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RE: [PATCH] MIPS: Remove race window in page fault handling

To: David Daney <ddaney.cavm@gmail.com>
Subject: RE: [PATCH] MIPS: Remove race window in page fault handling
From: Lars Persson <lars.persson@axis.com>
Date: Tue, 3 Jun 2014 12:29:17 +0200
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Thread-topic: [PATCH] MIPS: Remove race window in page fault handling
Hi

Good point. Would adding !cpu_has_ic_fills_f_dc as an extra condition in 
set_pte_at be sufficient to address your concern ?

BR,
 Lars

> -----Original Message-----
> From: David Daney [mailto:ddaney.cavm@gmail.com]
> Sent: den 2 juni 2014 18:48
> To: Lars Persson
> Cc: linux-mips@linux-mips.org; Lars Persson
> Subject: Re: [PATCH] MIPS: Remove race window in page fault handling
> 
> On 05/31/2014 03:36 AM, Lars Persson wrote:
> > Multicore MIPSes without I/D hardware coherency suffered from a race
> > condition in the page fault handler. The page table entry was
> > published before any pending lazy D-cache flush was committed, hence
> > it allowed execution of stale page cache data by other VPEs in the
> system.
> >
> 
> Shouldn't this only be done on machines that suffer from the problem?
> 
> There are many SMP MIPS machines that don't need this, so they
> shouldn't have to pay the price for doing this.
> 
> David Daney
> 
> 


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