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SubjectRe: [Bug 3317] New: Kernel oops in aio_complete while running AIO application
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On Fri, 2004-09-03 at 08:52, Badari Pulavarty wrote:
> On Tue, 2004-08-31 at 08:18, Andrew Morton wrote:
> > Begin forwarded message:
> >
> > Date: Tue, 31 Aug 2004 06:15:18 -0700
> > From: bugme-daemon@osdl.org
> > To: bugme-new@lists.osdl.org
> > Subject: [Bugme-new] [Bug 3317] New: Kernel oops in aio_complete while running AIO application
> >
> >
> > http://bugme.osdl.org/show_bug.cgi?id=3317
> >
>
> Hi Andrew,
>
> I debugged this some more. Here is whats happening:
>
> The test program used program text address as buffer to do the READ to.
> DIO get_user_pages() returned EFAULT. We called finished_one_bio()
> as part of dropping the ref. to dio. It called aio_complete().
> do_direct_IO() returned EFAULT to the caller. aio_run_iocb() expects
> to see EIOCBQUEUED/RETRY, otherwise it calls aio_complete() with the
> "ret" value. This is where the second aio_complete() is coming from.
> So we cleanup "req" and on the next de-ref we get OOPS.
>
> The problem here is, finished_one_bio() shouldn't call aio_complete()
> since no work has been done. I have a fix for this - can you verify this
> ? I am not really comfortable with this "tweaking". (I am not really
> sure about IO errors like EIO etc. - if they can lead to calling
> aio_complete() twice)
>
>
> Fix is to call aio_complete() ONLY if there is something to report.
> Note the we don't update dio->result with any error codes from
> get_user_pages(), they just passed as "ret" value from do_direct_IO().
>
> Thanks,
> Badari

Badari,

This does fix the problem when running on my system (ext3).

One question, finished_one_bio() is called in 3 places,
are you sure the other places won't be harmed by this
change?

I'm also looking over the code and will let you know if
I see any problems.

Daniel

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