diff --git a/.cirrus.yml b/.cirrus.yml
index 4bef869c24f..a2df2ddca8d 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -1,6 +1,8 @@
 freebsd_instance:
   image: freebsd-12-2-release-amd64
 env:
+  RUST_STABLE: 1.56.0
+  RUST_NIGHTLY: nightly-2021-10-25
   RUSTFLAGS: -D warnings
 
 # Test FreeBSD in a full VM on cirrus-ci.com.  Test the i686 target too, in the
@@ -12,7 +14,7 @@ task:
   setup_script:
     - pkg install -y bash curl
     - curl https://sh.rustup.rs -sSf --output rustup.sh
-    - sh rustup.sh -y --profile minimal --default-toolchain stable
+    - sh rustup.sh -y --profile minimal --default-toolchain $RUST_STABLE
     - . $HOME/.cargo/env
     - |
       echo "~~~~ rustc --version ~~~~"
@@ -29,7 +31,7 @@ task:
   setup_script:
     - pkg install -y bash curl
     - curl https://sh.rustup.rs -sSf --output rustup.sh
-    - sh rustup.sh -y --profile minimal --default-toolchain nightly-2021-10-25
+    - sh rustup.sh -y --profile minimal --default-toolchain $RUST_NIGHTLY
     - . $HOME/.cargo/env
     - |
       echo "~~~~ rustc --version ~~~~"
@@ -43,7 +45,7 @@ task:
   setup_script:
     - pkg install -y bash curl
     - curl https://sh.rustup.rs -sSf --output rustup.sh
-    - sh rustup.sh -y --profile minimal --default-toolchain stable
+    - sh rustup.sh -y --profile minimal --default-toolchain $RUST_STABLE
     - . $HOME/.cargo/env
     - rustup target add i686-unknown-freebsd
     - |
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9fec5837e3c..d5ae4d7c61f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,7 +10,15 @@ env:
   RUSTFLAGS: -Dwarnings
   RUST_BACKTRACE: 1
   nightly: nightly-2021-10-25
-  minrust: 1.45.2
+  # Change to specific Rust release to pin
+  rust_stable: 1.56.0
+  rust_nightly: nightly-2021-10-25
+  rust_clippy: 1.52.0
+  rust_min: 1.45.2
+
+defaults:
+  run:
+    shell: bash
 
 jobs:
   # Depends on all action sthat are required for a "successful" CI run.
@@ -44,6 +52,11 @@ jobs:
           - macos-latest
     steps:
       - uses: actions/checkout@v2
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: ${{ env.rust_stable }}
+            override: true
       - name: Install Rust
         run: rustup update stable
       - uses: Swatinem/rust-cache@v1
@@ -82,8 +95,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - name: Install Rust
-        run: rustup update stable
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: ${{ env.rust_stable }}
+            override: true
       - uses: Swatinem/rust-cache@v1
 
       - name: Install Valgrind
@@ -120,10 +136,12 @@ jobs:
           - macos-latest
     steps:
       - uses: actions/checkout@v2
-      - name: Install Rust
-        run: rustup update stable
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: ${{ env.rust_stable }}
+            override: true
       - uses: Swatinem/rust-cache@v1
-
       # Run `tokio` with "unstable" cfg flag.
       - name: test tokio full --cfg unstable
         run: cargo test --all-features
@@ -136,29 +154,29 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - name: Install Rust ${{ env.rust_nightly }}
+        uses: actions-rs/toolchain@v1
         with:
-          toolchain: ${{ env.nightly }}
+          toolchain: ${{ env.rust_nightly }}
+          components: miri
           override: true
       - uses: Swatinem/rust-cache@v1
-      - name: Install Miri
+      - name: miri
         run: |
           set -e
-          rustup component add miri
-          cargo miri setup
-          rm -rf tokio/tests
-
-      - name: miri
-        run: cargo miri test --features rt,rt-multi-thread,sync task
+          rm -rf tests
+          cargo miri test --features rt,rt-multi-thread,sync task
         working-directory: tokio
+
   san:
     name: san
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - name: Install Rust ${{ env.rust_nightly }}
+        uses: actions-rs/toolchain@v1
         with:
-          toolchain: ${{ env.nightly }}
+          toolchain: ${{ env.rust_nightly }}
           override: true
       - uses: Swatinem/rust-cache@v1
       - name: asan
@@ -181,9 +199,10 @@ jobs:
           - arm-linux-androideabi
     steps:
       - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          toolchain: ${{ env.rust_stable }}
           target: ${{ matrix.target }}
           override: true
       - uses: Swatinem/rust-cache@v1
@@ -198,17 +217,17 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - name: Install Rust ${{ env.rust_nightly }}
+        uses: actions-rs/toolchain@v1
         with:
-          toolchain: ${{ env.nightly }}
+          toolchain: ${{ env.rust_nightly }}
+          target: ${{ matrix.target }}
           override: true
       - uses: Swatinem/rust-cache@v1
       - name: Install cargo-hack
         run: cargo install cargo-hack
-
       - name: check --each-feature
         run: cargo hack check --all --each-feature -Z avoid-dev-deps
-
       # Try with unstable feature flags
       - name: check --each-feature --unstable
         run: cargo hack check --all --each-feature -Z avoid-dev-deps
@@ -220,9 +239,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - name: Install Rust ${{ env.rust_min }}
+        uses: actions-rs/toolchain@v1
         with:
-          toolchain: ${{ env.minrust }}
+          toolchain: ${{ env.rust_min }}
           override: true
       - uses: Swatinem/rust-cache@v1
       - name: "test --workspace --all-features"
@@ -233,9 +253,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - name: Install Rust ${{ env.rust_nightly }}
+        uses: actions-rs/toolchain@v1
         with:
-          toolchain: ${{ env.nightly }}
+          toolchain: ${{ env.rust_nightly }}
           override: true
       - uses: Swatinem/rust-cache@v1
       - name: Install cargo-hack
@@ -264,12 +285,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - name: Install Rust
-        run: rustup update stable
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ env.rust_stable }}
+          override: true
+          components: rustfmt
       - uses: Swatinem/rust-cache@v1
-      - name: Install rustfmt
-        run: rustup component add rustfmt
-
       # Check fmt
       - name: "rustfmt --check"
         # Workaround for rust-lang/cargo#7732
@@ -284,12 +306,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - name: Install Rust
-        run: rustup update 1.52.1 && rustup default 1.52.1
+      - name: Install Rust ${{ env.rust_clippy }}
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ env.rust_clippy }}
+          override: true
+          components: clippy
       - uses: Swatinem/rust-cache@v1
-      - name: Install clippy
-        run: rustup component add clippy
-
       # Run clippy
       - name: "clippy --all"
         run: cargo clippy --all --tests --all-features
@@ -299,9 +322,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - name: Install Rust ${{ env.rust_nightly }}
+        uses: actions-rs/toolchain@v1
         with:
-          toolchain: ${{ env.nightly }}
+          toolchain: ${{ env.rust_nightly }}
           override: true
       - uses: Swatinem/rust-cache@v1
       - name: "doc --lib --all-features"
@@ -315,8 +339,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - name: Install Rust
-        run: rustup update stable
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ env.rust_stable }}
+          override: true
       - uses: Swatinem/rust-cache@v1
       - name: build --cfg loom
         run: cargo test --no-run --lib --features full
diff --git a/.github/workflows/loom.yml b/.github/workflows/loom.yml
index fde9f1114e1..704728f13fb 100644
--- a/.github/workflows/loom.yml
+++ b/.github/workflows/loom.yml
@@ -10,6 +10,8 @@ name: Loom
 env:
   RUSTFLAGS: -Dwarnings
   RUST_BACKTRACE: 1
+  # Change to specific Rust release to pin
+  rust_stable: 1.56.0
 
 jobs:
   loom:
@@ -28,8 +30,11 @@ jobs:
           - time::driver
     steps:
       - uses: actions/checkout@v2
-      - name: Install Rust
-        run: rustup update stable
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: ${{ env.rust_stable }}
+            override: true
       - uses: Swatinem/rust-cache@v1
       - name: loom ${{ matrix.scope }}
         run: cargo test --lib --release --features full -- --nocapture $SCOPE
diff --git a/.github/workflows/stress-test.yml b/.github/workflows/stress-test.yml
index 3619d419742..b456b39525d 100644
--- a/.github/workflows/stress-test.yml
+++ b/.github/workflows/stress-test.yml
@@ -5,6 +5,12 @@ on:
     branches:
       - master
 
+env:
+  RUSTFLAGS: -Dwarnings
+  RUST_BACKTRACE: 1
+  # Change to specific Rust release to pin
+  rust_stable: 1.56.0
+
 jobs:
   stess-test:
     name: Stress Test
@@ -15,8 +21,11 @@ jobs:
           - simple_echo_tcp
     steps:
       - uses: actions/checkout@v2
-      - name: Install Rust
-        run: rustup update stable
+      - name: Install Rust ${{ env.rust_stable }}
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: ${{ env.rust_stable }}
+            override: true
       - uses: Swatinem/rust-cache@v1
       - name: Install Valgrind
         run: |