static inline void make_migration_entry_read(swp_entry_t *entry)
*entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
}
+extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
+ spinlock_t *ptl);
extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
unsigned long address);
extern void migration_entry_wait_huge(struct vm_area_struct *vma,
@@ -148,6 +150,8 @@ static inline int is_migration_entry(swp_entry_t swp)
}
#define migration_entry_to_page(swp) NULL
static inline void make_migration_entry_read(swp_entry_t *entryp) { }
+static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
+ spinlock_t *ptl) { }
static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
unsigned long address) { }
static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
diff --git a/mm/gup.c b/mm/gup.c
index 12bc2bc33da7..1a8ab05918e0 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -167,10 +167,10 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
if (pud_none(*pud))
return no_page_table(vma, flags);
if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
- if (flags & FOLL_GET)
- return NULL;
- page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
- return page;
+ page = follow_huge_pud(mm, address, pud, flags);
+ if (page)
+ return page;
+ return no_page_table(vma, flags);
}
if (unlikely(pud_bad(*pud)))
return no_page_table(vma, flags);
@@ -179,19 +179,10 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
if (pmd_none(*pmd))
return no_page_table(vma, flags);
if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
- page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
- if (flags & FOLL_GET) {
- /*
- * Refcount on tail pages are not well-defined and
- * shouldn't be taken. The caller should handle a NULL
- * return when trying to follow tail pages.
- */
- if (PageHead(page))
- get_page(page);
- else
- page = NULL;
- }
- return page;
+ page = follow_huge_pmd(mm, address, pmd, flags);
+ if (page)
+ return page;
+ return no_page_table(vma, flags);
}
if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
return no_page_table(vma, flags);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index d96b8bfa748f..5aca3707450f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3675,28 +3675,48 @@ follow_huge_addr(struct mm_struct *mm, unsigned long address,
struct page * __weak
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
- pmd_t *pmd, int write)
+ pmd_t *pmd, int flags)
{
- struct page *page;
-
- if (!pmd_present(*pmd))
- return NULL;
- page = pte_page(*(pte_t *)pmd);
- if (page)
- page += ((address & ~PMD_MASK) >> PAGE_SHIFT);
+ struct page *page = NULL;
+ spinlock_t *ptl;
+retry:
+ ptl = pmd_lockptr(mm, pmd);
+ spin_lock(ptl);
+ /*
+ * make sure that the address range covered by this pmd is not
+ * unmapped from other threads.
+ */
+ if (!pmd_huge(*pmd))
+ goto out;
+ if (pmd_present(*pmd)) {
+ page = pte_page(*(pte_t *)pmd) +
+ ((address & ~PMD_MASK) >> PAGE_SHIFT);
+ if (flags & FOLL_GET)
+ get_page(page);
+ } else {
+ if (is_hugetlb_entry_migration(huge_ptep_get((pte_t *)pmd))) {
+ spin_unlock(ptl);
+ __migration_entry_wait(mm, (pte_t *)pmd, ptl);
+ goto retry;
+ }
+ /*
+ * hwpoisoned entry is treated as no_page_table in
+ * follow_page_mask().
+ */
+ }
+out:
+ spin_unlock(ptl);
return page;
}
struct page * __weak
follow_huge_pud(struct mm_struct *mm, unsigned long address,
- pud_t *pud, int write)
+ pud_t *pud, int flags)
{
- struct page *page;
+ if (flags & FOLL_GET)
+ return NULL;
- page = pte_page(*(pte_t *)pud);
- if (page)
- page += ((address & ~PUD_MASK) >> PAGE_SHIFT);
- return page;
+ return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT);
}
#ifdef CONFIG_MEMORY_FAILURE
diff --git a/mm/migrate.c b/mm/migrate.c
index 6e284bcca8bb..f98067e5d353 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -197,7 +197,7 @@ static void remove_migration_ptes(struct page *old, struct page *new)
* get to the page and wait until migration is finished.
* When we return from this function the fault will be retried.
*/
-static void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
+void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
spinlock_t *ptl)
{
pte_t pte;
@@ -1236,7 +1236,8 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
goto put_and_set;
if (PageHuge(page)) {
- isolate_huge_page(page, &pagelist);
+ if (PageHead(page))
+ isolate_huge_page(page, &pagelist);
goto put_and_set;
}