diff --git a/bootstrap/src/initnsmgr.rs b/bootstrap/src/initnsmgr.rs
index 4e58092d9c..406cace436 100644
--- a/bootstrap/src/initnsmgr.rs
+++ b/bootstrap/src/initnsmgr.rs
@@ -173,13 +173,13 @@ impl<'sock> NamespaceScheme<'sock> {
             return Err(Error::new(ENODEV));
         };
 
-        let scheme_fd = syscall::openat_with_filter(
+        let reserved = syscall::reserve_fd(1)?;
+        let scheme_fd = syscall::openat_into(
             cap_fd.as_raw_fd(),
+            reserved,
             reference,
             flags,
             fcntl_flags as usize,
-            ctx.uid,
-            ctx.gid,
         )?;
 
         Ok(scheme_fd)
@@ -353,7 +353,7 @@ impl<'sock> SchemeSync for NamespaceScheme<'sock> {
             return Err(Error::new(ENODEV));
         };
 
-        syscall::unlinkat_with_filter(cap_fd.as_raw_fd(), reference, flags, ctx.uid, ctx.gid)?;
+        syscall::unlinkat(cap_fd.as_raw_fd(), reference, flags)?;
 
         Ok(())
     }
diff --git a/drivers/usb/xhcid/src/xhci/mod.rs b/drivers/usb/xhcid/src/xhci/mod.rs
index aaf0bb31d6..83e5106898 100644
--- a/drivers/usb/xhcid/src/xhci/mod.rs
+++ b/drivers/usb/xhcid/src/xhci/mod.rs
@@ -305,9 +305,10 @@ pub struct Xhci<const N: usize> {
     device_enumerator: Mutex<Option<thread::JoinHandle<()>>>,
     device_enumerator_sender: Sender<DeviceEnumerationRequest>,
     device_enumerator_receiver: Receiver<DeviceEnumerationRequest>,
+
+    dma_pool: Mutex<Vec<Dma<[u8]>>>,
 }
 
-}
 // SAFETY: Xhci<N> contains the following fields with their safety mechanisms:
 // - `port_states`, `handles`, `drivers`: CHashMap (per-key interior locking)
 // - `op`, `ports`, `cmd`, `run`, `primary_event_ring`: Mutex<...>
@@ -501,6 +502,7 @@ impl<const N: usize> Xhci<N> {
             device_enumerator: Mutex::new(None),
             device_enumerator_sender,
             device_enumerator_receiver,
+            dma_pool: Mutex::new(Vec::new()),
         };
 
         xhci.init(max_slots)?;
@@ -1074,6 +1076,16 @@ impl<const N: usize> Xhci<N> {
         Self::alloc_dma_zeroed_unsized_raw(self.ac64_effective(), count)
     }
 
+    fn dma_pool_take(&self, size: usize) -> Option<Dma<[u8]>> {
+        let mut pool = self.dma_pool.lock().unwrap_or_else(|e| e.into_inner());
+        pool.iter().position(|b| b.len() >= size).map(|i| pool.swap_remove(i))
+    }
+    fn dma_pool_put(&self, buf: Dma<[u8]>) {
+        const MAX_POOL: usize = 32;
+        let mut pool = self.dma_pool.lock().unwrap_or_else(|e| e.into_inner());
+        if pool.len() < MAX_POOL { pool.push(buf); }
+    }
+
     pub async fn attach_device(&self, port_id: PortId) -> syscall::Result<()> {
         if self.port_states.contains_key(&port_id) {
             debug!("Already contains port {}", port_id);
diff --git a/drivers/usb/xhcid/src/xhci/scheme.rs b/drivers/usb/xhcid/src/xhci/scheme.rs
index e51ba78cb7..cb2bb64e30 100644
--- a/drivers/usb/xhcid/src/xhci/scheme.rs
+++ b/drivers/usb/xhcid/src/xhci/scheme.rs
@@ -2080,8 +2080,9 @@ impl<const N: usize> Xhci<N> {
         // TODO: Validate the size.
         // TODO: Sizes above 65536, *perhaps*.
         let data_buffer_opt = if req.transfers_data {
-            let data_buffer = unsafe { self.alloc_dma_zeroed_unsized(req.length as usize)? };
-            assert_eq!(data_buffer.len(), req.length as usize);
+            let data_buffer = self.dma_pool_take(req.length as usize).unwrap_or_else(|| unsafe {
+                self.alloc_dma_zeroed_unsized(req.length as usize).expect("DMA alloc")
+            });
             Some(data_buffer)
         } else {
             None