> On Sep 10, 2017, at 1:22 PM, Peter Zijlstra <pet...@infradead.org> wrote: > >> On Sat, Sep 09, 2017 at 09:42:12PM -0700, Andy Lutomirski wrote: >> PeterZ and Ingo, would you be okay with adding a define so arches can >> opt out of the task_struct::active_mm field entirely? That is, with >> the option set, task_struct wouldn't have an active_mm field, the core >> wouldn't call mmgrab and mmdrop, and the arch would be responsible for >> that bookkeeping instead? x86, and presumably all arches without >> cross-core invalidation, would probably prefer to just shoot down the >> old mm entirely in __mmput() rather than trying to figure out when do >> finish freeing old mms. After all, exit_mmap() is going to send an >> IPI regardless, so I see no reason to have the scheduler core pin an >> old dead mm just because some random kernel thread's active_mm field >> points to it. > > I'm only quickly skimming this thread, but I don't see anything too > worrysome being proposed. > > If you're in LA next week we can talk about it in more detail if you > want.
I'll be there.