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Date: Fri, 26 Jun 2026 10:33:34 -0600
From: Keith Busch <kbusch@kernel.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: Ben Carey <benjamin.james.carey3@gmail.com>, io-uring@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [BUG] RCU hang with io_uring nvme polling
Message-ID: <aj6p3kZy1a8Mf68S@kbusch-mbp>
References: <20260626150946.287781-1-benjamin.james.carey3@gmail.com>
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On Fri, Jun 26, 2026 at 10:06:49AM -0600, Jens Axboe wrote:
> Ah good catch, I missed that. Should've grepped! In general, IO should
> either get polled, or if the device is misbehaving, then timeouts will
> catch it. That said, haven't looked at the actual report yet, will do
> so next week (unless you beat me to it...?)

I'll give it a shot!

The test has 1 polling queue with 2 jobs dispatching. One of the job's
polled the completions for both. The other job is polling for no reason
at all with nothing outstanding. The only thing that can break us out of
that loop now is need_resched(), but that appears to never return true.