Check to see if there actually is data from a previously
crashed kernel waiting.  If so, allow user-space tools to
grab the data (by reading /proc/kcore).  When user-space
finishes dumping a section, it must release that memory
by writing to sysfs. For example,

  echo "0x40000000 0x10000000" > /sys/kernel/release_region

will release 256MB starting at the 1GB.  The released memory
becomes free for general use.
Signed-off-by: NLinas Vepstas <linasvepstas@gmail.com>
Signed-off-by: NManish Ahuja <mahuja@us.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>