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/20240830040101.822209-3-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Bert Karwatzki <spasswolf@web.de>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/vma.c b/mm/vma.c
index 066de79b7b733af9c4d878c904ddafa0d226be68..58ecd447670d725f039becfb4921e8b52baf14cb 100644 (file)
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -668,6 +668,22 @@ again:
        validate_mm(mm);
 }
 
+/*
+ * 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
@@ -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);