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Re: [PATCH] MIPS: Fix get_user_page_fast() for mips with cache alias

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [PATCH] MIPS: Fix get_user_page_fast() for mips with cache alias
From: Kevin Cernekee <cernekee@gmail.com>
Date: Fri, 19 Jul 2013 08:34:50 -0700
Cc: Kamal Dasu <kdasu.kdev@gmail.com>, linux-mips@linux-mips.org, John Crispin <blogic@openwrt.org>
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On Tue, Jun 18, 2013 at 9:47 AM, Ralf Baechle <ralf@linux-mips.org> wrote:
> On Fri, Jun 14, 2013 at 02:10:03PM -0400, Kamal Dasu wrote:
>
>> get_user_pages_fast() is missing cache flushes for MIPS platforms
>> with cache alias. Filesystem failures observed with DirectIO
>> operations due to missing flush_anon_page() that use page coloring
>> logic to work with cache aliases. This fix falls through to take
>> slow_irqon path that calls get_user_pages() that has required
>> logic for platforms where cpu_has_dc_aliases is true.
>
> A bit unsatisfying to always fall back to the slow variant yet I like
> the patch because of it's simplicity but I wonder if there's not a
> better solution.

Hi Ralf,

What are your thoughts on pushing this fix to the stable tree for
3.4+?  Without Kamal's patch, ntfs-3g is completely broken on MIPS
platforms that have cache aliases.

Thanks.

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