src/hotspot/os/linux/os_linux.cpp

*** 126,135 ****
--- 126,136 ----
  
  // for timer info max values which include all bits
  #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
  
  #define LARGEPAGES_BIT (1 << 6)
+ #define DAX_SHARED_BIT (1 << 8)
  ////////////////////////////////////////////////////////////////////////////////
  // global variables
  julong os::Linux::_physical_memory = 0;
  
  address   os::Linux::_initial_thread_stack_bottom = NULL;
*** 3261,3274 ****
  // - (bit 3) file-backed shared memory
  // - (bit 4) ELF header pages in file-backed private memory areas (it is
  //           effective only if the bit 2 is cleared)
  // - (bit 5) hugetlb private memory
  // - (bit 6) hugetlb shared memory
  //
! static void set_coredump_filter(void) {
    FILE *f;
    long cdm;
  
    if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
      return;
    }
  
--- 3262,3278 ----
  // - (bit 3) file-backed shared memory
  // - (bit 4) ELF header pages in file-backed private memory areas (it is
  //           effective only if the bit 2 is cleared)
  // - (bit 5) hugetlb private memory
  // - (bit 6) hugetlb shared memory
+ // - (bit 7) dax private memory
+ // - (bit 8) dax shared memory
  //
! static void set_coredump_filter(bool largepages, bool dax_shared) {
    FILE *f;
    long cdm;
+   bool filter_changed = false;
  
    if ((f = fopen("/proc/self/coredump_filter", "r+")) == NULL) {
      return;
    }
  
*** 3277,3288 ****
      return;
    }
  
    rewind(f);
  
!   if ((cdm & LARGEPAGES_BIT) == 0) {
      cdm |= LARGEPAGES_BIT;
      fprintf(f, "%#lx", cdm);
    }
  
    fclose(f);
  }
--- 3281,3299 ----
      return;
    }
  
    rewind(f);
  
!   if (largepages && (cdm & LARGEPAGES_BIT) == 0) {
      cdm |= LARGEPAGES_BIT;
+     filter_changed = true;
+   }
+   if (dax_shared && (cdm & DAX_SHARED_BIT) == 0) {
+     cdm |= DAX_SHARED_BIT;
+     filter_changed = true;
+   }
+   if (filter_changed) {
      fprintf(f, "%#lx", cdm);
    }
  
    fclose(f);
  }
*** 3417,3427 ****
    }
  
    size_t large_page_size = Linux::setup_large_page_size();
    UseLargePages          = Linux::setup_large_page_type(large_page_size);
  
!   set_coredump_filter();
  }
  
  #ifndef SHM_HUGETLB
    #define SHM_HUGETLB 04000
  #endif
--- 3428,3438 ----
    }
  
    size_t large_page_size = Linux::setup_large_page_size();
    UseLargePages          = Linux::setup_large_page_type(large_page_size);
  
!   set_coredump_filter(true /*largepages*/, false /*dax_shared*/);
  }
  
  #ifndef SHM_HUGETLB
    #define SHM_HUGETLB 04000
  #endif
*** 3788,3797 ****
--- 3799,3819 ----
  
  bool os::can_execute_large_page_memory() {
    return UseTransparentHugePages || UseHugeTLBFS;
  }
  
+ char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr, int file_desc) {
+   assert(file_desc >= 0, "file_desc is not valid");
+   char* result = pd_attempt_reserve_memory_at(bytes, requested_addr);
+   if (result != NULL) {
+     if (replace_existing_mapping_with_file_mapping(result, bytes, file_desc) == NULL) {
+       vm_exit_during_initialization(err_msg("Error in mapping Java heap at the given filesystem directory"));
+     }
+   }
+   return result;
+ }
+ 
  // Reserve memory at an arbitrary address, only if that area is
  // available (and not reserved for something else).
  
  char* os::pd_attempt_reserve_memory_at(size_t bytes, char* requested_addr) {
    const int max_tries = 10;
*** 4915,4924 ****
--- 4937,4949 ----
    }
  
    // initialize thread priority policy
    prio_init();
  
+   if (!FLAG_IS_DEFAULT(AllocateHeapAt)) {
+     set_coredump_filter(false /*largepages*/, true /*dax_shared*/); 
+   }
    return JNI_OK;
  }
  
  // Mark the polling page as unreadable
  void os::make_polling_page_unreadable(void) {