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From: Will Deacon <will@kernel.org>
To: John Garry <john.garry@huawei.com>
Cc: "Isaac J. Manjarres" <isaacm@codeaurora.org>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Saravana Kannan <saravanak@google.com>,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	Bjorn Helgaas <bhelgaas@google.com>,
	Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH v2 6/9] Revert "iommu/arm-smmu: Make arm-smmu-v3 explicitly non-modular"
Date: Fri, 8 Nov 2019 17:48:46 +0000
Message-ID: <20191108174846.GA22677@willie-the-truck> (raw)
In-Reply-To: <20191108173248.GA22448@willie-the-truck>

On Fri, Nov 08, 2019 at 05:32:48PM +0000, Will Deacon wrote:
> On Fri, Nov 08, 2019 at 05:25:09PM +0000, John Garry wrote:
> > On 08/11/2019 16:47, Will Deacon wrote:
> > > On Fri, Nov 08, 2019 at 04:44:25PM +0000, John Garry wrote:
> > > > BTW, it now looks like it was your v1 series I was testing there, on your
> > > > branch iommu/module. It would be helpful to update for ease of testing.
> > > 
> > > Yes, sorry about that. I'll update it now (although I'm not sure it will
> > > help with this -- I was going to see what happens with other devices such
> > > as the intel-iommu or storage controllers)
> > 
> > So I tried your v2 series for this - it has the same issue, as I
> > anticipated.
> 
> Right, I'm just not sure how resilient drivers are expected to be to force
> unbinding like this. You can break lots of stuff with root...
> 
> > It seems that some iommu drivers do call iommu_device_register(), so maybe a
> > decent reference. Or simply stop the driver being unbound.
> 
> I'm not sure what you mean about iommu_device_register() (we call that
> already), but I guess we can keep the '.suppress_bind_attrs = true' if
> necessary. I'll have a play on my laptop and see how well that works if
> you start unbinding stuff.

So unbinding the nvme driver goes bang:

[90139.090158] nvme nvme0: failed to set APST feature (-19)
[90141.966780] Aborting journal on device dm-1-8.
[90141.967124] Buffer I/O error on dev dm-1, logical block 26247168, lost sync page write
[90141.967169] JBD2: Error -5 detected when updating journal superblock for dm-1-8.
[90141.967403] Buffer I/O error on dev dm-1, logical block 0, lost sync page write
[90141.967454] EXT4-fs (dm-1): I/O error while writing superblock
[90141.967467] EXT4-fs error (device dm-1): ext4_journal_check_start:61: Detected aborted journal
[90141.967473] EXT4-fs (dm-1): Remounting filesystem read-only
[90141.967569] Buffer I/O error on dev dm-1, logical block 0, lost sync page write
[90141.967682] EXT4-fs (dm-1): I/O error while writing superblock

and I've not managed to recover the thing yet (it's stuck trying to reboot.)

What state was your system in after unbinding the SMMU?

Will
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Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-08 15:15 [PATCH v2 0/9] iommu: Permit modular builds of ARM SMMU[v3] drivers Will Deacon
2019-11-08 15:16 ` [PATCH v2 1/9] drivers/iommu: Export core IOMMU API symbols to permit modular drivers Will Deacon
2019-11-08 15:16 ` [PATCH v2 2/9] iommu/of: Request ACS from the PCI core when configuring IOMMU linkage Will Deacon
2019-11-08 15:16 ` [PATCH v2 3/9] PCI: Export pci_ats_disabled() as a GPL symbol to modules Will Deacon
2019-11-08 15:16 ` [PATCH v2 4/9] drivers/iommu: Take a ref to the IOMMU driver prior to ->add_device() Will Deacon
2019-11-08 15:16 ` [PATCH v2 5/9] iommu/of: Take a ref to the IOMMU driver during ->of_xlate() Will Deacon
2019-11-08 15:16 ` [PATCH v2 6/9] Revert "iommu/arm-smmu: Make arm-smmu-v3 explicitly non-modular" Will Deacon
2019-11-08 16:17   ` John Garry
2019-11-08 16:44     ` John Garry
2019-11-08 16:47       ` Will Deacon
2019-11-08 17:25         ` John Garry
2019-11-08 17:32           ` Will Deacon
2019-11-08 17:48             ` Will Deacon [this message]
2019-11-08 18:00               ` John Garry
2019-11-08 17:49             ` John Garry
2019-11-08 15:16 ` [PATCH v2 7/9] iommu/arm-smmu-v3: Allow building as a module Will Deacon
2019-11-08 15:16 ` [PATCH v2 8/9] Revert "iommu/arm-smmu: Make arm-smmu explicitly non-modular" Will Deacon
2019-11-08 15:16 ` [PATCH v2 9/9] iommu/arm-smmu: Allow building as a module Will Deacon

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