From: Sagi Grimberg <sagi@grimberg.me>
To: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <kbusch@kernel.org>,
Anton Eidelman <anton@lightbitslabs.com>,
linux-nvme@lists.infradead.org
Subject: Re: [PATCH v2 for-5.8-rc 1/6] nvme: fix possible deadlock when I/O is blocked
Date: Wed, 24 Jun 2020 00:09:27 -0700 [thread overview]
Message-ID: <bd52aca5-6f66-5b7a-1276-91b9e7fa3f24@grimberg.me> (raw)
In-Reply-To: <20200624065745.GA18207@lst.de>
>>>> Revert fab7772bfbcf ("nvme-multipath: revalidate nvme_ns_head gendisk
>>>> in nvme_validate_ns")
>>>>
>>>> When adding a new namespace to the head disk (via nvme_mpath_set_live)
>>>> we will see partition scan which triggers I/O on the mpath device node.
>>>> This process will usually be triggered from the scan_work which holds
>>>> the scan_lock. If I/O blocks (if we got ana change currently have only
>>>> available paths but none are accessible) this can deadlock on the head
>>>> disk bd_mutex as both partition scan I/O takes it, and head disk revalidation
>>>> takes it to check for resize (also triggered from scan_work on a different
>>>> path). See trace [1].
>>>>
>>>> This is no longer needed since commit cb224c3af4df ("nvme: Convert to
>>>> use set_capacity_revalidate_and_notify") which already updates resize
>>>> info without unnecessarily revalidating the disk.
>>>
>>> Did you look if any other revalidation gets skipped this way? E.g.
>>> LBA size change?
>>>
>>> From purely the size POV this looks good, though.
>>
>> The only reason the revalidate was added was to update on a size change,
>> which is redundant.
>>
>> And if you look at revalidate, it only calls fops->revalidate_disk
>> (which is a noop in the mpath device) and checks the size change.
>
> Please add this blurb to the changelog for the next version.
Will do. thanks
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next prev parent reply other threads:[~2020-06-24 7:09 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 [this message]
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
2020-06-24 7:13 ` Sagi Grimberg
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