Re: [PATCH 1/1] workqueue: fix ghost PENDING flag while doing MQ IO

[Tejun Heo]

Hello,

On Tue, Apr 26, 2016 at 01:15:35PM +0200, Roman Pen wrote:
...
> This behaviour can be explained by speculative LOAD of hctx->ctx_map on
> CPU#0, which is reordered with clear of PENDING bit and executed _before_
> actual STORE of bit 1 on CPU#1.
> 
> The proper fix is an explicit full barrier <mfence>, which guarantees
> that clear of PENDING bit is to be executed before all possible
> speculative LOADS or STORES inside actual work function.

Applied to workqueue/for-4.6-fixes.

Thanks.

-- 
tejun