diff --git a/core/libs/prx/libkernel/DirectMemory/DirectMemory.cpp b/core/libs/prx/libkernel/DirectMemory/DirectMemory.cpp
index 25147d08a..ef114beba 100644
--- a/core/libs/prx/libkernel/DirectMemory/DirectMemory.cpp
+++ b/core/libs/prx/libkernel/DirectMemory/DirectMemory.cpp
@@ -226,7 +226,12 @@ public:
 #ifdef _WIN32
         const auto size = static_cast<std::uint64_t>(bytes);
         section = CreateFileMappingW(INVALID_HANDLE_VALUE, nullptr, PAGE_EXECUTE_READWRITE, static_cast<DWORD>(size >> 32), static_cast<DWORD>(size), nullptr);
-        if (!section) throw std::system_error(static_cast<int>(GetLastError()), std::system_category(), "create direct memory backing");
+        if (!section) {
+            const auto error = static_cast<int>(GetLastError());
+            char message[96];
+            std::snprintf(message, sizeof(message), "create direct memory backing of 0x%llx bytes (%llu MiB)", static_cast<unsigned long long>(size), static_cast<unsigned long long>((size + 0xFFFFF) >> 20));
+            throw std::system_error(error, std::system_category(), message);
+        }
 #else
         file = memfd_create("direct memory", MFD_CLOEXEC);
         if (file < 0) throw std::system_error(errno, std::generic_category(), "create direct memory backing");
diff --git a/docs/user/USAGE.md b/docs/user/USAGE.md
index 3b8a408be..7cb429298 100644
--- a/docs/user/USAGE.md
+++ b/docs/user/USAGE.md
@@ -70,6 +70,8 @@ app0/
 
 Use `sce_modules/` or `prx/` instead of `sce_module/` if that is the input directory name. Relinker preserves each module's directory under `app0/` and prints its exact path. Place app resources in `app0/` separately. Copy the built system libraries from `build/core/libs/libs/*.prx` into `libs/`; use libraries built for the target OS. A custom `--rpath` changes the system library location.
 
+On Windows, direct memory (`sceKernelAllocateDirectMemory`, up to 13824 MiB per title) is committed in full when the title allocates it, not when its pages are first used. The system commit limit (installed memory plus page file size, the second value of Committed in Task Manager) must cover it together with all other committed memory. Otherwise the allocation throws `create direct memory backing of 0x<n> bytes (<m> MiB)` with the Windows error; enlarge the page file or close other applications.
+
 Linux:
 
 ```sh