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Date:   Wed, 15 Jul 2020 12:19:42 +1000
From:   Stephen Rothwell <sfr@canb.auug.org.au>
To:     Qian Cai <cai@lca.pw>
Cc:     Guo Xuenan <guoxuenan@huawei.com>, axboe@kernel.dk,
        linux-block@vger.kernel.org, wangli74@huawei.com,
        fangwei1@huawei.com, ming.lei@redhat.com, josef@toxicpanda.com,
        linux-next@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] blk-rq-qos: remove redundant finish_wait to
 rq_qos_wait.
Message-ID: <20200715121942.33bb34d8@canb.auug.org.au>
In-Reply-To: <20200714232123.GA49251@lca.pw>
References: <20200628135625.3396636-1-guoxuenan@huawei.com>
        <20200714232123.GA49251@lca.pw>
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Hi all,

On Tue, 14 Jul 2020 19:21:24 -0400 Qian Cai <cai@lca.pw> wrote:
>
> On Sun, Jun 28, 2020 at 09:56:25AM -0400, Guo Xuenan wrote:
> > It is no need do finish_wait twice after acquiring inflight.
> >=20
> > Signed-off-by: Guo Xuenan <guoxuenan@huawei.com>
> > ---
> >  block/blk-rq-qos.c | 2 --
> >  1 file changed, 2 deletions(-)
> >=20
> > diff --git a/block/blk-rq-qos.c b/block/blk-rq-qos.c
> > index 656460636ad3..18f3eab9f768 100644
> > --- a/block/blk-rq-qos.c
> > +++ b/block/blk-rq-qos.c
> > @@ -273,8 +273,6 @@ void rq_qos_wait(struct rq_wait *rqw, void *private=
_data,
> >  		if (data.got_token)
> >  			break;
> >  		if (!has_sleeper && acquire_inflight_cb(rqw, private_data)) {
> > -			finish_wait(&rqw->wait, &data.wq);
> > -
> >  			/*
> >  			 * We raced with wbt_wake_function() getting a token,
> >  			 * which means we now have two. Put our local token
> > --=20
> > 2.25.4 =20
>=20
> Reverting this commit fixed an issue that swapping workloads will stall f=
or
> days without being able to make any progress below.

I have reverted that commit from linux-next today.

--=20
Cheers,
Stephen Rothwell

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