[PATCH v8 02/21] mm/vma: Introduce abort_munmap_vmas()

From: Liam R. Howlett
Date: Fri Aug 30 2024 - 00:01:50 EST


From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>

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.

Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
---
mm/vma.c | 22 +++++++++++++++++-----
1 file 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
@@ -668,6 +668,22 @@ void vma_complete(struct vma_prepare *vp,
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 @@ do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
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);
--
2.43.0