From 8f83908be76b0b77e718221305ce625e83fc3daa Mon Sep 17 00:00:00 2001
From: Rhys Rustad-Elliott <me@rhysre.net>
Date: Sat, 22 Mar 2025 17:56:01 +0100
Subject: [PATCH] Fix attempting to core dump 100T of memory

It seems that commit
https://github.com/llvm/llvm-project/commit/c2a57034eff048cd36c563c8e0051db3a70991b3
from upstream LLVM was cherry-picked slightly incorrectly. MADV_DONTNEED
should have been used when _not_ executing a dry run.
---
 compiler-rt/lib/msan/msan_linux.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler-rt/lib/msan/msan_linux.cpp b/compiler-rt/lib/msan/msan_linux.cpp
index 1fa4d16386b2..138e43742611 100644
--- a/compiler-rt/lib/msan/msan_linux.cpp
+++ b/compiler-rt/lib/msan/msan_linux.cpp
@@ -155,7 +155,7 @@ static bool InitShadow(bool init_origins, bool dry_run) {
       if (!dry_run &&
           !MmapFixedSuperNoReserve(start, size, kMemoryLayout[i].name))
         return false;
-      if (dry_run && common_flags()->use_madv_dontdump)
+      if (!dry_run && common_flags()->use_madv_dontdump)
         DontDumpShadowMemory(start, size);
     }
     if (protect) {