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

From: Damien Wyart
Date: Wed May 27 2009 - 01:21:20 EST

* 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.


Damien Wyart
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