[PATCH] mm/mremap: reset VMI on unmap

[Lorenzo Stoakes]

Any separate VMA iterator may become invalidated when VMAs are unmapped at
nodes in proximity to the current position of the iterator.

Therefore, reset the iterator at each point where this occurs on a mremap
move.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
---
 mm/mremap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/mremap.c b/mm/mremap.c
index 7a2e7022139a..15cbd41515ed 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -1113,6 +1113,7 @@ static void unmap_source_vma(struct vma_remap_struct *vrm)

 	err = do_vmi_munmap(&vmi, mm, addr, len, vrm->uf_unmap, /* unlock= */false);
 	vrm->vma = NULL; /* Invalidated. */
+	vrm->vmi_needs_reset = true;
 	if (err) {
 		/* OOM: unable to split vma, just get accounts right */
 		vm_acct_memory(len >> PAGE_SHIFT);
@@ -1367,6 +1368,7 @@ static unsigned long mremap_to(struct vma_remap_struct *vrm)
 		err = do_munmap(mm, vrm->new_addr, vrm->new_len,
 				vrm->uf_unmap_early);
 		vrm->vma = NULL; /* Invalidated. */
+		vrm->vmi_needs_reset = true;
 		if (err)
 			return err;

--
2.50.1