diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index b21a7b246a0d..0c2161b1f057 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -1045,6 +1045,66 @@ static struct binder_ref *binder_get_ref_olocked(struct binder_proc *proc,
 	return NULL;
 }
 
+/* Find the smallest unused descriptor the "slow way" */
+static u32 slow_desc_lookup_olocked(struct binder_proc *proc)
+{
+	struct binder_ref *ref;
+	struct rb_node *n;
+	u32 desc;
+
+	desc = 1;
+	for (n = rb_first(&proc->refs_by_desc); n; n = rb_next(n)) {
+		ref = rb_entry(n, struct binder_ref, rb_node_desc);
+		if (ref->data.desc > desc)
+			break;
+		desc = ref->data.desc + 1;
+	}
+
+	return desc;
+}
+
+/*
+ * Find an available reference descriptor ID. The proc->outer_lock might
+ * be released in the process, in which case -EAGAIN is returned and the
+ * @desc should be considered invalid.
+ */
+static int get_ref_desc_olocked(struct binder_proc *proc,
+				struct binder_node *node,
+				u32 *desc)
+{
+	struct dbitmap *dmap = &proc->dmap;
+	unsigned long *new, bit;
+	unsigned int nbits;
+
+	/* 0 is reserved for the context manager */
+	if (node == proc->context->binder_context_mgr_node) {
+		*desc = 0;
+		return 0;
+	}
+
+	if (!dbitmap_enabled(dmap)) {
+		*desc = slow_desc_lookup_olocked(proc);
+		return 0;
+	}
+
+	if (dbitmap_acquire_first_zero_bit(dmap, &bit) == 0) {
+		*desc = bit;
+		return 0;
+	}
+
+	/*
+	 * The dbitmap is full and needs to grow. The proc->outer_lock
+	 * is briefly released to allocate the new bitmap safely.
+	 */
+	nbits = dbitmap_grow_nbits(dmap);
+	binder_proc_unlock(proc);
+	new = bitmap_zalloc(nbits, GFP_KERNEL);
+	binder_proc_lock(proc);
+	dbitmap_grow(dmap, new, nbits);
+
+	return -EAGAIN;
+}
+
 /**
  * binder_get_ref_for_node_olocked() - get the ref associated with given node
  * @proc:	binder_proc that owns the ref
@@ -1068,12 +1128,14 @@ static struct binder_ref *binder_get_ref_for_node_olocked(
 					struct binder_node *node,
 					struct binder_ref *new_ref)
 {
-	struct binder_context *context = proc->context;
-	struct rb_node **p = &proc->refs_by_node.rb_node;
-	struct rb_node *parent = NULL;
 	struct binder_ref *ref;
-	struct rb_node *n;
+	struct rb_node *parent;
+	struct rb_node **p;
+	u32 desc;
 
+retry:
+	p = &proc->refs_by_node.rb_node;
+	parent = NULL;
 	while (*p) {
 		parent = *p;
 		ref = rb_entry(parent, struct binder_ref, rb_node_node);
@@ -1088,6 +1150,10 @@ static struct binder_ref *binder_get_ref_for_node_olocked(
 	if (!new_ref)
 		return NULL;
 
+	/* might release the proc->outer_lock */
+	if (get_ref_desc_olocked(proc, node, &desc) == -EAGAIN)
+		goto retry;
+
 	binder_stats_created(BINDER_STAT_REF);
 	new_ref->data.debug_id = atomic_inc_return(&binder_last_id);
 	new_ref->proc = proc;
@@ -1095,14 +1161,7 @@ static struct binder_ref *binder_get_ref_for_node_olocked(
 	rb_link_node(&new_ref->rb_node_node, parent, p);
 	rb_insert_color(&new_ref->rb_node_node, &proc->refs_by_node);
 
-	new_ref->data.desc = (node == context->binder_context_mgr_node) ? 0 : 1;
-	for (n = rb_first(&proc->refs_by_desc); n != NULL; n = rb_next(n)) {
-		ref = rb_entry(n, struct binder_ref, rb_node_desc);
-		if (ref->data.desc > new_ref->data.desc)
-			break;
-		new_ref->data.desc = ref->data.desc + 1;
-	}
-
+	new_ref->data.desc = desc;
 	p = &proc->refs_by_desc.rb_node;
 	while (*p) {
 		parent = *p;
@@ -1131,6 +1190,7 @@ static struct binder_ref *binder_get_ref_for_node_olocked(
 
 static void binder_cleanup_ref_olocked(struct binder_ref *ref)
 {
+	struct dbitmap *dmap = &ref->proc->dmap;
 	bool delete_node = false;
 
 	binder_debug(BINDER_DEBUG_INTERNAL_REFS,
@@ -1138,6 +1198,8 @@ static void binder_cleanup_ref_olocked(struct binder_ref *ref)
 		      ref->proc->pid, ref->data.debug_id, ref->data.desc,
 		      ref->node->debug_id);
 
+	if (dbitmap_enabled(dmap))
+		dbitmap_clear_bit(dmap, ref->data.desc);
 	rb_erase(&ref->rb_node_desc, &ref->proc->refs_by_desc);
 	rb_erase(&ref->rb_node_node, &ref->proc->refs_by_node);
 
@@ -1298,6 +1360,25 @@ static void binder_free_ref(struct binder_ref *ref)
 	kfree(ref);
 }
 
+/* shrink descriptor bitmap if needed */
+static void try_shrink_dmap(struct binder_proc *proc)
+{
+	unsigned long *new;
+	int nbits;
+
+	binder_proc_lock(proc);
+	nbits = dbitmap_shrink_nbits(&proc->dmap);
+	binder_proc_unlock(proc);
+
+	if (!nbits)
+		return;
+
+	new = bitmap_zalloc(nbits, GFP_KERNEL);
+	binder_proc_lock(proc);
+	dbitmap_shrink(&proc->dmap, new, nbits);
+	binder_proc_unlock(proc);
+}
+
 /**
  * binder_update_ref_for_handle() - inc/dec the ref for given handle
  * @proc:	proc containing the ref
@@ -1334,8 +1415,10 @@ static int binder_update_ref_for_handle(struct binder_proc *proc,
 		*rdata = ref->data;
 	binder_proc_unlock(proc);
 
-	if (delete_ref)
+	if (delete_ref) {
 		binder_free_ref(ref);
+		try_shrink_dmap(proc);
+	}
 	return ret;
 
 err_no_ref:
@@ -4931,6 +5014,7 @@ static void binder_free_proc(struct binder_proc *proc)
 	put_task_struct(proc->tsk);
 	put_cred(proc->cred);
 	binder_stats_deleted(BINDER_STAT_PROC);
+	dbitmap_free(&proc->dmap);
 	kfree(proc);
 }
 
@@ -5634,6 +5718,8 @@ static int binder_open(struct inode *nodp, struct file *filp)
 	proc = kzalloc(sizeof(*proc), GFP_KERNEL);
 	if (proc == NULL)
 		return -ENOMEM;
+
+	dbitmap_init(&proc->dmap);
 	spin_lock_init(&proc->inner_lock);
 	spin_lock_init(&proc->outer_lock);
 	get_task_struct(current->group_leader);
diff --git a/drivers/android/binder_internal.h b/drivers/android/binder_internal.h
index 5b7c80b99ae8..7d4fc53f7a73 100644
--- a/drivers/android/binder_internal.h
+++ b/drivers/android/binder_internal.h
@@ -14,6 +14,7 @@
 #include <linux/uidgid.h>
 #include <uapi/linux/android/binderfs.h>
 #include "binder_alloc.h"
+#include "dbitmap.h"
 
 struct binder_context {
 	struct binder_node *binder_context_mgr_node;
@@ -368,6 +369,8 @@ struct binder_ref {
  * @freeze_wait:          waitqueue of processes waiting for all outstanding
  *                        transactions to be processed
  *                        (protected by @inner_lock)
+ * @dmap                  dbitmap to manage available reference descriptors
+ *                        (protected by @outer_lock)
  * @todo:                 list of work for this process
  *                        (protected by @inner_lock)
  * @stats:                per-process binder statistics
@@ -417,7 +420,7 @@ struct binder_proc {
 	bool sync_recv;
 	bool async_recv;
 	wait_queue_head_t freeze_wait;
-
+	struct dbitmap dmap;
 	struct list_head todo;
 	struct binder_stats stats;
 	struct list_head delivered_death;
diff --git a/drivers/android/dbitmap.h b/drivers/android/dbitmap.h
new file mode 100644
index 000000000000..b8ac7b4764fd
--- /dev/null
+++ b/drivers/android/dbitmap.h
@@ -0,0 +1,176 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2024 Google LLC
+ *
+ * dbitmap - dynamically sized bitmap library.
+ *
+ * Used by the binder driver to optimize the allocation of the smallest
+ * available descriptor ID. Each bit in the bitmap represents the state
+ * of an ID, with the exception of BIT(0) which is used exclusively to
+ * reference binder's context manager.
+ *
+ * A dbitmap can grow or shrink as needed. This part has been designed
+ * considering that users might need to briefly release their locks in
+ * order to allocate memory for the new bitmap. These operations then,
+ * are verified to determine if the grow or shrink is sill valid.
+ *
+ * This library does not provide protection against concurrent access
+ * by itself. Binder uses the proc->outer_lock for this purpose.
+ */
+
+#ifndef _LINUX_DBITMAP_H
+#define _LINUX_DBITMAP_H
+#include <linux/bitmap.h>
+
+#define NBITS_MIN	BITS_PER_TYPE(unsigned long)
+
+struct dbitmap {
+	unsigned int nbits;
+	unsigned long *map;
+};
+
+static inline int dbitmap_enabled(struct dbitmap *dmap)
+{
+	return !!dmap->nbits;
+}
+
+static inline void dbitmap_free(struct dbitmap *dmap)
+{
+	dmap->nbits = 0;
+	kfree(dmap->map);
+}
+
+/* Returns the nbits that a dbitmap can shrink to, 0 if not possible. */
+static inline unsigned int dbitmap_shrink_nbits(struct dbitmap *dmap)
+{
+	unsigned int bit;
+
+	if (dmap->nbits <= NBITS_MIN)
+		return 0;
+
+	/*
+	 * Determine if the bitmap can shrink based on the position of
+	 * its last set bit. If the bit is within the first quarter of
+	 * the bitmap then shrinking is possible. In this case, the
+	 * bitmap should shrink to half its current size.
+	 */
+	bit = find_last_bit(dmap->map, dmap->nbits);
+	if (bit < (dmap->nbits >> 2))
+		return dmap->nbits >> 1;
+
+	/*
+	 * Note that find_last_bit() returns dmap->nbits when no bits
+	 * are set. While this is technically not possible here since
+	 * BIT(0) is always set, this check is left for extra safety.
+	 */
+	if (bit == dmap->nbits)
+		return NBITS_MIN;
+
+	return 0;
+}
+
+/* Replace the internal bitmap with a new one of different size */
+static inline void
+dbitmap_replace(struct dbitmap *dmap, unsigned long *new, unsigned int nbits)
+{
+	bitmap_copy(new, dmap->map, min(dmap->nbits, nbits));
+	kfree(dmap->map);
+	dmap->map = new;
+	dmap->nbits = nbits;
+}
+
+static inline void
+dbitmap_shrink(struct dbitmap *dmap, unsigned long *new, unsigned int nbits)
+{
+	if (!new)
+		return;
+
+	/*
+	 * Verify that shrinking to @nbits is still possible. The @new
+	 * bitmap might have been allocated without locks, so this call
+	 * could now be outdated. In this case, free @new and move on.
+	 */
+	if (!dbitmap_enabled(dmap) || dbitmap_shrink_nbits(dmap) != nbits) {
+		kfree(new);
+		return;
+	}
+
+	dbitmap_replace(dmap, new, nbits);
+}
+
+/* Returns the nbits that a dbitmap can grow to. */
+static inline unsigned int dbitmap_grow_nbits(struct dbitmap *dmap)
+{
+	return dmap->nbits << 1;
+}
+
+static inline void
+dbitmap_grow(struct dbitmap *dmap, unsigned long *new, unsigned int nbits)
+{
+	/*
+	 * Verify that growing to @nbits is still possible. The @new
+	 * bitmap might have been allocated without locks, so this call
+	 * could now be outdated. In this case, free @new and move on.
+	 */
+	if (!dbitmap_enabled(dmap) || nbits <= dmap->nbits) {
+		kfree(new);
+		return;
+	}
+
+	/*
+	 * Check for ENOMEM after confirming the grow operation is still
+	 * required. This ensures we only disable the dbitmap when it's
+	 * necessary. Once the dbitmap is disabled, binder will fallback
+	 * to slow_desc_lookup_olocked().
+	 */
+	if (!new) {
+		dbitmap_free(dmap);
+		return;
+	}
+
+	dbitmap_replace(dmap, new, nbits);
+}
+
+/*
+ * Finds and sets the first zero bit in the bitmap. Upon success @bit
+ * is populated with the index and 0 is returned. Otherwise, -ENOSPC
+ * is returned to indicate that a dbitmap_grow() is needed.
+ */
+static inline int
+dbitmap_acquire_first_zero_bit(struct dbitmap *dmap, unsigned long *bit)
+{
+	unsigned long n;
+
+	n = find_first_zero_bit(dmap->map, dmap->nbits);
+	if (n == dmap->nbits)
+		return -ENOSPC;
+
+	*bit = n;
+	set_bit(n, dmap->map);
+
+	return 0;
+}
+
+static inline void
+dbitmap_clear_bit(struct dbitmap *dmap, unsigned long bit)
+{
+	/* BIT(0) should always set for the context manager */
+	if (bit)
+		clear_bit(bit, dmap->map);
+}
+
+static inline int dbitmap_init(struct dbitmap *dmap)
+{
+	dmap->map = bitmap_zalloc(NBITS_MIN, GFP_KERNEL);
+	if (!dmap->map) {
+		dmap->nbits = 0;
+		return -ENOMEM;
+	}
+
+	dmap->nbits = NBITS_MIN;
+	/* BIT(0) is reserved for the context manager */
+	set_bit(0, dmap->map);
+
+	return 0;
+}
+#endif