From 81bafd9daf3da761ba0a40f6bc796a8711725344 Mon Sep 17 00:00:00 2001
From: "Jeff Washington (jwash)"
 <75863576+jeffwashington@users.noreply.github.com>
Date: Thu, 3 Jun 2021 22:22:12 -0500
Subject: [PATCH] add info for vm.max_map_count incorrectly set. (#17727)

---
 runtime/src/append_vec.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/runtime/src/append_vec.rs b/runtime/src/append_vec.rs
index fe38721fd6..2ede4b6aa2 100644
--- a/runtime/src/append_vec.rs
+++ b/runtime/src/append_vec.rs
@@ -305,7 +305,14 @@ impl AppendVec {
         let file_size = std::fs::metadata(&path)?.len();
         AppendVec::sanitize_len_and_size(current_len, file_size as usize)?;
 
-        let map = unsafe { MmapMut::map_mut(&data)? };
+        let map = unsafe {
+            let result = MmapMut::map_mut(&data);
+            if result.is_err() {
+                // for vm.max_map_count, error is: {code: 12, kind: Other, message: "Cannot allocate memory"}
+                info!("memory map error: {:?}. This may be because vm.max_map_count is not set correctly.", result);
+            }
+            result?
+        };
 
         let new = AppendVec {
             path: path.as_ref().to_path_buf(),