mm/vma: introduce abort_munmap_vmas()

Extract clean up of failed munmap() operations from do_vmi_align_munmap().
This simplifies later patches in the series.

It is worth noting that the mas_for_each() loop now has a different upper
limit.  This should not change the number of vmas visited for reattaching
to the main vma tree (mm_mt), as all vmas are reattached in both
scenarios.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Reviewed-by: Lorenzo Stoakes <[email protected]>
Reviewed-by: Suren Baghdasaryan <[email protected]>
Cc: Bert Karwatzki <[email protected]>
Cc: Jeff Xu <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Cc: Paul Moore <[email protected]>
Cc: Sidhartha Kumar <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 17 insertions, 5 deletions

diff --git a/mm/vma.c b/mm/vma.c
index 066de79b7b73..58ecd447670d 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -669,6 +669,22 @@ again:
 }
 
 /*
+ * abort_munmap_vmas - Undo any munmap work and free resources
+ *
+ * Reattach any detached vmas and free up the maple tree used to track the vmas.
+ */
+static inline void abort_munmap_vmas(struct ma_state *mas_detach)
+{
+	struct vm_area_struct *vma;
+
+	mas_set(mas_detach, 0);
+	mas_for_each(mas_detach, vma, ULONG_MAX)
+		vma_mark_detached(vma, false);
+
+	__mt_destroy(mas_detach->tree);
+}
+
+/*
  * do_vmi_align_munmap() - munmap the aligned region from @start to @end.
  * @vmi: The vma iterator
  * @vma: The starting vm_area_struct
@@ -834,11 +850,7 @@ clear_tree_failed:
 userfaultfd_error:
 munmap_gather_failed:
 end_split_failed:
-	mas_set(&mas_detach, 0);
-	mas_for_each(&mas_detach, next, end)
-		vma_mark_detached(next, false);
-
-	__mt_destroy(&mt_detach);
+	abort_munmap_vmas(&mas_detach);
 start_split_failed:
 map_count_exceeded:
 	validate_mm(mm);