Use MAP_FIXED_NOREPLACE on host

It seems that the new Ubuntu kernel completely ignores the
address hint, but it will honour the MAP_FIXED_NOREPLACE flag.

Test: Run tests on LUCI on Ubuntu-22
Change-Id: I8a1cebdf66b0eac8ac028e3c10210230e6b4a693

3 files changed, 20 insertions, 10 deletions

diff --git a/libartbase/base/mem_map.cc b/libartbase/base/mem_map.cc
index 0ab47f2384..08d452b5ff 100644
--- a/libartbase/base/mem_map.cc
+++ b/libartbase/base/mem_map.cc
@@ -344,13 +344,20 @@ MemMap MemMap::MapAnonymous(const char* name,
   // We need to store and potentially set an error number for pretty printing of errors
   int saved_errno = 0;
 
-  void* actual = MapInternal(addr,
-                             page_aligned_byte_count,
-                             prot,
-                             flags,
-                             fd.get(),
-                             0,
-                             low_4gb);
+  void* actual = nullptr;
+
+  // New Ubuntu linux kerners seem to ignore the address hint, so make it a firm request.
+  // Whereas old kernels allocated at 'addr' if provided, newer kernels seem to ignore it.
+  // However, MAP_FIXED_NOREPLACE tells the kernel it must allocate at the address or fail.
+  // Do this only on host since android kernels still obey the hint without flag (for now).
+  if (!kIsTargetBuild && (flags & MAP_FIXED) == 0 && addr != nullptr) {
+    actual = MapInternal(
+        addr, page_aligned_byte_count, prot, flags | MAP_FIXED_NOREPLACE, fd.get(), 0, low_4gb);
+    // If the fixed-address allocation failed, fallback to the default path (random address).
+  }
+  if (actual == nullptr || actual == MAP_FAILED) {
+    actual = MapInternal(addr, page_aligned_byte_count, prot, flags, fd.get(), 0, low_4gb);
+  }
   saved_errno = errno;
 
   if (actual == MAP_FAILED) {
diff --git a/libartbase/base/mem_map.h b/libartbase/base/mem_map.h
index 90e2031cf9..a3af44fadb 100644
--- a/libartbase/base/mem_map.h
+++ b/libartbase/base/mem_map.h
@@ -29,6 +29,12 @@
 #include "globals.h"
 #include "macros.h"
 
+#ifndef __BIONIC__
+#ifndef MAP_FIXED_NOREPLACE
+#define MAP_FIXED_NOREPLACE 0x100000
+#endif
+#endif  // __BIONIC__
+
 namespace art {
 
 #if defined(__LP64__) && !defined(__Fuchsia__) && \
diff --git a/runtime/gc/collector/mark_compact.cc b/runtime/gc/collector/mark_compact.cc
index 25f30ec485..2ef1ec5c9f 100644
--- a/runtime/gc/collector/mark_compact.cc
+++ b/runtime/gc/collector/mark_compact.cc
@@ -67,9 +67,6 @@
 #ifndef MREMAP_DONTUNMAP
 #define MREMAP_DONTUNMAP 4
 #endif
-#ifndef MAP_FIXED_NOREPLACE
-#define MAP_FIXED_NOREPLACE 0x100000
-#endif
 #endif  // __BIONIC__
 
 // See aosp/2996596 for where these values came from.