diff --git a/.git-blame-ignore-revs b/.git-blame-ignore-revs
index 1eed0e2b5fc96f..d7526120853318 100644
--- a/.git-blame-ignore-revs
+++ b/.git-blame-ignore-revs
@@ -14,6 +14,7 @@ d1474affa8e105bece209cc9d594bb0a989859e1
 
 # Indentation
 0e4bad888e605d424b9222ae0ca43f85c1634e5e
+61aa46c41648c6d1e9b0daa1a292de551fde78df
 
 # Enable Style/StringLiterals cop for RubyGems/Bundler
 d7ffd3fea402239b16833cc434404a7af82d44f3
@@ -42,6 +43,8 @@ d4e24021d39e1f80f0055b55d91f8d5f22e15084
 e90282be7ba1bc8e3119f6e1a2c80356ceb3f80a
 26a9e0b4e31f7b5a9cbd755e0a15823a8fa51bae
 2f53985da9ee593fe524d408256835667938c7d7
+bf01f6ae89a95d8f5572e050facfe311c8c28aaf
+7480cd8d37fd71a41ce12b759090051c7e14fb5a
 
 # Win32: EOL code of batch files
 23f9a0d655c4d405bb2397a147a1523436205486
diff --git a/.github/actions/setup/baseruby/action.yml b/.github/actions/setup/baseruby/action.yml
new file mode 100644
index 00000000000000..76fe068897a163
--- /dev/null
+++ b/.github/actions/setup/baseruby/action.yml
@@ -0,0 +1,73 @@
+name: Setup directories etc.
+description: >-
+  Build baseruby for cross-compiling
+
+inputs:
+  srcdir:
+    required: true
+    default: ${{ github.workspace }}
+    description: >-
+      Directory of source codes.
+
+  builddir:
+    required: false
+    default: ${{ github.workspace }}/baseruby
+    description: >-
+      Where baseruby will be built.
+
+  installdir:
+    required: false
+    default: install
+    description: >-
+      The path where the baseruby will be installed to.
+      This is relative from the workspace.
+
+outputs:
+  ruby:
+    value: ${{ steps.build.outputs.installdir }}/bin/ruby
+    description: >-
+      The path of the executable baseruby.
+  dump_ast:
+    value: ${{ steps.build.outputs.installdir }}/bin/dump_ast
+    description: >-
+      The path of the executable dump_ast.
+
+runs:
+  using: composite
+
+  steps:
+    - name: Build baseruby
+      shell: bash
+      id: build
+      run: |
+        case "$installdir" in /*) ;; *) installdir="$PWD/$installdir";; esac
+        mkdir "$builddir"
+        ln -sr "$srcdir" "$builddir/.src"
+        pushd "$builddir"
+        .src/configure "--prefix=${installdir}" --disable-install-doc
+        CONFIGURE_ARGS=--with-out-ext=-test- make install
+        install dump_ast "${installdir}/bin"
+        {
+          echo "${installdir}/bin/dump_ast"
+          echo "${installdir}/.installed.list"
+          echo "${installdir}/"
+        } >> .installed.list
+        cp .installed.list "${installdir}/"
+        make distclean
+        rm .src
+        popd
+        rmdir "$builddir"
+        {
+          echo "installdir=${installdir}"
+        } | tee -a "$GITHUB_OUTPUT"
+      env:
+        srcdir: ${{ inputs.srcdir }}
+        builddir: ${{ inputs.builddir }}
+        installdir: ${{ inputs.installdir }}
+
+    - name: clean
+      uses: gacts/run-and-post-run@598d7a875d5620e0457490555b5e18e46082aa47 # v1.4.4
+      with:
+        working-directory: ${{ inputs.srcdir }}
+        post: |
+          ruby tool/rbuninstall.rb "${{ steps.build.outputs.installdir }}/.installed.list" > /dev/null
diff --git a/.github/actions/setup/ubuntu/action.yml b/.github/actions/setup/ubuntu/action.yml
index b4454d49c72c96..5209ccc03f19b1 100644
--- a/.github/actions/setup/ubuntu/action.yml
+++ b/.github/actions/setup/ubuntu/action.yml
@@ -24,18 +24,38 @@ runs:
   using: composite
 
   steps:
+    - id: uname
+      name: uname
+      shell: bash
+      env:
+        arch: ${{ inputs.arch }}
+      run: |
+        setarch="${arch:+setarch $arch --}"
+        # normalize `uname`
+        if uname=$(${setarch} uname -m 2> /dev/null); then
+          # `setarch` works, `$arch` is a valid architecture name.
+          echo "setarch=${setarch}" >> "$GITHUB_OUTPUT"
+        else
+          # if `setarch` failed, take the given `arch` as-is.
+          uname="${arch}"
+          setarch=""
+        fi
+        echo "uname=$uname" >> "$GITHUB_OUTPUT"
+        echo "dpkg=${uname/686/386}" >> "$GITHUB_OUTPUT"
+
     - name: set SETARCH
       shell: bash
       run: echo "SETARCH=${setarch}" >> "$GITHUB_ENV" # zizmor: ignore[github-env]
       env:
-        setarch: ${{ inputs.arch && format('setarch {0} --', inputs.arch) }}
+        setarch: ${{ steps.uname.outputs.setarch }} # validated
 
-    - id: uname
-      name: uname
+    - name: dpkg setup
       shell: bash
-      run: |
-        echo uname=`${SETARCH} uname -m` >> "$GITHUB_OUTPUT"
-        echo dpkg=`${SETARCH} uname -m | sed s/686/386/` >> "$GITHUB_OUTPUT"
+      run: sudo dpkg --add-architecture "${dpkg}"
+      # `dpkg` is valid, also `uname`.
+      if: ${{ inputs.arch }}
+      env:
+        dpkg: ${{ steps.uname.outputs.dpkg }}
 
     - name: apt-get
       shell: bash
@@ -43,7 +63,6 @@ runs:
         arch: ${{ inputs.arch && format(':{0}', steps.uname.outputs.dpkg) || '' }}
       run: |
         set -x
-        ${arch:+sudo dpkg --add-architecture ${arch#:}}
         sudo apt-get update -qq || :
         sudo apt-get install --no-install-recommends -qq -y -o=Dpkg::Use-Pty=0 \
         ${arch:+cross}build-essential${arch/:/-} \
diff --git a/.github/workflows/crosscompile.yml b/.github/workflows/crosscompile.yml
index 2b75a75df4078e..4c28516e25bd2c 100644
--- a/.github/workflows/crosscompile.yml
+++ b/.github/workflows/crosscompile.yml
@@ -64,9 +64,8 @@ jobs:
           builddir: build
           makeup: true
 
-      - name: Install cross-compilation toolchain
+      - name: Setup cross-compilation toolchain sources
         run: |
-          sudo dpkg --add-architecture ${{ matrix.arch }}
           native_arch=$(dpkg --print-architecture)
           # Restrict existing sources to native arch
           sudo sed -i '/^Architectures:/d' /etc/apt/sources.list.d/ubuntu.sources
@@ -84,24 +83,15 @@ jobs:
             "Components: main universe" \
             "Architectures: ${{ matrix.arch }}" \
             | sudo tee /etc/apt/sources.list.d/cross-${{ matrix.arch }}.sources
-          sudo apt-get update -qq
-          sudo apt-get install --no-install-recommends -qq -y \
-            crossbuild-essential-${{ matrix.arch }} \
-            libssl-dev:${{ matrix.arch }} \
-            libyaml-dev:${{ matrix.arch }} \
-            zlib1g-dev:${{ matrix.arch }} \
-            libffi-dev:${{ matrix.arch }} \
-            libreadline-dev:${{ matrix.arch }} \
-            libncurses-dev:${{ matrix.arch }} \
-            autoconf ruby
-
-      - name: Build baseruby
-        run: |
-          mkdir ../baseruby
-          cd ../baseruby
-          ../src/configure --prefix=$PWD/install --disable-install-doc
-          make
-          make install
+
+      - uses: ./.github/actions/setup/ubuntu
+        with:
+          arch: ${{ matrix.arch }}
+
+      - uses: ./.github/actions/setup/baseruby
+        id: baseruby
+        with:
+          srcdir: src
 
       - name: Run configure
         run: >-
@@ -109,7 +99,9 @@ jobs:
           --prefix=/usr
           --build=${{ matrix.build }}
           --host=${{ matrix.host }}
-          --with-baseruby=$PWD/../baseruby/install/bin/ruby
+          --with-baseruby="$baseruby"
+        env:
+          baseruby: ${{ steps.baseruby.outputs.ruby }}
 
       - run: make
 
diff --git a/.github/workflows/wasm.yml b/.github/workflows/wasm.yml
index 0d1fb61cc376dc..1a428f4f1c5405 100644
--- a/.github/workflows/wasm.yml
+++ b/.github/workflows/wasm.yml
@@ -104,17 +104,10 @@ jobs:
         run: |
           echo "WASI_SDK_PATH=/opt/wasi-sdk" >> $GITHUB_ENV
 
-      - name: Build baseruby
+      - uses: ./.github/actions/setup/baseruby
         id: baseruby
-        run: |
-          set -ex
-          mkdir ../baseruby
-          pushd ../baseruby
-          echo "ruby=$PWD/install/bin/ruby" >> $GITHUB_OUTPUT
-          echo "dump_ast=$PWD/dump_ast" >> $GITHUB_OUTPUT
-          ../src/configure --prefix=$PWD/install
-          make
-          make install
+        with:
+          srcdir: src
 
       - name: Download config.guess with wasi version
         run: |
diff --git a/gc/mmtk/mmtk.c b/gc/mmtk/mmtk.c
index aa6ac39d7495ea..143999c6a19c76 100644
--- a/gc/mmtk/mmtk.c
+++ b/gc/mmtk/mmtk.c
@@ -813,19 +813,25 @@ rb_gc_impl_get_vm_context(void *objspace_ptr)
 // Object allocation
 
 static VALUE
-rb_mmtk_alloc_fast_path(struct objspace *objspace, struct MMTk_ractor_cache *ractor_cache, size_t size)
+rb_mmtk_alloc_fast_path(struct objspace *objspace, struct MMTk_ractor_cache *ractor_cache, size_t size, size_t align)
 {
     MMTk_BumpPointer *bump_pointer = ractor_cache->bump_pointer;
     if (bump_pointer == NULL) return 0;
 
-    uintptr_t new_cursor = bump_pointer->cursor + size;
+    uintptr_t cursor = bump_pointer->cursor;
 
-    if (new_cursor > bump_pointer->limit) {
+    // Ensure cursor is aligned
+    size_t mask = align - 1;
+    cursor = (cursor + mask) & ~mask;
+
+    cursor += size;
+
+    if (cursor > bump_pointer->limit) {
         return 0;
     }
     else {
-        VALUE obj = (VALUE)bump_pointer->cursor;
-        bump_pointer->cursor = new_cursor;
+        VALUE obj = cursor - size;
+        bump_pointer->cursor = cursor;
         return obj;
     }
 }
@@ -910,7 +916,7 @@ rb_gc_impl_new_obj(void *objspace_ptr, void *cache_ptr, VALUE klass, VALUE flags
     // Layout: [hidden size header (sizeof(VALUE))][payload (alloc_size)][suffix (RVALUE_SUFFIX_SIZE)]
     alloc_size += sizeof(VALUE) + RVALUE_SUFFIX_SIZE;
 
-    VALUE *alloc_obj = (VALUE *)rb_mmtk_alloc_fast_path(objspace, ractor_cache, alloc_size);
+    VALUE *alloc_obj = (VALUE *)rb_mmtk_alloc_fast_path(objspace, ractor_cache, alloc_size, MMTk_MIN_OBJ_ALIGN);
     if (!alloc_obj) {
         alloc_obj = mmtk_alloc(ractor_cache->mutator, alloc_size, MMTk_MIN_OBJ_ALIGN, 0, MMTK_ALLOCATION_SEMANTICS_DEFAULT);
     }
diff --git a/string.c b/string.c
index c72e2a8e36b17b..eb249662db74eb 100644
--- a/string.c
+++ b/string.c
@@ -11122,48 +11122,48 @@ rb_str_justify(int argc, VALUE *argv, VALUE str, char jflag)
     rlen = n - llen;
     cr = ENC_CODERANGE(str);
     if (flen > 1) {
-       llen2 = str_offset(f, f + flen, llen % fclen, enc, singlebyte);
-       rlen2 = str_offset(f, f + flen, rlen % fclen, enc, singlebyte);
+        llen2 = str_offset(f, f + flen, llen % fclen, enc, singlebyte);
+        rlen2 = str_offset(f, f + flen, rlen % fclen, enc, singlebyte);
     }
     size = RSTRING_LEN(str);
     if ((len = llen / fclen + rlen / fclen) >= LONG_MAX / flen ||
-       (len *= flen) >= LONG_MAX - llen2 - rlen2 ||
-       (len += llen2 + rlen2) >= LONG_MAX - size) {
-       rb_raise(rb_eArgError, "argument too big");
+        (len *= flen) >= LONG_MAX - llen2 - rlen2 ||
+        (len += llen2 + rlen2) >= LONG_MAX - size) {
+        rb_raise(rb_eArgError, "argument too big");
     }
     len += size;
     res = str_enc_new(rb_cString, 0, len, enc);
     p = RSTRING_PTR(res);
     if (flen <= 1) {
-       memset(p, *f, llen);
-       p += llen;
+        memset(p, *f, llen);
+        p += llen;
     }
     else {
-       while (llen >= fclen) {
+        while (llen >= fclen) {
             memcpy(p,f,flen);
             p += flen;
             llen -= fclen;
         }
-       if (llen > 0) {
-           memcpy(p, f, llen2);
-           p += llen2;
+        if (llen > 0) {
+            memcpy(p, f, llen2);
+            p += llen2;
         }
     }
     memcpy(p, RSTRING_PTR(str), size);
     p += size;
     if (flen <= 1) {
-       memset(p, *f, rlen);
-       p += rlen;
+        memset(p, *f, rlen);
+        p += rlen;
     }
     else {
-       while (rlen >= fclen) {
+        while (rlen >= fclen) {
             memcpy(p,f,flen);
             p += flen;
             rlen -= fclen;
         }
-       if (rlen > 0) {
-           memcpy(p, f, rlen2);
-           p += rlen2;
+        if (rlen > 0) {
+            memcpy(p, f, rlen2);
+            p += rlen2;
         }
     }
     TERM_FILL(p, termlen);