Is it okay to define a totally general `swap()` function?

The following snippet:

#include <memory>
#include <utility>

namespace foo
{
    template <typename T>
    void swap(T& a, T& b)
    {
        T tmp = std::move(a);
        a = std::move(b);
        b = std::move(tmp);
    }

    struct bar { };
}

void baz()
{
    std::unique_ptr<foo::bar> ptr;
    ptr.reset();
}

does not compile for me:

$ g++ -std=c++11 -c foo.cpp
In file included from /usr/include/c++/5.3.0/memory:81:0,
                 from foo.cpp:1:
/usr/include/c++/5.3.0/bits/unique_ptr.h: In instantiation of ‘void std::unique_ptr<_Tp, _Dp>::reset(std::unique_ptr<_Tp, _Dp>::pointer) [with _Tp = foo::bar; _Dp = std::default_delete<foo::bar>; std::unique_ptr<_Tp, _Dp>::pointer = foo::bar*]’:
foo.cpp:20:15:   required from here
/usr/include/c++/5.3.0/bits/unique_ptr.h:342:6: error: call of overloaded ‘swap(foo::bar*&, foo::bar*&)’ is ambiguous
  swap(std::get<0>(_M_t), __p);
      ^
In file included from /usr/include/c++/5.3.0/bits/stl_pair.h:59:0,
                 from /usr/include/c++/5.3.0/bits/stl_algobase.h:64,
                 from /usr/include/c++/5.3.0/memory:62,
                 from foo.cpp:1:
/usr/include/c++/5.3.0/bits/move.h:176:5: note: candidate: void std::swap(_Tp&, _Tp&) [with _Tp = foo::bar*]
     swap(_Tp& __a, _Tp& __b)
     ^
foo.cpp:7:10: note: candidate: void foo::swap(T&, T&) [with T = foo::bar*]
     void swap(T& a, T& b)

Is this my fault for declaring a swap() function so general that it conflicts with std::swap?

If so, is there a way to define foo::swap() so that it doesn't get hauled in by Koenig lookup?