PRB: Using MEM_TOP_DOWN Flag With VirtualAlloc May Cause DLL Loading to Fail

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This article was previously published under Q303444

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SYMPTOMS

When you are using the MEM_TOP_DOWN flag with calls to VirtualAlloc, loading of a dynamic link library (DLL) may fail.

The MEM_TOP_DOWN flag causes VirtualAlloc to allocate memory at the highest possible address. An inadvertent side effect of using this flag is that it may cause attempts to load a DLL to fail. This is because DLLs are loaded at the high end of the process address space. If this address space is used up, there is no room to load a DLL.