On Fri, May 8, 2020 at 2:36 PM Joerg Roedel <jroedel@xxxxxxx> wrote: > > On Fri, May 08, 2020 at 02:33:19PM -0700, Andy Lutomirski wrote: > > On Fri, May 8, 2020 at 7:40 AM Joerg Roedel <joro@xxxxxxxxxx> wrote: > > > What's the maximum on other system types? It might make more sense to > > take the memory hit and pre-populate all the tables at boot so we > > never have to sync them. > > Need to look it up for 5-level paging, with 4-level paging its 64 pages > to pre-populate the vmalloc area. > > But that would not solve the problem on x86-32, which needs to > synchronize unmappings on the PMD level. What changes in this series with x86-32? We already do that synchronization, right? IOW, in the cases where the vmalloc *fault* code does anything at all, we should have a small bound for how much memory to preallocate and, if we preallocate it, then there is nothing to sync and nothing to fault. And we have the benefit that we never need to sync anything on 64-bit, which is kind of nice. Do we actually need PMD-level things for 32-bit? What if we just outlawed huge pages in the vmalloc space on 32-bit non-PAE? Or maybe the net result isn't much of a cleanup after all given the need to support 32-bit. > > > Joerg
