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From: Keith Busch <kbusch@kernel.org>
To: John Garry <john.garry@huawei.com>
Cc: sagi@grimberg.me, Robin Murphy <robin.murphy@arm.com>,
	linux-nvme@lists.infradead.org, Christoph Hellwig <hch@lst.de>,
	axboe@fb.com, Will Deacon <will@kernel.org>,
	Alexey Dobriyan <adobriyan@gmail.com>
Subject: Re: [PATCH] nvme-pci: slimmer CQ head update
Date: Thu, 7 May 2020 07:23:52 -0700	[thread overview]
Message-ID: <20200507142352.GA2621422@dhcp-10-100-145-180.wdl.wdc.com> (raw)
In-Reply-To: <e1643b53-d362-0b5e-573f-72f0ea249ebf@huawei.com>

On Thu, May 07, 2020 at 02:55:37PM +0100, John Garry wrote:
> On 07/05/2020 12:04, Robin Murphy wrote:
> > > [  177.132810] DMA-API: nvme 0000:85:00.0: device driver tries to
> > > free DMA memor
> > > y it has not allocated [device address=0x00000000ef371000]
> > > [size=4096 bytes]
> > [...]
> > > [  177.276322]  debug_dma_unmap_page+0x6c/0x78
> > > [  177.280487]  nvme_unmap_data+0x7c/0x23c
> > > [  177.284305]  nvme_pci_complete_rq+0x28/0x58
> > 
> > OK, so there's clearly something amiss there. I would have suggested
> > next sticking the SMMU in passthrough to help focus on the DMA API
> > debugging, but since that "DMA address" looks suspiciously like a
> > physical address rather than an IOVA, I suspect that things might
> > suddenly appear to be working fine if you do...
> 
> OK, seems sensible. However it looks like this guy triggers the issue:
> 
> 324b494c2862 nvme-pci: Remove two-pass completions
> 
> With carrying the revert of $subject, it's a quick bisect to that patch.

That's weird. Do you see this with different nvme controllers? Does your
controller write the phase bit before writing the command id in the cqe?
Asking because this looks like we're seeing an older command id in the
cqe, and the only thing that patch you've bisected should do is remove a
delay between observing the new phase and reading the command id.

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  reply	other threads:[~2020-05-07 14:23 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-28 18:45 [PATCH] nvme-pci: slimmer CQ head update Alexey Dobriyan
2020-02-29  5:53 ` Keith Busch
2020-05-06 11:03   ` John Garry
2020-05-06 12:47     ` Keith Busch
2020-05-06 13:24       ` Alexey Dobriyan
2020-05-06 13:44         ` John Garry
2020-05-06 14:01           ` Alexey Dobriyan
2020-05-06 14:35           ` Christoph Hellwig
2020-05-06 16:26             ` John Garry
2020-05-06 16:31               ` Will Deacon
2020-05-06 16:52                 ` Robin Murphy
2020-05-06 17:02                   ` John Garry
2020-05-07  8:18                     ` John Garry
2020-05-07 11:04                       ` Robin Murphy
2020-05-07 13:55                         ` John Garry
2020-05-07 14:23                           ` Keith Busch [this message]
2020-05-07 15:11                             ` John Garry
2020-05-07 15:35                               ` Keith Busch
2020-05-07 15:41                                 ` John Garry
2020-05-08 16:16                                   ` Keith Busch
2020-05-08 17:04                                     ` John Garry
2020-05-07 16:26                                 ` Robin Murphy
2020-05-07 17:35                                   ` Keith Busch
2020-05-07 17:44                                     ` Will Deacon
2020-05-07 18:06                                       ` Keith Busch
2020-05-08 11:40                                         ` Will Deacon
2020-05-08 14:07                                           ` Keith Busch
2020-05-08 15:34                                             ` Keith Busch
2020-05-06 14:44         ` Keith Busch
2020-05-07 15:58           ` Keith Busch
2020-05-07 20:07             ` [PATCH] nvme-pci: fix "slimmer CQ head update" Alexey Dobriyan

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