lkml.org 
[lkml]   [2005]   [Jun]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    Subjectget_user_pages() and shared memory question
    Hi,

    Is it possible for a page of memory that's been "grabbed" with get_user_pages() to ever be
    allocated to another process? I'm assuming the answer is no, but I have a specific case I
    want to ask about.

    Let's say an application allocates some shared memory, and then calls into a driver which
    calls get_user_pages(). The driver exits without releasing the pages, so they now have a
    reference count on them. Then the application deallocates the shared memory. At this
    point, the virtual addresses disappear, and no process owns them, but the pages still have
    a reference count.

    Another process now tries to allocate a shared memory buffer. Is there any way that this
    new buffer can contain those pages that were grabbed with get_user_pages() (i.e. that
    already have a reference count)?

    Until 2.6.7, there was a bug in the VM where a page that was grabbed with get_user_pages()
    could be swapped out. Those of you familar with the OpenIB work know what I'm talking
    about. Would that bug affect anything I'm talking about?

    --
    Timur Tabi
    Staff Software Engineer
    timur.tabi@ammasso.com

    One thing a Southern boy will never say is,
    "I don't think duct tape will fix it."
    -- Ed Smylie, NASA engineer for Apollo 13
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-06-21 17:22    [W:0.032 / U:117.860 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site