From: Leon Romanovsky <leon@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Anumula Murali Mohan Reddy <anumula@chelsio.com>,
jgg@nvidia.com, linux-rdma@vger.kernel.org,
Potnuri Bharat Teja <bharat@chelsio.com>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH for-next] RDMA/cxgb4: use dma_mmap_coherent() for mapping non-contiguous memory
Date: Sun, 7 Jul 2024 14:39:57 +0300 [thread overview]
Message-ID: <20240707113957.GJ6695@unreal> (raw)
In-Reply-To: <20240707113103.GA4441@lst.de>
On Sun, Jul 07, 2024 at 01:31:03PM +0200, Christoph Hellwig wrote:
> On Sun, Jul 07, 2024 at 12:11:05PM +0300, Leon Romanovsky wrote:
> > On Fri, Jul 05, 2024 at 06:47:53PM +0530, Anumula Murali Mohan Reddy wrote:
> > > dma_alloc_coherent() allocates contiguous memory irrespective of
> > > iommu mode, but after commit f5ff79fddf0e ("dma-mapping: remove
> > > CONFIG_DMA_REMAP") if iommu is enabled in translate mode,
> > > dma_alloc_coherent() may allocate non-contiguous memory.
> > > Attempt to map this memory results in panic.
> > > This patch fixes the issue by using dma_mmap_coherent() to map each page
> > > to user space.
> >
> > It is perfect time to move to use rdma_user_mmap_io(), instead of
> > open-code it in the driver.
>
> rdma_user_mmap_io does not work on dma coherent allocations.
They used dma_mmap_coherent() to implement workaround, original cxgb4
didn't use it and probably doesn't need too.
Thanks
next prev parent reply other threads:[~2024-07-07 11:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-05 13:17 [PATCH for-next] RDMA/cxgb4: use dma_mmap_coherent() for mapping non-contiguous memory Anumula Murali Mohan Reddy
2024-07-06 0:16 ` Zhu Yanjun
2024-07-07 9:11 ` Leon Romanovsky
2024-07-07 11:31 ` Christoph Hellwig
2024-07-07 11:39 ` Leon Romanovsky [this message]
2024-07-08 10:05 ` Christoph Hellwig
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