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    SubjectRe: mlockall and mmap of IO devices don't mix
    Joe Korty <joe.korty@ccur.com> wrote:
    >
    > On Fri, May 21, 2004 at 07:13:26PM -0700, Andrew Morton wrote:
    > > Mark Hounschell <markh@compro.net> wrote:
    > > >
    > > > Joe Korty wrote:
    > > > >
    > > > > 2.6.0-test6: the use of mlockall(2) in a process that has mmap(2)ed
    > > > > the registers of an IO device will hang that process uninterruptibly.
    > > > > The task runs in an infinite loop in get_user_pages(), invoking
    > > > > follow_page() forever.
    > > > >
    > > > > Using binary search I discovered that the problem was introduced
    > > > > in 2.5.14, specifically in ChangeSetKey
    > > > >
    > > > > zippel@linux-m68k.org|ChangeSet|20020503210330|37095
    > > > >
    > > >
    > > > I know this is an old thread but can anyone tell me if this problem is
    > > > resolved in the current 2.6.6 kernel?
    > > >
    > >
    > > There's an utterly ancient patch in -mm which might fix this.
    > >
    > > http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.6/2.6.6-mm4/broken-out/get_user_pages-handle-VM_IO.patch
    >
    > [ 2nd send -- corporate email system in the throes of being scrambled / updated ]
    >
    > Andrew,
    > I have been using this patch for ages. Any chance of it being forwared to
    > the official tree?

    That patch had its first birthday last week. I wrote it in response to
    some long-forgotten problem, failed to changelog it at the time then forgot
    why I wrote it. I kept it in the hope that I'd remember why I wrote it. I
    subsequently wrote a best-effort changelog but am unconvinced by it. Ho
    hum.

    Let me genuflect a bit. I guess we can be reasonably confident it won't
    break anything.
    -
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