[PATCH RFC] use WQ_MEM_RECLAIM for m_log_workqueue

[Dave Chinner]

On Thu, Nov 05, 2015 at 07:10:59AM -0500, Chris Mason wrote:
> On Wed, Nov 04, 2015 at 01:51:03PM -0500, Chris Mason wrote:
> > I think we should be using WQ_MEM_RECLAIM to make sure this thread pool
> > makes progress when we're not able to allocate new workers.
> 
> Thinking harder, it's probably best to just flag them all
> WQ_MEM_RECLAIM.  This is what btrfs does, and it saves you from painful
> discoveries about how different queues depend on each other.

Makes sense, we missed this one because the original use of the
workqueue was just for a periodic, non-critical function. Then we
move the log IO completion to it in 3.19 in commit b29c70f ("xfs:
split metadata and log buffer completion to separate workqueues").

> I'll start testing and send a v2.

Seems like a no-brainer to me...

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com