On 07/02/2014 09:50 AM, Andrea Arcangeli wrote: > The MADV_USERFAULT feature should be generic enough that it can > provide the userfaults to the Android volatile range feature too, on > access of reclaimed volatile pages.
Maybe. I certainly can't keep track of all the versions of the variations of the volatile ranges patches. But, I don't think it's a given that this can be reused. First of all, volatile ranges is trying to replace ashmem and is going to require _some_ form of sharing. This mechanism, being tightly coupled to anonymous memory at the moment, is not a close fit for that. It's also important to call out that this is a VMA-based mechanism. I certainly can't predict what we'll merge for volatile ranges, but not all of them are VMA-based. We'd also need a mechanism on top of this to differentiate plain not-present pages from not-present-because-purged pages. That said, I _think_ this might fit well in to what the Mozilla guys wanted out of volatile ranges. I'm not confident about it, though.
