Messages in this thread | | | Date | Sun, 17 Sep 2017 19:04:11 +0200 | From | Ingo Molnar <> | Subject | Re: Current mainline git (24e700e291d52bd2) hangs when building e.g. perf |
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* Andy Lutomirski <luto@kernel.org> 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. > > IOW, if I'm going to reintroduce something like what the old lazy mode > did on x86, I'd rather do it right.
How realistic would it be to get rid of ::active_mm on all architectures at once?
Thanks,
Ingo
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