Description of problem:
when I did ltp test, there were some cases  blocked, at least I found sync() make the mistakes, and also it couldn't use 'Ctrl-C' or 'kill -9' to kill the process.

Version-Release number of selected component (if applicable):
[zliu@ZhoupingLiu mtest06]$ uname -ri
3.3.2-1.fc17.x86_64 x86_64
[zliu@ZhoupingLiu mtest06]$ rpm -q coreutils
coreutils-8.15-6.fc17.x86_6

How reproducible:
100%

Steps to Reproduce:
[zliu@ZhoupingLiu ~]$ cat test.c 
#include <unistd.h>
#include <stdio.h>

int main()
{
	printf("test sync()\n");

	sync();
	return 0;
}
[zliu@ZhoupingLiu zliu]# ./test 
test sync()


^C^C^

as the above, can't endup the process

Or you can directly run sync command to reproduce the issue:
[root@ZhoupingLiu zliu]# sync

^C^C^

Actual results:
the sync hang up

Expected results:
sync work fine

Additional info:
couldn't find the issue in RHEL7 Alpha and RHEL6.