From 18a4c8dc91f351f9aa317c2d69113563e9509cce Mon Sep 17 00:00:00 2001
From: Venkatesh Srinivas <me@endeavour.zapto.org>
Date: Tue, 14 Jun 2011 07:09:43 -0700
Subject: [PATCH] kernel -- vm_object DEBUG_LOCKS: Record file/line of
 vm_object holds.

---
 sys/vm/vm_object.c | 12 ++++++++++++
 sys/vm/vm_object.h | 10 ++++++++++
 2 files changed, 22 insertions(+)

diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 19dfef9111..b658995450 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -157,6 +157,8 @@ vm_object_lock_init(vm_object_t obj)
 	obj->debug_hold_ovfl = 0;
 	for (i = 0; i < VMOBJ_DEBUG_ARRAY_SIZE; i++) {
 		obj->debug_hold_thrs[i] = NULL;
+		obj->debug_hold_file[i] = NULL;
+		obj->debug_hold_line[i] = 0;
 	}
 #endif
 }
@@ -186,7 +188,11 @@ vm_object_assert_held(vm_object_t obj)
 }
 
 void
+#ifndef DEBUG_LOCKS
 vm_object_hold(vm_object_t obj)
+#else
+debugvm_object_hold(vm_object_t obj, char *file, int line)
+#endif
 {
 	if (obj == NULL)
 		return;
@@ -211,6 +217,8 @@ vm_object_hold(vm_object_t obj)
 
 	obj->debug_hold_bitmap |= (1 << i);
 	obj->debug_hold_thrs[i] = curthread;
+	obj->debug_hold_file[i] = file;
+	obj->debug_hold_line[i] = line;
 #endif
 }
 
@@ -229,6 +237,8 @@ vm_object_drop(vm_object_t obj)
 		    (obj->debug_hold_thrs[i] == curthread)) {
 			obj->debug_hold_bitmap &= ~(1 << i);
 			obj->debug_hold_thrs[i] = NULL;
+			obj->debug_hold_file[i] = NULL;
+			obj->debug_hold_line[i] = 0;
 			found = 1;
 			break;
 		}
@@ -263,6 +273,8 @@ vm_object_hold_wait(vm_object_t obj)
 	for (i = 0; i < VMOBJ_DEBUG_ARRAY_SIZE; i++) {
 		if ((obj->debug_hold_bitmap & (1 << i)) &&
 		    (obj->debug_hold_thrs[i] == curthread))  {
+			kprintf("vm_object %p: self-hold in at %s:%d\n", obj,
+				obj->debug_hold_file[i], obj->debug_hold_line[i]);
 			panic("vm_object: self-hold in terminate or collapse");
 		}
 	}
diff --git a/sys/vm/vm_object.h b/sys/vm/vm_object.h
index 9af6d8c9f3..145c52e7a5 100644
--- a/sys/vm/vm_object.h
+++ b/sys/vm/vm_object.h
@@ -155,6 +155,8 @@ struct vm_object {
 #define VMOBJ_DEBUG_ARRAY_SIZE		(32)
 	u_int debug_hold_bitmap;
 	thread_t debug_hold_thrs[VMOBJ_DEBUG_ARRAY_SIZE];
+	char *debug_hold_file[VMOBJ_DEBUG_ARRAY_SIZE];
+	int debug_hold_line[VMOBJ_DEBUG_ARRAY_SIZE];
 	u_int debug_hold_ovfl;
 #endif
 
@@ -304,7 +306,15 @@ void vm_object_dead_sleep(vm_object_t, const char *);
 void vm_object_dead_wakeup(vm_object_t);
 void vm_object_lock(vm_object_t);
 void vm_object_unlock(vm_object_t);
+
+#ifndef DEBUG_LOCKS
 void vm_object_hold(vm_object_t);
+#else
+#define vm_object_hold(obj)	\
+	debugvm_object_hold(obj, __FILE__, __LINE__)
+void debugvm_object_hold(vm_object_t, char *, int);
+#endif
+
 void vm_object_drop(vm_object_t);
 
 #endif				/* _KERNEL */
-- 
2.41.0