From c4389a66758798fefa8bfe3bfda3328b51c81786 Mon Sep 17 00:00:00 2001
From: "Jeff Washington (jwash)" <wash678@gmail.com>
Date: Thu, 16 Dec 2021 23:25:22 -0600
Subject: [PATCH] AcctIdx: held ranges search in lifo order (#21964)

---
 runtime/src/in_mem_accounts_index.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/runtime/src/in_mem_accounts_index.rs b/runtime/src/in_mem_accounts_index.rs
index e3e6fbef20..6af671cc45 100644
--- a/runtime/src/in_mem_accounts_index.rs
+++ b/runtime/src/in_mem_accounts_index.rs
@@ -654,7 +654,8 @@ impl<T: IndexValue> InMemAccountsIndex<T> {
             ranges.push(inclusive_range);
         } else {
             // find the matching range and delete it since we don't want to hold it anymore
-            for (i, r) in ranges.iter().enumerate() {
+            // search backwards, assuming LIFO ordering
+            for (i, r) in ranges.iter().enumerate().rev() {
                 if let (Bound::Included(start_found), Bound::Included(end_found)) =
                     (r.start_bound(), r.end_bound())
                 {