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OS communication primitive idea: "inverse mmap" an application creates a file where pages are backed by the application itself, i.e. when someone tries to access that file, a trap gives the application an opportunity to fill in whatever page is being accessed

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Linux supports userfaultfd for shared memory and hugetlbfs since Linux 4.11, which seems like a fairly close match to this functionality.

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close but I really want to handle page faults for another process

Daniel Micay

@DanielMicay

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@whitequark

I thought it did work that way, by pausing threads triggering user faults and handling them in another thread. I might be wrong, but my understanding is that it would work the same way across processes, so that you could handle a fault triggered in one process in the other one.

2:44 PM · May 4, 2019Twitter Web Client

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the manpage says that it only works within a process, but if that's not true, yeah, it should be enough to at least prototype what i want

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You might be looking at an out-of-date copy of the man page. It seems to at least have cross-process handling of faults for fork, and I'd expect that the shared memory / hugetlbfs implementation works the same way. man7.org/linux/man-page

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