Messages in this thread | | | Date | Thu, 30 Sep 2021 16:25:02 -0700 | From | Kees Cook <> | Subject | Re: [PATCH v9 2/3] mm: add a field to store names for private anonymous memory |
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On Thu, Sep 30, 2021 at 11:56:12AM -0700, Suren Baghdasaryan wrote: > I thought more about these alternative suggestions for userspace to > record allocations but that would introduce considerable complexity > into userspace. Userspace would have to collect and consolidate this > data by some daemon, all users would have to query it for the data > (IPC or something similar), in case this daemon crashes the data would > need to be somehow recovered. So, in short, it's possible but makes > things much more complex compared to proposed in-kernel > implementation.
Agreed: this is something for the kernel to manage.
> OTOH, the only downside of the current implementation is the > additional memory required to store anon vma names. I checked the > memory consumption on the latest Android with these patches and > because we share vma names during fork, the actual memory required to > store vma names is no more than 600kB. Even on older phones like Pixel > 3 with 4GB RAM, this is less than 0.015% of total memory. IMHO, this > is an acceptable price to pay.
I think that's entirely fine. We don't end up with any GUP games, and everything is refcounted.
I think a v10 with the various nits fixed would be a good next step here. What do you think Matthew?
-- Kees Cook
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