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: Wed, 19 May 2021 19:25:02 +0200 [thread overview]
Message-ID: <YKVJ7vjUmIUAmdC0@kroah.com> (raw)
In-Reply-To: <CAA03e5E9ojmsVNcHK4MyuYKCCFLo-RTFa17dA5Ay5v9rCMH+kg@mail.gmail.com>
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.
Good luck!
greg k-h
next prev parent reply other threads:[~2021-05-19 17:25 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 [this message]
2021-05-19 20:01 ` Marc Orr
2021-05-20 8:32 ` Greg KH
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