From: "Michel Dänzer" <michel@daenzer.net>
To: Christoph Hellwig <hch@lst.de>, Daniel Vetter <daniel@ffwll.ch>
Cc: "Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
"Christian König" <christian.koenig@amd.com>,
iommu@lists.linux-foundation.org
Subject: Re: [PATCH] swiotlb: Fix inversed DMA_ATTR_NO_WARN test
Date: Wed, 2 May 2018 16:31:09 +0200 [thread overview]
Message-ID: <1066dfa2-2f78-815d-c65a-9d09eb35458c@daenzer.net> (raw)
In-Reply-To: <20180502124151.GA22857@lst.de>
On 2018-05-02 02:41 PM, Christoph Hellwig wrote:
> On Wed, May 02, 2018 at 02:18:56PM +0200, Daniel Vetter wrote:
>> Other dma-api backends like cma just shut up when __GFP_NOWARN is
>> passed. And afaiui Christoph Hellwig has plans to nuke the DMA_ATTR
>> stuff (or at least clean it up) - should we just remove
>> DMA_ATTR_NO_WARN and instead only look at __GFP_NOWARN?
>
> No. __GFP_NOWARN (and gfp_t flags in general) are the wrong interface
> for dma allocations and just cause problems. I actually plan to
> get rid of the gfp_t argument in dma_alloc_attrs sooner, and only
> allow either GFP_KERNEL or GFP_DMA passed in dma_alloc_coherent.
How about GFP_TRANSHUGE_LIGHT? TTM uses that to opportunistically
allocate huge pages (GFP_TRANSHUGE can result in unacceptably long
delays with memory pressure).
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Mesa and X developer
next prev parent reply other threads:[~2018-05-02 14:31 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-01 13:24 [PATCH] swiotlb: Fix inversed DMA_ATTR_NO_WARN test Michel Dänzer
2018-05-02 9:49 ` Christian König
2018-05-02 12:18 ` Daniel Vetter
2018-05-02 12:41 ` Christoph Hellwig
2018-05-02 14:31 ` Michel Dänzer [this message]
2018-05-02 16:21 ` Christoph Hellwig
2018-05-02 16:59 ` Michel Dänzer
2018-05-22 13:13 ` Christian König
2018-05-25 8:41 ` Christoph Hellwig
2018-05-25 8:41 ` Michel Dänzer
2018-05-02 12:42 ` Christoph Hellwig
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