Messages in this thread | | | Date | Mon, 7 Jun 2021 18:48:05 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH v4 1/4] lazy tlb: introduce lazy mm refcount helper functions |
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On Tue, 08 Jun 2021 11:39:56 +1000 Nicholas Piggin <npiggin@gmail.com> wrote:
> > Looks like a functional change. What's happening here? > > That's kthread_use_mm being clever about the lazy tlb mm. If it happened > that the kthread had inherited a the lazy tlb mm that happens to be the > one we want to use here, then we already have a refcount to it via the > lazy tlb ref. > > So then it doesn't have to touch the refcount, but rather just converts > it from the lazy tlb ref to the returned reference. If the lazy tlb mm > doesn't get a reference, we can't do that.
Please cover this in the changelog and perhaps a code comment.
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