mm: migration: fix migration of huge PMD shared pages

[linux.git] / mm / hugetlb.c

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3c21775f196b2f38a25ed05687791a4c79a3d3d4..b903d746e1320209e15c22e681f606982f73af50 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4545,12 +4545,40 @@ static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
        /*
         * check on proper vm_flags and page table alignment
         */
-       if (vma->vm_flags & VM_MAYSHARE &&
-           vma->vm_start <= base && end <= vma->vm_end)
+       if (vma->vm_flags & VM_MAYSHARE && range_in_vma(vma, base, end))
                return true;
        return false;
 }
 
+/*
+ * Determine if start,end range within vma could be mapped by shared pmd.
+ * If yes, adjust start and end to cover range associated with possible
+ * shared pmd mappings.
+ */
+void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
+                               unsigned long *start, unsigned long *end)
+{
+       unsigned long check_addr = *start;
+
+       if (!(vma->vm_flags & VM_MAYSHARE))
+               return;
+
+       for (check_addr = *start; check_addr < *end; check_addr += PUD_SIZE) {
+               unsigned long a_start = check_addr & PUD_MASK;
+               unsigned long a_end = a_start + PUD_SIZE;
+
+               /*
+                * If sharing is possible, adjust start/end if necessary.
+                */
+               if (range_in_vma(vma, a_start, a_end)) {
+                       if (a_start < *start)
+                               *start = a_start;
+                       if (a_end > *end)
+                               *end = a_end;
+               }
+       }
+}
+
 /*
  * Search for a shareable pmd page for hugetlb. In any case calls pmd_alloc()
  * and returns the corresponding pte. While this is not necessary for the
@@ -4648,6 +4676,11 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
 {
        return 0;
 }
+
+void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
+                               unsigned long *start, unsigned long *end)
+{
+}
 #define want_pmd_share()       (0)
 #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */