Repository: nodejs/node
Pull request: assert available memory can be calculated for max-old-space-size-percentage

Add validation to ensure that --max-old-space-size-percentage cannot
be used when available memory cannot be calculated, preventing
undefined behavior when memory detection fails.

Also enhance test-process-constrained-memory.js to support testing
in constrained environments where memory calculation may fail

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Changed files:
filename: src/node_options.cc
patch: @@ -138,6 +138,11 @@ void PerIsolateOptions::HandleMaxOldSpaceSizePercentage(
           ? constrained_memory
           : total_memory;
 
+  if (available_memory == 0) {
+    errors->push_back("the available memory can not be calculated");
+    return;
+  }
+
   // Convert to MB and calculate the percentage
   uint64_t memory_mb = available_memory / (1024 * 1024);
   uint64_t calculated_mb = static_cast<size_t>(memory_mb * percentage / 100.0);

filename: test/parallel/test-max-old-space-size-percentage.js
patch: @@ -119,14 +119,19 @@ assert(
 
 // Validate heap sizes against system memory
 const totalMemoryMB = Math.floor(os.totalmem() / 1024 / 1024);
-const margin = 10; // 5% margin
+const uint64Max = 2 ** 64 - 1;
+const constrainedMemory = process.constrainedMemory();
+const constrainedMemoryMB = Math.floor(constrainedMemory / 1024 / 1024);
+const effectiveMemoryMB =
+  constrainedMemory > 0 && constrainedMemory !== uint64Max ? constrainedMemoryMB : totalMemoryMB;
+const margin = 10; // 10% margin
 testPercentages.forEach((percentage) => {
-  const upperLimit = totalMemoryMB * ((percentage + margin) / 100);
+  const upperLimit = effectiveMemoryMB * ((percentage + margin) / 100);
   assert(
     heapSizes[percentage] <= upperLimit,
     `Heap size for ${percentage}% (${heapSizes[percentage]} MB) should not exceed upper limit (${upperLimit} MB)`
   );
-  const lowerLimit = totalMemoryMB * ((percentage - margin) / 100);
+  const lowerLimit = effectiveMemoryMB * ((percentage - margin) / 100);
   assert(
     heapSizes[percentage] >= lowerLimit,
     `Heap size for ${percentage}% (${heapSizes[percentage]} MB) should not be less than lower limit (${lowerLimit} MB)`