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    SubjectRe: [RFC 2.6.11-rc2-mm2 0/7] mm: manual page migration -- overview II
    > OK, so what is the alternative?  Well, if we had a va_start and
    > va_end (or a va_start and length) we could move the shared object
    > once using a call of the form
    > migrate_pages(pid, va_start, va_end, count, old_node_list,
    > new_node_list);
    > with old_node_list = 0 1 2 ... 31
    > new_node_list = 2 3 4 ... 33
    > for one of the pid's in the job.

    I still don't like it. It would be bad to make migrate_pages another
    ptrace() [and ptrace at least really enforces a stopped process]

    But I can see your point that migration DEFAULT pages with first touch
    aware applications pretty much needs the old_node, new_node lists.
    I just don't think an external process should mess with other processes
    VA. But I can see that it makes sense to do this on SHM that
    is mapped into a management process.

    How about you add the va_start, va_end but only accept them
    when pid is 0 (= current process). Otherwise enforce with EINVAL
    that they are both 0. This way you could map the
    shared object into the batch manager, migrate it there, then
    mark it somehow to not be migrated further, and then
    migrate the anonymous pages using migrate_pages(pid, ...)

    BTW it might be better to make va_end a size, just to be more
    symmetric with mlock,madvise,mmap

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