diff --git a/kmod/src/Makefile.kernelcompat b/kmod/src/Makefile.kernelcompat
index 312d8bf4..d683cb71 100644
--- a/kmod/src/Makefile.kernelcompat
+++ b/kmod/src/Makefile.kernelcompat
@@ -518,3 +518,11 @@ endif
 ifneq (,$(shell grep 'struct posix_acl ...get_acl..struct mnt_idmap ., struct dentry' include/linux/fs.h))
 ccflags-y += -DKC_GET_ACL_DENTRY
 endif
+
+#
+# v5.1-rc3-29-gaa30f47cf666
+#
+# struct kobj_type now has member `default_groups`
+ifneq (,$(shell grep 'const struct attribute_group ..default_groups;' include/linux/kobject.h))
+ccflags-y += -DKC_KOBJECT_DEFAULT_GROUPS
+endif
diff --git a/kmod/src/counters.c b/kmod/src/counters.c
index 5578ae26..f879cc83 100644
--- a/kmod/src/counters.c
+++ b/kmod/src/counters.c
@@ -24,31 +24,51 @@
  * makes this a whole lot more noisy than it needs to be.
  */
 
+static ssize_t scoutfs_counter_attr_show(struct kobject *, struct kobj_attribute *, char *);
+
 #undef EXPAND_COUNTER
-#define EXPAND_COUNTER(which) { .name = __stringify(which), .mode = 0644 },
-static struct attribute scoutfs_counter_attrs[] = {
+#define EXPAND_COUNTER(which) static struct kobj_attribute which##_attr = \
+	__ATTR(which, 0444, scoutfs_counter_attr_show, NULL);
+EXPAND_EACH_COUNTER
+
+#undef EXPAND_COUNTER
+#define EXPAND_COUNTER(which) &which##_attr.attr,
+static struct attribute *scoutfs_counter_attrs[] = {
 	EXPAND_EACH_COUNTER
+	NULL,
 };
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+ATTRIBUTE_GROUPS(scoutfs_counter);
+#endif
 
 /* zero BSS and + 1 makes this null terminated */
 #define NR_ATTRS ARRAY_SIZE(scoutfs_counter_attrs)
-static struct attribute *scoutfs_counter_attr_ptrs[NR_ATTRS + 1];
 
-static ssize_t scoutfs_counter_attr_show(struct kobject *kobj,
-				         struct attribute *attr, char *buf)
+#ifndef KC_KOBJECT_DEFAULT_GROUPS
+static struct attribute *scoutfs_counter_attr_ptrs[NR_ATTRS + 1];
+#endif
+
+static ssize_t scoutfs_counter_show(struct kobject *kobj,
+				    struct attribute *attr, char *buf)
 {
 	struct scoutfs_counters *counters;
 	struct percpu_counter *pcpu;
 	size_t index;
 
-	/* use the index in the _attrs array to discover the pcpu pointer */
 	counters = container_of(kobj, struct scoutfs_counters, kobj);
-	index = attr - scoutfs_counter_attrs;
+	index = scoutfs_counter_attrs[0] - attr;	//WAT
+	index = index / 2;				// sizeof(attr) / sizeof(pcpu)
 	pcpu = &counters->FIRST_COUNTER + index;
 
 	return snprintf(buf, PAGE_SIZE, "%lld\n", percpu_counter_sum(pcpu));
 }
 
+static ssize_t scoutfs_counter_attr_show(struct kobject *kobj,
+				         struct kobj_attribute *attr, char *buf)
+{
+	return scoutfs_counter_show(kobj, &attr->attr, buf);
+}
+
 static void scoutfs_counters_kobj_release(struct kobject *kobj)
 {
 	struct scoutfs_counters *counters;
@@ -59,11 +79,15 @@ static void scoutfs_counters_kobj_release(struct kobject *kobj)
 }
 
 static const struct sysfs_ops scoutfs_counter_attr_ops = {
-	.show   = scoutfs_counter_attr_show,
+	.show   = scoutfs_counter_show,
 };
 
 static struct kobj_type scoutfs_counters_ktype = {
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+	.default_groups = scoutfs_counter_groups,
+#else
 	.default_attrs  = scoutfs_counter_attr_ptrs,
+#endif
 	.sysfs_ops      = &scoutfs_counter_attr_ops,
 	.release        = scoutfs_counters_kobj_release,
 };
@@ -124,9 +148,11 @@ void scoutfs_destroy_counters(struct super_block *sb)
 
 void __init scoutfs_init_counters(void)
 {
+#ifndef KC_KOBJECT_DEFAULT_GROUPS
 	int i;
 
 	/* not ARRAY_SIZE because that would clobber null term */
 	for (i = 0; i < NR_ATTRS; i++)
-		scoutfs_counter_attr_ptrs[i] = &scoutfs_counter_attrs[i];
+		scoutfs_counter_attr_ptrs[i] = scoutfs_counter_attrs[i];
+#endif
 }
diff --git a/kmod/src/fence.c b/kmod/src/fence.c
index 3669dc2d..4139da8b 100644
--- a/kmod/src/fence.c
+++ b/kmod/src/fence.c
@@ -217,6 +217,9 @@ static struct attribute *fence_attrs[] = {
 	SCOUTFS_ATTR_PTR(rid),
 	NULL,
 };
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+ATTRIBUTE_GROUPS(fence);
+#endif
 
 #define FENCE_TIMEOUT_MS (MSEC_PER_SEC * 30)
 
@@ -255,7 +258,8 @@ int scoutfs_fence_start(struct super_block *sb, u64 rid, __be32 ipv4_addr, int r
 	fence->rid = rid;
 
 	ret = scoutfs_sysfs_create_attrs_parent(sb, &fi->kset->kobj,
-						&fence->ssa, fence_attrs,
+						&fence->ssa,
+						KC_KOBJ_DEFAULT(fence),
 						"%016llx", rid);
 	if (ret < 0) {
 		kfree(fence);
diff --git a/kmod/src/kernelcompat.h b/kmod/src/kernelcompat.h
index 0fde3ef2..91d13fc9 100644
--- a/kmod/src/kernelcompat.h
+++ b/kmod/src/kernelcompat.h
@@ -562,4 +562,12 @@ static inline long inode_get_atime_nsec(const struct inode *inode)
 #define kc__assign_str(a, b) __assign_str(a)
 #endif
 
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+#define KC_KOBJ_DEFAULT_OP default_groups
+#define KC_KOBJ_DEFAULT(name) name##_groups
+#else
+#define KC_KOBJ_DEFAULT_OP default_attrs
+#define KC_KOBJ_DEFAULT(name) name##_attrs
+#endif
+
 #endif
diff --git a/kmod/src/options.c b/kmod/src/options.c
index 8ce78067..dd340543 100644
--- a/kmod/src/options.c
+++ b/kmod/src/options.c
@@ -599,13 +599,18 @@ static struct attribute *options_attrs[] = {
 	SCOUTFS_ATTR_PTR(quorum_slot_nr),
 	NULL,
 };
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+ATTRIBUTE_GROUPS(options);
+#endif
 
 int scoutfs_options_setup(struct super_block *sb)
 {
 	DECLARE_OPTIONS_INFO(sb, optinf);
 	int ret;
 
-	ret = scoutfs_sysfs_create_attrs(sb, &optinf->sysfs_attrs, options_attrs, "mount_options");
+	ret = scoutfs_sysfs_create_attrs(sb, &optinf->sysfs_attrs,
+					 KC_KOBJ_DEFAULT(options),
+					 "mount_options");
 	if (ret < 0)
 		scoutfs_options_destroy(sb);
 	return ret;
diff --git a/kmod/src/quorum.c b/kmod/src/quorum.c
index ee969bdb..a65d5011 100644
--- a/kmod/src/quorum.c
+++ b/kmod/src/quorum.c
@@ -1201,6 +1201,9 @@ static struct attribute *quorum_attrs[] = {
 	SCOUTFS_ATTR_PTR(is_leader),
 	NULL,
 };
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+ATTRIBUTE_GROUPS(quorum);
+#endif
 
 static inline bool valid_ipv4_unicast(__be32 addr)
 {
@@ -1361,7 +1364,8 @@ int scoutfs_quorum_setup(struct super_block *sb)
 	if (ret < 0)
 		goto out;
 
-	ret = scoutfs_sysfs_create_attrs(sb, &qinf->ssa, quorum_attrs,
+	ret = scoutfs_sysfs_create_attrs(sb, &qinf->ssa,
+					 KC_KOBJ_DEFAULT(quorum),
 					 "quorum");
 	if (ret < 0)
 		goto out;
diff --git a/kmod/src/srch.c b/kmod/src/srch.c
index d8b2ba35..5a7d7742 100644
--- a/kmod/src/srch.c
+++ b/kmod/src/srch.c
@@ -2356,6 +2356,9 @@ static struct attribute *srch_attrs[] = {
 	SCOUTFS_ATTR_PTR(compact_delay_ms),
 	NULL,
 };
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+ATTRIBUTE_GROUPS(srch);
+#endif
 
 void scoutfs_srch_destroy(struct super_block *sb)
 {
@@ -2397,7 +2400,9 @@ int scoutfs_srch_setup(struct super_block *sb)
 
 	sbi->srch_info = srinf;
 
-	ret = scoutfs_sysfs_create_attrs(sb, &srinf->ssa, srch_attrs, "srch");
+	ret = scoutfs_sysfs_create_attrs(sb, &srinf->ssa,
+					 KC_KOBJ_DEFAULT(srch),
+					 "srch");
 	if (ret < 0)
 		goto out;
 
diff --git a/kmod/src/sysfs.c b/kmod/src/sysfs.c
index b3c7ddbf..3b7e176f 100644
--- a/kmod/src/sysfs.c
+++ b/kmod/src/sysfs.c
@@ -103,12 +103,11 @@ static ssize_t attr_funcs_show(struct kobject *kobj, struct attribute *attr,
 	};								\
 									\
 	static struct kobj_type _name##_ktype = {			\
-		.default_attrs  = _name##_attrs,			\
+		.KC_KOBJ_DEFAULT_OP = KC_KOBJ_DEFAULT(_name),		\
 		.sysfs_ops      = &_name##_sysfs_ops,			\
 		.release        = _name##_release,			\
 	};
 
-
 static struct attribute *sb_id_attrs[] = {
 	&data_device_maj_min_attr_funcs.attr,
 	&format_version_attr_funcs.attr,
@@ -116,6 +115,9 @@ static struct attribute *sb_id_attrs[] = {
 	&rid_attr_funcs.attr,
 	NULL,
 };
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+ATTRIBUTE_GROUPS(sb_id);
+#endif
 KTYPE(sb_id);
 
 struct kobject *scoutfs_sysfs_sb_dir(struct super_block *sb)
@@ -155,7 +157,12 @@ void scoutfs_sysfs_init_attrs(struct super_block *sb,
 int scoutfs_sysfs_create_attrs_parent(struct super_block *sb,
 				      struct kobject *parent,
 				      struct scoutfs_sysfs_attrs *ssa,
-				      struct attribute **attrs, char *fmt, ...)
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+				      const struct attribute_group **groups,
+#else
+				      struct attribute **attrs,
+#endif
+				      char *fmt, ...)
 {
 	va_list args;
 	size_t name_len;
@@ -168,7 +175,11 @@ int scoutfs_sysfs_create_attrs_parent(struct super_block *sb,
 
 	ssa->sb = sb;
 	init_completion(&ssa->comp);
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+	ssa->ktype.default_groups = groups;
+#else
 	ssa->ktype.default_attrs = attrs;
+#endif
 	ssa->ktype.sysfs_ops = &kobj_sysfs_ops;
 	ssa->ktype.release = scoutfs_sysfs_release;
 
diff --git a/kmod/src/sysfs.h b/kmod/src/sysfs.h
index 70b85af8..5e323044 100644
--- a/kmod/src/sysfs.h
+++ b/kmod/src/sysfs.h
@@ -39,10 +39,15 @@ void scoutfs_sysfs_init_attrs(struct super_block *sb,
 int scoutfs_sysfs_create_attrs_parent(struct super_block *sb,
 				      struct kobject *parent,
 				      struct scoutfs_sysfs_attrs *ssa,
-				      struct attribute **attrs, char *fmt, ...);
-#define scoutfs_sysfs_create_attrs(sb, ssa, attrs, fmt, args...)	\
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+				      const struct attribute_group **groups,
+#else
+				      struct attribute **attrs,
+#endif
+				      char *fmt, ...);
+#define scoutfs_sysfs_create_attrs(sb, ssa, attrs_or_group, fmt, args...)	\
 	scoutfs_sysfs_create_attrs_parent(sb, scoutfs_sysfs_sb_dir(sb),	\
-					  ssa, attrs, fmt, ##args)
+					  ssa, attrs_or_group, fmt, ##args)
 
 void scoutfs_sysfs_destroy_attrs(struct super_block *sb,
 				 struct scoutfs_sysfs_attrs *ssa);
diff --git a/kmod/src/volopt.c b/kmod/src/volopt.c
index 303d94b0..763e82a3 100644
--- a/kmod/src/volopt.c
+++ b/kmod/src/volopt.c
@@ -52,6 +52,15 @@ static struct volopt_nr_name {
 /* initialized by setup, pointer array is null terminated */
 static struct kobj_attribute volopt_attrs[ARRAY_SIZE(volopt_table)];
 static struct attribute *volopt_attr_ptrs[ARRAY_SIZE(volopt_table) + 1];
+#ifdef KC_KOBJECT_DEFAULT_GROUPS
+static const struct attribute_group volopt_group = {
+	.attrs = volopt_attr_ptrs,
+};
+static const struct attribute_group *volopt_groups[] = {
+	&volopt_group,
+	NULL,
+};
+#endif
 
 static void get_opt_data(struct kobj_attribute *attr, struct scoutfs_volume_options *volopt,
 			 u64 *bit, __le64 **opt)
@@ -164,7 +173,9 @@ int scoutfs_volopt_setup(struct super_block *sb)
 	BUILD_BUG_ON(ARRAY_SIZE(volopt_table) != ARRAY_SIZE(volopt_attr_ptrs) - 1);
 	volopt_attr_ptrs[i] = NULL;
 
-	ret = scoutfs_sysfs_create_attrs(sb, &vinf->ssa, volopt_attr_ptrs, "volume_options");
+	ret = scoutfs_sysfs_create_attrs(sb, &vinf->ssa,
+					 KC_KOBJ_DEFAULT(volopt),
+					 "volume_options");
 	if (ret < 0)
 		goto out;