From: Robin Murphy <robin.murphy@arm.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Marek Szyprowski <m.szyprowski@samsung.com>,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org
Subject: Re: [PATCH] Fix folio conversion in __dma_page_dev_to_cpu()
Date: Thu, 24 Aug 2023 18:14:38 +0100 [thread overview]
Message-ID: <89c1361e-3b0f-193f-647e-909d970cb1d1@arm.com> (raw)
In-Reply-To: <ZOeKGeAvLPBp1WVs@casper.infradead.org>
On 24/08/2023 5:49 pm, Matthew Wilcox wrote:
> On Thu, Aug 24, 2023 at 05:39:38PM +0100, Robin Murphy wrote:
>> As for >2GB segments, we've certainly seen cases of users mapping absurdly
>> large buffers and overflowing dma_length[2], so I would imagine it's only
>> the improbability of allocating that much physically-contiguous memory which
>> keeps individual segment lengths from getting up to UINT_MAX ;)
>
> With a 32-bit kernel though? ;-)
Oh, indeed, that's more of a challenge... I guess take an LPAE system
with enough RAM, run VMSPLIT_3G and convince a dma-buf heap to let you
import ~2.5GB of contiguous highmem for some kind of in-place media
processing, maybe? Not exactly 4, but still more than 2. In principle :D
Robin.
prev parent reply other threads:[~2023-08-24 17:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-23 19:18 Matthew Wilcox (Oracle)
2023-08-24 16:39 ` Robin Murphy
2023-08-24 16:49 ` Matthew Wilcox
2023-08-24 17:14 ` Robin Murphy [this message]
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