From: Dean Luick <dean.luick@cornelisnetworks.com>
To: Christoph Hellwig <hch@lst.de>, Robin Murphy <robin.murphy@arm.com>
Cc: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Alexandra Winter <wintera@linux.ibm.com>,
Wenjia Zhang <wenjia@linux.ibm.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>,
Russell King <linux@armlinux.org.uk>,
linux-arm-kernel@lists.infradead.org, linux-rdma@vger.kernel.org,
iommu@lists.linux.dev, linux-media@vger.kernel.org,
netdev@vger.kernel.org, linux-s390@vger.kernel.org,
alsa-devel@alsa-project.org
Subject: Re: [PATCH 2/7] RDMA/hfi1: don't pass bogus GFP_ flags to dma_alloc_coherent
Date: Sun, 20 Nov 2022 14:41:45 -0600 [thread overview]
Message-ID: <b4481009-68fb-19f0-4d75-c4d242ed3b64@cornelisnetworks.com> (raw)
In-Reply-To: <2c60c692-58d7-d06d-826e-ea49bb1eca13@cornelisnetworks.com>
On 11/16/2022 11:49 AM, Dean Luick wrote:
> On 11/16/2022 9:45 AM, Christoph Hellwig wrote:
>> On Wed, Nov 16, 2022 at 03:15:10PM +0000, Robin Murphy wrote:
>>> Coherent DMA buffers are allocated by a kernel driver or subsystem for the
>>> use of a device managed by that driver or subsystem, and thus they
>>> fundamentally belong to the kernel as proxy for the device. Any coherent
>>> DMA buffer may be mapped to userspace with the dma_mmap_*() interfaces, but
>>> they're never a "userspace allocation" in that sense.
>>
>> Exactly. I could not find a place to map the buffers to userspace,
>> so if it does that without using the proper interfaces we need to fix
>> that as well. Dean, can you point me to the mmap code?
>
> See hfi1_file_mmap(), cases RCV_HDRQ and RCV_EGRBUF, for the two items you changed in hfi1. Both directly use remap_pfn_range(), which is probably the original approved call, but now is now buried deep within dma_mmap_*(). As you say - these should be updated. That said, the eager buffer mapping will stitch together multiple eager buffers into a single user map/vma. I don't see how to do that with the dma_mmap_*() interface.
I have tested the proposed hfi1 changes. They are fine.
Acked-by: Dean Luick <dean.luick@cornelisnetworks.com>
Tested-by: Dean Luick <dean.luick@cornelisnetworks.com>
Using dma_mmap_*() for the changed cases (e.g. rcvhdrq) fails. They are being looked at. I don't think they need to be part of this change.
-Dean
External recipient
next prev parent reply other threads:[~2022-11-20 20:42 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-13 16:35 stop drivers from passing GFP_COMP to dma_alloc_coherent Christoph Hellwig
2022-11-13 16:35 ` [PATCH 1/7] media: videobuf-dma-contig: use dma_mmap_coherent Christoph Hellwig
2022-11-24 14:10 ` Hans Verkuil
2022-11-29 14:00 ` Christoph Hellwig
2022-11-13 16:35 ` [PATCH 2/7] RDMA/hfi1: don't pass bogus GFP_ flags to dma_alloc_coherent Christoph Hellwig
2022-11-15 20:39 ` Jason Gunthorpe
2022-11-16 14:40 ` Dean Luick
2022-11-16 15:15 ` Robin Murphy
2022-11-16 15:45 ` Christoph Hellwig
2022-11-16 17:49 ` Dean Luick
2022-11-20 20:41 ` Dean Luick [this message]
2022-11-16 16:21 ` Dean Luick
2022-11-16 18:37 ` Robin Murphy
2022-11-13 16:35 ` [PATCH 3/7] RDMA/qib: " Christoph Hellwig
2022-11-15 20:40 ` Jason Gunthorpe
2022-11-13 16:35 ` [PATCH 4/7] cnic: " Christoph Hellwig
2022-11-13 16:35 ` [PATCH 5/7] s390/ism: " Christoph Hellwig
2022-11-16 12:39 ` Wenjia Zhang
2022-11-13 16:35 ` [PATCH 6/7] ALSA: memalloc: don't pass bogus GFP_ flags to dma_alloc_* Christoph Hellwig
2022-11-14 9:04 ` Takashi Iwai
2022-11-21 8:37 ` Christoph Hellwig
2022-11-13 16:35 ` [PATCH 7/7] dma-mapping: reject __GFP_COMP in dma_alloc_attrs Christoph Hellwig
2022-11-14 8:11 ` Leon Romanovsky
2022-11-16 6:11 ` Christoph Hellwig
2022-11-16 7:11 ` Leon Romanovsky
2022-11-14 12:16 ` Marek Szyprowski
2022-11-21 8:39 ` stop drivers from passing GFP_COMP to dma_alloc_coherent Christoph Hellwig
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