Linus Torvalds writes: (Summary) On Thu, Oct 26, 2017 at 9:02 PM, Ingo Molnar <mingo@kernel.org> You should very much be able to map in IO memory or whatever
above the 2G address even if the high_memory itself might be limited
to 2GB.
to 2GB.
So I think that commit ce56a86e2ade ("x86/mm: Limit mmap() of /dev/mem to valid physical addresses") is wrong, in that "high_memory" is very much the wrong thing to test.
much the wrong thing to test.
The memory mapping limit might validly be something like The memory mapping limit might validly be something like 1ull <<
to 2GB.
So I think that commit ce56a86e2ade ("x86/mm: Limit mmap() of /dev/mem to valid physical addresses") is wrong, in that "high_memory" is very much the wrong thing to test.
much the wrong thing to test.
The memory mapping limit might validly be something like The memory mapping limit might validly be something like 1ull <<