mm: use totalram_pages instead of num_physpages at runtime

The global variable num_physpages is scheduled to be removed, so use
totalram_pages instead of num_physpages at runtime.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index 7e06641..cec5394 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -93,7 +93,7 @@
 	}
 	rwlock_init(&f->lock);
 
-	f->rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
+	f->rnd = (u32) ((totalram_pages ^ (totalram_pages >> 7)) ^
 				   (jiffies ^ (jiffies >> 6)));
 
 	setup_timer(&f->secret_timer, inet_frag_secret_rebuild,