lkml.org 
[lkml]   [2004]   [Mar]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: can device drivers return non-ram via vm_ops->nopage?


    On Sat, 20 Mar 2004, Andrea Arcangeli wrote:
    >
    > The only bugreport I've got so far for the latest anon_vma code is from
    > Jens, and it's a device driver bug in my opinion, but I'd like to have a
    > definitive confirmation from you about the ->nopage API.

    I'd say that this is definitely a driver bug.

    If a driver wants to map non-RAM pages, that's perfectly ok, but it MUST
    NOT happen through "nopage()". The driver should map them with
    "remap_page_range()", and thus never take a page fault for such pages at
    all.

    There is no reason to ever lazily map non-RAM pages - clearly they aren't
    using any "real memory", so there is no reason to not fill the page tables
    at mmap() time.

    In other words, the driver is horribly broken.

    Linus
    -
    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: 2009-11-18 23:46    [W:0.019 / U:5.140 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site