hugetlb: abort a hugepage pool resize if a signal is pending

If a user asks for a hugepage pool resize but specified a large number,
the machine can begin trashing.  In response, they might hit ctrl-c but
signals are ignored and the pool resize continues until it fails an
allocation.  This can take a considerable amount of time so this patch
aborts a pool resize if a signal is pending.

Suggested by Dave Hansen.
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb.c

@@ -1278,6 +1278,9 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
 		if (!ret)
 			goto out;
 
+		/* Bail for signals. Probably ctrl-c from user */
+		if (signal_pending(current))
+			goto out;
 	}
 
 	/*