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Date:   Fri, 17 Jun 2022 08:04:29 -0600
From:   Keith Busch <kbusch@kernel.org>
To:     Yu Kuai <yukuai3@huawei.com>
Cc:     axboe@kernel.dk, ming.lei@redhat.com, jack@suse.cz,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        yi.zhang@huawei.com
Subject: Re: [PATCH RFC -next] sbitmap: fix possible io hung due to lost
 wakeups
Message-ID: <YqyJ7dwUB0z0puNc@kbusch-mbp.dhcp.thefacebook.com>
References: <20220617141125.3024491-1-yukuai3@huawei.com>
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On Fri, Jun 17, 2022 at 10:11:25PM +0800, Yu Kuai wrote:
> 
> What's worse, io hung is possible in theory because wakeups might be
> missed. For example, 2 * wake_batch tags are put, while only wake_batch
> threads are worken:

Not just in theory, io hanging sounds like the problem reported here:

  https://bugzilla.kernel.org/show_bug.cgi?id=215679

I only knew that it had nothing to do with the nvme driver, though, but they
closed the bug after it stopped happening with different hardware.