* BUG? linux-mips flush_dcache_page
@ 2009-10-16 5:17 Minchan Kim
2009-10-16 9:24 ` Ralf Baechle
0 siblings, 1 reply; 3+ messages in thread
From: Minchan Kim @ 2009-10-16 5:17 UTC (permalink / raw)
To: Ralf Baechle, Atsushi Nemoto; +Cc: lkml, linux-mips, Chungki woo
Hi, Ralf.
I suffered form data consistency problem.
Many code of kernel fs usually allocate high page and flush.
But flush_dcache_page of mips checks PageHighMem to avoid flush
so that data consistency is broken, I think.
I found it's by you and Atsushi-san on 585fa724.
Why do we need the check?
Could you elaborte please?
--
Kind regards,
Minchan Kim
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: BUG? linux-mips flush_dcache_page
2009-10-16 5:17 BUG? linux-mips flush_dcache_page Minchan Kim
@ 2009-10-16 9:24 ` Ralf Baechle
2009-10-16 10:43 ` Minchan Kim
0 siblings, 1 reply; 3+ messages in thread
From: Ralf Baechle @ 2009-10-16 9:24 UTC (permalink / raw)
To: Minchan Kim; +Cc: Atsushi Nemoto, lkml, linux-mips, Chungki woo
On Fri, Oct 16, 2009 at 02:17:19PM +0900, Minchan Kim wrote:
> Many code of kernel fs usually allocate high page and flush.
> But flush_dcache_page of mips checks PageHighMem to avoid flush
> so that data consistency is broken, I think.
What processor and cache configuration?
> I found it's by you and Atsushi-san on 585fa724.
> Why do we need the check?
> Could you elaborte please?
The if statement exists because __flush_dcache_page would crash if a page
is not mapped. This of course isn't correct but that wasn't a problem
since highmem still is only supported on machines that don't have aliases.
Ralf
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: BUG? linux-mips flush_dcache_page
2009-10-16 9:24 ` Ralf Baechle
@ 2009-10-16 10:43 ` Minchan Kim
0 siblings, 0 replies; 3+ messages in thread
From: Minchan Kim @ 2009-10-16 10:43 UTC (permalink / raw)
To: Ralf Baechle; +Cc: Atsushi Nemoto, lkml, linux-mips, Chungki woo
On Fri, Oct 16, 2009 at 6:24 PM, Ralf Baechle <ralf@linux-mips.org> wrote:
> On Fri, Oct 16, 2009 at 02:17:19PM +0900, Minchan Kim wrote:
>
>> Many code of kernel fs usually allocate high page and flush.
>> But flush_dcache_page of mips checks PageHighMem to avoid flush
>> so that data consistency is broken, I think.
>
> What processor and cache configuration?
Chungki. Could you anwer this question ?
>> I found it's by you and Atsushi-san on 585fa724.
>> Why do we need the check?
>> Could you elaborte please?
>
> The if statement exists because __flush_dcache_page would crash if a page
> is not mapped. This of course isn't correct but that wasn't a problem
> since highmem still is only supported on machines that don't have aliases.
Thansk for good explanation.
Chungki. Please let us know your machine(processor and cache configuration)
>
> Ralf
>
--
Kind regards,
Minchan Kim
^ permalink raw reply [flat|nested] 3+ messages in thread
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2009-10-16 5:17 BUG? linux-mips flush_dcache_page Minchan Kim
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2009-10-16 10:43 ` Minchan Kim
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