Messages in this thread | | | Date | Mon, 6 Aug 2018 19:50:13 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 11/11] mm,sched: conditionally skip lazy TLB mm refcounting |
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On Fri, Aug 03, 2018 at 01:39:52PM -0400, Rik van Riel wrote:
> > At the very least the Changelog needs to explain why we cannot do > > away with the swizzle now and how doing the swizzle without the > > refcounting is not completely broken (I think I see, but urgh). > > The changelog for patches 9 & 10 explains, I think.
They hint at it :-)
> What is missing from my explanation? > How would you like to see it explained?
Maybe a few words like:
"Since ->active_mm is still used in a few sites, we must keep the current tracking, such that we will not hit a kthread's NULL mm. Note that lazy_tlb_exit_mmap() switches ->active_mm to &init_mm before taking out the lazy mm."
That said; I'm not entirely sure we'll actually touch active_mm if we're not a user task. The perf thing for example will only touch active_mm when user_mode(regs).
But whatever, this was the only hickup.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> [unhandled content-type:application/pgp-signature] | |