Update skc_obj_alloc for spl kmem caches that are backed by Linux

module/os/linux/spl/spl-kmem-cache.c

@@ -1467,6 +1467,17 @@ spl_kmem_cache_alloc(spl_kmem_cache_t *skc, int flags)
 			obj = kmem_cache_alloc(slc, kmem_flags_convert(flags));
 		} while ((obj == NULL) && !(flags & KM_NOSLEEP));
 
+		if (obj != NULL) {
+			/*
+			 * Even though we leave everything up to the
+			 * underlying cache we still keep track of
+			 * how many objects we've allocated in it for
+			 * better debuggability.
+			 */
+			spin_lock(&skc->skc_lock);
+			skc->skc_obj_alloc++;
+			spin_unlock(&skc->skc_lock);
+		}
 		goto ret;
 	}
 
@@ -1540,6 +1551,9 @@ spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj)
 	 */
 	if (skc->skc_flags & KMC_SLAB) {
 		kmem_cache_free(skc->skc_linux_cache, obj);
+		spin_lock(&skc->skc_lock);
+		skc->skc_obj_alloc--;
+		spin_unlock(&skc->skc_lock);
 		return;
 	}
 

module/os/linux/spl/spl-proc.c

@@ -437,11 +437,29 @@ slab_seq_show(struct seq_file *f, void *p)
 
 	ASSERT(skc->skc_magic == SKC_MAGIC);
 
-	/*
-	 * Backed by Linux slab see /proc/slabinfo.
-	 */
-	if (skc->skc_flags & KMC_SLAB)
+	if (skc->skc_flags & KMC_SLAB) {
+		/*
+		 * This cache is backed by a generic Linux kmem cache which
+		 * has its own accounting. For these caches we only track
+		 * the number of active allocated objects that exist within
+		 * the underlying Linux slabs. For the overall statistics of
+		 * the underlying Linux cache please refer to /proc/slabinfo.
+		 */
+		spin_lock(&skc->skc_lock);
+		seq_printf(f, "%-36s  ", skc->skc_name);
+		seq_printf(f, "0x%05lx %9s %9lu %8s %8u  "
+		    "%5s %5s %5s  %5s %5lu %5s  %5s %5s %5s\n",
+		    (long unsigned)skc->skc_flags,
+		    "-",
+		    (long unsigned)(skc->skc_obj_size * skc->skc_obj_alloc),
+		    "-",
+		    (unsigned)skc->skc_obj_size,
+		    "-", "-", "-", "-",
+		    (long unsigned)skc->skc_obj_alloc,
+		    "-", "-", "-", "-");
+		spin_unlock(&skc->skc_lock);
 		return (0);
+	}
 
 	spin_lock(&skc->skc_lock);
 	seq_printf(f, "%-36s  ", skc->skc_name);
@@ -461,9 +479,7 @@ slab_seq_show(struct seq_file *f, void *p)
 	    (long unsigned)skc->skc_obj_deadlock,
 	    (long unsigned)skc->skc_obj_emergency,
 	    (long unsigned)skc->skc_obj_emergency_max);
-
 	spin_unlock(&skc->skc_lock);
-
 	return (0);
 }