On Tue, Mar 14, 2017 at 10:48:51AM -0700, Linus Torvalds wrote: > On Tue, Mar 14, 2017 at 12:47 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote: > > > > I've also applied the GUP patch, with the assumption that you'll address Linus's > > request to switch x86 over to the generic version. > > Note that switching over to the generic version is somewhat fraught > with subtle issues: > > (a) we need to make sure that x86 actually matches the required > semantics for the generic GUP. > > (b) we need to make sure the atomicity of the page table reads is ok. > > (c) need to verify the maximum VM address properly There's another difference with generic version: it uses page_cache_get_speculative() instead of plain get_page() on x86. That's somewhat more expensive, but probably fine. -- Kirill A. Shutemov
