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authorUladzislau Rezki (Sony) <urezki@gmail.com>2020-08-07 08:24:09 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-07 20:33:27 +0200
commit5dd7864094033a281aeffccaf9703468cbcfccfc (patch)
tree148c6fa3b2e252bde0c46aba922048b355a2cba5 /mm
parentvmalloc: convert to XArray (diff)
downloadlinux-5dd7864094033a281aeffccaf9703468cbcfccfc.tar.xz
linux-5dd7864094033a281aeffccaf9703468cbcfccfc.zip
mm/vmalloc: simplify merge_or_add_vmap_area()
Currently when a VA is deallocated and is about to be placed back to the tree, it can be either: merged with next/prev neighbors or inserted if not coalesced. On those steps the tree can be populated several times. For example when both neighbors are merged. It can be avoided and simplified in fact. Therefore do it only once when VA points to final merged area, after all manipulations: merging/removing/inserting. Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200527205054.1696-1-urezki@gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/vmalloc.c25
1 files changed, 14 insertions, 11 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d496856bd408..d0ec02308d7c 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -797,9 +797,6 @@ merge_or_add_vmap_area(struct vmap_area *va,
if (sibling->va_start == va->va_end) {
sibling->va_start = va->va_start;
- /* Check and update the tree if needed. */
- augment_tree_propagate_from(sibling);
-
/* Free vmap_area object. */
kmem_cache_free(vmap_area_cachep, va);
@@ -819,14 +816,18 @@ merge_or_add_vmap_area(struct vmap_area *va,
if (next->prev != head) {
sibling = list_entry(next->prev, struct vmap_area, list);
if (sibling->va_end == va->va_start) {
- sibling->va_end = va->va_end;
-
- /* Check and update the tree if needed. */
- augment_tree_propagate_from(sibling);
-
+ /*
+ * If both neighbors are coalesced, it is important
+ * to unlink the "next" node first, followed by merging
+ * with "previous" one. Otherwise the tree might not be
+ * fully populated if a sibling's augmented value is
+ * "normalized" because of rotation operations.
+ */
if (merged)
unlink_va(va, root);
+ sibling->va_end = va->va_end;
+
/* Free vmap_area object. */
kmem_cache_free(vmap_area_cachep, va);
@@ -837,11 +838,13 @@ merge_or_add_vmap_area(struct vmap_area *va,
}
insert:
- if (!merged) {
+ if (!merged)
link_va(va, root, parent, link, head);
- augment_tree_propagate_from(va);
- }
+ /*
+ * Last step is to check and update the tree.
+ */
+ augment_tree_propagate_from(va);
return va;
}