This issue has been proposed when we are only considering blocker
issues in the current Red Hat Enterprise Linux release.

** If you would still like this issue considered for the current
release, ask your support representative to file as a blocker on
your behalf. Otherwise ask that it be considered for the next
Red Hat Enterprise Linux release. **

I just hit this myself consistently on a system with substantial
memory pressure: 4GB total and ~10% free.  Launching with -m 1024
the abort triggers faithfully and with -m 512 qemu launches
successfully.  From the user's perspective of stumbling into this
caveat myself it's rather ugly and isn't at a minor usage issue.
Providing a clue to the cause of failure is trivial.  Dump attached.
Patch attached.

Still not sure why the about() is in there unless as a debug
aid such that a core image exists to help puzzle out the
posix_memalign() failure.  Although in this case the cause is
clear.

Odd this apparently hasn't been more widely seen.  Likely
related not only to memory pressure but perhaps a host memory
fragmentation sensitivity as well.

Created attachment 443114 [details]
gdb stack trace of abort

Created attachment 443115 [details]
posix_memalign failure patch

Disregard above patch -- already upstream as
d2d5adcb58d32e8ac6c168c4c2e72cf0f90dcab0.

Reproduced on qemu-kvm-0.12.1.2-2.113.el6.x86_64,when assign to guest memory higher than host free memory,guest aborted without notification.
/usr/libexec/qemu-kvm -m 4G -smp 2 -drive file=/root/zhangjunyi/win2008-64bit.img,if=none,id=test,boot=on,cache=none,format=raw,werror=stop,rerror=stop -device virtio-blk-pci,drive=test -cpu qemu64,+sse2,+x2apic -monitor stdio -boot c -netdev tap,id=hostnet0,vhost=on -device virtio-net-pci,netdev=hostnet0,id=net0,mac=22:11:22:45:66:94 -vnc :10 -qmp tcp:0:4445,server,nowait -chardev socket,path=/tmp/amit/test0,server,nowait,id=test0 -chardev socket,path=/tmp/amit/test1,server,nowait,id=test1 -chardev socket,path=/tmp/amit/test2,server,nowait,id=test2 -chardev socket,path=/tmp/amit/test3,server,nowait,id=test3 -chardev socket,path=/tmp/amit/test4,server,nowait,id=test4 -device virtio-serial -device virtconsole,chardev=test0,name=console.0 -device virtserialport,chardev=test1,name=test1 -device virtserialport,chardev=test2,name=test2 -device virtserialport,chardev=test3,name=test3 -device virtserialport,chardev=test4,name=test4 -serial file:/tmp/amit/test-serial.log
Aborted

Verified on qemu-kvm-0.12.1.2-2.129.el6.x86_64,when assign to guest memory higher than host free memory,guest aborted with message "Failed to allocate 4294967296 B: Cannot allocate memory".
#/usr/libexec/qemu-kvm -m 4G -smp 2 -drive file=/root/zhangjunyi/win2008-64bit.img,if=none,id=test,boot=on,cache=none,format=raw,werror=stop,rerror=stop -device virtio-blk-pci,drive=test -cpu qemu64,+sse2,+x2apic -monitor stdio -boot c -netdev tap,id=hostnet0,vhost=on -device virtio-net-pci,netdev=hostnet0,id=net0,mac=22:11:22:45:66:94 -vnc :10 -qmp tcp:0:4445,server,nowait -chardev socket,path=/tmp/amit/test0,server,nowait,id=test0 -chardev socket,path=/tmp/amit/test1,server,nowait,id=test1 -chardev socket,path=/tmp/amit/test2,server,nowait,id=test2 -chardev socket,path=/tmp/amit/test3,server,nowait,id=test3 -chardev socket,path=/tmp/amit/test4,server,nowait,id=test4 -device virtio-serial -device virtconsole,chardev=test0,name=console.0 -device virtserialport,chardev=test1,name=test1 -device virtserialport,chardev=test2,name=test2 -device virtserialport,chardev=test3,name=test3 -device virtserialport,chardev=test4,name=test4 -serial file:/tmp/amit/test-serial.log
Failed to allocate 4294967296 B: Cannot allocate memory

According to above description,this issue has been fixed.

    Technical note added. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    New Contents:
Cause
    In the case of certain memory allocation failures, qemu
exits with only a self inflicted SIGABORT rather than
clearly indicating this cause for failure to the user.

Consequence
    Confusion and possible unhappiness on behalf of the
qemu user.

Change
    The condition of allocation failure is detected.


Result
    A message is emitted clearly indication the failure cause.

Added CCFR

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2011-0534.html

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2011-0534.html