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Sender: Konrad Rzeszutek Wilk <konrad.r.wilk@gmail.com>
Date:   Mon, 21 Jun 2021 09:16:43 -0400
From:   Konrad Rzeszutek Wilk <konrad@darnok.org>
To:     'Dominique MARTINET' <dominique.martinet@atmark-techno.com>
Cc:     Chanho Park <chanho61.park@samsung.com>,
        'Jianxiong Gao' <jxgao@google.com>,
        'Christoph Hellwig' <hch@lst.de>,
        'Konrad Rzeszutek Wilk' <konrad.wilk@oracle.com>,
        'Linus Torvalds' <torvalds@linux-foundation.org>,
        'Horia =?utf-8?Q?Geant=C4=83'?= <horia.geanta@nxp.com>,
        linux-kernel@vger.kernel.org, 'Lukas Hartmann' <lukas@mntmn.com>,
        'Aymen Sghaier' <aymen.sghaier@nxp.com>,
        'Herbert Xu' <herbert@gondor.apana.org.au>,
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        'Marc Orr' <marcorr@google.com>,
        'Erdem Aktas' <erdemaktas@google.com>,
        'Peter Gonda' <pgonda@google.com>,
        'Bumyong Lee' <bumyong.lee@samsung.com>
Subject: Re: swiotlb/caamjr regression (Was: [GIT PULL] (swiotlb)
 stable/for-linus-5.12)
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On Mon, Jun 21, 2021 at 01:14:48PM +0900, 'Dominique MARTINET' wrote:
> Chanho Park wrote on Mon, Jun 21, 2021 at 11:55:22AM +0900:
> > Sure. No problem. But, the patch was already stacked on Konrad's tree
> > and linux-next as well.
> > 
> > https://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb.git/commit/?h=devel/for-linus-5.14&id=33d1641f38f0c327bc3e5c21de585c77a6512bc6 
> 
> That patch is slightly different, it's a rewrite Konrad did that mixes
> in Linus' suggestion[1], which breaks things for the NVMe usecase
> Jianxiong Gao has.
> 
> [1] offset = (tlb_addr - mem->start) & (IO_TLB_SIZE - 1)
> 
> 
> Konrad is aware so I think it shouldn't be submitted :)

The beaty of 'devel' and 'linux-next' is that they can be reshuffled and
mangled. I pushed them original patch from Bumyong there and will let
it sit for a day and then create a stable branch and give it to Linus.

Then I need to expand the test-regression bucket so that this does not
happen again. Dominique, how easy would it be to purchase one of those
devices?

I was originally thinking to create a crypto device in QEMU to simulate
this but that may take longer to write than just getting the real thing.

Or I could create some fake devices with weird offsets and write a driver
for it to exercise this.. like this one I had done some time ago that
needs some brushing off.