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

To: Kamal Dasu <kdasu.kdev@gmail.com>
Subject: Re: [PATCH] MIPS: Fix get_user_page_fast() for mips with cache alias
From: Ralf Baechle <ralf@linux-mips.org>
Date: Tue, 18 Jun 2013 18:47:44 +0200
Cc: linux-mips@linux-mips.org
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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.

  Ralf

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