From b5c6495f69fa0d642aa40211df61274b801c8915 Mon Sep 17 00:00:00 2001
From: daanx <daan@effp.org>
Date: Tue, 20 Aug 2024 15:58:36 -0700
Subject: [PATCH] don't consider memory as large OS pages if only madvise'd

---
 ide/vs2022/mimalloc-override.vcxproj |  8 +++---
 src/prim/unix/prim.c                 |  9 ++++---
 test/main-override-static.c          | 39 +++++++++++++++++++++++++++-
 3 files changed, 47 insertions(+), 9 deletions(-)

diff --git a/ide/vs2022/mimalloc-override.vcxproj b/ide/vs2022/mimalloc-override.vcxproj
index e895fa3c..4383d886 100644
--- a/ide/vs2022/mimalloc-override.vcxproj
+++ b/ide/vs2022/mimalloc-override.vcxproj
@@ -98,7 +98,7 @@
       <PreprocessorDefinitions>MI_SHARED_LIB;MI_SHARED_LIB_EXPORT;MI_MALLOC_OVERRIDE;%(PreprocessorDefinitions);</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
       <SupportJustMyCode>false</SupportJustMyCode>
-      <CompileAs>Default</CompileAs>
+      <CompileAs>CompileAsCpp</CompileAs>
     </ClCompile>
     <Link>
       <AdditionalDependencies>$(ProjectDir)\..\..\bin\mimalloc-redirect32.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -126,7 +126,7 @@
       <PreprocessorDefinitions>MI_DEBUG=4;MI_SHARED_LIB;MI_SHARED_LIB_EXPORT;MI_MALLOC_OVERRIDE;%(PreprocessorDefinitions);</PreprocessorDefinitions>
       <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
       <SupportJustMyCode>false</SupportJustMyCode>
-      <CompileAs>Default</CompileAs>
+      <CompileAs>CompileAsCpp</CompileAs>
     </ClCompile>
     <Link>
       <AdditionalDependencies>$(ProjectDir)\..\..\bin\mimalloc-redirect.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -157,7 +157,7 @@
       <AssemblerListingLocation>$(IntDir)</AssemblerListingLocation>
       <WholeProgramOptimization>false</WholeProgramOptimization>
       <RuntimeLibrary>MultiThreadedDLL</RuntimeLibrary>
-      <CompileAs>Default</CompileAs>
+      <CompileAs>CompileAsCpp</CompileAs>
       <BufferSecurityCheck>false</BufferSecurityCheck>
     </ClCompile>
     <Link>
@@ -189,7 +189,7 @@
       <AssemblerListingLocation>$(IntDir)</AssemblerListingLocation>
       <WholeProgramOptimization>false</WholeProgramOptimization>
       <RuntimeLibrary>MultiThreadedDLL</RuntimeLibrary>
-      <CompileAs>Default</CompileAs>
+      <CompileAs>CompileAsCpp</CompileAs>
       <BufferSecurityCheck>false</BufferSecurityCheck>
     </ClCompile>
     <Link>
diff --git a/src/prim/unix/prim.c b/src/prim/unix/prim.c
index 63a36f25..0ea8189c 100644
--- a/src/prim/unix/prim.c
+++ b/src/prim/unix/prim.c
@@ -181,10 +181,11 @@ int _mi_prim_free(void* addr, size_t size ) {
 
 static int unix_madvise(void* addr, size_t size, int advice) {
   #if defined(__sun)
-  return madvise((caddr_t)addr, size, advice);  // Solaris needs cast (issue #520)
+  int res = madvise((caddr_t)addr, size, advice);  // Solaris needs cast (issue #520)
   #else
-  return madvise(addr, size, advice);
+  int res = madvise(addr, size, advice);
   #endif
+  return (res==0 ? 0 : errno);
 }
 
 static void* unix_mmap_prim(void* addr, size_t size, size_t try_alignment, int protect_flags, int flags, int fd) {
@@ -331,7 +332,7 @@ static void* unix_mmap(void* addr, size_t size, size_t try_alignment, int protec
       // when large OS pages are enabled for mimalloc, we call `madvise` anyways.
       if (allow_large && _mi_os_use_large_page(size, try_alignment)) {
         if (unix_madvise(p, size, MADV_HUGEPAGE) == 0) {
-          *is_large = true; // possibly
+          // *is_large = true; // possibly
         };
       }
       #elif defined(__sun)
@@ -340,7 +341,7 @@ static void* unix_mmap(void* addr, size_t size, size_t try_alignment, int protec
         cmd.mha_pagesize = _mi_os_large_page_size();
         cmd.mha_cmd = MHA_MAPSIZE_VA;
         if (memcntl((caddr_t)p, size, MC_HAT_ADVISE, (caddr_t)&cmd, 0, 0) == 0) {
-          *is_large = true;
+          // *is_large = true; // possibly
         }
       }
       #endif
diff --git a/test/main-override-static.c b/test/main-override-static.c
index bf1cc416..535a9aaf 100644
--- a/test/main-override-static.c
+++ b/test/main-override-static.c
@@ -18,11 +18,13 @@ static void test_reserved(void);
 static void negative_stat(void);
 static void alloc_huge(void);
 static void test_heap_walk(void);
+// static void test_large_pages(void);
 
 
 int main() {
   mi_version();
   mi_stats_reset();
+  // test_large_pages();
   // detect double frees and heap corruption
   // double_free1();
   // double_free2();
@@ -61,7 +63,7 @@ int main() {
   //mi_stats_print(NULL);
 
   // test_process_info();
-  
+
   return 0;
 }
 
@@ -216,6 +218,41 @@ static void test_heap_walk(void) {
   mi_heap_visit_blocks(heap, true, &test_visit, NULL);
 }
 
+// Experiment with huge OS pages
+#if 0
+
+#include <mimalloc/types.h>
+#include <mimalloc/internal.h>
+#include <unistd.h>
+#include <sys/mman.h>
+
+static void test_large_pages(void) {
+  mi_memid_t memid;
+
+  #if 0
+  size_t pages_reserved;
+  size_t page_size;
+  uint8_t* p = (uint8_t*)_mi_os_alloc_huge_os_pages(1, -1, 30000, &pages_reserved, &page_size, &memid);
+  const size_t req_size = pages_reserved * page_size;
+  #else
+  const size_t req_size = 64*MI_MiB;
+  uint8_t* p = (uint8_t*)_mi_os_alloc(req_size,&memid,NULL);
+  #endif
+
+  p[0] = 1;
+
+  //_mi_os_protect(p, _mi_os_page_size());
+  //_mi_os_unprotect(p, _mi_os_page_size());
+  //_mi_os_decommit(p, _mi_os_page_size(), NULL);
+  if (madvise(p, req_size, MADV_HUGEPAGE) == 0) {
+    printf("advised huge pages\n");
+    _mi_os_decommit(p, _mi_os_page_size(), NULL);
+  };
+  _mi_os_free(p, req_size, memid, NULL);
+}
+
+#endif
+
 // ----------------------------
 // bin size experiments
 // ------------------------------