I can not reproduce this simply, so could you please test with this patch?

diff --git a/ext/opcache/ZendAccelerator.c b/ext/opcache/ZendAccelerator.c
index e23e751..ae10d12 100644
--- a/ext/opcache/ZendAccelerator.c
+++ b/ext/opcache/ZendAccelerator.c
@@ -2531,7 +2531,7 @@ static int accel_remap_huge_pages(void *start, size_t size, const char *name, si
                        PROT_READ | PROT_WRITE | PROT_EXEC,
                        MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
                        -1, 0);
-           if (-1 == madvise(start, size, MADV_HUGEPAGE)) {
+         if (ret == MAP_FAILED || -1 == madvise(start, size, MADV_HUGEPAGE)) {
                        munmap(mem, size);
                        return -1;
                }

No, the bug still exists. With the patch applied the function accel_move_code_to_huge_pages() returns and segfault raises later:

(gdb) br /usr/src/debug/php-7.0.0RC8/ext/opcache/ZendAccelerator.c:2620
(gdb) run
Breakpoint 1, accel_startup (extension=<value optimized out>) at /usr/src/debug/php-7.0.0RC8/ext/opcache/ZendAccelerator.c:2620
2620                    if (!ZCG(accel_directives).enable_cli &&
(gdb) n
2619                    accel_startup_ok = 0;
(gdb)
2620                    if (!ZCG(accel_directives).enable_cli &&
(gdb)
2621                        strcmp(sapi_module.name, "cli") == 0) {
(gdb)
2620                    if (!ZCG(accel_directives).enable_cli &&
(gdb)
2622                            zps_startup_failure("Opcode Caching is disabled for CLI", NULL, accelerator_remove_cb);
(gdb)

Program received signal SIGSEGV, Segmentation fault.
zend_llist_del_element (l=0x9dc8e0, element=0x0, compare=0x7fffedf40590 <accelerator_remove_cb>) at /usr/src/debug/php-7.0.0RC8/Zend/zend_llist.c:91
91      {

how about this one? http://pastebin.com/sqXMzZLT

thanks

The fix for this bug has been committed.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.

 For Windows:

http://windows.php.net/snapshots/
 
Thank you for the report, and for helping us make PHP better.

it should be fixed  http://git.php.net/?p=php-src.git;a=commit;h=e9a8d7ff1d59cbcaf4b5cec728a94fb0d54dd993

I've just checked on commit e9a8d7ff1d59cbcaf4b5cec728a94fb0d54dd993, it's all right. Got warning "Zend OPcachehuge_code_pages: mmap(HUGETLB) failed: Cannot allocate memory (12)" and than run continues fine.

Fix confirmed, thanks.