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    SubjectRe: [PATCH 5/6] mlock: do not hold mmap_sem for extended periods of time
    On Thu,  2 Dec 2010 16:16:51 -0800
    Michel Lespinasse <> wrote:

    > __get_user_pages gets a new 'nonblocking' parameter to signal that the
    > caller is prepared to re-acquire mmap_sem and retry the operation if needed.
    > This is used to split off long operations if they are going to block on
    > a disk transfer, or when we detect contention on the mmap_sem.

    Doesn't apply to linux-next because the KVM guys snuck in a new
    FAULT_FLAG_MINOR (who knew?). With a bonus, undocumented,
    exported-to-modules get_user_pages_noio().

    I liked your code better so I munged __get_user_pages() together thusly:

    while (!(page = follow_page(vma, start, foll_flags))) {
    int ret;
    unsigned int fault_flags = 0;

    if (foll_flags & FOLL_WRITE)
    fault_flags |= FAULT_FLAG_WRITE;
    if (nonblocking)
    fault_flags |= FAULT_FLAG_ALLOW_RETRY;
    if (foll_flags & FOLL_MINOR)
    fault_flags |= FAULT_FLAG_MINOR;

    ret = handle_mm_fault(mm, vma, start,

    please review the end result..

     \ /
      Last update: 2010-12-09 00:45    [W:0.020 / U:18.792 seconds]
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