changeset 56099:0cd210d5cb9c

8230092: ZGC: Consolidate ZBackingFile, ZBackingPath and ZPhysicalMemoryBacking on Linux Reviewed-by: stefank
author pliden
date Wed, 28 Aug 2019 09:50:21 +0200
parents 54845835747f
children 53ed0cf870b0
files src/hotspot/os/linux/gc/z/zBackingFile_linux.cpp src/hotspot/os/linux/gc/z/zBackingFile_linux.hpp src/hotspot/os/linux/gc/z/zBackingPath_linux.cpp src/hotspot/os/linux/gc/z/zBackingPath_linux.hpp src/hotspot/os/linux/gc/z/zPhysicalMemoryBacking_linux.cpp src/hotspot/os/linux/gc/z/zPhysicalMemoryBacking_linux.hpp src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingFile_linux_aarch64.cpp src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingFile_linux_aarch64.hpp src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingPath_linux_aarch64.cpp src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingPath_linux_aarch64.hpp src/hotspot/os_cpu/linux_aarch64/gc/z/zPhysicalMemoryBacking_linux_aarch64.cpp src/hotspot/os_cpu/linux_aarch64/gc/z/zPhysicalMemoryBacking_linux_aarch64.hpp src/hotspot/os_cpu/linux_x86/gc/z/zBackingFile_linux_x86.cpp src/hotspot/os_cpu/linux_x86/gc/z/zBackingFile_linux_x86.hpp src/hotspot/os_cpu/linux_x86/gc/z/zBackingPath_linux_x86.cpp src/hotspot/os_cpu/linux_x86/gc/z/zBackingPath_linux_x86.hpp src/hotspot/os_cpu/linux_x86/gc/z/zPhysicalMemoryBacking_linux_x86.cpp src/hotspot/os_cpu/linux_x86/gc/z/zPhysicalMemoryBacking_linux_x86.hpp src/hotspot/share/gc/z/zPhysicalMemory.hpp
diffstat 19 files changed, 1252 insertions(+), 2505 deletions(-) [+]
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os/linux/gc/z/zBackingFile_linux.cpp	Wed Aug 28 09:50:21 2019 +0200
@@ -0,0 +1,574 @@
+/*
+ * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zArray.inline.hpp"
+#include "gc/z/zBackingFile_linux.hpp"
+#include "gc/z/zBackingPath_linux.hpp"
+#include "gc/z/zErrno.hpp"
+#include "gc/z/zGlobals.hpp"
+#include "gc/z/zLargePages.inline.hpp"
+#include "gc/z/zSyscall_linux.hpp"
+#include "logging/log.hpp"
+#include "runtime/init.hpp"
+#include "runtime/os.hpp"
+#include "utilities/align.hpp"
+#include "utilities/debug.hpp"
+
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+//
+// Support for building on older Linux systems
+//
+
+// memfd_create(2) flags
+#ifndef MFD_CLOEXEC
+#define MFD_CLOEXEC                      0x0001U
+#endif
+#ifndef MFD_HUGETLB
+#define MFD_HUGETLB                      0x0004U
+#endif
+
+// open(2) flags
+#ifndef O_CLOEXEC
+#define O_CLOEXEC                        02000000
+#endif
+#ifndef O_TMPFILE
+#define O_TMPFILE                        (020000000 | O_DIRECTORY)
+#endif
+
+// fallocate(2) flags
+#ifndef FALLOC_FL_KEEP_SIZE
+#define FALLOC_FL_KEEP_SIZE              0x01
+#endif
+#ifndef FALLOC_FL_PUNCH_HOLE
+#define FALLOC_FL_PUNCH_HOLE             0x02
+#endif
+
+// Filesystem types, see statfs(2)
+#ifndef TMPFS_MAGIC
+#define TMPFS_MAGIC                      0x01021994
+#endif
+#ifndef HUGETLBFS_MAGIC
+#define HUGETLBFS_MAGIC                  0x958458f6
+#endif
+
+// Filesystem names
+#define ZFILESYSTEM_TMPFS                "tmpfs"
+#define ZFILESYSTEM_HUGETLBFS            "hugetlbfs"
+
+// Sysfs file for transparent huge page on tmpfs
+#define ZFILENAME_SHMEM_ENABLED          "/sys/kernel/mm/transparent_hugepage/shmem_enabled"
+
+// Java heap filename
+#define ZFILENAME_HEAP                   "java_heap"
+
+// Preferred tmpfs mount points, ordered by priority
+static const char* z_preferred_tmpfs_mountpoints[] = {
+  "/dev/shm",
+  "/run/shm",
+  NULL
+};
+
+// Preferred hugetlbfs mount points, ordered by priority
+static const char* z_preferred_hugetlbfs_mountpoints[] = {
+  "/dev/hugepages",
+  "/hugepages",
+  NULL
+};
+
+static int z_fallocate_hugetlbfs_attempts = 3;
+static bool z_fallocate_supported = true;
+
+ZBackingFile::ZBackingFile() :
+    _fd(-1),
+    _size(0),
+    _filesystem(0),
+    _block_size(0),
+    _available(0),
+    _initialized(false) {
+
+  // Create backing file
+  _fd = create_fd(ZFILENAME_HEAP);
+  if (_fd == -1) {
+    return;
+  }
+
+  // Get filesystem statistics
+  struct statfs buf;
+  if (fstatfs(_fd, &buf) == -1) {
+    ZErrno err;
+    log_error(gc)("Failed to determine filesystem type for backing file (%s)", err.to_string());
+    return;
+  }
+
+  _filesystem = buf.f_type;
+  _block_size = buf.f_bsize;
+  _available = buf.f_bavail * _block_size;
+
+  // Make sure we're on a supported filesystem
+  if (!is_tmpfs() && !is_hugetlbfs()) {
+    log_error(gc)("Backing file must be located on a %s or a %s filesystem",
+                  ZFILESYSTEM_TMPFS, ZFILESYSTEM_HUGETLBFS);
+    return;
+  }
+
+  // Make sure the filesystem type matches requested large page type
+  if (ZLargePages::is_transparent() && !is_tmpfs()) {
+    log_error(gc)("-XX:+UseTransparentHugePages can only be enable when using a %s filesystem",
+                  ZFILESYSTEM_TMPFS);
+    return;
+  }
+
+  if (ZLargePages::is_transparent() && !tmpfs_supports_transparent_huge_pages()) {
+    log_error(gc)("-XX:+UseTransparentHugePages on a %s filesystem not supported by kernel",
+                  ZFILESYSTEM_TMPFS);
+    return;
+  }
+
+  if (ZLargePages::is_explicit() && !is_hugetlbfs()) {
+    log_error(gc)("-XX:+UseLargePages (without -XX:+UseTransparentHugePages) can only be enabled "
+                  "when using a %s filesystem", ZFILESYSTEM_HUGETLBFS);
+    return;
+  }
+
+  if (!ZLargePages::is_explicit() && is_hugetlbfs()) {
+    log_error(gc)("-XX:+UseLargePages must be enabled when using a %s filesystem",
+                  ZFILESYSTEM_HUGETLBFS);
+    return;
+  }
+
+  const size_t expected_block_size = is_tmpfs() ? os::vm_page_size() : os::large_page_size();
+  if (expected_block_size != _block_size) {
+    log_error(gc)("%s filesystem has unexpected block size " SIZE_FORMAT " (expected " SIZE_FORMAT ")",
+                  is_tmpfs() ? ZFILESYSTEM_TMPFS : ZFILESYSTEM_HUGETLBFS, _block_size, expected_block_size);
+    return;
+  }
+
+  // Successfully initialized
+  _initialized = true;
+}
+
+int ZBackingFile::create_mem_fd(const char* name) const {
+  // Create file name
+  char filename[PATH_MAX];
+  snprintf(filename, sizeof(filename), "%s%s", name, ZLargePages::is_explicit() ? ".hugetlb" : "");
+
+  // Create file
+  const int extra_flags = ZLargePages::is_explicit() ? MFD_HUGETLB : 0;
+  const int fd = ZSyscall::memfd_create(filename, MFD_CLOEXEC | extra_flags);
+  if (fd == -1) {
+    ZErrno err;
+    log_debug(gc, init)("Failed to create memfd file (%s)",
+                        ((ZLargePages::is_explicit() && err == EINVAL) ? "Hugepages not supported" : err.to_string()));
+    return -1;
+  }
+
+  log_info(gc, init)("Heap backed by file: /memfd:%s", filename);
+
+  return fd;
+}
+
+int ZBackingFile::create_file_fd(const char* name) const {
+  const char* const filesystem = ZLargePages::is_explicit()
+                                 ? ZFILESYSTEM_HUGETLBFS
+                                 : ZFILESYSTEM_TMPFS;
+  const char** const preferred_mountpoints = ZLargePages::is_explicit()
+                                             ? z_preferred_hugetlbfs_mountpoints
+                                             : z_preferred_tmpfs_mountpoints;
+
+  // Find mountpoint
+  ZBackingPath path(filesystem, preferred_mountpoints);
+  if (path.get() == NULL) {
+    log_error(gc)("Use -XX:ZPath to specify the path to a %s filesystem", filesystem);
+    return -1;
+  }
+
+  // Try to create an anonymous file using the O_TMPFILE flag. Note that this
+  // flag requires kernel >= 3.11. If this fails we fall back to open/unlink.
+  const int fd_anon = os::open(path.get(), O_TMPFILE|O_EXCL|O_RDWR|O_CLOEXEC, S_IRUSR|S_IWUSR);
+  if (fd_anon == -1) {
+    ZErrno err;
+    log_debug(gc, init)("Failed to create anonymous file in %s (%s)", path.get(),
+                        (err == EINVAL ? "Not supported" : err.to_string()));
+  } else {
+    // Get inode number for anonymous file
+    struct stat stat_buf;
+    if (fstat(fd_anon, &stat_buf) == -1) {
+      ZErrno err;
+      log_error(gc)("Failed to determine inode number for anonymous file (%s)", err.to_string());
+      return -1;
+    }
+
+    log_info(gc, init)("Heap backed by file: %s/#" UINT64_FORMAT, path.get(), (uint64_t)stat_buf.st_ino);
+
+    return fd_anon;
+  }
+
+  log_debug(gc, init)("Falling back to open/unlink");
+
+  // Create file name
+  char filename[PATH_MAX];
+  snprintf(filename, sizeof(filename), "%s/%s.%d", path.get(), name, os::current_process_id());
+
+  // Create file
+  const int fd = os::open(filename, O_CREAT|O_EXCL|O_RDWR|O_CLOEXEC, S_IRUSR|S_IWUSR);
+  if (fd == -1) {
+    ZErrno err;
+    log_error(gc)("Failed to create file %s (%s)", filename, err.to_string());
+    return -1;
+  }
+
+  // Unlink file
+  if (unlink(filename) == -1) {
+    ZErrno err;
+    log_error(gc)("Failed to unlink file %s (%s)", filename, err.to_string());
+    return -1;
+  }
+
+  log_info(gc, init)("Heap backed by file: %s", filename);
+
+  return fd;
+}
+
+int ZBackingFile::create_fd(const char* name) const {
+  if (ZPath == NULL) {
+    // If the path is not explicitly specified, then we first try to create a memfd file
+    // instead of looking for a tmpfd/hugetlbfs mount point. Note that memfd_create() might
+    // not be supported at all (requires kernel >= 3.17), or it might not support large
+    // pages (requires kernel >= 4.14). If memfd_create() fails, then we try to create a
+    // file on an accessible tmpfs or hugetlbfs mount point.
+    const int fd = create_mem_fd(name);
+    if (fd != -1) {
+      return fd;
+    }
+
+    log_debug(gc, init)("Falling back to searching for an accessible mount point");
+  }
+
+  return create_file_fd(name);
+}
+
+bool ZBackingFile::is_initialized() const {
+  return _initialized;
+}
+
+int ZBackingFile::fd() const {
+  return _fd;
+}
+
+size_t ZBackingFile::size() const {
+  return _size;
+}
+
+size_t ZBackingFile::available() const {
+  return _available;
+}
+
+bool ZBackingFile::is_tmpfs() const {
+  return _filesystem == TMPFS_MAGIC;
+}
+
+bool ZBackingFile::is_hugetlbfs() const {
+  return _filesystem == HUGETLBFS_MAGIC;
+}
+
+bool ZBackingFile::tmpfs_supports_transparent_huge_pages() const {
+  // If the shmem_enabled file exists and is readable then we
+  // know the kernel supports transparent huge pages for tmpfs.
+  return access(ZFILENAME_SHMEM_ENABLED, R_OK) == 0;
+}
+
+ZErrno ZBackingFile::fallocate_compat_ftruncate(size_t size) const {
+  while (ftruncate(_fd, size) == -1) {
+    if (errno != EINTR) {
+      // Failed
+      return errno;
+    }
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate_compat_mmap(size_t offset, size_t length, bool touch) const {
+  // On hugetlbfs, mapping a file segment will fail immediately, without
+  // the need to touch the mapped pages first, if there aren't enough huge
+  // pages available to back the mapping.
+  void* const addr = mmap(0, length, PROT_READ|PROT_WRITE, MAP_SHARED, _fd, offset);
+  if (addr == MAP_FAILED) {
+    // Failed
+    return errno;
+  }
+
+  // Once mapped, the huge pages are only reserved. We need to touch them
+  // to associate them with the file segment. Note that we can not punch
+  // hole in file segments which only have reserved pages.
+  if (touch) {
+    char* const start = (char*)addr;
+    char* const end = start + length;
+    os::pretouch_memory(start, end, _block_size);
+  }
+
+  // Unmap again. From now on, the huge pages that were mapped are allocated
+  // to this file. There's no risk in getting SIGBUS when touching them.
+  if (munmap(addr, length) == -1) {
+    // Failed
+    return errno;
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate_compat_pwrite(size_t offset, size_t length) const {
+  uint8_t data = 0;
+
+  // Allocate backing memory by writing to each block
+  for (size_t pos = offset; pos < offset + length; pos += _block_size) {
+    if (pwrite(_fd, &data, sizeof(data), pos) == -1) {
+      // Failed
+      return errno;
+    }
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate_fill_hole_compat(size_t offset, size_t length) {
+  // fallocate(2) is only supported by tmpfs since Linux 3.5, and by hugetlbfs
+  // since Linux 4.3. When fallocate(2) is not supported we emulate it using
+  // ftruncate/pwrite (for tmpfs) or ftruncate/mmap/munmap (for hugetlbfs).
+
+  const size_t end = offset + length;
+  if (end > _size) {
+    // Increase file size
+    const ZErrno err = fallocate_compat_ftruncate(end);
+    if (err) {
+      // Failed
+      return err;
+    }
+  }
+
+  // Allocate backing memory
+  const ZErrno err = is_hugetlbfs() ? fallocate_compat_mmap(offset, length, false /* touch */)
+                                    : fallocate_compat_pwrite(offset, length);
+  if (err) {
+    if (end > _size) {
+      // Restore file size
+      fallocate_compat_ftruncate(_size);
+    }
+
+    // Failed
+    return err;
+  }
+
+  if (end > _size) {
+    // Record new file size
+    _size = end;
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate_fill_hole_syscall(size_t offset, size_t length) {
+  const int mode = 0; // Allocate
+  const int res = ZSyscall::fallocate(_fd, mode, offset, length);
+  if (res == -1) {
+    // Failed
+    return errno;
+  }
+
+  const size_t end = offset + length;
+  if (end > _size) {
+    // Record new file size
+    _size = end;
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate_fill_hole(size_t offset, size_t length) {
+  // Using compat mode is more efficient when allocating space on hugetlbfs.
+  // Note that allocating huge pages this way will only reserve them, and not
+  // associate them with segments of the file. We must guarantee that we at
+  // some point touch these segments, otherwise we can not punch hole in them.
+  if (z_fallocate_supported && !is_hugetlbfs()) {
+     const ZErrno err = fallocate_fill_hole_syscall(offset, length);
+     if (!err) {
+       // Success
+       return 0;
+     }
+
+     if (err != ENOSYS && err != EOPNOTSUPP) {
+       // Failed
+       return err;
+     }
+
+     // Not supported
+     log_debug(gc)("Falling back to fallocate() compatibility mode");
+     z_fallocate_supported = false;
+  }
+
+  return fallocate_fill_hole_compat(offset, length);
+}
+
+ZErrno ZBackingFile::fallocate_punch_hole(size_t offset, size_t length) {
+  if (is_hugetlbfs()) {
+    // We can only punch hole in pages that have been touched. Non-touched
+    // pages are only reserved, and not associated with any specific file
+    // segment. We don't know which pages have been previously touched, so
+    // we always touch them here to guarantee that we can punch hole.
+    const ZErrno err = fallocate_compat_mmap(offset, length, true /* touch */);
+    if (err) {
+      // Failed
+      return err;
+    }
+  }
+
+  const int mode = FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE;
+  if (ZSyscall::fallocate(_fd, mode, offset, length) == -1) {
+    // Failed
+    return errno;
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::split_and_fallocate(bool punch_hole, size_t offset, size_t length) {
+  // Try first half
+  const size_t offset0 = offset;
+  const size_t length0 = align_up(length / 2, _block_size);
+  const ZErrno err0 = fallocate(punch_hole, offset0, length0);
+  if (err0) {
+    return err0;
+  }
+
+  // Try second half
+  const size_t offset1 = offset0 + length0;
+  const size_t length1 = length - length0;
+  const ZErrno err1 = fallocate(punch_hole, offset1, length1);
+  if (err1) {
+    return err1;
+  }
+
+  // Success
+  return 0;
+}
+
+ZErrno ZBackingFile::fallocate(bool punch_hole, size_t offset, size_t length) {
+  assert(is_aligned(offset, _block_size), "Invalid offset");
+  assert(is_aligned(length, _block_size), "Invalid length");
+
+  const ZErrno err = punch_hole ? fallocate_punch_hole(offset, length) : fallocate_fill_hole(offset, length);
+  if (err == EINTR && length > _block_size) {
+    // Calling fallocate(2) with a large length can take a long time to
+    // complete. When running profilers, such as VTune, this syscall will
+    // be constantly interrupted by signals. Expanding the file in smaller
+    // steps avoids this problem.
+    return split_and_fallocate(punch_hole, offset, length);
+  }
+
+  return err;
+}
+
+bool ZBackingFile::commit_inner(size_t offset, size_t length) {
+  log_trace(gc, heap)("Committing memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)",
+                      offset / M, (offset + length) / M, length / M);
+
+retry:
+  const ZErrno err = fallocate(false /* punch_hole */, offset, length);
+  if (err) {
+    if (err == ENOSPC && !is_init_completed() && is_hugetlbfs() && z_fallocate_hugetlbfs_attempts-- > 0) {
+      // If we fail to allocate during initialization, due to lack of space on
+      // the hugetlbfs filesystem, then we wait and retry a few times before
+      // giving up. Otherwise there is a risk that running JVMs back-to-back
+      // will fail, since there is a delay between process termination and the
+      // huge pages owned by that process being returned to the huge page pool
+      // and made available for new allocations.
+      log_debug(gc, init)("Failed to commit memory (%s), retrying", err.to_string());
+
+      // Wait and retry in one second, in the hope that huge pages will be
+      // available by then.
+      sleep(1);
+      goto retry;
+    }
+
+    // Failed
+    log_error(gc)("Failed to commit memory (%s)", err.to_string());
+    return false;
+  }
+
+  // Success
+  return true;
+}
+
+size_t ZBackingFile::commit(size_t offset, size_t length) {
+  // Try to commit the whole region
+  if (commit_inner(offset, length)) {
+    // Success
+    return length;
+  }
+
+  // Failed, try to commit as much as possible
+  size_t start = offset;
+  size_t end = offset + length;
+
+  for (;;) {
+    length = align_down((end - start) / 2, ZGranuleSize);
+    if (length < ZGranuleSize) {
+      // Done, don't commit more
+      return start - offset;
+    }
+
+    if (commit_inner(start, length)) {
+      // Success, try commit more
+      start += length;
+    } else {
+      // Failed, try commit less
+      end -= length;
+    }
+  }
+}
+
+size_t ZBackingFile::uncommit(size_t offset, size_t length) {
+  log_trace(gc, heap)("Uncommitting memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)",
+                      offset / M, (offset + length) / M, length / M);
+
+  const ZErrno err = fallocate(true /* punch_hole */, offset, length);
+  if (err) {
+    log_error(gc)("Failed to uncommit memory (%s)", err.to_string());
+    return 0;
+  }
+
+  return length;
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os/linux/gc/z/zBackingFile_linux.hpp	Wed Aug 28 09:50:21 2019 +0200
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#ifndef OS_LINUX_GC_Z_ZBACKINGFILE_LINUX_HPP
+#define OS_LINUX_GC_Z_ZBACKINGFILE_LINUX_HPP
+
+#include "memory/allocation.hpp"
+
+class ZErrno;
+
+class ZBackingFile {
+private:
+  int      _fd;
+  size_t   _size;
+  uint64_t _filesystem;
+  size_t   _block_size;
+  size_t   _available;
+  bool     _initialized;
+
+  int create_mem_fd(const char* name) const;
+  int create_file_fd(const char* name) const;
+  int create_fd(const char* name) const;
+
+  bool is_tmpfs() const;
+  bool is_hugetlbfs() const;
+  bool tmpfs_supports_transparent_huge_pages() const;
+
+  ZErrno fallocate_compat_ftruncate(size_t size) const;
+  ZErrno fallocate_compat_mmap(size_t offset, size_t length, bool reserve_only) const;
+  ZErrno fallocate_compat_pwrite(size_t offset, size_t length) const;
+  ZErrno fallocate_fill_hole_compat(size_t offset, size_t length);
+  ZErrno fallocate_fill_hole_syscall(size_t offset, size_t length);
+  ZErrno fallocate_fill_hole(size_t offset, size_t length);
+  ZErrno fallocate_punch_hole(size_t offset, size_t length);
+  ZErrno split_and_fallocate(bool punch_hole, size_t offset, size_t length);
+  ZErrno fallocate(bool punch_hole, size_t offset, size_t length);
+
+  bool commit_inner(size_t offset, size_t length);
+
+public:
+  ZBackingFile();
+
+  bool is_initialized() const;
+
+  int fd() const;
+  size_t size() const;
+  size_t available() const;
+
+  size_t commit(size_t offset, size_t length);
+  size_t uncommit(size_t offset, size_t length);
+};
+
+#endif // OS_LINUX_GC_Z_ZBACKINGFILE_LINUX_HPP
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os/linux/gc/z/zBackingPath_linux.cpp	Wed Aug 28 09:50:21 2019 +0200
@@ -0,0 +1,149 @@
+/*
+ * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zArray.inline.hpp"
+#include "gc/z/zBackingPath_linux.hpp"
+#include "gc/z/zErrno.hpp"
+#include "logging/log.hpp"
+
+#include <stdio.h>
+#include <unistd.h>
+
+// Mount information, see proc(5) for more details.
+#define PROC_SELF_MOUNTINFO        "/proc/self/mountinfo"
+
+ZBackingPath::ZBackingPath(const char* filesystem, const char** preferred_mountpoints) {
+  if (ZPath != NULL) {
+    // Use specified path
+    _path = strdup(ZPath);
+  } else {
+    // Find suitable path
+    _path = find_mountpoint(filesystem, preferred_mountpoints);
+  }
+}
+
+ZBackingPath::~ZBackingPath() {
+  free(_path);
+  _path = NULL;
+}
+
+char* ZBackingPath::get_mountpoint(const char* line, const char* filesystem) const {
+  char* line_mountpoint = NULL;
+  char* line_filesystem = NULL;
+
+  // Parse line and return a newly allocated string containing the mount point if
+  // the line contains a matching filesystem and the mount point is accessible by
+  // the current user.
+  if (sscanf(line, "%*u %*u %*u:%*u %*s %ms %*[^-]- %ms", &line_mountpoint, &line_filesystem) != 2 ||
+      strcmp(line_filesystem, filesystem) != 0 ||
+      access(line_mountpoint, R_OK|W_OK|X_OK) != 0) {
+    // Not a matching or accessible filesystem
+    free(line_mountpoint);
+    line_mountpoint = NULL;
+  }
+
+  free(line_filesystem);
+
+  return line_mountpoint;
+}
+
+void ZBackingPath::get_mountpoints(const char* filesystem, ZArray<char*>* mountpoints) const {
+  FILE* fd = fopen(PROC_SELF_MOUNTINFO, "r");
+  if (fd == NULL) {
+    ZErrno err;
+    log_error(gc)("Failed to open %s: %s", PROC_SELF_MOUNTINFO, err.to_string());
+    return;
+  }
+
+  char* line = NULL;
+  size_t length = 0;
+
+  while (getline(&line, &length, fd) != -1) {
+    char* const mountpoint = get_mountpoint(line, filesystem);
+    if (mountpoint != NULL) {
+      mountpoints->add(mountpoint);
+    }
+  }
+
+  free(line);
+  fclose(fd);
+}
+
+void ZBackingPath::free_mountpoints(ZArray<char*>* mountpoints) const {
+  ZArrayIterator<char*> iter(mountpoints);
+  for (char* mountpoint; iter.next(&mountpoint);) {
+    free(mountpoint);
+  }
+  mountpoints->clear();
+}
+
+char* ZBackingPath::find_preferred_mountpoint(const char* filesystem,
+                                              ZArray<char*>* mountpoints,
+                                              const char** preferred_mountpoints) const {
+  // Find preferred mount point
+  ZArrayIterator<char*> iter1(mountpoints);
+  for (char* mountpoint; iter1.next(&mountpoint);) {
+    for (const char** preferred = preferred_mountpoints; *preferred != NULL; preferred++) {
+      if (!strcmp(mountpoint, *preferred)) {
+        // Preferred mount point found
+        return strdup(mountpoint);
+      }
+    }
+  }
+
+  // Preferred mount point not found
+  log_error(gc)("More than one %s filesystem found:", filesystem);
+  ZArrayIterator<char*> iter2(mountpoints);
+  for (char* mountpoint; iter2.next(&mountpoint);) {
+    log_error(gc)("  %s", mountpoint);
+  }
+
+  return NULL;
+}
+
+char* ZBackingPath::find_mountpoint(const char* filesystem, const char** preferred_mountpoints) const {
+  char* path = NULL;
+  ZArray<char*> mountpoints;
+
+  get_mountpoints(filesystem, &mountpoints);
+
+  if (mountpoints.size() == 0) {
+    // No mount point found
+    log_error(gc)("Failed to find an accessible %s filesystem", filesystem);
+  } else if (mountpoints.size() == 1) {
+    // One mount point found
+    path = strdup(mountpoints.at(0));
+  } else {
+    // More than one mount point found
+    path = find_preferred_mountpoint(filesystem, &mountpoints, preferred_mountpoints);
+  }
+
+  free_mountpoints(&mountpoints);
+
+  return path;
+}
+
+const char* ZBackingPath::get() const {
+  return _path;
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os/linux/gc/z/zBackingPath_linux.hpp	Wed Aug 28 09:50:21 2019 +0200
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#ifndef OS_LINUX_GC_Z_ZBACKINGPATH_LINUX_HPP
+#define OS_LINUX_GC_Z_ZBACKINGPATH_LINUX_HPP
+
+#include "gc/z/zArray.hpp"
+#include "memory/allocation.hpp"
+
+class ZBackingPath : public StackObj {
+private:
+  char* _path;
+
+  char* get_mountpoint(const char* line,
+                       const char* filesystem) const;
+  void get_mountpoints(const char* filesystem,
+                       ZArray<char*>* mountpoints) const;
+  void free_mountpoints(ZArray<char*>* mountpoints) const;
+  char* find_preferred_mountpoint(const char* filesystem,
+                                  ZArray<char*>* mountpoints,
+                                  const char** preferred_mountpoints) const;
+  char* find_mountpoint(const char* filesystem,
+                        const char** preferred_mountpoints) const;
+
+public:
+  ZBackingPath(const char* filesystem, const char** preferred_mountpoints);
+  ~ZBackingPath();
+
+  const char* get() const;
+};
+
+#endif // OS_LINUX_GC_Z_ZBACKINGPATH_LINUX_HPP
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os/linux/gc/z/zPhysicalMemoryBacking_linux.cpp	Wed Aug 28 09:50:21 2019 +0200
@@ -0,0 +1,333 @@
+/*
+ * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zAddress.inline.hpp"
+#include "gc/z/zErrno.hpp"
+#include "gc/z/zGlobals.hpp"
+#include "gc/z/zLargePages.inline.hpp"
+#include "gc/z/zMemory.hpp"
+#include "gc/z/zNUMA.hpp"
+#include "gc/z/zPhysicalMemory.inline.hpp"
+#include "gc/z/zPhysicalMemoryBacking_linux.hpp"
+#include "logging/log.hpp"
+#include "runtime/globals.hpp"
+#include "runtime/init.hpp"
+#include "runtime/os.hpp"
+#include "utilities/align.hpp"
+#include "utilities/debug.hpp"
+
+#include <stdio.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+
+//
+// Support for building on older Linux systems
+//
+
+// madvise(2) flags
+#ifndef MADV_HUGEPAGE
+#define MADV_HUGEPAGE                        14
+#endif
+
+// Proc file entry for max map mount
+#define ZFILENAME_PROC_MAX_MAP_COUNT         "/proc/sys/vm/max_map_count"
+
+bool ZPhysicalMemoryBacking::is_initialized() const {
+  return _file.is_initialized();
+}
+
+void ZPhysicalMemoryBacking::warn_available_space(size_t max) const {
+  // Note that the available space on a tmpfs or a hugetlbfs filesystem
+  // will be zero if no size limit was specified when it was mounted.
+  const size_t available = _file.available();
+  if (available == 0) {
+    // No size limit set, skip check
+    log_info(gc, init)("Available space on backing filesystem: N/A");
+    return;
+  }
+
+  log_info(gc, init)("Available space on backing filesystem: " SIZE_FORMAT "M", available / M);
+
+  // Warn if the filesystem doesn't currently have enough space available to hold
+  // the max heap size. The max heap size will be capped if we later hit this limit
+  // when trying to expand the heap.
+  if (available < max) {
+    log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****");
+    log_warning(gc)("Not enough space available on the backing filesystem to hold the current max Java heap");
+    log_warning(gc)("size (" SIZE_FORMAT "M). Please adjust the size of the backing filesystem accordingly "
+                    "(available", max / M);
+    log_warning(gc)("space is currently " SIZE_FORMAT "M). Continuing execution with the current filesystem "
+                    "size could", available / M);
+    log_warning(gc)("lead to a premature OutOfMemoryError being thrown, due to failure to map memory.");
+  }
+}
+
+void ZPhysicalMemoryBacking::warn_max_map_count(size_t max) const {
+  const char* const filename = ZFILENAME_PROC_MAX_MAP_COUNT;
+  FILE* const file = fopen(filename, "r");
+  if (file == NULL) {
+    // Failed to open file, skip check
+    log_debug(gc, init)("Failed to open %s", filename);
+    return;
+  }
+
+  size_t actual_max_map_count = 0;
+  const int result = fscanf(file, SIZE_FORMAT, &actual_max_map_count);
+  fclose(file);
+  if (result != 1) {
+    // Failed to read file, skip check
+    log_debug(gc, init)("Failed to read %s", filename);
+    return;
+  }
+
+  // The required max map count is impossible to calculate exactly since subsystems
+  // other than ZGC are also creating memory mappings, and we have no control over that.
+  // However, ZGC tends to create the most mappings and dominate the total count.
+  // In the worst cases, ZGC will map each granule three times, i.e. once per heap view.
+  // We speculate that we need another 20% to allow for non-ZGC subsystems to map memory.
+  const size_t required_max_map_count = (max / ZGranuleSize) * 3 * 1.2;
+  if (actual_max_map_count < required_max_map_count) {
+    log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****");
+    log_warning(gc)("The system limit on number of memory mappings per process might be too low for the given");
+    log_warning(gc)("max Java heap size (" SIZE_FORMAT "M). Please adjust %s to allow for at",
+                    max / M, filename);
+    log_warning(gc)("least " SIZE_FORMAT " mappings (current limit is " SIZE_FORMAT "). Continuing execution "
+                    "with the current", required_max_map_count, actual_max_map_count);
+    log_warning(gc)("limit could lead to a fatal error, due to failure to map memory.");
+  }
+}
+
+void ZPhysicalMemoryBacking::warn_commit_limits(size_t max) const {
+  // Warn if available space is too low
+  warn_available_space(max);
+
+  // Warn if max map count is too low
+  warn_max_map_count(max);
+}
+
+bool ZPhysicalMemoryBacking::supports_uncommit() {
+  assert(!is_init_completed(), "Invalid state");
+  assert(_file.size() >= ZGranuleSize, "Invalid size");
+
+  // Test if uncommit is supported by uncommitting and then re-committing a granule
+  return commit(uncommit(ZGranuleSize)) == ZGranuleSize;
+}
+
+size_t ZPhysicalMemoryBacking::commit(size_t size) {
+  size_t committed = 0;
+
+  // Fill holes in the backing file
+  while (committed < size) {
+    size_t allocated = 0;
+    const size_t remaining = size - committed;
+    const uintptr_t start = _uncommitted.alloc_from_front_at_most(remaining, &allocated);
+    if (start == UINTPTR_MAX) {
+      // No holes to commit
+      break;
+    }
+
+    // Try commit hole
+    const size_t filled = _file.commit(start, allocated);
+    if (filled > 0) {
+      // Successful or partialy successful
+      _committed.free(start, filled);
+      committed += filled;
+    }
+    if (filled < allocated) {
+      // Failed or partialy failed
+      _uncommitted.free(start + filled, allocated - filled);
+      return committed;
+    }
+  }
+
+  // Expand backing file
+  if (committed < size) {
+    const size_t remaining = size - committed;
+    const uintptr_t start = _file.size();
+    const size_t expanded = _file.commit(start, remaining);
+    if (expanded > 0) {
+      // Successful or partialy successful
+      _committed.free(start, expanded);
+      committed += expanded;
+    }
+  }
+
+  return committed;
+}
+
+size_t ZPhysicalMemoryBacking::uncommit(size_t size) {
+  size_t uncommitted = 0;
+
+  // Punch holes in backing file
+  while (uncommitted < size) {
+    size_t allocated = 0;
+    const size_t remaining = size - uncommitted;
+    const uintptr_t start = _committed.alloc_from_back_at_most(remaining, &allocated);
+    assert(start != UINTPTR_MAX, "Allocation should never fail");
+
+    // Try punch hole
+    const size_t punched = _file.uncommit(start, allocated);
+    if (punched > 0) {
+      // Successful or partialy successful
+      _uncommitted.free(start, punched);
+      uncommitted += punched;
+    }
+    if (punched < allocated) {
+      // Failed or partialy failed
+      _committed.free(start + punched, allocated - punched);
+      return uncommitted;
+    }
+  }
+
+  return uncommitted;
+}
+
+ZPhysicalMemory ZPhysicalMemoryBacking::alloc(size_t size) {
+  assert(is_aligned(size, ZGranuleSize), "Invalid size");
+
+  ZPhysicalMemory pmem;
+
+  // Allocate segments
+  for (size_t allocated = 0; allocated < size; allocated += ZGranuleSize) {
+    const uintptr_t start = _committed.alloc_from_front(ZGranuleSize);
+    assert(start != UINTPTR_MAX, "Allocation should never fail");
+    pmem.add_segment(ZPhysicalMemorySegment(start, ZGranuleSize));
+  }
+
+  return pmem;
+}
+
+void ZPhysicalMemoryBacking::free(const ZPhysicalMemory& pmem) {
+  const size_t nsegments = pmem.nsegments();
+
+  // Free segments
+  for (size_t i = 0; i < nsegments; i++) {
+    const ZPhysicalMemorySegment& segment = pmem.segment(i);
+    _committed.free(segment.start(), segment.size());
+  }
+}
+
+void ZPhysicalMemoryBacking::map_failed(ZErrno err) const {
+  if (err == ENOMEM) {
+    fatal("Failed to map memory. Please check the system limit on number of "
+          "memory mappings allowed per process (see %s)", ZFILENAME_PROC_MAX_MAP_COUNT);
+  } else {
+    fatal("Failed to map memory (%s)", err.to_string());
+  }
+}
+
+void ZPhysicalMemoryBacking::advise_view(uintptr_t addr, size_t size, int advice) const {
+  if (madvise((void*)addr, size, advice) == -1) {
+    ZErrno err;
+    log_error(gc)("Failed to advise on memory (advice %d, %s)", advice, err.to_string());
+  }
+}
+
+void ZPhysicalMemoryBacking::pretouch_view(uintptr_t addr, size_t size) const {
+  const size_t page_size = ZLargePages::is_explicit() ? os::large_page_size() : os::vm_page_size();
+  os::pretouch_memory((void*)addr, (void*)(addr + size), page_size);
+}
+
+void ZPhysicalMemoryBacking::map_view(const ZPhysicalMemory& pmem, uintptr_t addr, bool pretouch) const {
+  const size_t nsegments = pmem.nsegments();
+  size_t size = 0;
+
+  // Map segments
+  for (size_t i = 0; i < nsegments; i++) {
+    const ZPhysicalMemorySegment& segment = pmem.segment(i);
+    const uintptr_t segment_addr = addr + size;
+    const void* const res = mmap((void*)segment_addr, segment.size(), PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, _file.fd(), segment.start());
+    if (res == MAP_FAILED) {
+      ZErrno err;
+      map_failed(err);
+    }
+
+    size += segment.size();
+  }
+
+  // Advise on use of transparent huge pages before touching it
+  if (ZLargePages::is_transparent()) {
+    advise_view(addr, size, MADV_HUGEPAGE);
+  }
+
+  // NUMA interleave memory before touching it
+  ZNUMA::memory_interleave(addr, size);
+
+  // Pre-touch memory
+  if (pretouch) {
+    pretouch_view(addr, size);
+  }
+}
+
+void ZPhysicalMemoryBacking::unmap_view(const ZPhysicalMemory& pmem, uintptr_t addr) const {
+  // Note that we must keep the address space reservation intact and just detach
+  // the backing memory. For this reason we map a new anonymous, non-accessible
+  // and non-reserved page over the mapping instead of actually unmapping.
+  const void* const res = mmap((void*)addr, pmem.size(), PROT_NONE, MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, -1, 0);
+  if (res == MAP_FAILED) {
+    ZErrno err;
+    map_failed(err);
+  }
+}
+
+uintptr_t ZPhysicalMemoryBacking::nmt_address(uintptr_t offset) const {
+  // From an NMT point of view we treat the first heap view (marked0) as committed
+  return ZAddress::marked0(offset);
+}
+
+void ZPhysicalMemoryBacking::map(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+  if (ZVerifyViews) {
+    // Map good view
+    map_view(pmem, ZAddress::good(offset), AlwaysPreTouch);
+  } else {
+    // Map all views
+    map_view(pmem, ZAddress::marked0(offset), AlwaysPreTouch);
+    map_view(pmem, ZAddress::marked1(offset), AlwaysPreTouch);
+    map_view(pmem, ZAddress::remapped(offset), AlwaysPreTouch);
+  }
+}
+
+void ZPhysicalMemoryBacking::unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+  if (ZVerifyViews) {
+    // Unmap good view
+    unmap_view(pmem, ZAddress::good(offset));
+  } else {
+    // Unmap all views
+    unmap_view(pmem, ZAddress::marked0(offset));
+    unmap_view(pmem, ZAddress::marked1(offset));
+    unmap_view(pmem, ZAddress::remapped(offset));
+  }
+}
+
+void ZPhysicalMemoryBacking::debug_map(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+  // Map good view
+  assert(ZVerifyViews, "Should be enabled");
+  map_view(pmem, ZAddress::good(offset), false /* pretouch */);
+}
+
+void ZPhysicalMemoryBacking::debug_unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const {
+  // Unmap good view
+  assert(ZVerifyViews, "Should be enabled");
+  unmap_view(pmem, ZAddress::good(offset));
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/os/linux/gc/z/zPhysicalMemoryBacking_linux.hpp	Wed Aug 28 09:50:21 2019 +0200
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#ifndef OS_LINUX_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_HPP
+#define OS_LINUX_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_HPP
+
+#include "gc/z/zBackingFile_linux.hpp"
+#include "gc/z/zMemory.hpp"
+
+class ZErrno;
+class ZPhysicalMemory;
+
+class ZPhysicalMemoryBacking {
+private:
+  ZBackingFile   _file;
+  ZMemoryManager _committed;
+  ZMemoryManager _uncommitted;
+
+  void warn_available_space(size_t max) const;
+  void warn_max_map_count(size_t max) const;
+
+  void map_failed(ZErrno err) const;
+
+  void advise_view(uintptr_t addr, size_t size, int advice) const;
+  void pretouch_view(uintptr_t addr, size_t size) const;
+  void map_view(const ZPhysicalMemory& pmem, uintptr_t addr, bool pretouch) const;
+  void unmap_view(const ZPhysicalMemory& pmem, uintptr_t addr) const;
+
+public:
+  bool is_initialized() const;
+
+  void warn_commit_limits(size_t max) const;
+  bool supports_uncommit();
+
+  size_t commit(size_t size);
+  size_t uncommit(size_t size);
+
+  ZPhysicalMemory alloc(size_t size);
+  void free(const ZPhysicalMemory& pmem);
+
+  uintptr_t nmt_address(uintptr_t offset) const;
+
+  void map(const ZPhysicalMemory& pmem, uintptr_t offset) const;
+  void unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const;
+
+  void debug_map(const ZPhysicalMemory& pmem, uintptr_t offset) const;
+  void debug_unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const;
+};
+
+#endif // OS_LINUX_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_HPP
--- a/src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingFile_linux_aarch64.cpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,574 +0,0 @@
-/*
- * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#include "precompiled.hpp"
-#include "gc/z/zArray.inline.hpp"
-#include "gc/z/zBackingFile_linux_aarch64.hpp"
-#include "gc/z/zBackingPath_linux_aarch64.hpp"
-#include "gc/z/zErrno.hpp"
-#include "gc/z/zGlobals.hpp"
-#include "gc/z/zLargePages.inline.hpp"
-#include "gc/z/zSyscall_linux.hpp"
-#include "logging/log.hpp"
-#include "runtime/init.hpp"
-#include "runtime/os.hpp"
-#include "utilities/align.hpp"
-#include "utilities/debug.hpp"
-
-#include <fcntl.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include <sys/statfs.h>
-#include <sys/types.h>
-#include <unistd.h>
-
-//
-// Support for building on older Linux systems
-//
-
-// memfd_create(2) flags
-#ifndef MFD_CLOEXEC
-#define MFD_CLOEXEC                      0x0001U
-#endif
-#ifndef MFD_HUGETLB
-#define MFD_HUGETLB                      0x0004U
-#endif
-
-// open(2) flags
-#ifndef O_CLOEXEC
-#define O_CLOEXEC                        02000000
-#endif
-#ifndef O_TMPFILE
-#define O_TMPFILE                        (020000000 | O_DIRECTORY)
-#endif
-
-// fallocate(2) flags
-#ifndef FALLOC_FL_KEEP_SIZE
-#define FALLOC_FL_KEEP_SIZE              0x01
-#endif
-#ifndef FALLOC_FL_PUNCH_HOLE
-#define FALLOC_FL_PUNCH_HOLE             0x02
-#endif
-
-// Filesystem types, see statfs(2)
-#ifndef TMPFS_MAGIC
-#define TMPFS_MAGIC                      0x01021994
-#endif
-#ifndef HUGETLBFS_MAGIC
-#define HUGETLBFS_MAGIC                  0x958458f6
-#endif
-
-// Filesystem names
-#define ZFILESYSTEM_TMPFS                "tmpfs"
-#define ZFILESYSTEM_HUGETLBFS            "hugetlbfs"
-
-// Sysfs file for transparent huge page on tmpfs
-#define ZFILENAME_SHMEM_ENABLED          "/sys/kernel/mm/transparent_hugepage/shmem_enabled"
-
-// Java heap filename
-#define ZFILENAME_HEAP                   "java_heap"
-
-// Preferred tmpfs mount points, ordered by priority
-static const char* z_preferred_tmpfs_mountpoints[] = {
-  "/dev/shm",
-  "/run/shm",
-  NULL
-};
-
-// Preferred hugetlbfs mount points, ordered by priority
-static const char* z_preferred_hugetlbfs_mountpoints[] = {
-  "/dev/hugepages",
-  "/hugepages",
-  NULL
-};
-
-static int z_fallocate_hugetlbfs_attempts = 3;
-static bool z_fallocate_supported = true;
-
-ZBackingFile::ZBackingFile() :
-    _fd(-1),
-    _size(0),
-    _filesystem(0),
-    _block_size(0),
-    _available(0),
-    _initialized(false) {
-
-  // Create backing file
-  _fd = create_fd(ZFILENAME_HEAP);
-  if (_fd == -1) {
-    return;
-  }
-
-  // Get filesystem statistics
-  struct statfs buf;
-  if (fstatfs(_fd, &buf) == -1) {
-    ZErrno err;
-    log_error(gc)("Failed to determine filesystem type for backing file (%s)", err.to_string());
-    return;
-  }
-
-  _filesystem = buf.f_type;
-  _block_size = buf.f_bsize;
-  _available = buf.f_bavail * _block_size;
-
-  // Make sure we're on a supported filesystem
-  if (!is_tmpfs() && !is_hugetlbfs()) {
-    log_error(gc)("Backing file must be located on a %s or a %s filesystem",
-                  ZFILESYSTEM_TMPFS, ZFILESYSTEM_HUGETLBFS);
-    return;
-  }
-
-  // Make sure the filesystem type matches requested large page type
-  if (ZLargePages::is_transparent() && !is_tmpfs()) {
-    log_error(gc)("-XX:+UseTransparentHugePages can only be enable when using a %s filesystem",
-                  ZFILESYSTEM_TMPFS);
-    return;
-  }
-
-  if (ZLargePages::is_transparent() && !tmpfs_supports_transparent_huge_pages()) {
-    log_error(gc)("-XX:+UseTransparentHugePages on a %s filesystem not supported by kernel",
-                  ZFILESYSTEM_TMPFS);
-    return;
-  }
-
-  if (ZLargePages::is_explicit() && !is_hugetlbfs()) {
-    log_error(gc)("-XX:+UseLargePages (without -XX:+UseTransparentHugePages) can only be enabled "
-                  "when using a %s filesystem", ZFILESYSTEM_HUGETLBFS);
-    return;
-  }
-
-  if (!ZLargePages::is_explicit() && is_hugetlbfs()) {
-    log_error(gc)("-XX:+UseLargePages must be enabled when using a %s filesystem",
-                  ZFILESYSTEM_HUGETLBFS);
-    return;
-  }
-
-  const size_t expected_block_size = is_tmpfs() ? os::vm_page_size() : os::large_page_size();
-  if (expected_block_size != _block_size) {
-    log_error(gc)("%s filesystem has unexpected block size " SIZE_FORMAT " (expected " SIZE_FORMAT ")",
-                  is_tmpfs() ? ZFILESYSTEM_TMPFS : ZFILESYSTEM_HUGETLBFS, _block_size, expected_block_size);
-    return;
-  }
-
-  // Successfully initialized
-  _initialized = true;
-}
-
-int ZBackingFile::create_mem_fd(const char* name) const {
-  // Create file name
-  char filename[PATH_MAX];
-  snprintf(filename, sizeof(filename), "%s%s", name, ZLargePages::is_explicit() ? ".hugetlb" : "");
-
-  // Create file
-  const int extra_flags = ZLargePages::is_explicit() ? MFD_HUGETLB : 0;
-  const int fd = ZSyscall::memfd_create(filename, MFD_CLOEXEC | extra_flags);
-  if (fd == -1) {
-    ZErrno err;
-    log_debug(gc, init)("Failed to create memfd file (%s)",
-                        ((ZLargePages::is_explicit() && err == EINVAL) ? "Hugepages not supported" : err.to_string()));
-    return -1;
-  }
-
-  log_info(gc, init)("Heap backed by file: /memfd:%s", filename);
-
-  return fd;
-}
-
-int ZBackingFile::create_file_fd(const char* name) const {
-  const char* const filesystem = ZLargePages::is_explicit()
-                                 ? ZFILESYSTEM_HUGETLBFS
-                                 : ZFILESYSTEM_TMPFS;
-  const char** const preferred_mountpoints = ZLargePages::is_explicit()
-                                             ? z_preferred_hugetlbfs_mountpoints
-                                             : z_preferred_tmpfs_mountpoints;
-
-  // Find mountpoint
-  ZBackingPath path(filesystem, preferred_mountpoints);
-  if (path.get() == NULL) {
-    log_error(gc)("Use -XX:ZPath to specify the path to a %s filesystem", filesystem);
-    return -1;
-  }
-
-  // Try to create an anonymous file using the O_TMPFILE flag. Note that this
-  // flag requires kernel >= 3.11. If this fails we fall back to open/unlink.
-  const int fd_anon = os::open(path.get(), O_TMPFILE|O_EXCL|O_RDWR|O_CLOEXEC, S_IRUSR|S_IWUSR);
-  if (fd_anon == -1) {
-    ZErrno err;
-    log_debug(gc, init)("Failed to create anonymous file in %s (%s)", path.get(),
-                        (err == EINVAL ? "Not supported" : err.to_string()));
-  } else {
-    // Get inode number for anonymous file
-    struct stat stat_buf;
-    if (fstat(fd_anon, &stat_buf) == -1) {
-      ZErrno err;
-      log_error(gc)("Failed to determine inode number for anonymous file (%s)", err.to_string());
-      return -1;
-    }
-
-    log_info(gc, init)("Heap backed by file: %s/#" UINT64_FORMAT, path.get(), (uint64_t)stat_buf.st_ino);
-
-    return fd_anon;
-  }
-
-  log_debug(gc, init)("Falling back to open/unlink");
-
-  // Create file name
-  char filename[PATH_MAX];
-  snprintf(filename, sizeof(filename), "%s/%s.%d", path.get(), name, os::current_process_id());
-
-  // Create file
-  const int fd = os::open(filename, O_CREAT|O_EXCL|O_RDWR|O_CLOEXEC, S_IRUSR|S_IWUSR);
-  if (fd == -1) {
-    ZErrno err;
-    log_error(gc)("Failed to create file %s (%s)", filename, err.to_string());
-    return -1;
-  }
-
-  // Unlink file
-  if (unlink(filename) == -1) {
-    ZErrno err;
-    log_error(gc)("Failed to unlink file %s (%s)", filename, err.to_string());
-    return -1;
-  }
-
-  log_info(gc, init)("Heap backed by file: %s", filename);
-
-  return fd;
-}
-
-int ZBackingFile::create_fd(const char* name) const {
-  if (ZPath == NULL) {
-    // If the path is not explicitly specified, then we first try to create a memfd file
-    // instead of looking for a tmpfd/hugetlbfs mount point. Note that memfd_create() might
-    // not be supported at all (requires kernel >= 3.17), or it might not support large
-    // pages (requires kernel >= 4.14). If memfd_create() fails, then we try to create a
-    // file on an accessible tmpfs or hugetlbfs mount point.
-    const int fd = create_mem_fd(name);
-    if (fd != -1) {
-      return fd;
-    }
-
-    log_debug(gc, init)("Falling back to searching for an accessible mount point");
-  }
-
-  return create_file_fd(name);
-}
-
-bool ZBackingFile::is_initialized() const {
-  return _initialized;
-}
-
-int ZBackingFile::fd() const {
-  return _fd;
-}
-
-size_t ZBackingFile::size() const {
-  return _size;
-}
-
-size_t ZBackingFile::available() const {
-  return _available;
-}
-
-bool ZBackingFile::is_tmpfs() const {
-  return _filesystem == TMPFS_MAGIC;
-}
-
-bool ZBackingFile::is_hugetlbfs() const {
-  return _filesystem == HUGETLBFS_MAGIC;
-}
-
-bool ZBackingFile::tmpfs_supports_transparent_huge_pages() const {
-  // If the shmem_enabled file exists and is readable then we
-  // know the kernel supports transparent huge pages for tmpfs.
-  return access(ZFILENAME_SHMEM_ENABLED, R_OK) == 0;
-}
-
-ZErrno ZBackingFile::fallocate_compat_ftruncate(size_t size) const {
-  while (ftruncate(_fd, size) == -1) {
-    if (errno != EINTR) {
-      // Failed
-      return errno;
-    }
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate_compat_mmap(size_t offset, size_t length, bool touch) const {
-  // On hugetlbfs, mapping a file segment will fail immediately, without
-  // the need to touch the mapped pages first, if there aren't enough huge
-  // pages available to back the mapping.
-  void* const addr = mmap(0, length, PROT_READ|PROT_WRITE, MAP_SHARED, _fd, offset);
-  if (addr == MAP_FAILED) {
-    // Failed
-    return errno;
-  }
-
-  // Once mapped, the huge pages are only reserved. We need to touch them
-  // to associate them with the file segment. Note that we can not punch
-  // hole in file segments which only have reserved pages.
-  if (touch) {
-    char* const start = (char*)addr;
-    char* const end = start + length;
-    os::pretouch_memory(start, end, _block_size);
-  }
-
-  // Unmap again. From now on, the huge pages that were mapped are allocated
-  // to this file. There's no risk in getting SIGBUS when touching them.
-  if (munmap(addr, length) == -1) {
-    // Failed
-    return errno;
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate_compat_pwrite(size_t offset, size_t length) const {
-  uint8_t data = 0;
-
-  // Allocate backing memory by writing to each block
-  for (size_t pos = offset; pos < offset + length; pos += _block_size) {
-    if (pwrite(_fd, &data, sizeof(data), pos) == -1) {
-      // Failed
-      return errno;
-    }
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate_fill_hole_compat(size_t offset, size_t length) {
-  // fallocate(2) is only supported by tmpfs since Linux 3.5, and by hugetlbfs
-  // since Linux 4.3. When fallocate(2) is not supported we emulate it using
-  // ftruncate/pwrite (for tmpfs) or ftruncate/mmap/munmap (for hugetlbfs).
-
-  const size_t end = offset + length;
-  if (end > _size) {
-    // Increase file size
-    const ZErrno err = fallocate_compat_ftruncate(end);
-    if (err) {
-      // Failed
-      return err;
-    }
-  }
-
-  // Allocate backing memory
-  const ZErrno err = is_hugetlbfs() ? fallocate_compat_mmap(offset, length, false /* touch */)
-                                    : fallocate_compat_pwrite(offset, length);
-  if (err) {
-    if (end > _size) {
-      // Restore file size
-      fallocate_compat_ftruncate(_size);
-    }
-
-    // Failed
-    return err;
-  }
-
-  if (end > _size) {
-    // Record new file size
-    _size = end;
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate_fill_hole_syscall(size_t offset, size_t length) {
-  const int mode = 0; // Allocate
-  const int res = ZSyscall::fallocate(_fd, mode, offset, length);
-  if (res == -1) {
-    // Failed
-    return errno;
-  }
-
-  const size_t end = offset + length;
-  if (end > _size) {
-    // Record new file size
-    _size = end;
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate_fill_hole(size_t offset, size_t length) {
-  // Using compat mode is more efficient when allocating space on hugetlbfs.
-  // Note that allocating huge pages this way will only reserve them, and not
-  // associate them with segments of the file. We must guarantee that we at
-  // some point touch these segments, otherwise we can not punch hole in them.
-  if (z_fallocate_supported && !is_hugetlbfs()) {
-     const ZErrno err = fallocate_fill_hole_syscall(offset, length);
-     if (!err) {
-       // Success
-       return 0;
-     }
-
-     if (err != ENOSYS && err != EOPNOTSUPP) {
-       // Failed
-       return err;
-     }
-
-     // Not supported
-     log_debug(gc)("Falling back to fallocate() compatibility mode");
-     z_fallocate_supported = false;
-  }
-
-  return fallocate_fill_hole_compat(offset, length);
-}
-
-ZErrno ZBackingFile::fallocate_punch_hole(size_t offset, size_t length) {
-  if (is_hugetlbfs()) {
-    // We can only punch hole in pages that have been touched. Non-touched
-    // pages are only reserved, and not associated with any specific file
-    // segment. We don't know which pages have been previously touched, so
-    // we always touch them here to guarantee that we can punch hole.
-    const ZErrno err = fallocate_compat_mmap(offset, length, true /* touch */);
-    if (err) {
-      // Failed
-      return err;
-    }
-  }
-
-  const int mode = FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE;
-  if (ZSyscall::fallocate(_fd, mode, offset, length) == -1) {
-    // Failed
-    return errno;
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::split_and_fallocate(bool punch_hole, size_t offset, size_t length) {
-  // Try first half
-  const size_t offset0 = offset;
-  const size_t length0 = align_up(length / 2, _block_size);
-  const ZErrno err0 = fallocate(punch_hole, offset0, length0);
-  if (err0) {
-    return err0;
-  }
-
-  // Try second half
-  const size_t offset1 = offset0 + length0;
-  const size_t length1 = length - length0;
-  const ZErrno err1 = fallocate(punch_hole, offset1, length1);
-  if (err1) {
-    return err1;
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate(bool punch_hole, size_t offset, size_t length) {
-  assert(is_aligned(offset, _block_size), "Invalid offset");
-  assert(is_aligned(length, _block_size), "Invalid length");
-
-  const ZErrno err = punch_hole ? fallocate_punch_hole(offset, length) : fallocate_fill_hole(offset, length);
-  if (err == EINTR && length > _block_size) {
-    // Calling fallocate(2) with a large length can take a long time to
-    // complete. When running profilers, such as VTune, this syscall will
-    // be constantly interrupted by signals. Expanding the file in smaller
-    // steps avoids this problem.
-    return split_and_fallocate(punch_hole, offset, length);
-  }
-
-  return err;
-}
-
-bool ZBackingFile::commit_inner(size_t offset, size_t length) {
-  log_trace(gc, heap)("Committing memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)",
-                      offset / M, (offset + length) / M, length / M);
-
-retry:
-  const ZErrno err = fallocate(false /* punch_hole */, offset, length);
-  if (err) {
-    if (err == ENOSPC && !is_init_completed() && is_hugetlbfs() && z_fallocate_hugetlbfs_attempts-- > 0) {
-      // If we fail to allocate during initialization, due to lack of space on
-      // the hugetlbfs filesystem, then we wait and retry a few times before
-      // giving up. Otherwise there is a risk that running JVMs back-to-back
-      // will fail, since there is a delay between process termination and the
-      // huge pages owned by that process being returned to the huge page pool
-      // and made available for new allocations.
-      log_debug(gc, init)("Failed to commit memory (%s), retrying", err.to_string());
-
-      // Wait and retry in one second, in the hope that huge pages will be
-      // available by then.
-      sleep(1);
-      goto retry;
-    }
-
-    // Failed
-    log_error(gc)("Failed to commit memory (%s)", err.to_string());
-    return false;
-  }
-
-  // Success
-  return true;
-}
-
-size_t ZBackingFile::commit(size_t offset, size_t length) {
-  // Try to commit the whole region
-  if (commit_inner(offset, length)) {
-    // Success
-    return length;
-  }
-
-  // Failed, try to commit as much as possible
-  size_t start = offset;
-  size_t end = offset + length;
-
-  for (;;) {
-    length = align_down((end - start) / 2, ZGranuleSize);
-    if (length < ZGranuleSize) {
-      // Done, don't commit more
-      return start - offset;
-    }
-
-    if (commit_inner(start, length)) {
-      // Success, try commit more
-      start += length;
-    } else {
-      // Failed, try commit less
-      end -= length;
-    }
-  }
-}
-
-size_t ZBackingFile::uncommit(size_t offset, size_t length) {
-  log_trace(gc, heap)("Uncommitting memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)",
-                      offset / M, (offset + length) / M, length / M);
-
-  const ZErrno err = fallocate(true /* punch_hole */, offset, length);
-  if (err) {
-    log_error(gc)("Failed to uncommit memory (%s)", err.to_string());
-    return 0;
-  }
-
-  return length;
-}
--- a/src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingFile_linux_aarch64.hpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,73 +0,0 @@
-/*
- * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#ifndef OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGFILE_LINUX_AARCH64_HPP
-#define OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGFILE_LINUX_AARCH64_HPP
-
-#include "memory/allocation.hpp"
-
-class ZErrno;
-
-class ZBackingFile {
-private:
-  int      _fd;
-  size_t   _size;
-  uint64_t _filesystem;
-  size_t   _block_size;
-  size_t   _available;
-  bool     _initialized;
-
-  int create_mem_fd(const char* name) const;
-  int create_file_fd(const char* name) const;
-  int create_fd(const char* name) const;
-
-  bool is_tmpfs() const;
-  bool is_hugetlbfs() const;
-  bool tmpfs_supports_transparent_huge_pages() const;
-
-  ZErrno fallocate_compat_ftruncate(size_t size) const;
-  ZErrno fallocate_compat_mmap(size_t offset, size_t length, bool reserve_only) const;
-  ZErrno fallocate_compat_pwrite(size_t offset, size_t length) const;
-  ZErrno fallocate_fill_hole_compat(size_t offset, size_t length);
-  ZErrno fallocate_fill_hole_syscall(size_t offset, size_t length);
-  ZErrno fallocate_fill_hole(size_t offset, size_t length);
-  ZErrno fallocate_punch_hole(size_t offset, size_t length);
-  ZErrno split_and_fallocate(bool punch_hole, size_t offset, size_t length);
-  ZErrno fallocate(bool punch_hole, size_t offset, size_t length);
-
-  bool commit_inner(size_t offset, size_t length);
-
-public:
-  ZBackingFile();
-
-  bool is_initialized() const;
-
-  int fd() const;
-  size_t size() const;
-  size_t available() const;
-
-  size_t commit(size_t offset, size_t length);
-  size_t uncommit(size_t offset, size_t length);
-};
-
-#endif // OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGFILE_LINUX_AARCH64_HPP
--- a/src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingPath_linux_aarch64.cpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,149 +0,0 @@
-/*
- * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#include "precompiled.hpp"
-#include "gc/z/zArray.inline.hpp"
-#include "zBackingPath_linux_aarch64.hpp"
-#include "gc/z/zErrno.hpp"
-#include "logging/log.hpp"
-
-#include <stdio.h>
-#include <unistd.h>
-
-// Mount information, see proc(5) for more details.
-#define PROC_SELF_MOUNTINFO        "/proc/self/mountinfo"
-
-ZBackingPath::ZBackingPath(const char* filesystem, const char** preferred_mountpoints) {
-  if (ZPath != NULL) {
-    // Use specified path
-    _path = strdup(ZPath);
-  } else {
-    // Find suitable path
-    _path = find_mountpoint(filesystem, preferred_mountpoints);
-  }
-}
-
-ZBackingPath::~ZBackingPath() {
-  free(_path);
-  _path = NULL;
-}
-
-char* ZBackingPath::get_mountpoint(const char* line, const char* filesystem) const {
-  char* line_mountpoint = NULL;
-  char* line_filesystem = NULL;
-
-  // Parse line and return a newly allocated string containing the mount point if
-  // the line contains a matching filesystem and the mount point is accessible by
-  // the current user.
-  if (sscanf(line, "%*u %*u %*u:%*u %*s %ms %*[^-]- %ms", &line_mountpoint, &line_filesystem) != 2 ||
-      strcmp(line_filesystem, filesystem) != 0 ||
-      access(line_mountpoint, R_OK|W_OK|X_OK) != 0) {
-    // Not a matching or accessible filesystem
-    free(line_mountpoint);
-    line_mountpoint = NULL;
-  }
-
-  free(line_filesystem);
-
-  return line_mountpoint;
-}
-
-void ZBackingPath::get_mountpoints(const char* filesystem, ZArray<char*>* mountpoints) const {
-  FILE* fd = fopen(PROC_SELF_MOUNTINFO, "r");
-  if (fd == NULL) {
-    ZErrno err;
-    log_error(gc)("Failed to open %s: %s", PROC_SELF_MOUNTINFO, err.to_string());
-    return;
-  }
-
-  char* line = NULL;
-  size_t length = 0;
-
-  while (getline(&line, &length, fd) != -1) {
-    char* const mountpoint = get_mountpoint(line, filesystem);
-    if (mountpoint != NULL) {
-      mountpoints->add(mountpoint);
-    }
-  }
-
-  free(line);
-  fclose(fd);
-}
-
-void ZBackingPath::free_mountpoints(ZArray<char*>* mountpoints) const {
-  ZArrayIterator<char*> iter(mountpoints);
-  for (char* mountpoint; iter.next(&mountpoint);) {
-    free(mountpoint);
-  }
-  mountpoints->clear();
-}
-
-char* ZBackingPath::find_preferred_mountpoint(const char* filesystem,
-                                              ZArray<char*>* mountpoints,
-                                              const char** preferred_mountpoints) const {
-  // Find preferred mount point
-  ZArrayIterator<char*> iter1(mountpoints);
-  for (char* mountpoint; iter1.next(&mountpoint);) {
-    for (const char** preferred = preferred_mountpoints; *preferred != NULL; preferred++) {
-      if (!strcmp(mountpoint, *preferred)) {
-        // Preferred mount point found
-        return strdup(mountpoint);
-      }
-    }
-  }
-
-  // Preferred mount point not found
-  log_error(gc)("More than one %s filesystem found:", filesystem);
-  ZArrayIterator<char*> iter2(mountpoints);
-  for (char* mountpoint; iter2.next(&mountpoint);) {
-    log_error(gc)("  %s", mountpoint);
-  }
-
-  return NULL;
-}
-
-char* ZBackingPath::find_mountpoint(const char* filesystem, const char** preferred_mountpoints) const {
-  char* path = NULL;
-  ZArray<char*> mountpoints;
-
-  get_mountpoints(filesystem, &mountpoints);
-
-  if (mountpoints.size() == 0) {
-    // No mount point found
-    log_error(gc)("Failed to find an accessible %s filesystem", filesystem);
-  } else if (mountpoints.size() == 1) {
-    // One mount point found
-    path = strdup(mountpoints.at(0));
-  } else {
-    // More than one mount point found
-    path = find_preferred_mountpoint(filesystem, &mountpoints, preferred_mountpoints);
-  }
-
-  free_mountpoints(&mountpoints);
-
-  return path;
-}
-
-const char* ZBackingPath::get() const {
-  return _path;
-}
--- a/src/hotspot/os_cpu/linux_aarch64/gc/z/zBackingPath_linux_aarch64.hpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,52 +0,0 @@
-/*
- * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#ifndef OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGPATH_LINUX_AARCH64_HPP
-#define OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGPATH_LINUX_AARCH64_HPP
-
-#include "gc/z/zArray.hpp"
-#include "memory/allocation.hpp"
-
-class ZBackingPath : public StackObj {
-private:
-  char* _path;
-
-  char* get_mountpoint(const char* line,
-                       const char* filesystem) const;
-  void get_mountpoints(const char* filesystem,
-                       ZArray<char*>* mountpoints) const;
-  void free_mountpoints(ZArray<char*>* mountpoints) const;
-  char* find_preferred_mountpoint(const char* filesystem,
-                                  ZArray<char*>* mountpoints,
-                                  const char** preferred_mountpoints) const;
-  char* find_mountpoint(const char* filesystem,
-                        const char** preferred_mountpoints) const;
-
-public:
-  ZBackingPath(const char* filesystem, const char** preferred_mountpoints);
-  ~ZBackingPath();
-
-  const char* get() const;
-};
-
-#endif // OS_CPU_LINUX_AARCH64_GC_Z_ZBACKINGPATH_LINUX_AARCH64_HPP
--- a/src/hotspot/os_cpu/linux_aarch64/gc/z/zPhysicalMemoryBacking_linux_aarch64.cpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,334 +0,0 @@
-/*
- * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#include "precompiled.hpp"
-#include "gc/z/zAddress.inline.hpp"
-#include "gc/z/zBackingFile_linux_aarch64.hpp"
-#include "gc/z/zErrno.hpp"
-#include "gc/z/zGlobals.hpp"
-#include "gc/z/zLargePages.inline.hpp"
-#include "gc/z/zMemory.hpp"
-#include "gc/z/zNUMA.hpp"
-#include "gc/z/zPhysicalMemory.inline.hpp"
-#include "gc/z/zPhysicalMemoryBacking_linux_aarch64.hpp"
-#include "logging/log.hpp"
-#include "runtime/globals.hpp"
-#include "runtime/init.hpp"
-#include "runtime/os.hpp"
-#include "utilities/align.hpp"
-#include "utilities/debug.hpp"
-
-#include <stdio.h>
-#include <sys/mman.h>
-#include <sys/types.h>
-
-//
-// Support for building on older Linux systems
-//
-
-// madvise(2) flags
-#ifndef MADV_HUGEPAGE
-#define MADV_HUGEPAGE                        14
-#endif
-
-// Proc file entry for max map mount
-#define ZFILENAME_PROC_MAX_MAP_COUNT         "/proc/sys/vm/max_map_count"
-
-bool ZPhysicalMemoryBacking::is_initialized() const {
-  return _file.is_initialized();
-}
-
-void ZPhysicalMemoryBacking::warn_available_space(size_t max) const {
-  // Note that the available space on a tmpfs or a hugetlbfs filesystem
-  // will be zero if no size limit was specified when it was mounted.
-  const size_t available = _file.available();
-  if (available == 0) {
-    // No size limit set, skip check
-    log_info(gc, init)("Available space on backing filesystem: N/A");
-    return;
-  }
-
-  log_info(gc, init)("Available space on backing filesystem: " SIZE_FORMAT "M", available / M);
-
-  // Warn if the filesystem doesn't currently have enough space available to hold
-  // the max heap size. The max heap size will be capped if we later hit this limit
-  // when trying to expand the heap.
-  if (available < max) {
-    log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****");
-    log_warning(gc)("Not enough space available on the backing filesystem to hold the current max Java heap");
-    log_warning(gc)("size (" SIZE_FORMAT "M). Please adjust the size of the backing filesystem accordingly "
-                    "(available", max / M);
-    log_warning(gc)("space is currently " SIZE_FORMAT "M). Continuing execution with the current filesystem "
-                    "size could", available / M);
-    log_warning(gc)("lead to a premature OutOfMemoryError being thrown, due to failure to map memory.");
-  }
-}
-
-void ZPhysicalMemoryBacking::warn_max_map_count(size_t max) const {
-  const char* const filename = ZFILENAME_PROC_MAX_MAP_COUNT;
-  FILE* const file = fopen(filename, "r");
-  if (file == NULL) {
-    // Failed to open file, skip check
-    log_debug(gc, init)("Failed to open %s", filename);
-    return;
-  }
-
-  size_t actual_max_map_count = 0;
-  const int result = fscanf(file, SIZE_FORMAT, &actual_max_map_count);
-  fclose(file);
-  if (result != 1) {
-    // Failed to read file, skip check
-    log_debug(gc, init)("Failed to read %s", filename);
-    return;
-  }
-
-  // The required max map count is impossible to calculate exactly since subsystems
-  // other than ZGC are also creating memory mappings, and we have no control over that.
-  // However, ZGC tends to create the most mappings and dominate the total count.
-  // In the worst cases, ZGC will map each granule three times, i.e. once per heap view.
-  // We speculate that we need another 20% to allow for non-ZGC subsystems to map memory.
-  const size_t required_max_map_count = (max / ZGranuleSize) * 3 * 1.2;
-  if (actual_max_map_count < required_max_map_count) {
-    log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****");
-    log_warning(gc)("The system limit on number of memory mappings per process might be too low for the given");
-    log_warning(gc)("max Java heap size (" SIZE_FORMAT "M). Please adjust %s to allow for at",
-                    max / M, filename);
-    log_warning(gc)("least " SIZE_FORMAT " mappings (current limit is " SIZE_FORMAT "). Continuing execution "
-                    "with the current", required_max_map_count, actual_max_map_count);
-    log_warning(gc)("limit could lead to a fatal error, due to failure to map memory.");
-  }
-}
-
-void ZPhysicalMemoryBacking::warn_commit_limits(size_t max) const {
-  // Warn if available space is too low
-  warn_available_space(max);
-
-  // Warn if max map count is too low
-  warn_max_map_count(max);
-}
-
-bool ZPhysicalMemoryBacking::supports_uncommit() {
-  assert(!is_init_completed(), "Invalid state");
-  assert(_file.size() >= ZGranuleSize, "Invalid size");
-
-  // Test if uncommit is supported by uncommitting and then re-committing a granule
-  return commit(uncommit(ZGranuleSize)) == ZGranuleSize;
-}
-
-size_t ZPhysicalMemoryBacking::commit(size_t size) {
-  size_t committed = 0;
-
-  // Fill holes in the backing file
-  while (committed < size) {
-    size_t allocated = 0;
-    const size_t remaining = size - committed;
-    const uintptr_t start = _uncommitted.alloc_from_front_at_most(remaining, &allocated);
-    if (start == UINTPTR_MAX) {
-      // No holes to commit
-      break;
-    }
-
-    // Try commit hole
-    const size_t filled = _file.commit(start, allocated);
-    if (filled > 0) {
-      // Successful or partialy successful
-      _committed.free(start, filled);
-      committed += filled;
-    }
-    if (filled < allocated) {
-      // Failed or partialy failed
-      _uncommitted.free(start + filled, allocated - filled);
-      return committed;
-    }
-  }
-
-  // Expand backing file
-  if (committed < size) {
-    const size_t remaining = size - committed;
-    const uintptr_t start = _file.size();
-    const size_t expanded = _file.commit(start, remaining);
-    if (expanded > 0) {
-      // Successful or partialy successful
-      _committed.free(start, expanded);
-      committed += expanded;
-    }
-  }
-
-  return committed;
-}
-
-size_t ZPhysicalMemoryBacking::uncommit(size_t size) {
-  size_t uncommitted = 0;
-
-  // Punch holes in backing file
-  while (uncommitted < size) {
-    size_t allocated = 0;
-    const size_t remaining = size - uncommitted;
-    const uintptr_t start = _committed.alloc_from_back_at_most(remaining, &allocated);
-    assert(start != UINTPTR_MAX, "Allocation should never fail");
-
-    // Try punch hole
-    const size_t punched = _file.uncommit(start, allocated);
-    if (punched > 0) {
-      // Successful or partialy successful
-      _uncommitted.free(start, punched);
-      uncommitted += punched;
-    }
-    if (punched < allocated) {
-      // Failed or partialy failed
-      _committed.free(start + punched, allocated - punched);
-      return uncommitted;
-    }
-  }
-
-  return uncommitted;
-}
-
-ZPhysicalMemory ZPhysicalMemoryBacking::alloc(size_t size) {
-  assert(is_aligned(size, ZGranuleSize), "Invalid size");
-
-  ZPhysicalMemory pmem;
-
-  // Allocate segments
-  for (size_t allocated = 0; allocated < size; allocated += ZGranuleSize) {
-    const uintptr_t start = _committed.alloc_from_front(ZGranuleSize);
-    assert(start != UINTPTR_MAX, "Allocation should never fail");
-    pmem.add_segment(ZPhysicalMemorySegment(start, ZGranuleSize));
-  }
-
-  return pmem;
-}
-
-void ZPhysicalMemoryBacking::free(const ZPhysicalMemory& pmem) {
-  const size_t nsegments = pmem.nsegments();
-
-  // Free segments
-  for (size_t i = 0; i < nsegments; i++) {
-    const ZPhysicalMemorySegment& segment = pmem.segment(i);
-    _committed.free(segment.start(), segment.size());
-  }
-}
-
-void ZPhysicalMemoryBacking::map_failed(ZErrno err) const {
-  if (err == ENOMEM) {
-    fatal("Failed to map memory. Please check the system limit on number of "
-          "memory mappings allowed per process (see %s)", ZFILENAME_PROC_MAX_MAP_COUNT);
-  } else {
-    fatal("Failed to map memory (%s)", err.to_string());
-  }
-}
-
-void ZPhysicalMemoryBacking::advise_view(uintptr_t addr, size_t size, int advice) const {
-  if (madvise((void*)addr, size, advice) == -1) {
-    ZErrno err;
-    log_error(gc)("Failed to advise on memory (advice %d, %s)", advice, err.to_string());
-  }
-}
-
-void ZPhysicalMemoryBacking::pretouch_view(uintptr_t addr, size_t size) const {
-  const size_t page_size = ZLargePages::is_explicit() ? os::large_page_size() : os::vm_page_size();
-  os::pretouch_memory((void*)addr, (void*)(addr + size), page_size);
-}
-
-void ZPhysicalMemoryBacking::map_view(const ZPhysicalMemory& pmem, uintptr_t addr, bool pretouch) const {
-  const size_t nsegments = pmem.nsegments();
-  size_t size = 0;
-
-  // Map segments
-  for (size_t i = 0; i < nsegments; i++) {
-    const ZPhysicalMemorySegment& segment = pmem.segment(i);
-    const uintptr_t segment_addr = addr + size;
-    const void* const res = mmap((void*)segment_addr, segment.size(), PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, _file.fd(), segment.start());
-    if (res == MAP_FAILED) {
-      ZErrno err;
-      map_failed(err);
-    }
-
-    size += segment.size();
-  }
-
-  // Advise on use of transparent huge pages before touching it
-  if (ZLargePages::is_transparent()) {
-    advise_view(addr, size, MADV_HUGEPAGE);
-  }
-
-  // NUMA interleave memory before touching it
-  ZNUMA::memory_interleave(addr, size);
-
-  // Pre-touch memory
-  if (pretouch) {
-    pretouch_view(addr, size);
-  }
-}
-
-void ZPhysicalMemoryBacking::unmap_view(const ZPhysicalMemory& pmem, uintptr_t addr) const {
-  // Note that we must keep the address space reservation intact and just detach
-  // the backing memory. For this reason we map a new anonymous, non-accessible
-  // and non-reserved page over the mapping instead of actually unmapping.
-  const void* const res = mmap((void*)addr, pmem.size(), PROT_NONE, MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, -1, 0);
-  if (res == MAP_FAILED) {
-    ZErrno err;
-    map_failed(err);
-  }
-}
-
-uintptr_t ZPhysicalMemoryBacking::nmt_address(uintptr_t offset) const {
-  // From an NMT point of view we treat the first heap view (marked0) as committed
-  return ZAddress::marked0(offset);
-}
-
-void ZPhysicalMemoryBacking::map(const ZPhysicalMemory& pmem, uintptr_t offset) const {
-  if (ZVerifyViews) {
-    // Map good view
-    map_view(pmem, ZAddress::good(offset), AlwaysPreTouch);
-  } else {
-    // Map all views
-    map_view(pmem, ZAddress::marked0(offset), AlwaysPreTouch);
-    map_view(pmem, ZAddress::marked1(offset), AlwaysPreTouch);
-    map_view(pmem, ZAddress::remapped(offset), AlwaysPreTouch);
-  }
-}
-
-void ZPhysicalMemoryBacking::unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const {
-  if (ZVerifyViews) {
-    // Unmap good view
-    unmap_view(pmem, ZAddress::good(offset));
-  } else {
-    // Unmap all views
-    unmap_view(pmem, ZAddress::marked0(offset));
-    unmap_view(pmem, ZAddress::marked1(offset));
-    unmap_view(pmem, ZAddress::remapped(offset));
-  }
-}
-
-void ZPhysicalMemoryBacking::debug_map(const ZPhysicalMemory& pmem, uintptr_t offset) const {
-  // Map good view
-  assert(ZVerifyViews, "Should be enabled");
-  map_view(pmem, ZAddress::good(offset), false /* pretouch */);
-}
-
-void ZPhysicalMemoryBacking::debug_unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const {
-  // Unmap good view
-  assert(ZVerifyViews, "Should be enabled");
-  unmap_view(pmem, ZAddress::good(offset));
-}
--- a/src/hotspot/os_cpu/linux_aarch64/gc/z/zPhysicalMemoryBacking_linux_aarch64.hpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,70 +0,0 @@
-/*
- * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#ifndef OS_CPU_LINUX_AARCH64_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_AARCH64_HPP
-#define OS_CPU_LINUX_AARCH64_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_AARCH64_HPP
-
-#include "gc/z/zBackingFile_linux_aarch64.hpp"
-#include "gc/z/zMemory.hpp"
-
-class ZErrno;
-class ZPhysicalMemory;
-
-class ZPhysicalMemoryBacking {
-private:
-  ZBackingFile   _file;
-  ZMemoryManager _committed;
-  ZMemoryManager _uncommitted;
-
-  void warn_available_space(size_t max) const;
-  void warn_max_map_count(size_t max) const;
-
-  void map_failed(ZErrno err) const;
-
-  void advise_view(uintptr_t addr, size_t size, int advice) const;
-  void pretouch_view(uintptr_t addr, size_t size) const;
-  void map_view(const ZPhysicalMemory& pmem, uintptr_t addr, bool pretouch) const;
-  void unmap_view(const ZPhysicalMemory& pmem, uintptr_t addr) const;
-
-public:
-  bool is_initialized() const;
-
-  void warn_commit_limits(size_t max) const;
-  bool supports_uncommit();
-
-  size_t commit(size_t size);
-  size_t uncommit(size_t size);
-
-  ZPhysicalMemory alloc(size_t size);
-  void free(const ZPhysicalMemory& pmem);
-
-  uintptr_t nmt_address(uintptr_t offset) const;
-
-  void map(const ZPhysicalMemory& pmem, uintptr_t offset) const;
-  void unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const;
-
-  void debug_map(const ZPhysicalMemory& pmem, uintptr_t offset) const;
-  void debug_unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const;
-};
-
-#endif // OS_CPU_LINUX_AARCH64_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_AARCH64_HPP
--- a/src/hotspot/os_cpu/linux_x86/gc/z/zBackingFile_linux_x86.cpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,574 +0,0 @@
-/*
- * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#include "precompiled.hpp"
-#include "gc/z/zArray.inline.hpp"
-#include "gc/z/zBackingFile_linux_x86.hpp"
-#include "gc/z/zBackingPath_linux_x86.hpp"
-#include "gc/z/zErrno.hpp"
-#include "gc/z/zGlobals.hpp"
-#include "gc/z/zLargePages.inline.hpp"
-#include "gc/z/zSyscall_linux.hpp"
-#include "logging/log.hpp"
-#include "runtime/init.hpp"
-#include "runtime/os.hpp"
-#include "utilities/align.hpp"
-#include "utilities/debug.hpp"
-
-#include <fcntl.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include <sys/statfs.h>
-#include <sys/types.h>
-#include <unistd.h>
-
-//
-// Support for building on older Linux systems
-//
-
-// memfd_create(2) flags
-#ifndef MFD_CLOEXEC
-#define MFD_CLOEXEC                      0x0001U
-#endif
-#ifndef MFD_HUGETLB
-#define MFD_HUGETLB                      0x0004U
-#endif
-
-// open(2) flags
-#ifndef O_CLOEXEC
-#define O_CLOEXEC                        02000000
-#endif
-#ifndef O_TMPFILE
-#define O_TMPFILE                        (020000000 | O_DIRECTORY)
-#endif
-
-// fallocate(2) flags
-#ifndef FALLOC_FL_KEEP_SIZE
-#define FALLOC_FL_KEEP_SIZE              0x01
-#endif
-#ifndef FALLOC_FL_PUNCH_HOLE
-#define FALLOC_FL_PUNCH_HOLE             0x02
-#endif
-
-// Filesystem types, see statfs(2)
-#ifndef TMPFS_MAGIC
-#define TMPFS_MAGIC                      0x01021994
-#endif
-#ifndef HUGETLBFS_MAGIC
-#define HUGETLBFS_MAGIC                  0x958458f6
-#endif
-
-// Filesystem names
-#define ZFILESYSTEM_TMPFS                "tmpfs"
-#define ZFILESYSTEM_HUGETLBFS            "hugetlbfs"
-
-// Sysfs file for transparent huge page on tmpfs
-#define ZFILENAME_SHMEM_ENABLED          "/sys/kernel/mm/transparent_hugepage/shmem_enabled"
-
-// Java heap filename
-#define ZFILENAME_HEAP                   "java_heap"
-
-// Preferred tmpfs mount points, ordered by priority
-static const char* z_preferred_tmpfs_mountpoints[] = {
-  "/dev/shm",
-  "/run/shm",
-  NULL
-};
-
-// Preferred hugetlbfs mount points, ordered by priority
-static const char* z_preferred_hugetlbfs_mountpoints[] = {
-  "/dev/hugepages",
-  "/hugepages",
-  NULL
-};
-
-static int z_fallocate_hugetlbfs_attempts = 3;
-static bool z_fallocate_supported = true;
-
-ZBackingFile::ZBackingFile() :
-    _fd(-1),
-    _size(0),
-    _filesystem(0),
-    _block_size(0),
-    _available(0),
-    _initialized(false) {
-
-  // Create backing file
-  _fd = create_fd(ZFILENAME_HEAP);
-  if (_fd == -1) {
-    return;
-  }
-
-  // Get filesystem statistics
-  struct statfs buf;
-  if (fstatfs(_fd, &buf) == -1) {
-    ZErrno err;
-    log_error(gc)("Failed to determine filesystem type for backing file (%s)", err.to_string());
-    return;
-  }
-
-  _filesystem = buf.f_type;
-  _block_size = buf.f_bsize;
-  _available = buf.f_bavail * _block_size;
-
-  // Make sure we're on a supported filesystem
-  if (!is_tmpfs() && !is_hugetlbfs()) {
-    log_error(gc)("Backing file must be located on a %s or a %s filesystem",
-                  ZFILESYSTEM_TMPFS, ZFILESYSTEM_HUGETLBFS);
-    return;
-  }
-
-  // Make sure the filesystem type matches requested large page type
-  if (ZLargePages::is_transparent() && !is_tmpfs()) {
-    log_error(gc)("-XX:+UseTransparentHugePages can only be enable when using a %s filesystem",
-                  ZFILESYSTEM_TMPFS);
-    return;
-  }
-
-  if (ZLargePages::is_transparent() && !tmpfs_supports_transparent_huge_pages()) {
-    log_error(gc)("-XX:+UseTransparentHugePages on a %s filesystem not supported by kernel",
-                  ZFILESYSTEM_TMPFS);
-    return;
-  }
-
-  if (ZLargePages::is_explicit() && !is_hugetlbfs()) {
-    log_error(gc)("-XX:+UseLargePages (without -XX:+UseTransparentHugePages) can only be enabled "
-                  "when using a %s filesystem", ZFILESYSTEM_HUGETLBFS);
-    return;
-  }
-
-  if (!ZLargePages::is_explicit() && is_hugetlbfs()) {
-    log_error(gc)("-XX:+UseLargePages must be enabled when using a %s filesystem",
-                  ZFILESYSTEM_HUGETLBFS);
-    return;
-  }
-
-  const size_t expected_block_size = is_tmpfs() ? os::vm_page_size() : os::large_page_size();
-  if (expected_block_size != _block_size) {
-    log_error(gc)("%s filesystem has unexpected block size " SIZE_FORMAT " (expected " SIZE_FORMAT ")",
-                  is_tmpfs() ? ZFILESYSTEM_TMPFS : ZFILESYSTEM_HUGETLBFS, _block_size, expected_block_size);
-    return;
-  }
-
-  // Successfully initialized
-  _initialized = true;
-}
-
-int ZBackingFile::create_mem_fd(const char* name) const {
-  // Create file name
-  char filename[PATH_MAX];
-  snprintf(filename, sizeof(filename), "%s%s", name, ZLargePages::is_explicit() ? ".hugetlb" : "");
-
-  // Create file
-  const int extra_flags = ZLargePages::is_explicit() ? MFD_HUGETLB : 0;
-  const int fd = ZSyscall::memfd_create(filename, MFD_CLOEXEC | extra_flags);
-  if (fd == -1) {
-    ZErrno err;
-    log_debug(gc, init)("Failed to create memfd file (%s)",
-                        ((ZLargePages::is_explicit() && err == EINVAL) ? "Hugepages not supported" : err.to_string()));
-    return -1;
-  }
-
-  log_info(gc, init)("Heap backed by file: /memfd:%s", filename);
-
-  return fd;
-}
-
-int ZBackingFile::create_file_fd(const char* name) const {
-  const char* const filesystem = ZLargePages::is_explicit()
-                                 ? ZFILESYSTEM_HUGETLBFS
-                                 : ZFILESYSTEM_TMPFS;
-  const char** const preferred_mountpoints = ZLargePages::is_explicit()
-                                             ? z_preferred_hugetlbfs_mountpoints
-                                             : z_preferred_tmpfs_mountpoints;
-
-  // Find mountpoint
-  ZBackingPath path(filesystem, preferred_mountpoints);
-  if (path.get() == NULL) {
-    log_error(gc)("Use -XX:ZPath to specify the path to a %s filesystem", filesystem);
-    return -1;
-  }
-
-  // Try to create an anonymous file using the O_TMPFILE flag. Note that this
-  // flag requires kernel >= 3.11. If this fails we fall back to open/unlink.
-  const int fd_anon = os::open(path.get(), O_TMPFILE|O_EXCL|O_RDWR|O_CLOEXEC, S_IRUSR|S_IWUSR);
-  if (fd_anon == -1) {
-    ZErrno err;
-    log_debug(gc, init)("Failed to create anonymous file in %s (%s)", path.get(),
-                        (err == EINVAL ? "Not supported" : err.to_string()));
-  } else {
-    // Get inode number for anonymous file
-    struct stat stat_buf;
-    if (fstat(fd_anon, &stat_buf) == -1) {
-      ZErrno err;
-      log_error(gc)("Failed to determine inode number for anonymous file (%s)", err.to_string());
-      return -1;
-    }
-
-    log_info(gc, init)("Heap backed by file: %s/#" UINT64_FORMAT, path.get(), (uint64_t)stat_buf.st_ino);
-
-    return fd_anon;
-  }
-
-  log_debug(gc, init)("Falling back to open/unlink");
-
-  // Create file name
-  char filename[PATH_MAX];
-  snprintf(filename, sizeof(filename), "%s/%s.%d", path.get(), name, os::current_process_id());
-
-  // Create file
-  const int fd = os::open(filename, O_CREAT|O_EXCL|O_RDWR|O_CLOEXEC, S_IRUSR|S_IWUSR);
-  if (fd == -1) {
-    ZErrno err;
-    log_error(gc)("Failed to create file %s (%s)", filename, err.to_string());
-    return -1;
-  }
-
-  // Unlink file
-  if (unlink(filename) == -1) {
-    ZErrno err;
-    log_error(gc)("Failed to unlink file %s (%s)", filename, err.to_string());
-    return -1;
-  }
-
-  log_info(gc, init)("Heap backed by file: %s", filename);
-
-  return fd;
-}
-
-int ZBackingFile::create_fd(const char* name) const {
-  if (ZPath == NULL) {
-    // If the path is not explicitly specified, then we first try to create a memfd file
-    // instead of looking for a tmpfd/hugetlbfs mount point. Note that memfd_create() might
-    // not be supported at all (requires kernel >= 3.17), or it might not support large
-    // pages (requires kernel >= 4.14). If memfd_create() fails, then we try to create a
-    // file on an accessible tmpfs or hugetlbfs mount point.
-    const int fd = create_mem_fd(name);
-    if (fd != -1) {
-      return fd;
-    }
-
-    log_debug(gc, init)("Falling back to searching for an accessible mount point");
-  }
-
-  return create_file_fd(name);
-}
-
-bool ZBackingFile::is_initialized() const {
-  return _initialized;
-}
-
-int ZBackingFile::fd() const {
-  return _fd;
-}
-
-size_t ZBackingFile::size() const {
-  return _size;
-}
-
-size_t ZBackingFile::available() const {
-  return _available;
-}
-
-bool ZBackingFile::is_tmpfs() const {
-  return _filesystem == TMPFS_MAGIC;
-}
-
-bool ZBackingFile::is_hugetlbfs() const {
-  return _filesystem == HUGETLBFS_MAGIC;
-}
-
-bool ZBackingFile::tmpfs_supports_transparent_huge_pages() const {
-  // If the shmem_enabled file exists and is readable then we
-  // know the kernel supports transparent huge pages for tmpfs.
-  return access(ZFILENAME_SHMEM_ENABLED, R_OK) == 0;
-}
-
-ZErrno ZBackingFile::fallocate_compat_ftruncate(size_t size) const {
-  while (ftruncate(_fd, size) == -1) {
-    if (errno != EINTR) {
-      // Failed
-      return errno;
-    }
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate_compat_mmap(size_t offset, size_t length, bool touch) const {
-  // On hugetlbfs, mapping a file segment will fail immediately, without
-  // the need to touch the mapped pages first, if there aren't enough huge
-  // pages available to back the mapping.
-  void* const addr = mmap(0, length, PROT_READ|PROT_WRITE, MAP_SHARED, _fd, offset);
-  if (addr == MAP_FAILED) {
-    // Failed
-    return errno;
-  }
-
-  // Once mapped, the huge pages are only reserved. We need to touch them
-  // to associate them with the file segment. Note that we can not punch
-  // hole in file segments which only have reserved pages.
-  if (touch) {
-    char* const start = (char*)addr;
-    char* const end = start + length;
-    os::pretouch_memory(start, end, _block_size);
-  }
-
-  // Unmap again. From now on, the huge pages that were mapped are allocated
-  // to this file. There's no risk in getting SIGBUS when touching them.
-  if (munmap(addr, length) == -1) {
-    // Failed
-    return errno;
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate_compat_pwrite(size_t offset, size_t length) const {
-  uint8_t data = 0;
-
-  // Allocate backing memory by writing to each block
-  for (size_t pos = offset; pos < offset + length; pos += _block_size) {
-    if (pwrite(_fd, &data, sizeof(data), pos) == -1) {
-      // Failed
-      return errno;
-    }
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate_fill_hole_compat(size_t offset, size_t length) {
-  // fallocate(2) is only supported by tmpfs since Linux 3.5, and by hugetlbfs
-  // since Linux 4.3. When fallocate(2) is not supported we emulate it using
-  // ftruncate/pwrite (for tmpfs) or ftruncate/mmap/munmap (for hugetlbfs).
-
-  const size_t end = offset + length;
-  if (end > _size) {
-    // Increase file size
-    const ZErrno err = fallocate_compat_ftruncate(end);
-    if (err) {
-      // Failed
-      return err;
-    }
-  }
-
-  // Allocate backing memory
-  const ZErrno err = is_hugetlbfs() ? fallocate_compat_mmap(offset, length, false /* touch */)
-                                    : fallocate_compat_pwrite(offset, length);
-  if (err) {
-    if (end > _size) {
-      // Restore file size
-      fallocate_compat_ftruncate(_size);
-    }
-
-    // Failed
-    return err;
-  }
-
-  if (end > _size) {
-    // Record new file size
-    _size = end;
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate_fill_hole_syscall(size_t offset, size_t length) {
-  const int mode = 0; // Allocate
-  const int res = ZSyscall::fallocate(_fd, mode, offset, length);
-  if (res == -1) {
-    // Failed
-    return errno;
-  }
-
-  const size_t end = offset + length;
-  if (end > _size) {
-    // Record new file size
-    _size = end;
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate_fill_hole(size_t offset, size_t length) {
-  // Using compat mode is more efficient when allocating space on hugetlbfs.
-  // Note that allocating huge pages this way will only reserve them, and not
-  // associate them with segments of the file. We must guarantee that we at
-  // some point touch these segments, otherwise we can not punch hole in them.
-  if (z_fallocate_supported && !is_hugetlbfs()) {
-     const ZErrno err = fallocate_fill_hole_syscall(offset, length);
-     if (!err) {
-       // Success
-       return 0;
-     }
-
-     if (err != ENOSYS && err != EOPNOTSUPP) {
-       // Failed
-       return err;
-     }
-
-     // Not supported
-     log_debug(gc)("Falling back to fallocate() compatibility mode");
-     z_fallocate_supported = false;
-  }
-
-  return fallocate_fill_hole_compat(offset, length);
-}
-
-ZErrno ZBackingFile::fallocate_punch_hole(size_t offset, size_t length) {
-  if (is_hugetlbfs()) {
-    // We can only punch hole in pages that have been touched. Non-touched
-    // pages are only reserved, and not associated with any specific file
-    // segment. We don't know which pages have been previously touched, so
-    // we always touch them here to guarantee that we can punch hole.
-    const ZErrno err = fallocate_compat_mmap(offset, length, true /* touch */);
-    if (err) {
-      // Failed
-      return err;
-    }
-  }
-
-  const int mode = FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE;
-  if (ZSyscall::fallocate(_fd, mode, offset, length) == -1) {
-    // Failed
-    return errno;
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::split_and_fallocate(bool punch_hole, size_t offset, size_t length) {
-  // Try first half
-  const size_t offset0 = offset;
-  const size_t length0 = align_up(length / 2, _block_size);
-  const ZErrno err0 = fallocate(punch_hole, offset0, length0);
-  if (err0) {
-    return err0;
-  }
-
-  // Try second half
-  const size_t offset1 = offset0 + length0;
-  const size_t length1 = length - length0;
-  const ZErrno err1 = fallocate(punch_hole, offset1, length1);
-  if (err1) {
-    return err1;
-  }
-
-  // Success
-  return 0;
-}
-
-ZErrno ZBackingFile::fallocate(bool punch_hole, size_t offset, size_t length) {
-  assert(is_aligned(offset, _block_size), "Invalid offset");
-  assert(is_aligned(length, _block_size), "Invalid length");
-
-  const ZErrno err = punch_hole ? fallocate_punch_hole(offset, length) : fallocate_fill_hole(offset, length);
-  if (err == EINTR && length > _block_size) {
-    // Calling fallocate(2) with a large length can take a long time to
-    // complete. When running profilers, such as VTune, this syscall will
-    // be constantly interrupted by signals. Expanding the file in smaller
-    // steps avoids this problem.
-    return split_and_fallocate(punch_hole, offset, length);
-  }
-
-  return err;
-}
-
-bool ZBackingFile::commit_inner(size_t offset, size_t length) {
-  log_trace(gc, heap)("Committing memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)",
-                      offset / M, (offset + length) / M, length / M);
-
-retry:
-  const ZErrno err = fallocate(false /* punch_hole */, offset, length);
-  if (err) {
-    if (err == ENOSPC && !is_init_completed() && is_hugetlbfs() && z_fallocate_hugetlbfs_attempts-- > 0) {
-      // If we fail to allocate during initialization, due to lack of space on
-      // the hugetlbfs filesystem, then we wait and retry a few times before
-      // giving up. Otherwise there is a risk that running JVMs back-to-back
-      // will fail, since there is a delay between process termination and the
-      // huge pages owned by that process being returned to the huge page pool
-      // and made available for new allocations.
-      log_debug(gc, init)("Failed to commit memory (%s), retrying", err.to_string());
-
-      // Wait and retry in one second, in the hope that huge pages will be
-      // available by then.
-      sleep(1);
-      goto retry;
-    }
-
-    // Failed
-    log_error(gc)("Failed to commit memory (%s)", err.to_string());
-    return false;
-  }
-
-  // Success
-  return true;
-}
-
-size_t ZBackingFile::commit(size_t offset, size_t length) {
-  // Try to commit the whole region
-  if (commit_inner(offset, length)) {
-    // Success
-    return length;
-  }
-
-  // Failed, try to commit as much as possible
-  size_t start = offset;
-  size_t end = offset + length;
-
-  for (;;) {
-    length = align_down((end - start) / 2, ZGranuleSize);
-    if (length < ZGranuleSize) {
-      // Done, don't commit more
-      return start - offset;
-    }
-
-    if (commit_inner(start, length)) {
-      // Success, try commit more
-      start += length;
-    } else {
-      // Failed, try commit less
-      end -= length;
-    }
-  }
-}
-
-size_t ZBackingFile::uncommit(size_t offset, size_t length) {
-  log_trace(gc, heap)("Uncommitting memory: " SIZE_FORMAT "M-" SIZE_FORMAT "M (" SIZE_FORMAT "M)",
-                      offset / M, (offset + length) / M, length / M);
-
-  const ZErrno err = fallocate(true /* punch_hole */, offset, length);
-  if (err) {
-    log_error(gc)("Failed to uncommit memory (%s)", err.to_string());
-    return 0;
-  }
-
-  return length;
-}
--- a/src/hotspot/os_cpu/linux_x86/gc/z/zBackingFile_linux_x86.hpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,73 +0,0 @@
-/*
- * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#ifndef OS_CPU_LINUX_X86_GC_Z_ZBACKINGFILE_LINUX_X86_HPP
-#define OS_CPU_LINUX_X86_GC_Z_ZBACKINGFILE_LINUX_X86_HPP
-
-#include "memory/allocation.hpp"
-
-class ZErrno;
-
-class ZBackingFile {
-private:
-  int      _fd;
-  size_t   _size;
-  uint64_t _filesystem;
-  size_t   _block_size;
-  size_t   _available;
-  bool     _initialized;
-
-  int create_mem_fd(const char* name) const;
-  int create_file_fd(const char* name) const;
-  int create_fd(const char* name) const;
-
-  bool is_tmpfs() const;
-  bool is_hugetlbfs() const;
-  bool tmpfs_supports_transparent_huge_pages() const;
-
-  ZErrno fallocate_compat_ftruncate(size_t size) const;
-  ZErrno fallocate_compat_mmap(size_t offset, size_t length, bool reserve_only) const;
-  ZErrno fallocate_compat_pwrite(size_t offset, size_t length) const;
-  ZErrno fallocate_fill_hole_compat(size_t offset, size_t length);
-  ZErrno fallocate_fill_hole_syscall(size_t offset, size_t length);
-  ZErrno fallocate_fill_hole(size_t offset, size_t length);
-  ZErrno fallocate_punch_hole(size_t offset, size_t length);
-  ZErrno split_and_fallocate(bool punch_hole, size_t offset, size_t length);
-  ZErrno fallocate(bool punch_hole, size_t offset, size_t length);
-
-  bool commit_inner(size_t offset, size_t length);
-
-public:
-  ZBackingFile();
-
-  bool is_initialized() const;
-
-  int fd() const;
-  size_t size() const;
-  size_t available() const;
-
-  size_t commit(size_t offset, size_t length);
-  size_t uncommit(size_t offset, size_t length);
-};
-
-#endif // OS_CPU_LINUX_X86_GC_Z_ZBACKINGFILE_LINUX_X86_HPP
--- a/src/hotspot/os_cpu/linux_x86/gc/z/zBackingPath_linux_x86.cpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,149 +0,0 @@
-/*
- * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#include "precompiled.hpp"
-#include "gc/z/zArray.inline.hpp"
-#include "gc/z/zBackingPath_linux_x86.hpp"
-#include "gc/z/zErrno.hpp"
-#include "logging/log.hpp"
-
-#include <stdio.h>
-#include <unistd.h>
-
-// Mount information, see proc(5) for more details.
-#define PROC_SELF_MOUNTINFO        "/proc/self/mountinfo"
-
-ZBackingPath::ZBackingPath(const char* filesystem, const char** preferred_mountpoints) {
-  if (ZPath != NULL) {
-    // Use specified path
-    _path = strdup(ZPath);
-  } else {
-    // Find suitable path
-    _path = find_mountpoint(filesystem, preferred_mountpoints);
-  }
-}
-
-ZBackingPath::~ZBackingPath() {
-  free(_path);
-  _path = NULL;
-}
-
-char* ZBackingPath::get_mountpoint(const char* line, const char* filesystem) const {
-  char* line_mountpoint = NULL;
-  char* line_filesystem = NULL;
-
-  // Parse line and return a newly allocated string containing the mount point if
-  // the line contains a matching filesystem and the mount point is accessible by
-  // the current user.
-  if (sscanf(line, "%*u %*u %*u:%*u %*s %ms %*[^-]- %ms", &line_mountpoint, &line_filesystem) != 2 ||
-      strcmp(line_filesystem, filesystem) != 0 ||
-      access(line_mountpoint, R_OK|W_OK|X_OK) != 0) {
-    // Not a matching or accessible filesystem
-    free(line_mountpoint);
-    line_mountpoint = NULL;
-  }
-
-  free(line_filesystem);
-
-  return line_mountpoint;
-}
-
-void ZBackingPath::get_mountpoints(const char* filesystem, ZArray<char*>* mountpoints) const {
-  FILE* fd = fopen(PROC_SELF_MOUNTINFO, "r");
-  if (fd == NULL) {
-    ZErrno err;
-    log_error(gc)("Failed to open %s: %s", PROC_SELF_MOUNTINFO, err.to_string());
-    return;
-  }
-
-  char* line = NULL;
-  size_t length = 0;
-
-  while (getline(&line, &length, fd) != -1) {
-    char* const mountpoint = get_mountpoint(line, filesystem);
-    if (mountpoint != NULL) {
-      mountpoints->add(mountpoint);
-    }
-  }
-
-  free(line);
-  fclose(fd);
-}
-
-void ZBackingPath::free_mountpoints(ZArray<char*>* mountpoints) const {
-  ZArrayIterator<char*> iter(mountpoints);
-  for (char* mountpoint; iter.next(&mountpoint);) {
-    free(mountpoint);
-  }
-  mountpoints->clear();
-}
-
-char* ZBackingPath::find_preferred_mountpoint(const char* filesystem,
-                                              ZArray<char*>* mountpoints,
-                                              const char** preferred_mountpoints) const {
-  // Find preferred mount point
-  ZArrayIterator<char*> iter1(mountpoints);
-  for (char* mountpoint; iter1.next(&mountpoint);) {
-    for (const char** preferred = preferred_mountpoints; *preferred != NULL; preferred++) {
-      if (!strcmp(mountpoint, *preferred)) {
-        // Preferred mount point found
-        return strdup(mountpoint);
-      }
-    }
-  }
-
-  // Preferred mount point not found
-  log_error(gc)("More than one %s filesystem found:", filesystem);
-  ZArrayIterator<char*> iter2(mountpoints);
-  for (char* mountpoint; iter2.next(&mountpoint);) {
-    log_error(gc)("  %s", mountpoint);
-  }
-
-  return NULL;
-}
-
-char* ZBackingPath::find_mountpoint(const char* filesystem, const char** preferred_mountpoints) const {
-  char* path = NULL;
-  ZArray<char*> mountpoints;
-
-  get_mountpoints(filesystem, &mountpoints);
-
-  if (mountpoints.size() == 0) {
-    // No mount point found
-    log_error(gc)("Failed to find an accessible %s filesystem", filesystem);
-  } else if (mountpoints.size() == 1) {
-    // One mount point found
-    path = strdup(mountpoints.at(0));
-  } else {
-    // More than one mount point found
-    path = find_preferred_mountpoint(filesystem, &mountpoints, preferred_mountpoints);
-  }
-
-  free_mountpoints(&mountpoints);
-
-  return path;
-}
-
-const char* ZBackingPath::get() const {
-  return _path;
-}
--- a/src/hotspot/os_cpu/linux_x86/gc/z/zBackingPath_linux_x86.hpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,52 +0,0 @@
-/*
- * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#ifndef OS_CPU_LINUX_X86_GC_Z_ZBACKINGPATH_LINUX_X86_HPP
-#define OS_CPU_LINUX_X86_GC_Z_ZBACKINGPATH_LINUX_X86_HPP
-
-#include "gc/z/zArray.hpp"
-#include "memory/allocation.hpp"
-
-class ZBackingPath : public StackObj {
-private:
-  char* _path;
-
-  char* get_mountpoint(const char* line,
-                       const char* filesystem) const;
-  void get_mountpoints(const char* filesystem,
-                       ZArray<char*>* mountpoints) const;
-  void free_mountpoints(ZArray<char*>* mountpoints) const;
-  char* find_preferred_mountpoint(const char* filesystem,
-                                  ZArray<char*>* mountpoints,
-                                  const char** preferred_mountpoints) const;
-  char* find_mountpoint(const char* filesystem,
-                        const char** preferred_mountpoints) const;
-
-public:
-  ZBackingPath(const char* filesystem, const char** preferred_mountpoints);
-  ~ZBackingPath();
-
-  const char* get() const;
-};
-
-#endif // OS_CPU_LINUX_X86_GC_Z_ZBACKINGPATH_LINUX_X86_HPP
--- a/src/hotspot/os_cpu/linux_x86/gc/z/zPhysicalMemoryBacking_linux_x86.cpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,334 +0,0 @@
-/*
- * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#include "precompiled.hpp"
-#include "gc/z/zAddress.inline.hpp"
-#include "gc/z/zBackingFile_linux_x86.hpp"
-#include "gc/z/zErrno.hpp"
-#include "gc/z/zGlobals.hpp"
-#include "gc/z/zLargePages.inline.hpp"
-#include "gc/z/zMemory.hpp"
-#include "gc/z/zNUMA.hpp"
-#include "gc/z/zPhysicalMemory.inline.hpp"
-#include "gc/z/zPhysicalMemoryBacking_linux_x86.hpp"
-#include "logging/log.hpp"
-#include "runtime/globals.hpp"
-#include "runtime/init.hpp"
-#include "runtime/os.hpp"
-#include "utilities/align.hpp"
-#include "utilities/debug.hpp"
-
-#include <stdio.h>
-#include <sys/mman.h>
-#include <sys/types.h>
-
-//
-// Support for building on older Linux systems
-//
-
-// madvise(2) flags
-#ifndef MADV_HUGEPAGE
-#define MADV_HUGEPAGE                        14
-#endif
-
-// Proc file entry for max map mount
-#define ZFILENAME_PROC_MAX_MAP_COUNT         "/proc/sys/vm/max_map_count"
-
-bool ZPhysicalMemoryBacking::is_initialized() const {
-  return _file.is_initialized();
-}
-
-void ZPhysicalMemoryBacking::warn_available_space(size_t max) const {
-  // Note that the available space on a tmpfs or a hugetlbfs filesystem
-  // will be zero if no size limit was specified when it was mounted.
-  const size_t available = _file.available();
-  if (available == 0) {
-    // No size limit set, skip check
-    log_info(gc, init)("Available space on backing filesystem: N/A");
-    return;
-  }
-
-  log_info(gc, init)("Available space on backing filesystem: " SIZE_FORMAT "M", available / M);
-
-  // Warn if the filesystem doesn't currently have enough space available to hold
-  // the max heap size. The max heap size will be capped if we later hit this limit
-  // when trying to expand the heap.
-  if (available < max) {
-    log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****");
-    log_warning(gc)("Not enough space available on the backing filesystem to hold the current max Java heap");
-    log_warning(gc)("size (" SIZE_FORMAT "M). Please adjust the size of the backing filesystem accordingly "
-                    "(available", max / M);
-    log_warning(gc)("space is currently " SIZE_FORMAT "M). Continuing execution with the current filesystem "
-                    "size could", available / M);
-    log_warning(gc)("lead to a premature OutOfMemoryError being thrown, due to failure to map memory.");
-  }
-}
-
-void ZPhysicalMemoryBacking::warn_max_map_count(size_t max) const {
-  const char* const filename = ZFILENAME_PROC_MAX_MAP_COUNT;
-  FILE* const file = fopen(filename, "r");
-  if (file == NULL) {
-    // Failed to open file, skip check
-    log_debug(gc, init)("Failed to open %s", filename);
-    return;
-  }
-
-  size_t actual_max_map_count = 0;
-  const int result = fscanf(file, SIZE_FORMAT, &actual_max_map_count);
-  fclose(file);
-  if (result != 1) {
-    // Failed to read file, skip check
-    log_debug(gc, init)("Failed to read %s", filename);
-    return;
-  }
-
-  // The required max map count is impossible to calculate exactly since subsystems
-  // other than ZGC are also creating memory mappings, and we have no control over that.
-  // However, ZGC tends to create the most mappings and dominate the total count.
-  // In the worst cases, ZGC will map each granule three times, i.e. once per heap view.
-  // We speculate that we need another 20% to allow for non-ZGC subsystems to map memory.
-  const size_t required_max_map_count = (max / ZGranuleSize) * 3 * 1.2;
-  if (actual_max_map_count < required_max_map_count) {
-    log_warning(gc)("***** WARNING! INCORRECT SYSTEM CONFIGURATION DETECTED! *****");
-    log_warning(gc)("The system limit on number of memory mappings per process might be too low for the given");
-    log_warning(gc)("max Java heap size (" SIZE_FORMAT "M). Please adjust %s to allow for at",
-                    max / M, filename);
-    log_warning(gc)("least " SIZE_FORMAT " mappings (current limit is " SIZE_FORMAT "). Continuing execution "
-                    "with the current", required_max_map_count, actual_max_map_count);
-    log_warning(gc)("limit could lead to a fatal error, due to failure to map memory.");
-  }
-}
-
-void ZPhysicalMemoryBacking::warn_commit_limits(size_t max) const {
-  // Warn if available space is too low
-  warn_available_space(max);
-
-  // Warn if max map count is too low
-  warn_max_map_count(max);
-}
-
-bool ZPhysicalMemoryBacking::supports_uncommit() {
-  assert(!is_init_completed(), "Invalid state");
-  assert(_file.size() >= ZGranuleSize, "Invalid size");
-
-  // Test if uncommit is supported by uncommitting and then re-committing a granule
-  return commit(uncommit(ZGranuleSize)) == ZGranuleSize;
-}
-
-size_t ZPhysicalMemoryBacking::commit(size_t size) {
-  size_t committed = 0;
-
-  // Fill holes in the backing file
-  while (committed < size) {
-    size_t allocated = 0;
-    const size_t remaining = size - committed;
-    const uintptr_t start = _uncommitted.alloc_from_front_at_most(remaining, &allocated);
-    if (start == UINTPTR_MAX) {
-      // No holes to commit
-      break;
-    }
-
-    // Try commit hole
-    const size_t filled = _file.commit(start, allocated);
-    if (filled > 0) {
-      // Successful or partialy successful
-      _committed.free(start, filled);
-      committed += filled;
-    }
-    if (filled < allocated) {
-      // Failed or partialy failed
-      _uncommitted.free(start + filled, allocated - filled);
-      return committed;
-    }
-  }
-
-  // Expand backing file
-  if (committed < size) {
-    const size_t remaining = size - committed;
-    const uintptr_t start = _file.size();
-    const size_t expanded = _file.commit(start, remaining);
-    if (expanded > 0) {
-      // Successful or partialy successful
-      _committed.free(start, expanded);
-      committed += expanded;
-    }
-  }
-
-  return committed;
-}
-
-size_t ZPhysicalMemoryBacking::uncommit(size_t size) {
-  size_t uncommitted = 0;
-
-  // Punch holes in backing file
-  while (uncommitted < size) {
-    size_t allocated = 0;
-    const size_t remaining = size - uncommitted;
-    const uintptr_t start = _committed.alloc_from_back_at_most(remaining, &allocated);
-    assert(start != UINTPTR_MAX, "Allocation should never fail");
-
-    // Try punch hole
-    const size_t punched = _file.uncommit(start, allocated);
-    if (punched > 0) {
-      // Successful or partialy successful
-      _uncommitted.free(start, punched);
-      uncommitted += punched;
-    }
-    if (punched < allocated) {
-      // Failed or partialy failed
-      _committed.free(start + punched, allocated - punched);
-      return uncommitted;
-    }
-  }
-
-  return uncommitted;
-}
-
-ZPhysicalMemory ZPhysicalMemoryBacking::alloc(size_t size) {
-  assert(is_aligned(size, ZGranuleSize), "Invalid size");
-
-  ZPhysicalMemory pmem;
-
-  // Allocate segments
-  for (size_t allocated = 0; allocated < size; allocated += ZGranuleSize) {
-    const uintptr_t start = _committed.alloc_from_front(ZGranuleSize);
-    assert(start != UINTPTR_MAX, "Allocation should never fail");
-    pmem.add_segment(ZPhysicalMemorySegment(start, ZGranuleSize));
-  }
-
-  return pmem;
-}
-
-void ZPhysicalMemoryBacking::free(const ZPhysicalMemory& pmem) {
-  const size_t nsegments = pmem.nsegments();
-
-  // Free segments
-  for (size_t i = 0; i < nsegments; i++) {
-    const ZPhysicalMemorySegment& segment = pmem.segment(i);
-    _committed.free(segment.start(), segment.size());
-  }
-}
-
-void ZPhysicalMemoryBacking::map_failed(ZErrno err) const {
-  if (err == ENOMEM) {
-    fatal("Failed to map memory. Please check the system limit on number of "
-          "memory mappings allowed per process (see %s)", ZFILENAME_PROC_MAX_MAP_COUNT);
-  } else {
-    fatal("Failed to map memory (%s)", err.to_string());
-  }
-}
-
-void ZPhysicalMemoryBacking::advise_view(uintptr_t addr, size_t size, int advice) const {
-  if (madvise((void*)addr, size, advice) == -1) {
-    ZErrno err;
-    log_error(gc)("Failed to advise on memory (advice %d, %s)", advice, err.to_string());
-  }
-}
-
-void ZPhysicalMemoryBacking::pretouch_view(uintptr_t addr, size_t size) const {
-  const size_t page_size = ZLargePages::is_explicit() ? os::large_page_size() : os::vm_page_size();
-  os::pretouch_memory((void*)addr, (void*)(addr + size), page_size);
-}
-
-void ZPhysicalMemoryBacking::map_view(const ZPhysicalMemory& pmem, uintptr_t addr, bool pretouch) const {
-  const size_t nsegments = pmem.nsegments();
-  size_t size = 0;
-
-  // Map segments
-  for (size_t i = 0; i < nsegments; i++) {
-    const ZPhysicalMemorySegment& segment = pmem.segment(i);
-    const uintptr_t segment_addr = addr + size;
-    const void* const res = mmap((void*)segment_addr, segment.size(), PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, _file.fd(), segment.start());
-    if (res == MAP_FAILED) {
-      ZErrno err;
-      map_failed(err);
-    }
-
-    size += segment.size();
-  }
-
-  // Advise on use of transparent huge pages before touching it
-  if (ZLargePages::is_transparent()) {
-    advise_view(addr, size, MADV_HUGEPAGE);
-  }
-
-  // NUMA interleave memory before touching it
-  ZNUMA::memory_interleave(addr, size);
-
-  // Pre-touch memory
-  if (pretouch) {
-    pretouch_view(addr, size);
-  }
-}
-
-void ZPhysicalMemoryBacking::unmap_view(const ZPhysicalMemory& pmem, uintptr_t addr) const {
-  // Note that we must keep the address space reservation intact and just detach
-  // the backing memory. For this reason we map a new anonymous, non-accessible
-  // and non-reserved page over the mapping instead of actually unmapping.
-  const void* const res = mmap((void*)addr, pmem.size(), PROT_NONE, MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, -1, 0);
-  if (res == MAP_FAILED) {
-    ZErrno err;
-    map_failed(err);
-  }
-}
-
-uintptr_t ZPhysicalMemoryBacking::nmt_address(uintptr_t offset) const {
-  // From an NMT point of view we treat the first heap view (marked0) as committed
-  return ZAddress::marked0(offset);
-}
-
-void ZPhysicalMemoryBacking::map(const ZPhysicalMemory& pmem, uintptr_t offset) const {
-  if (ZVerifyViews) {
-    // Map good view
-    map_view(pmem, ZAddress::good(offset), AlwaysPreTouch);
-  } else {
-    // Map all views
-    map_view(pmem, ZAddress::marked0(offset), AlwaysPreTouch);
-    map_view(pmem, ZAddress::marked1(offset), AlwaysPreTouch);
-    map_view(pmem, ZAddress::remapped(offset), AlwaysPreTouch);
-  }
-}
-
-void ZPhysicalMemoryBacking::unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const {
-  if (ZVerifyViews) {
-    // Unmap good view
-    unmap_view(pmem, ZAddress::good(offset));
-  } else {
-    // Unmap all views
-    unmap_view(pmem, ZAddress::marked0(offset));
-    unmap_view(pmem, ZAddress::marked1(offset));
-    unmap_view(pmem, ZAddress::remapped(offset));
-  }
-}
-
-void ZPhysicalMemoryBacking::debug_map(const ZPhysicalMemory& pmem, uintptr_t offset) const {
-  // Map good view
-  assert(ZVerifyViews, "Should be enabled");
-  map_view(pmem, ZAddress::good(offset), false /* pretouch */);
-}
-
-void ZPhysicalMemoryBacking::debug_unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const {
-  // Unmap good view
-  assert(ZVerifyViews, "Should be enabled");
-  unmap_view(pmem, ZAddress::good(offset));
-}
--- a/src/hotspot/os_cpu/linux_x86/gc/z/zPhysicalMemoryBacking_linux_x86.hpp	Wed Aug 28 09:50:20 2019 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,70 +0,0 @@
-/*
- * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-#ifndef OS_CPU_LINUX_X86_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_X86_HPP
-#define OS_CPU_LINUX_X86_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_X86_HPP
-
-#include "gc/z/zBackingFile_linux_x86.hpp"
-#include "gc/z/zMemory.hpp"
-
-class ZErrno;
-class ZPhysicalMemory;
-
-class ZPhysicalMemoryBacking {
-private:
-  ZBackingFile   _file;
-  ZMemoryManager _committed;
-  ZMemoryManager _uncommitted;
-
-  void warn_available_space(size_t max) const;
-  void warn_max_map_count(size_t max) const;
-
-  void map_failed(ZErrno err) const;
-
-  void advise_view(uintptr_t addr, size_t size, int advice) const;
-  void pretouch_view(uintptr_t addr, size_t size) const;
-  void map_view(const ZPhysicalMemory& pmem, uintptr_t addr, bool pretouch) const;
-  void unmap_view(const ZPhysicalMemory& pmem, uintptr_t addr) const;
-
-public:
-  bool is_initialized() const;
-
-  void warn_commit_limits(size_t max) const;
-  bool supports_uncommit();
-
-  size_t commit(size_t size);
-  size_t uncommit(size_t size);
-
-  ZPhysicalMemory alloc(size_t size);
-  void free(const ZPhysicalMemory& pmem);
-
-  uintptr_t nmt_address(uintptr_t offset) const;
-
-  void map(const ZPhysicalMemory& pmem, uintptr_t offset) const;
-  void unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const;
-
-  void debug_map(const ZPhysicalMemory& pmem, uintptr_t offset) const;
-  void debug_unmap(const ZPhysicalMemory& pmem, uintptr_t offset) const;
-};
-
-#endif // OS_CPU_LINUX_X86_GC_Z_ZPHYSICALMEMORYBACKING_LINUX_X86_HPP
--- a/src/hotspot/share/gc/z/zPhysicalMemory.hpp	Wed Aug 28 09:50:20 2019 +0200
+++ b/src/hotspot/share/gc/z/zPhysicalMemory.hpp	Wed Aug 28 09:50:21 2019 +0200
@@ -25,7 +25,7 @@
 #define SHARE_GC_Z_ZPHYSICALMEMORY_HPP
 
 #include "memory/allocation.hpp"
-#include OS_CPU_HEADER(gc/z/zPhysicalMemoryBacking)
+#include OS_HEADER(gc/z/zPhysicalMemoryBacking)
 
 class ZPhysicalMemorySegment : public CHeapObj<mtGC> {
 private: