Re: [PATCH 0/12] Per-bdi writeback flusher threads v7

From: Jens Axboe
Date: Wed May 27 2009 - 02:17:55 EST


On Wed, May 27 2009, Damien Wyart wrote:
> * Jens Axboe <jens.axboe@xxxxxxxxxx> [2009-05-26 23:11]:
> > > OK, I spotted the problem. If we fallback to the on-stack allocation in
> > > bdi_writeback_all(), then we do the wait for the work completion with
> > > the bdi_lock mutex held. This can deadlock with bdi_forker_task(), so if
> > > we require that to be invoked to make progress (happens if a thread
> > > needs to be restarted), then we have a deadlock on that mutex.
>
> > > I'll cook up a fix for this, but probably not before the morning.
>
> > Untested fix. I think it should work, but I haven't run it here yet.
>
> Thanks for your feedback and explanations. Will not be able to test the
> patch before the afternoon. Will then give feedback as soon as I can. Of
> course, I can also test a new fix or series if you send one in the
> morning, after your own testing.

Just wait for the new series, I'll be posting it this morning. And
thanks for your testing and report!

--
Jens Axboe

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