On 12/18/2017 12:41 PM, Peter Zijlstra wrote: >> I also don't think the user_shared area of the fixmap can get *that* >> big. Does anybody know offhand what the theoretical limits are there? > Problem there is the nr_cpus term I think, we currently have up to 8k > CPUs, but I can see that getting bigger in the future.
It only matters if we go over 512GB, though. Is the per-cpu part of the fixmap ever more than 512GB/8k=64MB? In any case, it's not hard to make a little loop. I think the common case, at least is that we only do 4 PGDs.
