From: Christoph Hellwig <hch@lst.de>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: Keith Busch <kbusch@kernel.org>,
Anton Eidelman <anton@lightbitslabs.com>,
Christoph Hellwig <hch@lst.de>,
linux-nvme@lists.infradead.org
Subject: Re: [PATCH v2 RFC 6/6] nvme-core: fix deadlock in disconnect during scan_work and/or ana_work
Date: Wed, 24 Jun 2020 08:43:09 +0200 [thread overview]
Message-ID: <20200624064309.GG17594@lst.de> (raw)
In-Reply-To: <20200624001853.5408-7-sagi@grimberg.me>
On Tue, Jun 23, 2020 at 05:18:53PM -0700, Sagi Grimberg wrote:
> From: Anton Eidelman <anton@lightbitslabs.com>
>
> A deadlock happens in the following scenario with multipath:
> 1) scan_work(nvme0) detects a new nsid while nvme0
> is an optimized path to it, path nvme1 happens to be
> inaccessible.
>
> 2) Before scan_work is complete nvme0 disconnect is initiated
> nvme_delete_ctrl_sync() sets nvme0 state to NVME_CTRL_DELETING
>
> 3) scan_work(1) attempts to submit IO,
> but nvme_path_is_optimized() observes nvme0 is not LIVE.
> Since nvme1 is a possible path IO is requeued and scan_work hangs.
I'm really worried about another flag outside the state machine. If
we really need a multi-step deletion we should have
NVME_CTRL_DELETE_START, NVME_CTRL_DELETE_CONT or so states and run
this via the state machine.
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next prev parent reply other threads:[~2020-06-24 6:43 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-24 0:18 [PATCH v2 for-5.8-rc 0/6] address deadlocks in high stress ns scanning and ana updates Sagi Grimberg
2020-06-24 0:18 ` [PATCH v2 for-5.8-rc 1/6] nvme: fix possible deadlock when I/O is blocked Sagi Grimberg
2020-06-24 6:29 ` Christoph Hellwig
2020-06-24 6:54 ` Sagi Grimberg
2020-06-24 6:57 ` Christoph Hellwig
2020-06-24 7:09 ` Sagi Grimberg
2020-07-07 10:57 ` Anthony Iliopoulos
2020-07-08 14:42 ` Christoph Hellwig
2020-07-10 4:47 ` Sagi Grimberg
2020-07-14 11:12 ` Christoph Hellwig
2020-06-24 0:18 ` [PATCH v2 for-5.8-rc 2/6] nvme-multipath: fix deadlock between ana_work and scan_work Sagi Grimberg
2020-06-24 6:34 ` Christoph Hellwig
2020-06-24 6:56 ` Sagi Grimberg
2020-06-24 0:18 ` [PATCH v2 for-5.8-rc 3/6] nvme: don't protect ns mutation with ns->head->lock Sagi Grimberg
2020-06-24 6:37 ` Christoph Hellwig
2020-06-24 6:58 ` Sagi Grimberg
2020-06-24 8:24 ` Sagi Grimberg
2020-06-24 0:18 ` [PATCH v2 for-5.8-rc 4/6] nvme-multipath: fix deadlock due to head->lock Sagi Grimberg
2020-06-24 6:39 ` Christoph Hellwig
2020-06-24 7:00 ` Sagi Grimberg
2020-06-24 0:18 ` [PATCH v2 for-5.8-rc 5/6] nvme-multipath: fix bogus request queue reference put Sagi Grimberg
2020-06-24 6:40 ` Christoph Hellwig
2020-06-24 0:18 ` [PATCH v2 RFC 6/6] nvme-core: fix deadlock in disconnect during scan_work and/or ana_work Sagi Grimberg
2020-06-24 6:43 ` Christoph Hellwig [this message]
2020-06-24 7:13 ` Sagi Grimberg
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