Add a test to reproduce the issue. Remove the assertion.

.github/scripts/ci-test.sh

@@ -2,4 +2,12 @@ set -xe
 
 cargo test --features nogc
 cargo test --features semispace
-python examples/build.py
+python examples/build.py
+
+# Test with DummyVM (each test in a separate run)
+cd vmbindings/dummyvm
+for p in nogc semispace; do
+    for t in $(ls src/tests/ -I mod.rs | sed -n 's/\.rs$//p'); do
+        cargo test --features $p -- $t;
+    done;
+done;

examples/build.py

@@ -8,7 +8,7 @@
 
 # check RUSTUP_TOOLCHAIN
 if "RUSTUP_TOOLCHAIN" in os.environ:
-    toolchain = os.environ["RUSTUP_TOOLCHAIN"]
+    toolchain = "+" + os.environ["RUSTUP_TOOLCHAIN"]
 else:
     toolchain = "+nightly"
 

src/util/alloc/allocator.rs

@@ -43,7 +43,6 @@ pub fn align_allocation(
     debug_assert!(!(fillalignmentgap && region.is_zero()));
     debug_assert!(alignment <= MAX_ALIGNMENT);
     debug_assert!(offset >= 0);
-    debug_assert!(region.is_aligned_to(MIN_ALIGNMENT));
     debug_assert!((alignment & (MIN_ALIGNMENT - 1)) == 0);
     debug_assert!((offset & (MIN_ALIGNMENT - 1) as isize) == 0);
 

vmbindings/dummyvm/src/lib.rs

@@ -13,6 +13,9 @@ pub mod active_plan;
 pub mod reference_glue;
 pub mod api;
 
+#[cfg(test)]
+mod tests;
+
 pub struct DummyVM;
 
 impl VMBinding for DummyVM {

vmbindings/dummyvm/src/tests/issue139.rs

@@ -0,0 +1,17 @@
+use crate::api::*;
+use mmtk::util::OpaquePointer;
+use mmtk::Allocator;
+
+#[test]
+pub fn issue139_alloc_non_multiple_of_min_alignment() {
+    gc_init(200*1024*1024);
+    let handle = bind_mutator(OpaquePointer::UNINITIALIZED);
+
+    // Allocate 6 bytes with 8 bytes ailgnment required
+    let addr = alloc(handle, 6, 8, 0, Allocator::Default);
+    assert!(addr.is_aligned_to(8));
+    // After the allocation, the cursor is not MIN_ALIGNMENT aligned. If we have the assertion in the next allocation to check if the cursor is aligned to MIN_ALIGNMENT, it fails.
+    // We have to remove that assertion.
+    let addr2 = alloc(handle, 6, 8, 0, Allocator::Default);
+    assert!(addr2.is_aligned_to(8));
+}

vmbindings/dummyvm/src/tests/mod.rs

@@ -0,0 +1,4 @@
+// Each module should only contain one #[test] function.
+// We should run each module in a separate test process, as we do not have proper
+// setup/teardown procedure for MMTk instances.
+mod issue139;