diff --git a/selfdrive/test/build.sh b/selfdrive/test/build.sh
index af295eb04b..977d2f8f1d 100755
--- a/selfdrive/test/build.sh
+++ b/selfdrive/test/build.sh
@@ -1,114 +1,38 @@
 #!/usr/bin/env bash
 set -e
-trap restore_root ERR
 ORG_PWD="$PWD"
+SELF_PATH="$(realpath $0)"
+SCRIPT_DIR="$(dirname "$SELF_PATH")"
 
 REPO="$HOME/work/openpilot/openpilot"
 CACHE_ROOTFS_TARBALL_PATH="/tmp/rootfs_cache.tar"
 
-unpack_rootfs_tarball() {
-    cd /
-    sudo tar -xf "$CACHE_ROOTFS_TARBALL_PATH" 2>/dev/null || true
-    cd
-}
-
-commit_root() {
-    sudo mkdir -p /base /newroot /upper /work
-    
-    sudo unshare -f --kill-child -m $ORG_PWD/selfdrive/test/build.sh build_inside_namespace
-    ec=$?
-    echo "end of ns"
-
-    sudo rm -rf /base /newroot /work
-
-    # finally, create the rootfs diff tarball (to be pushed into the CI native cache)
-    mkdir -p /tmp/rootfs_cache
-    sudo rm -f "$CACHE_ROOTFS_TARBALL_PATH" # remove the old tarball from previous run, if exists
-    cd /upper
-    sudo tar -cf "$CACHE_ROOTFS_TARBALL_PATH" .
-    cd
-
-    sudo rm -rf /upper
-
-    unpack_rootfs_tarball
-
-    # before the next tasks are run, finalize the environment for them
-    prepare_mounts
-
-    exit $ec
-}
-
-prepare_mounts() {
-    # create and mount the required volumes where they're expected
-    mkdir -p /tmp/openpilot /tmp/scons_cache /tmp/comma_download_cache /tmp/openpilot_cache
-    sudo mount --bind "$REPO" /tmp/openpilot
-
-    sudo mount --bind "$REPO/.ci_cache/scons_cache" /tmp/scons_cache || true
-    sudo mount --bind "$REPO/.ci_cache/comma_download_cache" /tmp/comma_download_cache || true
-    sudo mount --bind "$REPO/.ci_cache/openpilot_cache" /tmp/openpilot_cache || true
-
-    # needed for the unit tests not to fail
-    sudo chmod 755 /sys/fs/pstore
-}
-
-restore_root() {
-    echo failed at ${BASH_LINENO[0]}
-}
-
-build_inside_namespace() {
-    mount --bind / /base
-    mount -t overlay overlay -o lowerdir=/base,upperdir=/upper,workdir=/work /newroot
-    rm -f /newroot/etc/resolv.conf
-    touch /newroot/etc/resolv.conf
-    cat /etc/resolv.conf > /newroot/etc/resolv.conf
-
-    mkdir -p /newroot/old
-    cd /newroot
-    pivot_root . old
-
-    mount -t proc proc /proc
-    mount -t devtmpfs devtmpfs /dev
-    mkdir -p /dev/pts
-    mount -t devpts devpts /dev/pts
-    mount -t proc proc /proc
-    mount -t sysfs sysfs /sys
-
-    touch /root_committed
-    sudo -u runner /home/runner/work/openpilot/openpilot/selfdrive/test/build.sh
-    ec=$?
-    exit $ec
-}
-
-if [ "$1" = "build_inside_namespace" ]
-then
-    build_inside_namespace
-    exit
-fi
+source "$SCRIPT_DIR/build_common.sh"
 
+# if the rootfs diff tarball (also created by this script) got restored from the CI native cache
 if [ -f "$CACHE_ROOTFS_TARBALL_PATH" ]
 then
-    # if the rootfs diff tarball (also created by this script) got restored from the CI native cache, unpack it, upgrading the rootfs
+    # apply it, upgrading the rootfs
     echo "restoring rootfs from the native build cache"
-    unpack_rootfs_tarball
+    apply_rootfs_diff
     rm "$CACHE_ROOTFS_TARBALL_PATH"
 
     # before the next tasks are run, finalize the environment for them
-    prepare_mounts
+    prepare_build
 
     # EXITS HERE - if the rootfs could been prepared entirely from the cache, there's no need for any further action like re-building
     exit 0
 else
     # otherwise, we'll have to install everything from scratch and build the tarball to be available for the next run
-    echo "no native build cache entry restored, rebuilding"
+    if ! [ -f /root_committed ]
+    then
+        echo "no native build cache entry restored, rebuilding"
+    fi
 fi
 
-# in order to be able to build a diff rootfs tarball, we need to commit its initial state by moving it on-the-fly to overlayfs;
-# below, we prepare the system and the new rootfs itself
-
-if ! [ -e /root_committed ]
-then
+# in order to be able to build a diff rootfs tarball, we need to commit its initial state
+# by moving it on-the-fly to overlayfs; below, we prepare the system and the new rootfs itself
 commit_root
-fi
 
 # -------- at this point, the original rootfs was committed and all the changes to it done below will be saved to the newly created rootfs diff tarball --------
 
@@ -118,11 +42,11 @@ DEBIAN_FRONTEND=noninteractive
 
 mkdir -p /tmp/tools
 cp "$REPO/tools/install_ubuntu_dependencies.sh" /tmp/tools/
-sudo /tmp/tools/install_ubuntu_dependencies.sh &>/dev/null
+sudo /tmp/tools/install_ubuntu_dependencies.sh
 
 sudo apt-get install -y --no-install-recommends \
     sudo tzdata locales ssh pulseaudio xvfb x11-xserver-utils gnome-screenshot python3-tk python3-dev \
-    apt-utils alien unzip tar curl xz-utils dbus gcc-arm-none-eabi tmux vim libx11-6 wget &>/dev/null
+    apt-utils alien unzip tar curl xz-utils dbus gcc-arm-none-eabi tmux vim libx11-6 wget
 
 sudo rm -rf /var/lib/apt/lists/*
 sudo apt-get clean
@@ -155,7 +79,6 @@ sudo ln -s /opt/intel/oneapi-tbb-2021.12.0/lib/intel64/gcc4.8/libtbbmalloc.so.2
 sudo mkdir -p /etc/ld.so.conf.d
 sudo bash -c "echo /opt/intel/oclcpuexp_2024.17.3.0.09_rel/x64 > /etc/ld.so.conf.d/libintelopenclexp.conf"
 sudo ldconfig -f /etc/ld.so.conf.d/libintelopenclexp.conf
-cd /
 rm -rf /tmp/opencl-driver-intel
 cd
 
@@ -166,18 +89,16 @@ NVIDIA_DRIVER_CAPABILITIES=graphics,utility,compute
 QTWEBENGINE_DISABLE_SANDBOX=1
 
 # install and set up the Python dependencies needed
-sudo cp "/home/runner/work/openpilot/openpilot/pyproject.toml" "/home/runner/work/openpilot/openpilot/uv.lock" "/home/runner/work/openpilot/openpilot/tools/install_python_dependencies.sh" \
-    /home/runner/
+cp "$REPO/pyproject.toml" "$REPO/uv.lock" "$HOME/"
+mkdir "$HOME/tools"
+cp "$REPO/tools/install_python_dependencies.sh" "$HOME/tools/"
 
-cd
-rm -rf .venv
+VIRTUAL_ENV=/home/$USER/.venv
+PATH="$VIRTUAL_ENV/bin:$PATH"
 
-mkdir aaa
-cd aaa
-../install_python_dependencies.sh
 cd
-rm pyproject.toml uv.lock install_python_dependencies.sh
-
+tools/install_python_dependencies.sh
+rm -rf tools/ pyproject.toml uv.lock .cache
 
 # add a git safe directory for compiling openpilot
 sudo git config --global --add safe.directory /tmp/openpilot
diff --git a/selfdrive/test/build_common.sh b/selfdrive/test/build_common.sh
new file mode 100644
index 0000000000..a173288222
--- /dev/null
+++ b/selfdrive/test/build_common.sh
@@ -0,0 +1,113 @@
+error_handler() {
+    echo failed at ${BASH_LINENO[0]}
+}
+trap error_handler ERR
+
+create_rootfs_diff() {
+    sudo rm -f "$CACHE_ROOTFS_TARBALL_PATH" # remove the old diff tarball from previous run, if exists
+    cd /upper
+    sudo tar -cf "$CACHE_ROOTFS_TARBALL_PATH" .
+    cd
+}
+
+apply_rootfs_diff() {
+    cd /
+    sudo tar -xf "$CACHE_ROOTFS_TARBALL_PATH" 2>/dev/null || true
+    cd
+}
+
+prepare_build() {
+    # create and mount the required volumes where they're expected
+    mkdir -p /tmp/openpilot /tmp/scons_cache /tmp/comma_download_cache /tmp/openpilot_cache
+    sudo mount --bind "$REPO" /tmp/openpilot
+
+    sudo mount --bind "$REPO/.ci_cache/scons_cache" /tmp/scons_cache || true
+    sudo mount --bind "$REPO/.ci_cache/comma_download_cache" /tmp/comma_download_cache || true
+    sudo mount --bind "$REPO/.ci_cache/openpilot_cache" /tmp/openpilot_cache || true
+
+    # needed for the unit tests not to fail
+    sudo chmod 755 /sys/fs/pstore
+}
+
+post_commit_root() {
+    # we have the diff tarball, now let's remove the folder too
+    sudo rm -rf /upper
+
+    # now we apply it straight away
+    apply_rootfs_diff
+
+    # before the next tasks are run, finalize the environment for them
+    prepare_build
+}
+
+# warning: this function initiates a somewhat complicated program flow, follow carefully
+# (even despite this part was made sure to not be too relevant for the rest of the job)
+commit_root() {
+    # if that's a first execution
+    if ! [ -e /root_committed ]
+    then
+        # prepare directories
+        sudo mkdir -p /base /newroot /upper /work
+        
+        # re-execute the main script (causing it to go straight to `build_inside_namespace`), but
+        # inside the newly created namespace, in a way which would cause all mounts
+        # created to automatically umount before it exits
+        sudo unshare -f --kill-child -m "$SELF_PATH" build_inside_namespace
+        ec=$?
+
+        # after it exited, remove the created directories (except the one containing created diff)
+        sudo rm -rf /base /newroot /work
+
+        # finally, create the rootfs diff tarball (to be pushed into the CI native cache)
+        create_rootfs_diff
+
+        # after creating the rootfs diff, bring the system into a state as if it was restored from cache
+        post_commit_root
+
+        exit $ec
+    fi
+}
+
+reexecute() {
+    touch /root_committed
+    sudo -u runner "$SELF_PATH"
+    ec=$?
+    exit $ec
+}
+
+# that's where the script goes after being re-executed for the first time
+build_inside_namespace() {
+    # initialize the mounts namespace on overlayfs to be able to prepare the rootfs diff
+    mount --bind / /base
+    mount -t overlay overlay -o lowerdir=/base,upperdir=/upper,workdir=/work /newroot
+
+    # apply the current DNS config (beware: systemd often symlinks /etc/resolv.conf, that's why it's needed)
+    rm -f /newroot/etc/resolv.conf
+    touch /newroot/etc/resolv.conf
+    cat /etc/resolv.conf > /newroot/etc/resolv.conf
+
+    # switch the namespace's root mount to the newly created one
+    mkdir -p /newroot/old
+    cd /newroot
+    pivot_root . old
+
+    # initialize basic required POSIX-standard additional mounts
+    mount -t proc proc /proc
+    mount -t devtmpfs devtmpfs /dev
+    mkdir -p /dev/pts
+    mount -t devpts devpts /dev/pts
+    mount -t proc proc /proc
+    mount -t sysfs sysfs /sys
+
+    # re-execute the main script for the 2nd time, causing it to go back to the main flow
+    # (but this time already inside the newly created namespace)
+    reexecute
+
+    # after the main flow terminates and the namespace exist, post_commit_root is executed - be sure to look at it
+}
+
+if [ "$1" = "build_inside_namespace" ]
+then
+    build_inside_namespace
+    exit
+fi