nommu: fix memory leak in do_mmap() error path

The preallocation of the maple tree nodes may leak if the error path to
"error_just_free" is taken.  Fix this by moving the freeing of the maple
tree nodes to a shared location for all error paths.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 8220543 ("nommu: remove uses of VMA linked list")
Signed-off-by: Liam R. Howlett <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Yu Zhao <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: howlett

mm/nommu.c

@@ -1240,6 +1240,7 @@ unsigned long do_mmap(struct file *file,
 error_just_free:
 	up_write(&nommu_region_sem);
 error:
+	mas_destroy(&mas);
 	if (region->vm_file)
 		fput(region->vm_file);
 	kmem_cache_free(vm_region_jar, region);
@@ -1250,7 +1251,6 @@ unsigned long do_mmap(struct file *file,
 
 sharing_violation:
 	up_write(&nommu_region_sem);
-	mas_destroy(&mas);
 	pr_warn("Attempt to share mismatched mappings\n");
 	ret = -EINVAL;
 	goto error;