[PATCH] improved slab error diagnostics

slab does various consistency checks during `cat /proc/slabinfo'
processing.  If it finds one it stupidly goes BUG just before
displaying the info which is required to diagnose the bug.

Change it to not go BUG, but to emit some useful printks and continue.

The patch also removes an uninteresting printk from the boot process.

mm/slab.c

@@ -507,7 +507,6 @@ static void start_cpu_timer(int cpu)
 	struct timer_list *rt = &reap_timers[cpu];
 
 	if (rt->function == NULL) {
-		printk(KERN_INFO "slab: reap timer started for cpu %d\n", cpu);
 		init_timer(rt);
 		rt->expires = jiffies + HZ + 3*cpu;
 		rt->function = reap_timer_fnc;
@@ -2123,6 +2122,10 @@ static int s_show(struct seq_file *m, void *p)
 	unsigned long	active_slabs = 0;
 	unsigned long	num_slabs;
 	const char *name; 
+	char *error = NULL;
+	mm_segment_t old_fs;
+	char tmp; 
+
 
 	if (p == (void*)1) {
 		/*
@@ -2143,38 +2146,45 @@ static int s_show(struct seq_file *m, void *p)
 	num_slabs = 0;
 	list_for_each(q,&cachep->lists.slabs_full) {
 		slabp = list_entry(q, struct slab, list);
-		if (slabp->inuse != cachep->num)
-			BUG();
+		if (slabp->inuse != cachep->num && !error)
+			error = "slabs_full accounting error";
 		active_objs += cachep->num;
 		active_slabs++;
 	}
 	list_for_each(q,&cachep->lists.slabs_partial) {
 		slabp = list_entry(q, struct slab, list);
-		BUG_ON(slabp->inuse == cachep->num || !slabp->inuse);
+		if (slabp->inuse == cachep->num && !error)
+			error = "slabs_partial inuse accounting error";
+		if (!slabp->inuse && !error)
+			error = "slabs_partial/inuse accounting error";
 		active_objs += slabp->inuse;
 		active_slabs++;
 	}
 	list_for_each(q,&cachep->lists.slabs_free) {
 		slabp = list_entry(q, struct slab, list);
-		if (slabp->inuse)
-			BUG();
+		if (slabp->inuse && !error)
+			error = "slabs_free/inuse accounting error";
 		num_slabs++;
 	}
 	num_slabs+=active_slabs;
 	num_objs = num_slabs*cachep->num;
-	BUG_ON(num_objs - active_objs != cachep->lists.free_objects);
+	if (num_objs - active_objs != cachep->lists.free_objects && !error)
+		error = "free_objects accounting error";
 
 	name = cachep->name; 
-	{
-	char tmp; 
-	mm_segment_t old_fs;
 
+	/*
+	 * Check to see if `name' resides inside a module which has been
+	 * unloaded (someone forgot to destroy their cache)
+	 */
 	old_fs = get_fs();
 	set_fs(KERNEL_DS);
 	if (__get_user(tmp, name)) 
 		name = "broken"; 
 	set_fs(old_fs);
-	} 	
+
+	if (error)
+		printk(KERN_ERR "slab: cache %s error: %s\n", name, error);
 
 	seq_printf(m, "%-17s %6lu %6lu %6u %4lu %4lu %4u",
 		name, active_objs, num_objs, cachep->objsize,