8255254: Split os::reserve_memory and os::map_memory_to_file interfaces

Reviewed-by: stefank, stuefe

src/hotspot/os/aix/os_aix.cpp

@@ -2236,7 +2236,7 @@ bool os::can_execute_large_page_memory() {
   return false;
 }
 
-char* os::pd_attempt_reserve_memory_at(char* requested_addr, size_t bytes, int file_desc) {
+char* os::pd_attempt_map_memory_to_file_at(char* requested_addr, size_t bytes, int file_desc) {
   assert(file_desc >= 0, "file_desc is not valid");
   char* result = NULL;
 

src/hotspot/os/bsd/os_bsd.cpp

@@ -1905,7 +1905,7 @@ bool os::can_execute_large_page_memory() {
   return false;
 }
 
-char* os::pd_attempt_reserve_memory_at(char* requested_addr, size_t bytes, int file_desc) {
+char* os::pd_attempt_map_memory_to_file_at(char* requested_addr, size_t bytes, int file_desc) {
   assert(file_desc >= 0, "file_desc is not valid");
   char* result = pd_attempt_reserve_memory_at(requested_addr, bytes);
   if (result != NULL) {

src/hotspot/os/linux/os_linux.cpp

@@ -4214,7 +4214,7 @@ bool os::can_execute_large_page_memory() {
   return UseTransparentHugePages || UseHugeTLBFS;
 }
 
-char* os::pd_attempt_reserve_memory_at(char* requested_addr, size_t bytes, int file_desc) {
+char* os::pd_attempt_map_memory_to_file_at(char* requested_addr, size_t bytes, int file_desc) {
   assert(file_desc >= 0, "file_desc is not valid");
   char* result = pd_attempt_reserve_memory_at(requested_addr, bytes);
   if (result != NULL) {

src/hotspot/os/posix/os_posix.cpp

@@ -297,37 +297,18 @@ char* os::replace_existing_mapping_with_file_mapping(char* base, size_t size, in
   return map_memory_to_file(base, size, fd);
 }
 
-// Multiple threads can race in this code, and can remap over each other with MAP_FIXED,
+static size_t calculate_aligned_extra_size(size_t size, size_t alignment) {
-// so on posix, unmap the section at the start and at the end of the chunk that we mapped
-// rather than unmapping and remapping the whole chunk to get requested alignment.
-char* os::reserve_memory_aligned(size_t size, size_t alignment, int file_desc) {
   assert((alignment & (os::vm_allocation_granularity() - 1)) == 0,
       "Alignment must be a multiple of allocation granularity (page size)");
   assert((size & (alignment -1)) == 0, "size must be 'alignment' aligned");
 
   size_t extra_size = size + alignment;
   assert(extra_size >= size, "overflow, size is too large to allow alignment");
+  return extra_size;
+}
 
-  char* extra_base;
+// After a bigger chunk was mapped, unmaps start and end parts to get the requested alignment.
-  if (file_desc != -1) {
+static char* chop_extra_memory(size_t size, size_t alignment, char* extra_base, size_t extra_size) {
-    // For file mapping, we do not call os:reserve_memory_with_fd since:
-    // - we later chop away parts of the mapping using os::release_memory and that could fail if the
-    //   original mmap call had been tied to an fd.
-    // - The memory API os::reserve_memory uses is an implementation detail. It may (and usually is)
-    //   mmap but it also may System V shared memory which cannot be uncommitted as a whole, so
-    //   chopping off and unmapping excess bits back and front (see below) would not work.
-    extra_base = reserve_mmapped_memory(extra_size, NULL);
-    if (extra_base != NULL) {
-      MemTracker::record_virtual_memory_reserve((address)extra_base, extra_size, CALLER_PC);
-    }
-  } else {
-    extra_base = os::reserve_memory(extra_size);
-  }
-
-  if (extra_base == NULL) {
-    return NULL;
-  }
-
   // Do manual alignment
   char* aligned_base = align_up(extra_base, alignment);
 
@@ -349,13 +330,39 @@ char* os::reserve_memory_aligned(size_t size, size_t alignment, int file_desc) {
       os::release_memory(extra_base + begin_offset + size, end_offset);
   }
 
-  if (file_desc != -1) {
+  return aligned_base;
-    // After we have an aligned address, we can replace anonymous mapping with file mapping
+}
-    if (replace_existing_mapping_with_file_mapping(aligned_base, size, file_desc) == NULL) {
+
-      vm_exit_during_initialization(err_msg("Error in mapping Java heap at the given filesystem directory"));
+// Multiple threads can race in this code, and can remap over each other with MAP_FIXED,
-    }
+// so on posix, unmap the section at the start and at the end of the chunk that we mapped
-    MemTracker::record_virtual_memory_commit((address)aligned_base, size, CALLER_PC);
+// rather than unmapping and remapping the whole chunk to get requested alignment.
+char* os::reserve_memory_aligned(size_t size, size_t alignment) {
+  size_t extra_size = calculate_aligned_extra_size(size, alignment);
+  char* extra_base = os::reserve_memory(extra_size);
+  if (extra_base == NULL) {
+    return NULL;
   }
+  return chop_extra_memory(size, alignment, extra_base, extra_size);
+}
+
+char* os::map_memory_to_file_aligned(size_t size, size_t alignment, int file_desc) {
+  size_t extra_size = calculate_aligned_extra_size(size, alignment);
+  // For file mapping, we do not call os:map_memory_to_file(size,fd) since:
+  // - we later chop away parts of the mapping using os::release_memory and that could fail if the
+  //   original mmap call had been tied to an fd.
+  // - The memory API os::reserve_memory uses is an implementation detail. It may (and usually is)
+  //   mmap but it also may System V shared memory which cannot be uncommitted as a whole, so
+  //   chopping off and unmapping excess bits back and front (see below) would not work.
+  char* extra_base = reserve_mmapped_memory(extra_size, NULL);
+  if (extra_base == NULL) {
+    return NULL;
+  }
+  char* aligned_base = chop_extra_memory(size, alignment, extra_base, extra_size);
+  // After we have an aligned address, we can replace anonymous mapping with file mapping
+  if (replace_existing_mapping_with_file_mapping(aligned_base, size, file_desc) == NULL) {
+    vm_exit_during_initialization(err_msg("Error in mapping Java heap at the given filesystem directory"));
+  }
+  MemTracker::record_virtual_memory_commit((address)aligned_base, size, CALLER_PC);
   return aligned_base;
 }
 

src/hotspot/os/windows/os_windows.cpp

@@ -3137,7 +3137,7 @@ void os::split_reserved_memory(char *base, size_t size, size_t split) {
 // Multiple threads can race in this code but it's not possible to unmap small sections of
 // virtual space to get requested alignment, like posix-like os's.
 // Windows prevents multiple thread from remapping over each other so this loop is thread-safe.
-char* os::reserve_memory_aligned(size_t size, size_t alignment, int file_desc) {
+static char* map_or_reserve_memory_aligned(size_t size, size_t alignment, int file_desc) {
   assert((alignment & (os::vm_allocation_granularity() - 1)) == 0,
          "Alignment must be a multiple of allocation granularity (page size)");
   assert((size & (alignment -1)) == 0, "size must be 'alignment' aligned");
@@ -3148,7 +3148,9 @@ char* os::reserve_memory_aligned(size_t size, size_t alignment, int file_desc) {
   char* aligned_base = NULL;
 
   do {
-    char* extra_base = os::reserve_memory_with_fd(extra_size, file_desc);
+    char* extra_base = file_desc != -1 ?
+      os::map_memory_to_file(extra_size, file_desc) :
+      os::reserve_memory(extra_size);
     if (extra_base == NULL) {
       return NULL;
     }
@@ -3161,13 +3163,23 @@ char* os::reserve_memory_aligned(size_t size, size_t alignment, int file_desc) {
       os::release_memory(extra_base, extra_size);
     }
 
-    aligned_base = os::attempt_reserve_memory_at(aligned_base, size, file_desc);
+    aligned_base = file_desc != -1 ?
+      os::attempt_map_memory_to_file_at(aligned_base, size, file_desc) :
+      os::attempt_reserve_memory_at(aligned_base, size);
 
   } while (aligned_base == NULL);
 
   return aligned_base;
 }
 
+char* os::reserve_memory_aligned(size_t size, size_t alignment) {
+  return map_or_reserve_memory_aligned(size, alignment, -1 /* file_desc */);
+}
+
+char* os::map_memory_to_file_aligned(size_t size, size_t alignment, int fd) {
+  return map_or_reserve_memory_aligned(size, alignment, fd);
+}
+
 char* os::pd_reserve_memory(size_t bytes) {
   return pd_attempt_reserve_memory_at(NULL /* addr */, bytes);
 }
@@ -3205,7 +3217,7 @@ char* os::pd_attempt_reserve_memory_at(char* addr, size_t bytes) {
   return res;
 }
 
-char* os::pd_attempt_reserve_memory_at(char* requested_addr, size_t bytes, int file_desc) {
+char* os::pd_attempt_map_memory_to_file_at(char* requested_addr, size_t bytes, int file_desc) {
   assert(file_desc >= 0, "file_desc is not valid");
   return map_memory_to_file(requested_addr, bytes, file_desc);
 }

src/hotspot/share/gc/g1/g1RegionToSpaceMapper.cpp

@@ -220,7 +220,7 @@ static bool map_nvdimm_space(ReservedSpace rs) {
     return false;
   }
   // commit this memory in nv-dimm
-  char* ret = os::attempt_reserve_memory_at(rs.base(), rs.size(), _backing_fd);
+  char* ret = os::attempt_map_memory_to_file_at(rs.base(), rs.size(), _backing_fd);
 
   if (ret != rs.base()) {
     if (ret != NULL) {

src/hotspot/share/memory/virtualspace.cpp

@@ -80,6 +80,30 @@ ReservedSpace::ReservedSpace(char* base, size_t size, size_t alignment,
   _executable = executable;
 }
 
+// Helper method
+static char* attempt_map_or_reserve_memory_at(char* base, size_t size, int fd) {
+  if (fd != -1) {
+    return os::attempt_map_memory_to_file_at(base, size, fd);
+  }
+  return os::attempt_reserve_memory_at(base, size);
+}
+
+// Helper method
+static char* map_or_reserve_memory(size_t size, int fd) {
+  if (fd != -1) {
+    return os::map_memory_to_file(size, fd);
+  }
+  return os::reserve_memory(size);
+}
+
+// Helper method
+static char* map_or_reserve_memory_aligned(size_t size, size_t alignment, int fd) {
+  if (fd != -1) {
+    return os::map_memory_to_file_aligned(size, alignment, fd);
+  }
+  return os::reserve_memory_aligned(size, alignment);
+}
+
 // Helper method
 static void unmap_or_release_memory(char* base, size_t size, bool is_file_mapped) {
   if (is_file_mapped) {
@@ -188,13 +212,13 @@ void ReservedSpace::initialize(size_t size, size_t alignment, bool large,
     // important.  If available space is not detected, return NULL.
 
     if (requested_address != 0) {
-      base = os::attempt_reserve_memory_at(requested_address, size, _fd_for_heap);
+      base = attempt_map_or_reserve_memory_at(requested_address, size, _fd_for_heap);
       if (failed_to_reserve_as_requested(base, requested_address, size, false, _fd_for_heap != -1)) {
         // OS ignored requested address. Try different address.
         base = NULL;
       }
     } else {
-      base = os::reserve_memory_with_fd(size, _fd_for_heap);
+      base = map_or_reserve_memory(size, _fd_for_heap);
     }
 
     if (base == NULL) return;
@@ -206,7 +230,7 @@ void ReservedSpace::initialize(size_t size, size_t alignment, bool large,
 
       // Make sure that size is aligned
       size = align_up(size, alignment);
-      base = os::reserve_memory_aligned(size, alignment, _fd_for_heap);
+      base = map_or_reserve_memory_aligned(size, alignment, _fd_for_heap);
 
       if (requested_address != 0 &&
           failed_to_reserve_as_requested(base, requested_address, size, false, _fd_for_heap != -1)) {
@@ -372,13 +396,13 @@ void ReservedHeapSpace::try_reserve_heap(size_t size,
     }
 
     if (requested_address != 0) {
-      base = os::attempt_reserve_memory_at(requested_address, size, _fd_for_heap);
+      base = attempt_map_or_reserve_memory_at(requested_address, size, _fd_for_heap);
     } else {
       // Optimistically assume that the OSes returns an aligned base pointer.
       // When reserving a large address range, most OSes seem to align to at
       // least 64K.
       // If the returned memory is not aligned we will release and retry.
-      base = os::reserve_memory_with_fd(size, _fd_for_heap);
+      base = map_or_reserve_memory(size, _fd_for_heap);
     }
   }
   if (base == NULL) { return; }

src/hotspot/share/runtime/os.cpp

@@ -1658,38 +1658,10 @@ char* os::reserve_memory(size_t bytes, MEMFLAGS flags) {
   return result;
 }
 
-char* os::reserve_memory_with_fd(size_t bytes, int file_desc) {
+char* os::attempt_reserve_memory_at(char* addr, size_t bytes) {
-  char* result;
+  char* result = pd_attempt_reserve_memory_at(addr, bytes);
-
+  if (result != NULL) {
-  if (file_desc != -1) {
+    MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
-    // Could have called pd_reserve_memory() followed by replace_existing_mapping_with_file_mapping(),
-    // but AIX may use SHM in which case its more trouble to detach the segment and remap memory to the file.
-    result = os::map_memory_to_file(NULL /* addr */, bytes, file_desc);
-    if (result != NULL) {
-      MemTracker::record_virtual_memory_reserve_and_commit(result, bytes, CALLER_PC);
-    }
-  } else {
-    result = pd_reserve_memory(bytes);
-    if (result != NULL) {
-      MemTracker::record_virtual_memory_reserve(result, bytes, CALLER_PC);
-    }
-  }
-
-  return result;
-}
-
-char* os::attempt_reserve_memory_at(char* addr, size_t bytes, int file_desc) {
-  char* result = NULL;
-  if (file_desc != -1) {
-    result = pd_attempt_reserve_memory_at(addr, bytes, file_desc);
-    if (result != NULL) {
-      MemTracker::record_virtual_memory_reserve_and_commit((address)result, bytes, CALLER_PC);
-    }
-  } else {
-    result = pd_attempt_reserve_memory_at(addr, bytes);
-    if (result != NULL) {
-      MemTracker::record_virtual_memory_reserve((address)result, bytes, CALLER_PC);
-    }
   }
   return result;
 }
@@ -1758,6 +1730,25 @@ void os::pretouch_memory(void* start, void* end, size_t page_size) {
   }
 }
 
+char* os::map_memory_to_file(size_t bytes, int file_desc) {
+  // Could have called pd_reserve_memory() followed by replace_existing_mapping_with_file_mapping(),
+  // but AIX may use SHM in which case its more trouble to detach the segment and remap memory to the file.
+  // On all current implementations NULL is interpreted as any available address.
+  char* result = os::map_memory_to_file(NULL /* addr */, bytes, file_desc);
+  if (result != NULL) {
+    MemTracker::record_virtual_memory_reserve_and_commit(result, bytes, CALLER_PC);
+  }
+  return result;
+}
+
+char* os::attempt_map_memory_to_file_at(char* addr, size_t bytes, int file_desc) {
+  char* result = pd_attempt_map_memory_to_file_at(addr, bytes, file_desc);
+  if (result != NULL) {
+    MemTracker::record_virtual_memory_reserve_and_commit((address)result, bytes, CALLER_PC);
+  }
+  return result;
+}
+
 char* os::map_memory(int fd, const char* file_name, size_t file_offset,
                            char *addr, size_t bytes, bool read_only,
                            bool allow_exec, MEMFLAGS flags) {

src/hotspot/share/runtime/os.hpp

@@ -116,7 +116,6 @@ class os: AllStatic {
   static char*  pd_reserve_memory(size_t bytes);
 
   static char*  pd_attempt_reserve_memory_at(char* addr, size_t bytes);
-  static char*  pd_attempt_reserve_memory_at(char* addr, size_t bytes, int file_desc);
 
   static bool   pd_commit_memory(char* addr, size_t bytes, bool executable);
   static bool   pd_commit_memory(char* addr, size_t size, size_t alignment_hint,
@@ -131,6 +130,8 @@ class os: AllStatic {
   static bool   pd_uncommit_memory(char* addr, size_t bytes);
   static bool   pd_release_memory(char* addr, size_t bytes);
 
+  static char*  pd_attempt_map_memory_to_file_at(char* addr, size_t bytes, int file_desc);
+
   static char*  pd_map_memory(int fd, const char* file_name, size_t file_offset,
                            char *addr, size_t bytes, bool read_only = false,
                            bool allow_exec = false);
@@ -313,19 +314,14 @@ class os: AllStatic {
   static int    vm_allocation_granularity();
 
   // Reserves virtual memory.
-  // alignment_hint - currently only used by AIX
   static char*  reserve_memory(size_t bytes, MEMFLAGS flags = mtOther);
 
-  // Reserves virtual memory.
-  // if file_desc != -1, also attaches the memory to the file.
-  static char*  reserve_memory_with_fd(size_t bytes, int file_desc);
-
   // Reserves virtual memory that starts at an address that is aligned to 'alignment'.
-  static char*  reserve_memory_aligned(size_t size, size_t alignment, int file_desc = -1);
+  static char*  reserve_memory_aligned(size_t size, size_t alignment);
 
   // Attempts to reserve the virtual memory at [addr, addr + bytes).
   // Does not overwrite existing mappings.
-  static char*  attempt_reserve_memory_at(char* addr, size_t bytes, int file_desc = -1);
+  static char*  attempt_reserve_memory_at(char* addr, size_t bytes);
 
   // Split a reserved memory region [base, base+size) into two regions [base, base+split) and
   //  [base+split, base+size).
@@ -370,7 +366,10 @@ class os: AllStatic {
   static int create_file_for_heap(const char* dir);
   // Map memory to the file referred by fd. This function is slightly different from map_memory()
   // and is added to be used for implementation of -XX:AllocateHeapAt
+  static char* map_memory_to_file(size_t size, int fd);
+  static char* map_memory_to_file_aligned(size_t size, size_t alignment, int fd);
   static char* map_memory_to_file(char* base, size_t size, int fd);
+  static char* attempt_map_memory_to_file_at(char* base, size_t size, int fd);
   // Replace existing reserved memory with file mapping
   static char* replace_existing_mapping_with_file_mapping(char* base, size_t size, int fd);