Allow unmap to work with an mshare host mm.

Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
---
 mm/vma.c | 10 ++++++----
 mm/vma.h |  1 +
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/mm/vma.c b/mm/vma.c
index a7fbd339d259..c09b2e1a08e6 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -1265,7 +1265,7 @@ static void vms_complete_munmap_vmas(struct vma_munmap_struct *vms,
 	struct vm_area_struct *vma;
 	struct mm_struct *mm;
 
-	mm = current->mm;
+	mm = vms->mm;
 	mm->map_count -= vms->vma_count;
 	mm->locked_vm -= vms->locked_vm;
 	if (vms->unlock)
@@ -1473,13 +1473,15 @@ static int vms_gather_munmap_vmas(struct vma_munmap_struct *vms,
  * @start: The aligned start address to munmap
  * @end: The aligned end address to munmap
  * @uf: The userfaultfd list_head
+ * @mm: The mm struct
  * @unlock: Unlock after the operation.  Only unlocked on success
  */
 static void init_vma_munmap(struct vma_munmap_struct *vms,
 		struct vma_iterator *vmi, struct vm_area_struct *vma,
 		unsigned long start, unsigned long end, struct list_head *uf,
-		bool unlock)
+		struct mm_struct *mm, bool unlock)
 {
+	vms->mm = mm;
 	vms->vmi = vmi;
 	vms->vma = vma;
 	if (vma) {
@@ -1523,7 +1525,7 @@ int do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	struct vma_munmap_struct vms;
 	int error;
 
-	init_vma_munmap(&vms, vmi, vma, start, end, uf, unlock);
+	init_vma_munmap(&vms, vmi, vma, start, end, uf, mm, unlock);
 	error = vms_gather_munmap_vmas(&vms, &mas_detach);
 	if (error)
 		goto gather_failed;
@@ -2346,7 +2348,7 @@ static int __mmap_prepare(struct mmap_state *map, struct list_head *uf)
 
 	/* Find the first overlapping VMA and initialise unmap state. */
 	vms->vma = vma_find(vmi, map->end);
-	init_vma_munmap(vms, vmi, vms->vma, map->addr, map->end, uf,
+	init_vma_munmap(vms, vmi, vms->vma, map->addr, map->end, uf, map->mm,
 			/* unlock = */ false);
 
 	/* OK, we have overlapping VMAs - prepare to unmap them. */
diff --git a/mm/vma.h b/mm/vma.h
index 20fc1c2a32fd..4946d7dc13fd 100644
--- a/mm/vma.h
+++ b/mm/vma.h
@@ -51,6 +51,7 @@ struct vma_munmap_struct {
 	unsigned long exec_vm;
 	unsigned long stack_vm;
 	unsigned long data_vm;
+	struct mm_struct *mm;
 };
 
 enum vma_merge_state {
-- 
2.47.1