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Subject: Re: [PATCH 1/4] io_uring: fix hanging iopoll in case of -EAGAIN
To:     Pavel Begunkov <asml.silence@gmail.com>, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <cover.1592863245.git.asml.silence@gmail.com>
 <0301f35644823a01cbae87e440df7d58ebcf2279.1592863245.git.asml.silence@gmail.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <95b720a6-926c-a208-e929-1d0203fa8701@kernel.dk>
Date:   Mon, 22 Jun 2020 20:07:29 -0600
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On 6/22/20 4:16 PM, Pavel Begunkov wrote:
> io_do_iopoll() won't do anything with a request unless
> req->iopoll_completed is set. So io_complete_rw_iopoll() has to set
> it, otherwise io_do_iopoll() will poll a file again and again even
> though the request of interest was completed long ago.

I need to look at this again, because with this change, I previously
got various use-after-free. I haven't seen any issues with it, but
I agree, from a quick look that I'm not quite sure how it's currently
not causing hangs. Yet I haven't seen any, with targeted -EAGAIN
testing.

-- 
Jens Axboe