linux-kernel - Re: [PATCH] quiet down swiotlb warnings

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Message-ID: <46606306.2060203@redhat.com>
Date:	Fri, 01 Jun 2007 14:18:46 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Christoph Hellwig <hch@...radead.org>,
	Andi Kleen <andi@...stfloor.org>,
	Rik van Riel <riel@...hat.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	andrew.vasquez@...gic.com
Subject: Re: [PATCH] quiet down swiotlb warnings

Christoph Hellwig wrote:
> On Fri, Jun 01, 2007 at 09:01:45PM +0200, Andi Kleen wrote:
>> Bad idea imho. swiotlb mappings should always lead to printk by default
>> because it is pretty dangerous.
>>
>> One possible solution for this I could think of would be to define a
>> new pci_map_sg_couldfail() or similar that doesn't warn and use a weak
>> fallback just calling pci_map_sg on other IOMMU implementations. 
> 
> pci_map_sg is defined to be failing when running out of ressources, which
> is perfectly fine.  We don't printk on kmalloc failures either (actually
> in some cases which is highly annoying and leads people to stick a
> __GFP_NOWARN into various places)

Andi, I could see your "pretty dangerous" case applying
when do_panic is set, but not in any other circumstances.

Does the patch below look better to you?

Signed-off-by: Rik van Riel <riel@...hat.com>

View attachment "2.6.21-swiotlb-quiet.patch" of type "text/x-patch" (1046 bytes)