Comment 60 for bug 1751460

The failure occurs here:

            // FIXME: Randomize where this goes.
            // https://bugs.webkit.org/show_bug.cgi?id=175245
            void* base = tryVMAllocate(maxAlignment, totalSize);
            if (!base) {
                if (GIGACAGE_ALLOCATION_CAN_FAIL)
                    return;
                fprintf(stderr, "FATAL: Could not allocate gigacage memory with maxAlignment = %lu, totalSize = %lu.\n", maxAlignment, totalSize);
                BCRASH();
            }

So tryVMAllocate fails. That means bmalloc was unable to allocate virtual memory. That's not supposed to fail (obviously). Implementation is here:

inline void* tryVMAllocate(size_t vmSize)
{
    vmValidate(vmSize);
    void* result = mmap(0, vmSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | BMALLOC_NORESERVE, BMALLOC_VM_TAG, 0);
    if (result == MAP_FAILED)
        return nullptr;
    return result;
}

So the problem boils down to this mmap call. It's very strange that this is only happening with Deja Dup. Other applications are unaffected?