diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 6d853846a..15488ea99 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -1,7 +1,7 @@
-# linux CI tests, run "periodically", and on notable push to ci-linux,
-# and on notable pull request to master.
-# Periodic runs don't use caching.
-# Reasonably thorough build/test/benchmark/haddock/functest testing, with all GHC versions
+# linux CI tests, run on a periodic schedule, on notable pull request
+# to master, and on notable push to ci-linux. Reasonably thorough
+# build/test/benchmark/haddock/functest testing, with all GHC
+# versions. Note periodic runs don't use cache.
 
 name: linux / pull request CI
 
@@ -23,7 +23,6 @@ on:
       - '!**.5'
       - '!**.info'
       - '!**.txt'
-  # and on pushes to ci-linux branch
   push:
     branches: [ ci-linux ]
     paths:
@@ -128,23 +127,25 @@ jobs:
           ${{ runner.os }}-hledger-web-stack-work-${{ matrix.plan.key }}
           ${{ runner.os }}-hledger-web-stack-work
 
+    # For now due to
+    # https://github.com/actions/virtual-environments/issues/709
+    # there's only 4.8G free at this point, and we must free up space.
     - name: Free disk space
       run: |
         df -h /
+        # 8G:
         sudo swapoff -a
-        df -h /
-        ls -lh /swapfile
         sudo rm -f /swapfile
-        df -h /
+        # 3G:
         sudo apt clean
-        df -h /
+        # 3G:
         docker image ls -aq
         docker rmi $(docker image ls -aq)
-        df -h /
+        # 1G:
         find ~/work/_temp -name "cache.tgz" -exec rm -f {} \;
-        df -h /
+        # 4G:
         sudo rm -rf "/usr/local/share/boost"
-        df -h /
+        # 2G:
         sudo rm -rf "$AGENT_TOOLSDIRECTORY"
         df -h /
 
diff --git a/.github/workflows/mac.yml b/.github/workflows/mac.yml
index bb50ebf52..9765c8c10 100644
--- a/.github/workflows/mac.yml
+++ b/.github/workflows/mac.yml
@@ -1,5 +1,5 @@
-# mac CI tests, run "periodically", and on notable push to ci-mac.
-# Periodic runs don't use caching.
+# mac CI tests, run on a periodic schedule, and on notable push to
+# ci-mac. Note periodic runs don't use cache.
 
 name: mac CI
 
diff --git a/.github/workflows/push.yml b/.github/workflows/push.yml
index 563b94194..c4cd892d2 100644
--- a/.github/workflows/push.yml
+++ b/.github/workflows/push.yml
@@ -1,4 +1,4 @@
-# quick CI tests, run on notable push to master
+# quick CI tests, run on notable push to master.
 
 name: push CI
 
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index d7a9b7390..01d0d2cdb 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -1,6 +1,6 @@
-# windows CI tests, run "periodically", and on notable push to ci-windows
-# Periodic runs don't use caching.
-# Using GHC 8.8.2 to avoid "access violation" error with 8.8.3
+# windows CI tests, run on a periodic schedule, and on notable push to
+# ci-windows. Note periodic runs don't use cache. Using GHC 8.8.2 for
+# now to avoid https://gitlab.haskell.org/ghc/ghc/issues/17926.
 
 name: windows CI