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Message-ID: <ab061a6b-2aeb-fb62-3dd0-a20059ff10ac@samsung.com>
Date: Wed, 9 Aug 2023 19:05:04 +0200
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Matthew Wilcox <willy@...radead.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Russell King <linux@...linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
Mike Rapoport <rppt@...nel.org>
Subject: Re: [PATCH] arm: dma-mapping: fix potential endless loop in
__dma_page_dev_to_cpu()
Hi,
On 07.08.2023 18:23, Matthew Wilcox wrote:
> On Mon, Aug 07, 2023 at 05:26:57PM +0200, Marek Szyprowski wrote:
>> It is possible that the folio_size() of the next folio returns zero, so
> What? How can folio_size() return zero?
>
> return PAGE_SIZE << folio_order(folio);
>
> It is a minimum of PAGE_SIZE.
Well, the folio_order() on that next folio returns 255, so folio_size()
overflows to zero. However, the main source of this issue is relying on
the properties of the folio beyond the requested sync region.
> ...
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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