From: Greg KH <gregkh@linuxfoundation.org>
To: Marc Orr <marcorr@google.com>
Cc: Jianxiong Gao <jxgao@google.com>,
stable@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
sashal@kernel.org
Subject: Re: [PATCH 5.4 v2 0/9] preserve DMA offsets when using swiotlb
Date: Thu, 20 May 2021 10:32:59 +0200 [thread overview]
Message-ID: <YKYeuwIK2jL+ICgw@kroah.com> (raw)
In-Reply-To: <CAA03e5Fe7LZcQ3pwhaVCG-mMWeyfr1VyYjmM8tLkVbzOcAiECg@mail.gmail.com>
On Wed, May 19, 2021 at 01:01:25PM -0700, Marc Orr wrote:
> On Wed, May 19, 2021 at 10:25 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Wed, May 19, 2021 at 10:18:38AM -0700, Marc Orr wrote:
> > > On Wed, May 19, 2021 at 10:03 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > On Wed, May 19, 2021 at 09:42:42AM -0700, Jianxiong Gao wrote:
> > > > > On Wed, May 19, 2021 at 1:11 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> > > > > >
> > > > > > I still fail to understand why you can not just use the 5.10.y kernel or
> > > > > > newer. What is preventing you from doing this if you wish to use this
> > > > > > type of hardware? This is not a "regression" in that the 5.4.y kernel
> > > > > > has never worked with this hardware before, it feels like a new feature.
> > > > > >
> > > > > NVMe + SWIOTLB is not a new feature. From my understanding it should
> > > > > be supported by 5.4.y kernel correctly. Currently without the patch, any
> > > > > NVMe device (along with some other devices that relies on offset to
> > > > > work correctly), could be broken if the SWIOTLB is used on a 5.4.y kernel.
> > > >
> > > > Then do not do that, as obviously it never worked without your fixes, so
> > > > this isn't a "regression".
> > >
> > > NVMe + SWIOTLB works fine without this bug fix. By fine I mean that a
> > > guest kernel using this configuration boots and runs stably for weeks
> > > and months under general-purpose usage. The bug that this patch set
> > > fixes was only encountered when a user tried to format an xfs
> > > filesystem under a RHEL guest kernel.
> > >
> > > > And again, why can you not just use 5.10.y?
> > >
> > > For our use case, this fixes the guest kernel, not the host kernel.
> > > The guest distros that we support use 5.4 kernels. We do not control
> > > the kernel that the distros deploy for usage as a guest OS on cloud.
> > > We only control the host kernel.
> >
> > And how are you going to get your guest kernels to update to these
> > patches? What specific ones are you concerned about?
> >
> > RHEL ignores stable kernel updates, so if you are worried about them,
> > please just work with that company directly.
>
> We support COS as a guest [1], which does base their kernel on 5.4
> LTS. If these patches were accepted into 5.4 LTS, they would
> automatically get picked up by COS.
>
> [1] https://cloud.google.com/container-optimized-os
Then go work with that group to add this "required" set of new features
for your cloud systems that require this as again, I fail to see how
this is a "regression" at all.
Maybe I should just go rip out these from 5.10.y as well as it feels
like a _very_ platform-specific issue that you all are having here.
thanks,
greg k-h
prev parent reply other threads:[~2021-05-20 8:33 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-18 22:18 [PATCH 5.4 v2 0/9] preserve DMA offsets when using swiotlb Jianxiong Gao
2021-05-18 22:18 ` [PATCH 5.4 v2 1/9] driver core: add a min_align_mask field to struct device_dma_parameters Jianxiong Gao
2021-05-18 22:18 ` [PATCH 5.4 v2 2/9] swiotlb: add a IO_TLB_SIZE define Jianxiong Gao
2021-05-18 22:18 ` [PATCH 5.4 v2 3/9] swiotlb: factor out an io_tlb_offset helper Jianxiong Gao
2021-05-18 22:18 ` [PATCH 5.4 v2 4/9] swiotlb: factor out a nr_slots helper Jianxiong Gao
2021-05-18 22:18 ` [PATCH 5.4 v2 5/9] swiotlb: clean up swiotlb_tbl_unmap_single Jianxiong Gao
2021-05-18 22:18 ` [PATCH 5.4 v2 6/9] swiotlb: refactor swiotlb_tbl_map_single Jianxiong Gao
2021-05-18 22:18 ` [PATCH 5.4 v2 7/9] swiotlb: don't modify orig_addr in swiotlb_tbl_sync_single Jianxiong Gao
2021-05-18 22:18 ` [PATCH 5.4 v2 8/9] swiotlb: respect min_align_mask Jianxiong Gao
2021-05-18 22:18 ` [PATCH 5.4 v2 9/9] nvme-pci: set min_align_mask Jianxiong Gao
2021-05-19 8:11 ` [PATCH 5.4 v2 0/9] preserve DMA offsets when using swiotlb Greg KH
2021-05-19 16:42 ` Jianxiong Gao
2021-05-19 17:03 ` Greg KH
2021-05-19 17:18 ` Marc Orr
2021-05-19 17:25 ` Greg KH
2021-05-19 20:01 ` Marc Orr
2021-05-20 8:32 ` Greg KH [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YKYeuwIK2jL+ICgw@kroah.com \
--to=gregkh@linuxfoundation.org \
--cc=hch@lst.de \
--cc=jxgao@google.com \
--cc=marcorr@google.com \
--cc=sashal@kernel.org \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox