Description of problem:
Qemu core dump when boot up a guest on a non-existent hugepage path

Version-Release number of selected component (if applicable):
kernel-3.10.0-170.el7.x86_64
qemu-kvm-rhev-2.1.2-1.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. set the host with 15G hugepage (hugepage size=1G):
# cat /proc/cmdline 
BOOT_IMAGE=/vmlinuz-3.10.0-170.el7.x86_64 root=/dev/mapper/rhel_ibm--x3650m4--05-root ro rd.lvm.lv=rhel_ibm-x3650m4-05/root rd.lvm.lv=rhel_ibm-x3650m4-05/swap console=tty0 reboot=pci console=ttyS0,115200 vconsole.keymap=us vconsole.font=latarcyrheb-sun16 biosdevname=0 crashkernel=256M LANG=en_US.UTF-8 default_hugepagesz=1G hugepagesz=1G hugepages=15 

2. mount hugetlbfs
mount -t hugetlbfs none /mnt/kvm_hugepage

3. boot up the guest on a non-existent path with option '-mem-path'.
(the path should be /mnt/kvm_hugepage instead of /mnt/kvm_hugepag, the latter missed the last letter 'e')
    -m 2048  \
    -mem-path  /mnt/kvm_hugepag \

Actual results:
Qemu core dump

Expected results:
Qemu should prevent such condition

Additional info:
1. core dump info:
Using host libthread_db library "/lib64/libthread_db.so.1".
Core was generated by `/bin/qemu-kvm -S -name virt-tests-vm1 -sandbox off -M pc -nodefaults -vga qxl -'.
Program terminated with signal 6, Aborted.
#0  0x00007f07b449b989 in __GI_raise (sig=sig@entry=6)
    at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
56	  return INLINE_SYSCALL (tgkill, 3, pid, selftid, sig);
(gdb) bt
#0  0x00007f07b449b989 in __GI_raise (sig=sig@entry=6)
    at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1  0x00007f07b449d098 in __GI_abort () at abort.c:90
#2  0x00007f07b44948f6 in __assert_fail_base (
    fmt=0x7f07b45e43e8 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", 
    assertion=assertion@entry=0x7f07ba934bf5 "new_block", 
    file=file@entry=0x7f07ba934728 "/builddir/build/BUILD/qemu-2.1.2/exec.c", 
    line=line@entry=1220, 
    function=function@entry=0x7f07ba934d60 <__PRETTY_FUNCTION__.33297> "qemu_ram_set_idstr") at assert.c:92
#3  0x00007f07b44949a2 in __GI___assert_fail (
    assertion=assertion@entry=0x7f07ba934bf5 "new_block", 
    file=file@entry=0x7f07ba934728 "/builddir/build/BUILD/qemu-2.1.2/exec.c", 
    line=line@entry=1220, 
    function=function@entry=0x7f07ba934d60 <__PRETTY_FUNCTION__.33297> "qemu_ram_set_idstr") at assert.c:101
#4  0x00007f07ba6c8949 in qemu_ram_set_idstr (addr=<optimized out>, name=<optimized out>, 
    dev=dev@entry=0x0) at /usr/src/debug/qemu-2.1.2/exec.c:1220
#5  0x00007f07ba700e13 in vmstate_register_ram (mr=mr@entry=0x7f07bbb67d60, 
    dev=dev@entry=0x0) at /usr/src/debug/qemu-2.1.2/savevm.c:1407
#6  0x00007f07ba700e47 in vmstate_register_ram_global (mr=mr@entry=0x7f07bbb67d60)
    at /usr/src/debug/qemu-2.1.2/savevm.c:1418
#7  0x00007f07ba6f4f79 in allocate_system_memory_nonnuma (ram_size=2147483648, 
---Type <return> to continue, or q <return> to quit---
    name=0x7f07ba93ecb6 "pc.ram", owner=0x0, mr=0x7f07bbb67d60)
    at /usr/src/debug/qemu-2.1.2/numa.c:275
#8  memory_region_allocate_system_memory (mr=mr@entry=0x7f07bbb67d60, 
    owner=owner@entry=0x0, name=name@entry=0x7f07ba93ecb6 "pc.ram", ram_size=2147483648)
    at /usr/src/debug/qemu-2.1.2/numa.c:286
#9  0x00007f07ba72cd5e in pc_memory_init (machine=machine@entry=0x7f07bb9c3c80, 
    system_memory=system_memory@entry=0x7f07bb9c4bb0, below_4g_mem_size=2147483648, 
    above_4g_mem_size=0, rom_memory=rom_memory@entry=0x7f07bb9cf120, 
    ram_memory=ram_memory@entry=0x7fff00161040, guest_info=guest_info@entry=0x7f07bb9ced00)
    at /usr/src/debug/qemu-2.1.2/hw/i386/pc.c:1225
#10 0x00007f07ba72e586 in pc_init1 (machine=0x7f07bb9c3c80, kvmclock_enabled=1, 
    pci_enabled=1) at /usr/src/debug/qemu-2.1.2/hw/i386/pc_piix.c:181
#11 0x00007f07ba6c1993 in main (argc=<optimized out>, argv=<optimized out>, 
    envp=<optimized out>) at vl.c:4421

2. # sh qemu.sh 
Warning: option deprecated, use lost_tick_policy property of kvm-pit instead.
QEMU 2.1.2 monitor - type 'help' for more information
(qemu) /mnt/kvm_hugepag: No such file or directory
qemu-kvm: /builddir/build/BUILD/qemu-2.1.2/exec.c:1220: qemu_ram_set_idstr: Assertion `new_block' failed.
qemu.sh: line 35: 16144 Aborted                 (core dumped) 

3. Qemu CML:
/bin/qemu-kvm \
    -S  \
    -name 'virt-tests-vm1'  \
    -sandbox off  \
    -M pc  \
    -nodefaults  \
    -vga qxl  \
    -global qxl-vga.vram_size=33554432 \
    -device intel-hda,bus=pci.0,addr=03 \
    -device hda-duplex  \
    -chardev socket,id=qmp_id_qmpmonitor1,path=/tmp/monitor-qmpmonitor1-20140928-172700-4g3PfMTp,server,nowait \
    -mon chardev=qmp_id_qmpmonitor1,mode=control  \
    -chardev socket,id=serial_id_serial0,path=/tmp/serial-serial0-20140928-172700-4g3PfMTp,server,nowait \
    -device isa-serial,chardev=serial_id_serial0 \
    -device virtio-serial-pci,id=virtio_serial_pci0,bus=pci.0,addr=04  \
    -chardev socket,id=devvs,path=/tmp/virtio_port-vs-20140928-172700-4g3PfMTp,server,nowait \
    -device virtserialport,chardev=devvs,name=vs,id=vs,bus=virtio_serial_pci0.0  \
    -chardev socket,id=seabioslog_id_20140928-172700-4g3PfMTp,path=/tmp/seabios-20140928-172700-4g3PfMTp,server,nowait \
    -device isa-debugcon,chardev=seabioslog_id_20140928-172700-4g3PfMTp,iobase=0x402 \
    -device nec-usb-xhci,id=usb1,bus=pci.0,addr=05 \
    -drive id=drive_image1,if=none,cache=none,snapshot=off,aio=native,file=/home/staf-kvm-devel/autotest-devel/client/tests/virt/shared/data/images/RHEL-Server-6.6-64-virtio.qcow2 \
    -device virtio-blk-pci,id=image1,drive=drive_image1,bootindex=0,bus=pci.0,addr=06 \
    -device virtio-net-pci,mac=9a:eb:ec:ed:ee:ef,id=idcejB0N,vectors=4,netdev=idkbmGLy,bus=pci.0,addr=07  \
    -netdev tap,id=idkbmGLy,vhost=on  \
    -m 2048  \
    -mem-path  /mnt/kvm_hugepag \
    -smp 8,cores=4,threads=1,sockets=2  \
    -cpu 'SandyBridge',+kvm_pv_unhalt \
    -device usb-tablet,id=usb-tablet1,bus=usb1.0,port=1  \
    -rtc base=utc,clock=host,driftfix=slew  \
    -boot order=cdn,once=c,menu=off  \
    -no-kvm-pit-reinjection \
    -enable-kvm \
    -monitor stdio \
    -vnc :0

4. host info:
processor	: 23
vendor_id	: GenuineIntel
cpu family	: 6
model		: 45
model name	: Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz
stepping	: 7
microcode	: 0x710
cpu MHz		: 2277.265
cache size	: 15360 KB
physical id	: 1
siblings	: 12
core id		: 5
cpu cores	: 6
apicid		: 43
initial apicid	: 43
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm ida arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips	: 4004.38
clflush size	: 64
cache_alignment	: 64
address sizes	: 46 bits physical, 48 bits virtual
power management: