1 files changed, 30 insertions, 26 deletions

diff --git a/mm/vma.c b/mm/vma.c
index 0c5e391fe2e2..47469c036a72 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -1638,25 +1638,35 @@ static struct vm_area_struct *vma_modify(struct vma_merge_struct *vmg)
 	return vma;
 }
 
-struct vm_area_struct *vma_modify_flags(
-	struct vma_iterator *vmi, struct vm_area_struct *prev,
-	struct vm_area_struct *vma, unsigned long start, unsigned long end,
-	vm_flags_t vm_flags)
+struct vm_area_struct *vma_modify_flags(struct vma_iterator *vmi,
+		struct vm_area_struct *prev, struct vm_area_struct *vma,
+		unsigned long start, unsigned long end,
+		vm_flags_t *vm_flags_ptr)
 {
 	VMG_VMA_STATE(vmg, vmi, prev, vma, start, end);
+	const vm_flags_t vm_flags = *vm_flags_ptr;
+	struct vm_area_struct *ret;
 
 	vmg.vm_flags = vm_flags;
 
-	return vma_modify(&vmg);
+	ret = vma_modify(&vmg);
+	if (IS_ERR(ret))
+		return ret;
+
+	/*
+	 * For a merge to succeed, the flags must match those requested. For
+	 * flags which do not obey typical merge rules (i.e. do not need to
+	 * match), we must let the caller know about them.
+	 */
+	if (vmg.state == VMA_MERGE_SUCCESS)
+		*vm_flags_ptr = ret->vm_flags;
+	return ret;
 }
 
-struct vm_area_struct
-*vma_modify_name(struct vma_iterator *vmi,
-		       struct vm_area_struct *prev,
-		       struct vm_area_struct *vma,
-		       unsigned long start,
-		       unsigned long end,
-		       struct anon_vma_name *new_name)
+struct vm_area_struct *vma_modify_name(struct vma_iterator *vmi,
+		struct vm_area_struct *prev, struct vm_area_struct *vma,
+		unsigned long start, unsigned long end,
+		struct anon_vma_name *new_name)
 {
 	VMG_VMA_STATE(vmg, vmi, prev, vma, start, end);
 
@@ -1665,12 +1675,10 @@ struct vm_area_struct
 	return vma_modify(&vmg);
 }
 
-struct vm_area_struct
-*vma_modify_policy(struct vma_iterator *vmi,
-		   struct vm_area_struct *prev,
-		   struct vm_area_struct *vma,
-		   unsigned long start, unsigned long end,
-		   struct mempolicy *new_pol)
+struct vm_area_struct *vma_modify_policy(struct vma_iterator *vmi,
+		struct vm_area_struct *prev, struct vm_area_struct *vma,
+		unsigned long start, unsigned long end,
+		struct mempolicy *new_pol)
 {
 	VMG_VMA_STATE(vmg, vmi, prev, vma, start, end);
 
@@ -1679,14 +1687,10 @@ struct vm_area_struct
 	return vma_modify(&vmg);
 }
 
-struct vm_area_struct
-*vma_modify_flags_uffd(struct vma_iterator *vmi,
-		       struct vm_area_struct *prev,
-		       struct vm_area_struct *vma,
-		       unsigned long start, unsigned long end,
-		       vm_flags_t vm_flags,
-		       struct vm_userfaultfd_ctx new_ctx,
-		       bool give_up_on_oom)
+struct vm_area_struct *vma_modify_flags_uffd(struct vma_iterator *vmi,
+		struct vm_area_struct *prev, struct vm_area_struct *vma,
+		unsigned long start, unsigned long end, vm_flags_t vm_flags,
+		struct vm_userfaultfd_ctx new_ctx, bool give_up_on_oom)
 {
 	VMG_VMA_STATE(vmg, vmi, prev, vma, start, end);