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-rw-r--r--include/linux/mm.h1
-rw-r--r--mm/memory.c5
-rw-r--r--mm/migrate.c7
3 files changed, 12 insertions, 1 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 78adec4ba9f4..2ec5138badab 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1490,6 +1490,7 @@ struct page *follow_page(struct vm_area_struct *, unsigned long address,
#define FOLL_DUMP 0x08 /* give error on hole if it would be zero */
#define FOLL_FORCE 0x10 /* get_user_pages read/write w/o permission */
#define FOLL_MLOCK 0x40 /* mark page as mlocked */
+#define FOLL_SPLIT 0x80 /* don't return transhuge pages, split them */
typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,
void *data);
diff --git a/mm/memory.c b/mm/memory.c
index c1a80e00458d..12ee1ea237f5 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1305,6 +1305,10 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
goto out;
}
if (pmd_trans_huge(*pmd)) {
+ if (flags & FOLL_SPLIT) {
+ split_huge_page_pmd(mm, pmd);
+ goto split_fallthrough;
+ }
spin_lock(&mm->page_table_lock);
if (likely(pmd_trans_huge(*pmd))) {
if (unlikely(pmd_trans_splitting(*pmd))) {
@@ -1320,6 +1324,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
spin_unlock(&mm->page_table_lock);
/* fall through */
}
+split_fallthrough:
if (unlikely(pmd_bad(*pmd)))
goto no_page_table;
diff --git a/mm/migrate.c b/mm/migrate.c
index 690d0de993af..1a531b760b3b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -113,6 +113,8 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
goto out;
pmd = pmd_offset(pud, addr);
+ if (pmd_trans_huge(*pmd))
+ goto out;
if (!pmd_present(*pmd))
goto out;
@@ -632,6 +634,9 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
/* page was freed from under us. So we are done. */
goto move_newpage;
}
+ if (unlikely(PageTransHuge(page)))
+ if (unlikely(split_huge_page(page)))
+ goto move_newpage;
/* prepare cgroup just returns 0 or -ENOMEM */
rc = -EAGAIN;
@@ -1063,7 +1068,7 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma))
goto set_status;
- page = follow_page(vma, pp->addr, FOLL_GET);
+ page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT);
err = PTR_ERR(page);
if (IS_ERR(page))