tools/vm/page-types.c: fix "kpagecount returned fewer pages than expected" failures

Because kpagecount_read() fakes success if map counts are not being
collected, clamp the page count passed to it by walk_pfn() to the pages
value returned by the preceding call to kpageflags_read().

Link: http://lkml.kernel.org/r/1543962269-26116-1-git-send-email-anthony.yznaga@oracle.com
Fixes: 7f1d23e6 ("tools/vm/page-types.c: include shared map counts")
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/vm/page-types.c

@@ -701,7 +701,7 @@ static void walk_pfn(unsigned long voffset,
 		if (kpagecgroup_read(cgi, index, pages) != pages)
 			fatal("kpagecgroup returned fewer pages than expected");
 
-		if (kpagecount_read(cnt, index, batch) != pages)
+		if (kpagecount_read(cnt, index, pages) != pages)
 			fatal("kpagecount returned fewer pages than expected");
 
 		for (i = 0; i < pages; i++)