3 files changed, 49 insertions, 1 deletions

diff --git a/sys/vm/uma.h b/sys/vm/uma.h
index 8a12fe1..28d5ee0 100644
--- a/sys/vm/uma.h
+++ b/sys/vm/uma.h
@@ -476,6 +476,18 @@ int uma_zone_set_max(uma_zone_t zone, int nitems);
 int uma_zone_get_max(uma_zone_t zone);
 
 /*
+ * Sets a warning to be printed when limit is reached
+ *
+ * Arguments:
+ *	zone  The zone we will warn about
+ *	warning  Warning content
+ *
+ * Returns:
+ *	Nothing
+ */
+void uma_zone_set_warning(uma_zone_t zone, const char *warning);
+
+/*
  * Obtains the approximate current number of items allocated from a zone
  *
  * Arguments:
diff --git a/sys/vm/uma_core.c b/sys/vm/uma_core.c
index e58a86f..36a149e 100644
--- a/sys/vm/uma_core.c
+++ b/sys/vm/uma_core.c
@@ -265,6 +265,11 @@ SYSCTL_PROC(_vm, OID_AUTO, zone_count, CTLFLAG_RD|CTLTYPE_INT,
 SYSCTL_PROC(_vm, OID_AUTO, zone_stats, CTLFLAG_RD|CTLTYPE_STRUCT,
     0, 0, sysctl_vm_zone_stats, "s,struct uma_type_header", "Zone Stats");
 
+static int zone_warnings = 1;
+TUNABLE_INT("vm.zone_warnings", &zone_warnings);
+SYSCTL_INT(_vm, OID_AUTO, zone_warnings, CTLFLAG_RW, &zone_warnings, 0,
+    "Warn when UMA zones becomes full");
+
 /*
  * This routine checks to see whether or not it's safe to enable buckets.
  */
@@ -363,6 +368,18 @@ bucket_zone_drain(void)
 		zone_drain(ubz->ubz_zone);
 }
 
+static void
+zone_log_warning(uma_zone_t zone)
+{
+	static const struct timeval warninterval = { 300, 0 };
+
+	if (!zone_warnings || zone->uz_warning == NULL)
+		return;
+
+	if (ratecheck(&zone->uz_ratecheck, &warninterval))
+		printf("[zone: %s] %s\n", zone->uz_name, zone->uz_warning);
+}
+
 static inline uma_keg_t
 zone_first_keg(uma_zone_t zone)
 {
@@ -1432,6 +1449,8 @@ zone_ctor(void *mem, int size, void *udata, int flags)
 	zone->uz_sleeps = 0;
 	zone->uz_fills = zone->uz_count = 0;
 	zone->uz_flags = 0;
+	zone->uz_warning = NULL;
+	timevalclear(&zone->uz_ratecheck);
 	keg = arg->keg;
 
 	if (arg->flags & UMA_ZONE_SECONDARY) {
@@ -2191,8 +2210,10 @@ keg_fetch_slab(uma_keg_t keg, uma_zone_t zone, int flags)
 			 * If this is not a multi-zone, set the FULL bit.
 			 * Otherwise slab_multi() takes care of it.
 			 */
-			if ((zone->uz_flags & UMA_ZFLAG_MULTI) == 0)
+			if ((zone->uz_flags & UMA_ZFLAG_MULTI) == 0) {
 				zone->uz_flags |= UMA_ZFLAG_FULL;
+				zone_log_warning(zone);
+			}
 			if (flags & M_NOWAIT)
 				break;
 			zone->uz_sleeps++;
@@ -2339,6 +2360,7 @@ zone_fetch_slab_multi(uma_zone_t zone, uma_keg_t last, int rflags)
 		if (full && !empty) {
 			zone->uz_flags |= UMA_ZFLAG_FULL;
 			zone->uz_sleeps++;
+			zone_log_warning(zone);
 			msleep(zone, zone->uz_lock, PVM, "zonelimit", hz/100);
 			zone->uz_flags &= ~UMA_ZFLAG_FULL;
 			continue;
@@ -2881,6 +2903,16 @@ uma_zone_get_max(uma_zone_t zone)
 }
 
 /* See uma.h */
+void
+uma_zone_set_warning(uma_zone_t zone, const char *warning)
+{
+
+	ZONE_LOCK(zone);
+	zone->uz_warning = warning;
+	ZONE_UNLOCK(zone);
+}
+
+/* See uma.h */
 int
 uma_zone_get_cur(uma_zone_t zone)
 {
diff --git a/sys/vm/uma_int.h b/sys/vm/uma_int.h
index d9d5394..71788ea 100644
--- a/sys/vm/uma_int.h
+++ b/sys/vm/uma_int.h
@@ -331,6 +331,10 @@ struct uma_zone {
 	uint16_t	uz_fills;	/* Outstanding bucket fills */
 	uint16_t	uz_count;	/* Highest value ub_ptr can have */
 
+	/* The next three fields are used to print a rate-limited warnings. */
+	const char	*uz_warning;	/* Warning to print on failure */
+	struct timeval	uz_ratecheck;	/* Warnings rate-limiting */
+
 	/*
 	 * This HAS to be the last item because we adjust the zone size
 	 * based on NCPU and then allocate the space for the zones.