diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 94ec766432f5eb..e67cd45a85be47 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -386,19 +386,18 @@ struct bpf_verifier_state {
 	u32 jmp_history_cnt;
 };
 
-#define bpf_get_spilled_reg(slot, frame)				\
+#define bpf_get_spilled_reg(slot, frame, mask)				\
 	(((slot < frame->allocated_stack / BPF_REG_SIZE) &&		\
-	  (frame->stack[slot].slot_type[0] == STACK_SPILL))		\
+	  ((1 << frame->stack[slot].slot_type[0]) & (mask))) \
 	 ? &frame->stack[slot].spilled_ptr : NULL)
 
 /* Iterate over 'frame', setting 'reg' to either NULL or a spilled register. */
-#define bpf_for_each_spilled_reg(iter, frame, reg)			\
-	for (iter = 0, reg = bpf_get_spilled_reg(iter, frame);		\
+#define bpf_for_each_spilled_reg(iter, frame, reg, mask)			\
+	for (iter = 0, reg = bpf_get_spilled_reg(iter, frame, mask);		\
 	     iter < frame->allocated_stack / BPF_REG_SIZE;		\
-	     iter++, reg = bpf_get_spilled_reg(iter, frame))
+	     iter++, reg = bpf_get_spilled_reg(iter, frame, mask))
 
-/* Invoke __expr over regsiters in __vst, setting __state and __reg */
-#define bpf_for_each_reg_in_vstate(__vst, __state, __reg, __expr)   \
+#define bpf_for_each_reg_in_vstate_mask(__vst, __state, __reg, __mask, __expr)   \
 	({                                                               \
 		struct bpf_verifier_state *___vstate = __vst;            \
 		int ___i, ___j;                                          \
@@ -410,7 +409,7 @@ struct bpf_verifier_state {
 				__reg = &___regs[___j];                  \
 				(void)(__expr);                          \
 			}                                                \
-			bpf_for_each_spilled_reg(___j, __state, __reg) { \
+			bpf_for_each_spilled_reg(___j, __state, __reg, __mask) { \
 				if (!__reg)                              \
 					continue;                        \
 				(void)(__expr);                          \
@@ -418,6 +417,10 @@ struct bpf_verifier_state {
 		}                                                        \
 	})
 
+/* Invoke __expr over regsiters in __vst, setting __state and __reg */
+#define bpf_for_each_reg_in_vstate(__vst, __state, __reg, __expr) \
+	bpf_for_each_reg_in_vstate_mask(__vst, __state, __reg, 1 << STACK_SPILL, __expr)
+
 /* linked list of verifier states used to prune search */
 struct bpf_verifier_state_list {
 	struct bpf_verifier_state state;
diff --git a/include/linux/btf.h b/include/linux/btf.h
index 928113a80a9527..c2231c64d60b92 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -74,6 +74,7 @@
 #define KF_ITER_NEW     (1 << 8) /* kfunc implements BPF iter constructor */
 #define KF_ITER_NEXT    (1 << 9) /* kfunc implements BPF iter next method */
 #define KF_ITER_DESTROY (1 << 10) /* kfunc implements BPF iter destructor */
+#define KF_RCU_PROTECTED (1 << 11) /* kfunc should be protected by rcu cs when they are invoked */
 
 /*
  * Tag marking a kernel function as a kfunc. This is meant to minimize the
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index b307013b9c6c9a..0ef0af66080ed0 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -40,13 +40,11 @@ struct kernel_clone_args;
 #define CGROUP_WEIGHT_DFL		100
 #define CGROUP_WEIGHT_MAX		10000
 
-/* walk only threadgroup leaders */
-#define CSS_TASK_ITER_PROCS		(1U << 0)
-/* walk all threaded css_sets in the domain */
-#define CSS_TASK_ITER_THREADED		(1U << 1)
-
-/* internal flags */
-#define CSS_TASK_ITER_SKIPPED		(1U << 16)
+enum {
+	CSS_TASK_ITER_PROCS    = (1U << 0),  /* walk only threadgroup leaders */
+	CSS_TASK_ITER_THREADED = (1U << 1),  /* walk all threaded css_sets in the domain */
+	CSS_TASK_ITER_SKIPPED  = (1U << 16), /* internal flags */
+};
 
 /* a css_task_iter should be treated as an opaque object */
 struct css_task_iter {
diff --git a/kernel/bpf/cgroup_iter.c b/kernel/bpf/cgroup_iter.c
index 810378f04fbcac..209e5135f9fbc5 100644
--- a/kernel/bpf/cgroup_iter.c
+++ b/kernel/bpf/cgroup_iter.c
@@ -294,3 +294,68 @@ static int __init bpf_cgroup_iter_init(void)
 }
 
 late_initcall(bpf_cgroup_iter_init);
+
+struct bpf_iter_css {
+	__u64 __opaque[3];
+} __attribute__((aligned(8)));
+
+struct bpf_iter_css_kern {
+	struct cgroup_subsys_state *start;
+	struct cgroup_subsys_state *pos;
+	unsigned int flags;
+} __attribute__((aligned(8)));
+
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+		"Global functions as their definitions will be in vmlinux BTF");
+
+__bpf_kfunc int bpf_iter_css_new(struct bpf_iter_css *it,
+		struct cgroup_subsys_state *start, unsigned int flags)
+{
+	struct bpf_iter_css_kern *kit = (void *)it;
+
+	BUILD_BUG_ON(sizeof(struct bpf_iter_css_kern) > sizeof(struct bpf_iter_css));
+	BUILD_BUG_ON(__alignof__(struct bpf_iter_css_kern) != __alignof__(struct bpf_iter_css));
+
+	kit->start = NULL;
+	switch (flags) {
+	case BPF_CGROUP_ITER_DESCENDANTS_PRE:
+	case BPF_CGROUP_ITER_DESCENDANTS_POST:
+	case BPF_CGROUP_ITER_ANCESTORS_UP:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	kit->start = start;
+	kit->pos = NULL;
+	kit->flags = flags;
+	return 0;
+}
+
+__bpf_kfunc struct cgroup_subsys_state *bpf_iter_css_next(struct bpf_iter_css *it)
+{
+	struct bpf_iter_css_kern *kit = (void *)it;
+
+	if (!kit->start)
+		return NULL;
+
+	switch (kit->flags) {
+	case BPF_CGROUP_ITER_DESCENDANTS_PRE:
+		kit->pos = css_next_descendant_pre(kit->pos, kit->start);
+		break;
+	case BPF_CGROUP_ITER_DESCENDANTS_POST:
+		kit->pos = css_next_descendant_post(kit->pos, kit->start);
+		break;
+	case BPF_CGROUP_ITER_ANCESTORS_UP:
+		kit->pos = kit->pos ? kit->pos->parent : kit->start;
+	}
+
+	return kit->pos;
+}
+
+__bpf_kfunc void bpf_iter_css_destroy(struct bpf_iter_css *it)
+{
+}
+
+__diag_pop();
\ No newline at end of file
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 61f51dee844815..da058aead20c65 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2560,6 +2560,15 @@ BTF_ID_FLAGS(func, bpf_iter_num_destroy, KF_ITER_DESTROY)
 BTF_ID_FLAGS(func, bpf_iter_task_vma_new, KF_ITER_NEW | KF_RCU)
 BTF_ID_FLAGS(func, bpf_iter_task_vma_next, KF_ITER_NEXT | KF_RET_NULL)
 BTF_ID_FLAGS(func, bpf_iter_task_vma_destroy, KF_ITER_DESTROY)
+BTF_ID_FLAGS(func, bpf_iter_css_task_new, KF_ITER_NEW | KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_iter_css_task_next, KF_ITER_NEXT | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_iter_css_task_destroy, KF_ITER_DESTROY)
+BTF_ID_FLAGS(func, bpf_iter_task_new, KF_ITER_NEW | KF_TRUSTED_ARGS | KF_RCU_PROTECTED)
+BTF_ID_FLAGS(func, bpf_iter_task_next, KF_ITER_NEXT | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_iter_task_destroy, KF_ITER_DESTROY)
+BTF_ID_FLAGS(func, bpf_iter_css_new, KF_ITER_NEW | KF_TRUSTED_ARGS | KF_RCU_PROTECTED)
+BTF_ID_FLAGS(func, bpf_iter_css_next, KF_ITER_NEXT | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_iter_css_destroy, KF_ITER_DESTROY)
 BTF_ID_FLAGS(func, bpf_dynptr_adjust)
 BTF_ID_FLAGS(func, bpf_dynptr_is_null)
 BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly)
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c
index fef17628341fa1..59e747938bdbb1 100644
--- a/kernel/bpf/task_iter.c
+++ b/kernel/bpf/task_iter.c
@@ -894,6 +894,157 @@ __bpf_kfunc void bpf_iter_task_vma_destroy(struct bpf_iter_task_vma *it)
 
 __diag_pop();
 
+struct bpf_iter_css_task {
+	__u64 __opaque[1];
+} __attribute__((aligned(8)));
+
+struct bpf_iter_css_task_kern {
+	struct css_task_iter *css_it;
+} __attribute__((aligned(8)));
+
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+		  "Global functions as their definitions will be in vmlinux BTF");
+
+__bpf_kfunc int bpf_iter_css_task_new(struct bpf_iter_css_task *it,
+		struct cgroup_subsys_state *css, unsigned int flags)
+{
+	struct bpf_iter_css_task_kern *kit = (void *)it;
+
+	BUILD_BUG_ON(sizeof(struct bpf_iter_css_task_kern) != sizeof(struct bpf_iter_css_task));
+	BUILD_BUG_ON(__alignof__(struct bpf_iter_css_task_kern) !=
+					__alignof__(struct bpf_iter_css_task));
+	kit->css_it = NULL;
+	switch (flags) {
+	case CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED:
+	case CSS_TASK_ITER_PROCS:
+	case 0:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	kit->css_it = bpf_mem_alloc(&bpf_global_ma, sizeof(struct css_task_iter));
+	if (!kit->css_it)
+		return -ENOMEM;
+	css_task_iter_start(css, flags, kit->css_it);
+	return 0;
+}
+
+__bpf_kfunc struct task_struct *bpf_iter_css_task_next(struct bpf_iter_css_task *it)
+{
+	struct bpf_iter_css_task_kern *kit = (void *)it;
+
+	if (!kit->css_it)
+		return NULL;
+	return css_task_iter_next(kit->css_it);
+}
+
+__bpf_kfunc void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it)
+{
+	struct bpf_iter_css_task_kern *kit = (void *)it;
+
+	if (!kit->css_it)
+		return;
+	css_task_iter_end(kit->css_it);
+	bpf_mem_free(&bpf_global_ma, kit->css_it);
+}
+
+__diag_pop();
+
+struct bpf_iter_task {
+	__u64 __opaque[3];
+} __attribute__((aligned(8)));
+
+struct bpf_iter_task_kern {
+	struct task_struct *task;
+	struct task_struct *pos;
+	unsigned int flags;
+} __attribute__((aligned(8)));
+
+enum {
+	/* all process in the system */
+	BPF_TASK_ITER_ALL_PROCS,
+	/* all threads in the system */
+	BPF_TASK_ITER_ALL_THREADS,
+	/* all threads of a specific process */
+	BPF_TASK_ITER_PROC_THREADS
+};
+
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+		  "Global functions as their definitions will be in vmlinux BTF");
+
+__bpf_kfunc int bpf_iter_task_new(struct bpf_iter_task *it,
+		struct task_struct *task__nullable, unsigned int flags)
+{
+	struct bpf_iter_task_kern *kit = (void *)it;
+
+	BUILD_BUG_ON(sizeof(struct bpf_iter_task_kern) > sizeof(struct bpf_iter_task));
+	BUILD_BUG_ON(__alignof__(struct bpf_iter_task_kern) !=
+					__alignof__(struct bpf_iter_task));
+
+	kit->task = kit->pos = NULL;
+	switch (flags) {
+	case BPF_TASK_ITER_ALL_THREADS:
+	case BPF_TASK_ITER_ALL_PROCS:
+		break;
+	case BPF_TASK_ITER_PROC_THREADS:
+		if (!task__nullable)
+			return -EINVAL;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (flags == BPF_TASK_ITER_PROC_THREADS)
+		kit->task = task__nullable;
+	else
+		kit->task = &init_task;
+	kit->pos = kit->task;
+	kit->flags = flags;
+	return 0;
+}
+
+__bpf_kfunc struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it)
+{
+	struct bpf_iter_task_kern *kit = (void *)it;
+	struct task_struct *pos;
+	unsigned int flags;
+
+	flags = kit->flags;
+	pos = kit->pos;
+
+	if (!pos)
+		return pos;
+
+	if (flags == BPF_TASK_ITER_ALL_PROCS)
+		goto get_next_task;
+
+	kit->pos = next_thread(kit->pos);
+	if (kit->pos == kit->task) {
+		if (flags == BPF_TASK_ITER_PROC_THREADS) {
+			kit->pos = NULL;
+			return pos;
+		}
+	} else
+		return pos;
+
+get_next_task:
+	kit->pos = next_task(kit->pos);
+	kit->task = kit->pos;
+	if (kit->pos == &init_task)
+		kit->pos = NULL;
+
+	return pos;
+}
+
+__bpf_kfunc void bpf_iter_task_destroy(struct bpf_iter_task *it)
+{
+}
+
+__diag_pop();
+
 DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);
 
 static void do_mmap_read_unlock(struct irq_work *entry)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index bb58987e4844a5..e9bc5d4a25a176 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1173,7 +1173,12 @@ static bool is_dynptr_type_expected(struct bpf_verifier_env *env, struct bpf_reg
 
 static void __mark_reg_known_zero(struct bpf_reg_state *reg);
 
+static bool in_rcu_cs(struct bpf_verifier_env *env);
+
+static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta);
+
 static int mark_stack_slots_iter(struct bpf_verifier_env *env,
+				 struct bpf_kfunc_call_arg_meta *meta,
 				 struct bpf_reg_state *reg, int insn_idx,
 				 struct btf *btf, u32 btf_id, int nr_slots)
 {
@@ -1194,6 +1199,12 @@ static int mark_stack_slots_iter(struct bpf_verifier_env *env,
 
 		__mark_reg_known_zero(st);
 		st->type = PTR_TO_STACK; /* we don't have dedicated reg type */
+		if (is_kfunc_rcu_protected(meta)) {
+			if (in_rcu_cs(env))
+				st->type |= MEM_RCU;
+			else
+				st->type |= PTR_UNTRUSTED;
+		}
 		st->live |= REG_LIVE_WRITTEN;
 		st->ref_obj_id = i == 0 ? id : 0;
 		st->iter.btf = btf;
@@ -1268,7 +1279,7 @@ static bool is_iter_reg_valid_uninit(struct bpf_verifier_env *env,
 	return true;
 }
 
-static bool is_iter_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
+static int is_iter_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
 				   struct btf *btf, u32 btf_id, int nr_slots)
 {
 	struct bpf_func_state *state = func(env, reg);
@@ -1276,26 +1287,28 @@ static bool is_iter_reg_valid_init(struct bpf_verifier_env *env, struct bpf_reg_
 
 	spi = iter_get_spi(env, reg, nr_slots);
 	if (spi < 0)
-		return false;
+		return -EINVAL;
 
 	for (i = 0; i < nr_slots; i++) {
 		struct bpf_stack_state *slot = &state->stack[spi - i];
 		struct bpf_reg_state *st = &slot->spilled_ptr;
 
+		if (st->type & PTR_UNTRUSTED)
+			return -EPROTO;
 		/* only main (first) slot has ref_obj_id set */
 		if (i == 0 && !st->ref_obj_id)
-			return false;
+			return -EINVAL;
 		if (i != 0 && st->ref_obj_id)
-			return false;
+			return -EINVAL;
 		if (st->iter.btf != btf || st->iter.btf_id != btf_id)
-			return false;
+			return -EINVAL;
 
 		for (j = 0; j < BPF_REG_SIZE; j++)
 			if (slot->slot_type[j] != STACK_ITER)
-				return false;
+				return -EINVAL;
 	}
 
-	return true;
+	return 0;
 }
 
 /* Check if given stack slot is "special":
@@ -7640,15 +7653,24 @@ static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_id
 				return err;
 		}
 
-		err = mark_stack_slots_iter(env, reg, insn_idx, meta->btf, btf_id, nr_slots);
+		err = mark_stack_slots_iter(env, meta, reg, insn_idx, meta->btf, btf_id, nr_slots);
 		if (err)
 			return err;
 	} else {
 		/* iter_next() or iter_destroy() expect initialized iter state*/
-		if (!is_iter_reg_valid_init(env, reg, meta->btf, btf_id, nr_slots)) {
+		err = is_iter_reg_valid_init(env, reg, meta->btf, btf_id, nr_slots);
+		switch (err) {
+		case 0:
+			break;
+		case -EINVAL:
 			verbose(env, "expected an initialized iter_%s as arg #%d\n",
 				iter_type_str(meta->btf, btf_id), regno);
-			return -EINVAL;
+			return err;
+		case -EPROTO:
+			verbose(env, "expected an RCU CS when using %s\n", meta->func_name);
+			return err;
+		default:
+			return err;
 		}
 
 		spi = iter_get_spi(env, reg, nr_slots);
@@ -10231,6 +10253,11 @@ static bool is_kfunc_rcu(struct bpf_kfunc_call_arg_meta *meta)
 	return meta->kfunc_flags & KF_RCU;
 }
 
+static bool is_kfunc_rcu_protected(struct bpf_kfunc_call_arg_meta *meta)
+{
+	return meta->kfunc_flags & KF_RCU_PROTECTED;
+}
+
 static bool __kfunc_param_match_suffix(const struct btf *btf,
 				       const struct btf_param *arg,
 				       const char *suffix)
@@ -10305,6 +10332,11 @@ static bool is_kfunc_arg_refcounted_kptr(const struct btf *btf, const struct btf
 	return __kfunc_param_match_suffix(btf, arg, "__refcounted_kptr");
 }
 
+static bool is_kfunc_arg_nullable(const struct btf *btf, const struct btf_param *arg)
+{
+	return __kfunc_param_match_suffix(btf, arg, "__nullable");
+}
+
 static bool is_kfunc_arg_scalar_with_name(const struct btf *btf,
 					  const struct btf_param *arg,
 					  const char *name)
@@ -10447,6 +10479,7 @@ enum kfunc_ptr_arg_type {
 	KF_ARG_PTR_TO_CALLBACK,
 	KF_ARG_PTR_TO_RB_ROOT,
 	KF_ARG_PTR_TO_RB_NODE,
+	KF_ARG_PTR_TO_NULL,
 };
 
 enum special_kfunc_type {
@@ -10472,6 +10505,7 @@ enum special_kfunc_type {
 	KF_bpf_percpu_obj_new_impl,
 	KF_bpf_percpu_obj_drop_impl,
 	KF_bpf_throw,
+	KF_bpf_iter_css_task_new,
 };
 
 BTF_SET_START(special_kfunc_set)
@@ -10495,6 +10529,7 @@ BTF_ID(func, bpf_dynptr_clone)
 BTF_ID(func, bpf_percpu_obj_new_impl)
 BTF_ID(func, bpf_percpu_obj_drop_impl)
 BTF_ID(func, bpf_throw)
+BTF_ID(func, bpf_iter_css_task_new)
 BTF_SET_END(special_kfunc_set)
 
 BTF_ID_LIST(special_kfunc_list)
@@ -10520,6 +10555,7 @@ BTF_ID(func, bpf_dynptr_clone)
 BTF_ID(func, bpf_percpu_obj_new_impl)
 BTF_ID(func, bpf_percpu_obj_drop_impl)
 BTF_ID(func, bpf_throw)
+BTF_ID(func, bpf_iter_css_task_new)
 
 static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta)
 {
@@ -10600,6 +10636,8 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
 	if (is_kfunc_arg_callback(env, meta->btf, &args[argno]))
 		return KF_ARG_PTR_TO_CALLBACK;
 
+	if (is_kfunc_arg_nullable(meta->btf, &args[argno]) && register_is_null(reg))
+		return KF_ARG_PTR_TO_NULL;
 
 	if (argno + 1 < nargs &&
 	    (is_kfunc_arg_mem_size(meta->btf, &args[argno + 1], &regs[regno + 1]) ||
@@ -11050,6 +11088,20 @@ static int process_kf_arg_ptr_to_rbtree_node(struct bpf_verifier_env *env,
 						  &meta->arg_rbtree_root.field);
 }
 
+static bool check_css_task_iter_allowlist(struct bpf_verifier_env *env)
+{
+	enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
+
+	switch (prog_type) {
+	case BPF_PROG_TYPE_LSM:
+		return true;
+	case BPF_TRACE_ITER:
+		return env->prog->aux->sleepable;
+	default:
+		return false;
+	}
+}
+
 static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_arg_meta *meta,
 			    int insn_idx)
 {
@@ -11136,7 +11188,8 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
 		}
 
 		if ((is_kfunc_trusted_args(meta) || is_kfunc_rcu(meta)) &&
-		    (register_is_null(reg) || type_may_be_null(reg->type))) {
+		    (register_is_null(reg) || type_may_be_null(reg->type)) &&
+			!is_kfunc_arg_nullable(meta->btf, &args[i])) {
 			verbose(env, "Possibly NULL pointer passed to trusted arg%d\n", i);
 			return -EACCES;
 		}
@@ -11161,6 +11214,8 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
 			return kf_arg_type;
 
 		switch (kf_arg_type) {
+		case KF_ARG_PTR_TO_NULL:
+			continue;
 		case KF_ARG_PTR_TO_ALLOC_BTF_ID:
 		case KF_ARG_PTR_TO_BTF_ID:
 			if (!is_kfunc_trusted_args(meta) && !is_kfunc_rcu(meta))
@@ -11300,6 +11355,12 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
 			break;
 		}
 		case KF_ARG_PTR_TO_ITER:
+			if (meta->func_id == special_kfunc_list[KF_bpf_iter_css_task_new]) {
+				if (!check_css_task_iter_allowlist(env)) {
+					verbose(env, "css_task_iter is only allowed in bpf_lsm and bpf iter-s\n");
+					return -EINVAL;
+				}
+			}
 			ret = process_iter_arg(env, regno, insn_idx, meta);
 			if (ret < 0)
 				return ret;
@@ -11559,6 +11620,7 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 	if (env->cur_state->active_rcu_lock) {
 		struct bpf_func_state *state;
 		struct bpf_reg_state *reg;
+		u32 clear_mask = (1 << STACK_SPILL) | (1 << STACK_ITER);
 
 		if (in_rbtree_lock_required_cb(env) && (rcu_lock || rcu_unlock)) {
 			verbose(env, "Calling bpf_rcu_read_{lock,unlock} in unnecessary rbtree callback\n");
@@ -11569,7 +11631,7 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
 			verbose(env, "nested rcu read lock (kernel function %s)\n", func_name);
 			return -EINVAL;
 		} else if (rcu_unlock) {
-			bpf_for_each_reg_in_vstate(env->cur_state, state, reg, ({
+			bpf_for_each_reg_in_vstate_mask(env->cur_state, state, reg, clear_mask, ({
 				if (reg->type & MEM_RCU) {
 					reg->type &= ~(MEM_RCU | PTR_MAYBE_NULL);
 					reg->type |= PTR_UNTRUSTED;
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 1fb7f562289d53..b6d64f3b888832 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4917,9 +4917,11 @@ static void css_task_iter_advance(struct css_task_iter *it)
 void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
 			 struct css_task_iter *it)
 {
+	unsigned long irqflags;
+
 	memset(it, 0, sizeof(*it));
 
-	spin_lock_irq(&css_set_lock);
+	spin_lock_irqsave(&css_set_lock, irqflags);
 
 	it->ss = css->ss;
 	it->flags = flags;
@@ -4933,7 +4935,7 @@ void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
 
 	css_task_iter_advance(it);
 
-	spin_unlock_irq(&css_set_lock);
+	spin_unlock_irqrestore(&css_set_lock, irqflags);
 }
 
 /**
@@ -4946,12 +4948,14 @@ void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
  */
 struct task_struct *css_task_iter_next(struct css_task_iter *it)
 {
+	unsigned long irqflags;
+
 	if (it->cur_task) {
 		put_task_struct(it->cur_task);
 		it->cur_task = NULL;
 	}
 
-	spin_lock_irq(&css_set_lock);
+	spin_lock_irqsave(&css_set_lock, irqflags);
 
 	/* @it may be half-advanced by skips, finish advancing */
 	if (it->flags & CSS_TASK_ITER_SKIPPED)
@@ -4964,7 +4968,7 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it)
 		css_task_iter_advance(it);
 	}
 
-	spin_unlock_irq(&css_set_lock);
+	spin_unlock_irqrestore(&css_set_lock, irqflags);
 
 	return it->cur_task;
 }
@@ -4977,11 +4981,13 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it)
  */
 void css_task_iter_end(struct css_task_iter *it)
 {
+	unsigned long irqflags;
+
 	if (it->cur_cset) {
-		spin_lock_irq(&css_set_lock);
+		spin_lock_irqsave(&css_set_lock, irqflags);
 		list_del(&it->iters_node);
 		put_css_set_locked(it->cur_cset);
-		spin_unlock_irq(&css_set_lock);
+		spin_unlock_irqrestore(&css_set_lock, irqflags);
 	}
 
 	if (it->cur_dcset)
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index 2c8cb3f6152930..1386baf9ae4adf 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -458,4 +458,23 @@ extern void bpf_throw(u64 cookie) __ksym;
 		__bpf_assert_op(LHS, <=, END, value, false);		\
 	})
 
+struct bpf_iter_css_task;
+struct cgroup_subsys_state;
+extern int bpf_iter_css_task_new(struct bpf_iter_css_task *it,
+		struct cgroup_subsys_state *css, unsigned int flags) __weak __ksym;
+extern struct task_struct *bpf_iter_css_task_next(struct bpf_iter_css_task *it) __weak __ksym;
+extern void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it) __weak __ksym;
+
+struct bpf_iter_task;
+extern int bpf_iter_task_new(struct bpf_iter_task *it,
+		struct task_struct *task, unsigned int flags) __weak __ksym;
+extern struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it) __weak __ksym;
+extern void bpf_iter_task_destroy(struct bpf_iter_task *it) __weak __ksym;
+
+struct bpf_iter_css;
+extern int bpf_iter_css_new(struct bpf_iter_css *it,
+				struct cgroup_subsys_state *start, unsigned int flags) __weak __ksym;
+extern struct cgroup_subsys_state *bpf_iter_css_next(struct bpf_iter_css *it) __weak __ksym;
+extern void bpf_iter_css_destroy(struct bpf_iter_css *it) __weak __ksym;
+
 #endif
diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
index 41aba139b20b85..e3498f607b49d7 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
@@ -7,7 +7,7 @@
 #include "bpf_iter_ipv6_route.skel.h"
 #include "bpf_iter_netlink.skel.h"
 #include "bpf_iter_bpf_map.skel.h"
-#include "bpf_iter_task.skel.h"
+#include "bpf_iter_tasks.skel.h"
 #include "bpf_iter_task_stack.skel.h"
 #include "bpf_iter_task_file.skel.h"
 #include "bpf_iter_task_vmas.skel.h"
@@ -215,12 +215,12 @@ static void *do_nothing_wait(void *arg)
 static void test_task_common_nocheck(struct bpf_iter_attach_opts *opts,
 				     int *num_unknown, int *num_known)
 {
-	struct bpf_iter_task *skel;
+	struct bpf_iter_tasks *skel;
 	pthread_t thread_id;
 	void *ret;
 
-	skel = bpf_iter_task__open_and_load();
-	if (!ASSERT_OK_PTR(skel, "bpf_iter_task__open_and_load"))
+	skel = bpf_iter_tasks__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "bpf_iter_tasks__open_and_load"))
 		return;
 
 	ASSERT_OK(pthread_mutex_lock(&do_nothing_mutex), "pthread_mutex_lock");
@@ -239,7 +239,7 @@ static void test_task_common_nocheck(struct bpf_iter_attach_opts *opts,
 	ASSERT_FALSE(pthread_join(thread_id, &ret) || ret != NULL,
 		     "pthread_join");
 
-	bpf_iter_task__destroy(skel);
+	bpf_iter_tasks__destroy(skel);
 }
 
 static void test_task_common(struct bpf_iter_attach_opts *opts, int num_unknown, int num_known)
@@ -307,10 +307,10 @@ static void test_task_pidfd(void)
 
 static void test_task_sleepable(void)
 {
-	struct bpf_iter_task *skel;
+	struct bpf_iter_tasks *skel;
 
-	skel = bpf_iter_task__open_and_load();
-	if (!ASSERT_OK_PTR(skel, "bpf_iter_task__open_and_load"))
+	skel = bpf_iter_tasks__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "bpf_iter_tasks__open_and_load"))
 		return;
 
 	do_dummy_read(skel->progs.dump_task_sleepable);
@@ -320,7 +320,7 @@ static void test_task_sleepable(void)
 	ASSERT_GT(skel->bss->num_success_copy_from_user_task, 0,
 		  "num_success_copy_from_user_task");
 
-	bpf_iter_task__destroy(skel);
+	bpf_iter_tasks__destroy(skel);
 }
 
 static void test_task_stack(void)
diff --git a/tools/testing/selftests/bpf/prog_tests/iters.c b/tools/testing/selftests/bpf/prog_tests/iters.c
index b696873c54556b..c2425791c9232f 100644
--- a/tools/testing/selftests/bpf/prog_tests/iters.c
+++ b/tools/testing/selftests/bpf/prog_tests/iters.c
@@ -1,7 +1,14 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
 
+#include <sys/syscall.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <malloc.h>
+#include <stdlib.h>
 #include <test_progs.h>
+#include "cgroup_helpers.h"
 
 #include "iters.skel.h"
 #include "iters_state_safety.skel.h"
@@ -9,6 +16,10 @@
 #include "iters_num.skel.h"
 #include "iters_testmod_seq.skel.h"
 #include "iters_task_vma.skel.h"
+#include "iters_task.skel.h"
+#include "iters_css_task.skel.h"
+#include "iters_css.skel.h"
+#include "iters_task_failure.skel.h"
 
 static void subtest_num_iters(void)
 {
@@ -146,6 +157,138 @@ static void subtest_task_vma_iters(void)
 	iters_task_vma__destroy(skel);
 }
 
+static pthread_mutex_t do_nothing_mutex;
+
+static void *do_nothing_wait(void *arg)
+{
+	pthread_mutex_lock(&do_nothing_mutex);
+	pthread_mutex_unlock(&do_nothing_mutex);
+
+	pthread_exit(arg);
+}
+
+#define thread_num 2
+
+static void subtest_task_iters(void)
+{
+	struct iters_task *skel = NULL;
+	pthread_t thread_ids[thread_num];
+	void *ret;
+	int err;
+
+	skel = iters_task__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "open_and_load"))
+		goto cleanup;
+	skel->bss->target_pid = getpid();
+	err = iters_task__attach(skel);
+	if (!ASSERT_OK(err, "iters_task__attach"))
+		goto cleanup;
+	pthread_mutex_lock(&do_nothing_mutex);
+	for (int i = 0; i < thread_num; i++)
+		ASSERT_OK(pthread_create(&thread_ids[i], NULL, &do_nothing_wait, NULL),
+			"pthread_create");
+
+	syscall(SYS_getpgid);
+	iters_task__detach(skel);
+	ASSERT_EQ(skel->bss->procs_cnt, 1, "procs_cnt");
+	ASSERT_EQ(skel->bss->threads_cnt, thread_num + 1, "threads_cnt");
+	ASSERT_EQ(skel->bss->proc_threads_cnt, thread_num + 1, "proc_threads_cnt");
+	pthread_mutex_unlock(&do_nothing_mutex);
+	for (int i = 0; i < thread_num; i++)
+		ASSERT_OK(pthread_join(thread_ids[i], &ret), "pthread_join");
+cleanup:
+	iters_task__destroy(skel);
+}
+
+extern int stack_mprotect(void);
+
+static void subtest_css_task_iters(void)
+{
+	struct iters_css_task *skel = NULL;
+	int err, cg_fd, cg_id;
+	const char *cgrp_path = "/cg1";
+
+	err = setup_cgroup_environment();
+	if (!ASSERT_OK(err, "setup_cgroup_environment"))
+		goto cleanup;
+	cg_fd = create_and_get_cgroup(cgrp_path);
+	if (!ASSERT_GE(cg_fd, 0, "create_and_get_cgroup"))
+		goto cleanup;
+	cg_id = get_cgroup_id(cgrp_path);
+	err = join_cgroup(cgrp_path);
+	if (!ASSERT_OK(err, "join_cgroup"))
+		goto cleanup;
+
+	skel = iters_css_task__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "open_and_load"))
+		goto cleanup;
+
+	skel->bss->target_pid = getpid();
+	skel->bss->cg_id = cg_id;
+	err = iters_css_task__attach(skel);
+	if (!ASSERT_OK(err, "iters_task__attach"))
+		goto cleanup;
+	err = stack_mprotect();
+	if (!ASSERT_EQ(err, -1, "stack_mprotect") ||
+	    !ASSERT_EQ(errno, EPERM, "stack_mprotect"))
+		goto cleanup;
+	iters_css_task__detach(skel);
+	ASSERT_EQ(skel->bss->css_task_cnt, 1, "css_task_cnt");
+
+cleanup:
+	cleanup_cgroup_environment();
+	iters_css_task__destroy(skel);
+}
+
+static void subtest_css_iters(void)
+{
+	struct iters_css *skel = NULL;
+	struct {
+		const char *path;
+		int fd;
+	} cgs[] = {
+		{ "/cg1" },
+		{ "/cg1/cg2" },
+		{ "/cg1/cg2/cg3" },
+		{ "/cg1/cg2/cg3/cg4" },
+	};
+	int err, cg_nr = ARRAY_SIZE(cgs);
+	int i;
+
+	err = setup_cgroup_environment();
+	if (!ASSERT_OK(err, "setup_cgroup_environment"))
+		goto cleanup;
+	for (i = 0; i < cg_nr; i++) {
+		cgs[i].fd = create_and_get_cgroup(cgs[i].path);
+		if (!ASSERT_GE(cgs[i].fd, 0, "create_and_get_cgroup"))
+			goto cleanup;
+	}
+
+	skel = iters_css__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "open_and_load"))
+		goto cleanup;
+
+	skel->bss->target_pid = getpid();
+	skel->bss->root_cg_id = get_cgroup_id(cgs[0].path);
+	skel->bss->leaf_cg_id = get_cgroup_id(cgs[cg_nr - 1].path);
+	err = iters_css__attach(skel);
+
+	if (!ASSERT_OK(err, "iters_task__attach"))
+		goto cleanup;
+
+	syscall(SYS_getpgid);
+	ASSERT_EQ(skel->bss->pre_order_cnt, cg_nr, "pre_order_cnt");
+	ASSERT_EQ(skel->bss->first_cg_id, get_cgroup_id(cgs[0].path), "first_cg_id");
+
+	ASSERT_EQ(skel->bss->post_order_cnt, cg_nr, "post_order_cnt");
+	ASSERT_EQ(skel->bss->last_cg_id, get_cgroup_id(cgs[0].path), "last_cg_id");
+	ASSERT_EQ(skel->bss->tree_high, cg_nr - 1, "tree_high");
+	iters_css__detach(skel);
+cleanup:
+	cleanup_cgroup_environment();
+	iters_css__destroy(skel);
+}
+
 void test_iters(void)
 {
 	RUN_TESTS(iters_state_safety);
@@ -161,4 +304,11 @@ void test_iters(void)
 		subtest_testmod_seq_iters();
 	if (test__start_subtest("task_vma"))
 		subtest_task_vma_iters();
+	if (test__start_subtest("task"))
+		subtest_task_iters();
+	if (test__start_subtest("css_task"))
+		subtest_css_task_iters();
+	if (test__start_subtest("css"))
+		subtest_css_iters();
+	RUN_TESTS(iters_task_failure);
 }
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task.c b/tools/testing/selftests/bpf/progs/bpf_iter_tasks.c
similarity index 100%
rename from tools/testing/selftests/bpf/progs/bpf_iter_task.c
rename to tools/testing/selftests/bpf/progs/bpf_iter_tasks.c
diff --git a/tools/testing/selftests/bpf/progs/iters_css.c b/tools/testing/selftests/bpf/progs/iters_css.c
new file mode 100644
index 00000000000000..ec1f6c2f590bec
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/iters_css.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+
+char _license[] SEC("license") = "GPL";
+
+pid_t target_pid;
+u64 root_cg_id, leaf_cg_id;
+u64 first_cg_id, last_cg_id;
+
+int pre_order_cnt, post_order_cnt, tree_high;
+
+struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
+void bpf_cgroup_release(struct cgroup *p) __ksym;
+void bpf_rcu_read_lock(void) __ksym;
+void bpf_rcu_read_unlock(void) __ksym;
+
+SEC("fentry.s/" SYS_PREFIX "sys_getpgid")
+int iter_css_for_each(const void *ctx)
+{
+	struct task_struct *cur_task = bpf_get_current_task_btf();
+	struct cgroup_subsys_state *root_css, *leaf_css, *pos;
+	struct cgroup *root_cgrp, *leaf_cgrp, *cur_cgrp;
+
+	if (cur_task->pid != target_pid)
+		return 0;
+
+	root_cgrp = bpf_cgroup_from_id(root_cg_id);
+
+	if (!root_cgrp)
+		return 0;
+
+	leaf_cgrp = bpf_cgroup_from_id(leaf_cg_id);
+
+	if (!leaf_cgrp) {
+		bpf_cgroup_release(root_cgrp);
+		return 0;
+	}
+	root_css = &root_cgrp->self;
+	leaf_css = &leaf_cgrp->self;
+	pre_order_cnt = post_order_cnt = tree_high = 0;
+	first_cg_id = last_cg_id = 0;
+
+	bpf_rcu_read_lock();
+	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
+		cur_cgrp = pos->cgroup;
+		post_order_cnt++;
+		last_cg_id = cur_cgrp->kn->id;
+	}
+
+	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_PRE) {
+		cur_cgrp = pos->cgroup;
+		pre_order_cnt++;
+		if (!first_cg_id)
+			first_cg_id = cur_cgrp->kn->id;
+	}
+
+	bpf_for_each(css, pos, leaf_css, BPF_CGROUP_ITER_ANCESTORS_UP)
+		tree_high++;
+
+	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_ANCESTORS_UP)
+		tree_high--;
+	bpf_rcu_read_unlock();
+	bpf_cgroup_release(root_cgrp);
+	bpf_cgroup_release(leaf_cgrp);
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/iters_css_task.c b/tools/testing/selftests/bpf/progs/iters_css_task.c
new file mode 100644
index 00000000000000..5089ce384a1c7a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/iters_css_task.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */
+
+#include "vmlinux.h"
+#include <errno.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
+void bpf_cgroup_release(struct cgroup *p) __ksym;
+
+pid_t target_pid;
+int css_task_cnt;
+u64 cg_id;
+
+SEC("lsm/file_mprotect")
+int BPF_PROG(iter_css_task_for_each, struct vm_area_struct *vma,
+	    unsigned long reqprot, unsigned long prot, int ret)
+{
+	struct task_struct *cur_task = bpf_get_current_task_btf();
+	struct cgroup_subsys_state *css;
+	struct task_struct *task;
+	struct cgroup *cgrp;
+
+	if (cur_task->pid != target_pid)
+		return ret;
+
+	cgrp = bpf_cgroup_from_id(cg_id);
+
+	if (!cgrp)
+		return -EPERM;
+
+	css = &cgrp->self;
+	css_task_cnt = 0;
+
+	bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS)
+		if (task->pid == target_pid)
+			css_task_cnt++;
+
+	bpf_cgroup_release(cgrp);
+
+	return -EPERM;
+}
diff --git a/tools/testing/selftests/bpf/progs/iters_task.c b/tools/testing/selftests/bpf/progs/iters_task.c
new file mode 100644
index 00000000000000..c9b4055cd410ae
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/iters_task.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+
+char _license[] SEC("license") = "GPL";
+
+pid_t target_pid;
+int procs_cnt, threads_cnt, proc_threads_cnt;
+
+void bpf_rcu_read_lock(void) __ksym;
+void bpf_rcu_read_unlock(void) __ksym;
+
+SEC("fentry.s/" SYS_PREFIX "sys_getpgid")
+int iter_task_for_each_sleep(void *ctx)
+{
+	struct task_struct *cur_task = bpf_get_current_task_btf();
+	struct task_struct *pos;
+
+	if (cur_task->pid != target_pid)
+		return 0;
+	procs_cnt = threads_cnt = proc_threads_cnt = 0;
+
+	bpf_rcu_read_lock();
+	bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS)
+		if (pos->pid == target_pid)
+			procs_cnt++;
+
+	bpf_for_each(task, pos, cur_task, BPF_TASK_ITER_PROC_THREADS)
+		proc_threads_cnt++;
+
+	bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_THREADS)
+		if (pos->tgid == target_pid)
+			threads_cnt++;
+	bpf_rcu_read_unlock();
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/iters_task_failure.c b/tools/testing/selftests/bpf/progs/iters_task_failure.c
new file mode 100644
index 00000000000000..c3bf96a67dba9d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/iters_task_failure.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023 Chuyi Zhou <zhouchuyi@bytedance.com> */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
+void bpf_cgroup_release(struct cgroup *p) __ksym;
+void bpf_rcu_read_lock(void) __ksym;
+void bpf_rcu_read_unlock(void) __ksym;
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+__failure __msg("expected an RCU CS when using bpf_iter_task_next")
+int BPF_PROG(iter_tasks_without_lock)
+{
+	struct task_struct *pos;
+
+	bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS) {
+
+	}
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+__failure __msg("expected an RCU CS when using bpf_iter_css_next")
+int BPF_PROG(iter_css_without_lock)
+{
+	u64 cg_id = bpf_get_current_cgroup_id();
+	struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
+	struct cgroup_subsys_state *root_css, *pos;
+
+	if (!cgrp)
+		return 0;
+	root_css = &cgrp->self;
+
+	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
+
+	}
+	bpf_cgroup_release(cgrp);
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+__failure __msg("expected an RCU CS when using bpf_iter_task_next")
+int BPF_PROG(iter_tasks_lock_and_unlock)
+{
+	struct task_struct *pos;
+
+	bpf_rcu_read_lock();
+	bpf_for_each(task, pos, NULL, BPF_TASK_ITER_ALL_PROCS) {
+		bpf_rcu_read_unlock();
+
+		bpf_rcu_read_lock();
+	}
+	bpf_rcu_read_unlock();
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+__failure __msg("expected an RCU CS when using bpf_iter_css_next")
+int BPF_PROG(iter_css_lock_and_unlock)
+{
+	u64 cg_id = bpf_get_current_cgroup_id();
+	struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
+	struct cgroup_subsys_state *root_css, *pos;
+
+	if (!cgrp)
+		return 0;
+	root_css = &cgrp->self;
+
+	bpf_rcu_read_lock();
+	bpf_for_each(css, pos, root_css, BPF_CGROUP_ITER_DESCENDANTS_POST) {
+		bpf_rcu_read_unlock();
+
+		bpf_rcu_read_lock();
+	}
+	bpf_rcu_read_unlock();
+	bpf_cgroup_release(cgrp);
+	return 0;
+}
+
+SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
+__failure __msg("css_task_iter is only allowed in bpf_lsm and bpf iter-s")
+int BPF_PROG(iter_css_task_for_each)
+{
+	u64 cg_id = bpf_get_current_cgroup_id();
+	struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
+	struct cgroup_subsys_state *css;
+	struct task_struct *task;
+
+	if (cgrp == NULL)
+		return 0;
+	css = &cgrp->self;
+
+	bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS) {
+
+	}
+	bpf_cgroup_release(cgrp);
+	return 0;
+}