vmcoreinfo: add the array length of "free_list" for filtering free pages

This patch adds the array length of "free_area.free_list" to the vmcoreinfo
data so that makedumpfile (dump filtering command) can exclude all free pages
in linux-2.6.24.

makedumpfile creates a small dumpfile by excluding unnecessary pages for the
analysis. To distinguish unnecessary pages, makedumpfile gets the vmcoreinfo
data which has the minimum debugging information only for dump filtering.

In 2.6.24-rc1 or later, the free_area.free_list is an array which has one list
for each migrate types instead of a single list. makedumpfile needs the array
length of "free_area.free_list" and the vmcoreinfo data should contain it.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Tested-by: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Acked-by: Simon Horman <horms@verge.net.au>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/kexec.c

@@ -1404,6 +1404,7 @@ static int __init crash_save_vmcoreinfo_init(void)
 	VMCOREINFO_OFFSET(list_head, next);
 	VMCOREINFO_OFFSET(list_head, prev);
 	VMCOREINFO_LENGTH(zone.free_area, MAX_ORDER);
+	VMCOREINFO_LENGTH(free_area.free_list, MIGRATE_TYPES);
 	VMCOREINFO_NUMBER(NR_FREE_PAGES);
 
 	arch_crash_save_vmcoreinfo();