diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index fbb111616705..bcc80269bb6a 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -188,6 +188,17 @@ cgroup v2 currently supports the following mount options.
         modified through remount from the init namespace. The mount
         option is ignored on non-init namespace mounts.
 
+  memory_recursiveprot
+
+        Recursively apply memory.min and memory.low protection to
+        entire subtrees, without requiring explicit downward
+        propagation into leaf cgroups.  This allows protecting entire
+        subtrees from one another, while retaining free competition
+        within those subtrees.  This should have been the default
+        behavior but is a mount-option to avoid regressing setups
+        relying on the original semantics (e.g. specifying bogusly
+        high 'bypass' protection values at higher tree levels).
+
 
 Organizing Processes and Threads
 --------------------------------
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 63097cb243cb..e1fafed22db1 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -94,6 +94,11 @@ enum {
 	 * Enable legacy local memory.events.
 	 */
 	CGRP_ROOT_MEMORY_LOCAL_EVENTS = (1 << 5),
+
+	/*
+	 * Enable recursive subtree protection
+	 */
+	CGRP_ROOT_MEMORY_RECURSIVE_PROT = (1 << 6),
 };
 
 /* cftype->flags */
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 915dda3f7f19..755c07d845ce 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1813,12 +1813,14 @@ int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 enum cgroup2_param {
 	Opt_nsdelegate,
 	Opt_memory_localevents,
+	Opt_memory_recursiveprot,
 	nr__cgroup2_params
 };
 
 static const struct fs_parameter_spec cgroup2_fs_parameters[] = {
 	fsparam_flag("nsdelegate",		Opt_nsdelegate),
 	fsparam_flag("memory_localevents",	Opt_memory_localevents),
+	fsparam_flag("memory_recursiveprot",	Opt_memory_recursiveprot),
 	{}
 };
 
@@ -1839,6 +1841,9 @@ static int cgroup2_parse_param(struct fs_context *fc, struct fs_parameter *param
 	case Opt_memory_localevents:
 		ctx->flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS;
 		return 0;
+	case Opt_memory_recursiveprot:
+		ctx->flags |= CGRP_ROOT_MEMORY_RECURSIVE_PROT;
+		return 0;
 	}
 	return -EINVAL;
 }
@@ -1855,6 +1860,11 @@ static void apply_cgroup_root_flags(unsigned int root_flags)
 			cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS;
 		else
 			cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_LOCAL_EVENTS;
+
+		if (root_flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT)
+			cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_RECURSIVE_PROT;
+		else
+			cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_RECURSIVE_PROT;
 	}
 }
 
@@ -1864,6 +1874,8 @@ static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root
 		seq_puts(seq, ",nsdelegate");
 	if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS)
 		seq_puts(seq, ",memory_localevents");
+	if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT)
+		seq_puts(seq, ",memory_recursiveprot");
 	return 0;
 }
 
@@ -6412,7 +6424,10 @@ static struct kobj_attribute cgroup_delegate_attr = __ATTR_RO(delegate);
 static ssize_t features_show(struct kobject *kobj, struct kobj_attribute *attr,
 			     char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "nsdelegate\nmemory_localevents\n");
+	return snprintf(buf, PAGE_SIZE,
+			"nsdelegate\n"
+			"memory_localevents\n"
+			"memory_recursiveprot\n");
 }
 static struct kobj_attribute cgroup_features_attr = __ATTR_RO(features);
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0e3a8c11fb3b..07032c088608 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6264,13 +6264,27 @@ struct cgroup_subsys memory_cgrp_subsys = {
  *    budget is NOT proportional. A cgroup's protection from a sibling
  *    is capped to its own memory.min/low setting.
  *
+ * 5. However, to allow protecting recursive subtrees from each other
+ *    without having to declare each individual cgroup's fixed share
+ *    of the ancestor's claim to protection, any unutilized -
+ *    "floating" - protection from up the tree is distributed in
+ *    proportion to each cgroup's *usage*. This makes the protection
+ *    neutral wrt sibling cgroups and lets them compete freely over
+ *    the shared parental protection budget, but it protects the
+ *    subtree as a whole from neighboring subtrees.
+ *
+ * Note that 4. and 5. are not in conflict: 4. is about protecting
+ * against immediate siblings whereas 5. is about protecting against
+ * neighboring subtrees.
  */
 static unsigned long effective_protection(unsigned long usage,
+					  unsigned long parent_usage,
 					  unsigned long setting,
 					  unsigned long parent_effective,
 					  unsigned long siblings_protected)
 {
 	unsigned long protected;
+	unsigned long ep;
 
 	protected = min(usage, setting);
 	/*
@@ -6301,7 +6315,34 @@ static unsigned long effective_protection(unsigned long usage,
 	 * protection is always dependent on how memory is actually
 	 * consumed among the siblings anyway.
 	 */
-	return protected;
+	ep = protected;
+
+	/*
+	 * If the children aren't claiming (all of) the protection
+	 * afforded to them by the parent, distribute the remainder in
+	 * proportion to the (unprotected) memory of each cgroup. That
+	 * way, cgroups that aren't explicitly prioritized wrt each
+	 * other compete freely over the allowance, but they are
+	 * collectively protected from neighboring trees.
+	 *
+	 * We're using unprotected memory for the weight so that if
+	 * some cgroups DO claim explicit protection, we don't protect
+	 * the same bytes twice.
+	 */
+	if (!(cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT))
+		return ep;
+
+	if (parent_effective > siblings_protected && usage > protected) {
+		unsigned long unclaimed;
+
+		unclaimed = parent_effective - siblings_protected;
+		unclaimed *= usage - protected;
+		unclaimed /= parent_usage - siblings_protected;
+
+		ep += unclaimed;
+	}
+
+	return ep;
 }
 
 /**
@@ -6321,8 +6362,8 @@ static unsigned long effective_protection(unsigned long usage,
 enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
 						struct mem_cgroup *memcg)
 {
+	unsigned long usage, parent_usage;
 	struct mem_cgroup *parent;
-	unsigned long usage;
 
 	if (mem_cgroup_disabled())
 		return MEMCG_PROT_NONE;
@@ -6347,11 +6388,13 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
 		goto out;
 	}
 
-	memcg->memory.emin = effective_protection(usage,
+	parent_usage = page_counter_read(&parent->memory);
+
+	memcg->memory.emin = effective_protection(usage, parent_usage,
 			memcg->memory.min, READ_ONCE(parent->memory.emin),
 			atomic_long_read(&parent->memory.children_min_usage));
 
-	memcg->memory.elow = effective_protection(usage,
+	memcg->memory.elow = effective_protection(usage, parent_usage,
 			memcg->memory.low, READ_ONCE(parent->memory.elow),
 			atomic_long_read(&parent->memory.children_low_usage));