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
