From: Sasha Levin <sashal@kernel.org>
To: Thibaut Sautereau <thibaut@sautereau.fr>
Cc: stable@vger.kernel.org,
Jianchao Wang <jianchao.w.wang@oracle.com>,
m19@florianstecker.de, Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] blk-mq: fix a hung issue when fsync
Date: Sun, 17 Feb 2019 12:28:19 -0500 [thread overview]
Message-ID: <20190217172819.GE10616@sasha-vm> (raw)
In-Reply-To: <20190217153729.GA3835@gandi.net>
On Sun, Feb 17, 2019 at 04:37:29PM +0100, Thibaut Sautereau wrote:
>On Wed, Jan 30, 2019 at 08:54:09AM -0700, Jens Axboe wrote:
>> On 1/30/19 2:01 AM, Jianchao Wang wrote:
>> > Florian reported a io hung issue when fsync(). It should be
>> > triggered by following race condition.
>> >
>> > data + post flush a flush
>> >
>> > blk_flush_complete_seq
>> > case REQ_FSEQ_DATA
>> > blk_flush_queue_rq
>> > issued to driver blk_mq_dispatch_rq_list
>> > try to issue a flush req
>> > failed due to NON-NCQ command
>> > .queue_rq return BLK_STS_DEV_RESOURCE
>> >
>> > request completion
>> > req->end_io // doesn't check RESTART
>> > mq_flush_data_end_io
>> > case REQ_FSEQ_POSTFLUSH
>> > blk_kick_flush
>> > do nothing because previous flush
>> > has not been completed
>> > blk_mq_run_hw_queue
>> > insert rq to hctx->dispatch
>> > due to RESTART is still set, do nothing
>> >
>> > To fix this, replace the blk_mq_run_hw_queue in mq_flush_data_end_io
>> > with blk_mq_sched_restart to check and clear the RESTART flag.
>>
>> Applied, thanks.
>>
>> --
>> Jens Axboe
>
>Can this be applied to stable kernels please?
>
>It's commit 85bd6e61f34dffa8ec2dc75ff3c02ee7b2f1cbce upstream.
I've queued it for 4.20, 4.19 and 4.14.
--
Thanks,
Sasha
prev parent reply other threads:[~2019-02-17 17:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-30 9:01 [PATCH] blk-mq: fix a hung issue when fsync Jianchao Wang
2019-01-30 15:54 ` Jens Axboe
2019-02-17 15:37 ` Thibaut Sautereau
2019-02-17 17:28 ` Sasha Levin [this message]
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