From 8df36761038cf817c0410f0b808711137369d07b Mon Sep 17 00:00:00 2001
From: jmg <jmg@FreeBSD.org>
Date: Thu, 25 Jun 2015 20:44:46 +0000
Subject: [PATCH] If INVARIANTS is specified, add ctor/dtor to junk memory if
 they are unspecified...

Submitted by:	Suresh Gumpula at Netapp
Differential Revision:	https://reviews.freebsd.org/D2725
---
 sys/vm/uma_core.c | 14 ++++++++++++++
 sys/vm/uma_dbg.c  |  5 +++++
 2 files changed, 19 insertions(+)

diff --git a/sys/vm/uma_core.c b/sys/vm/uma_core.c
index 6780bad1ecac..04e000e5dff9 100644
--- a/sys/vm/uma_core.c
+++ b/sys/vm/uma_core.c
@@ -1940,6 +1940,20 @@ uma_zcreate(const char *name, size_t size, uma_ctor ctor, uma_dtor dtor,
 	args.dtor = dtor;
 	args.uminit = uminit;
 	args.fini = fini;
+#ifdef  INVARIANTS
+	/*
+	 * If a zone is being created with an empty constructor and
+	 * destructor, pass UMA constructor/destructor which checks for
+	 * memory use after free.
+	 */
+	if ((!(flags & UMA_ZONE_ZINIT)) && ctor == NULL && dtor == NULL &&
+	    uminit == NULL && fini == NULL) {
+		args.ctor = trash_ctor;
+		args.dtor = trash_dtor;
+		args.uminit = trash_init;
+		args.fini = trash_fini;
+	}
+#endif
 	args.align = align;
 	args.flags = flags;
 	args.keg = NULL;
diff --git a/sys/vm/uma_dbg.c b/sys/vm/uma_dbg.c
index 48a5e6d472f5..3fbd29b16dea 100644
--- a/sys/vm/uma_dbg.c
+++ b/sys/vm/uma_dbg.c
@@ -69,8 +69,13 @@ trash_ctor(void *mem, int size, void *arg, int flags)
 
 	for (p = mem; cnt > 0; cnt--, p++)
 		if (*p != uma_junk) {
+#ifdef INVARIANTS
+			panic("Memory modified after free %p(%d) val=%x @ %p\n",
+			    mem, size, *p, p);
+#else
 			printf("Memory modified after free %p(%d) val=%x @ %p\n",
 			    mem, size, *p, p);
+#endif
 			return (0);
 		}
 	return (0);