Subject: dma_alloc_coherent fails in framebuffer

From: [email-masked] (Tony Prisk)
Date: Tue, 16 Oct 2012 21:13:22 +1300

On Tue, 2012-10-16 at 08:58 +0100, Mel Gorman wrote:
> On Tue, Oct 16, 2012 at 07:50:07PM +1300, Tony Prisk wrote:
> > > > > Why it caused a problem on that particular commit I don't know - but it
> > > > > was reproducible by adding/removing it.
> > > > >
> > > 
> > > I finally found the link to this patch which caused the problem - and
> > > may still be the cause of my problems :)
> > > 
> 
> Blast, thanks. This was already identified as being a problem and "fixed"
> in https://lkml.org/lkml/2012/10/5/164 but I missed that the fix did not
> get picked up before RC1 after all the patches got collapsed together. I'm
> very sorry about that, I should have spotted that it didn't make it through.
> 
> > Any suggestions on how to fix this?
> > 
> 
> Can you test this to be sure and if it's fine I'll push it to Andrew.
> 
> ---8<---
> mm: compaction: Correct the strict_isolated check for CMA
> 
> Thierry reported that the "iron out" patch for isolate_freepages_block()
> had problems due to the strict check being too strict with "mm: compaction:
> Iron out isolate_freepages_block() and isolate_freepages_range() -fix1".
> It's possible that more pages than necessary are isolated but the check
> still fails and I missed that this fix was not picked up before RC1. This
> has also been identified in RC1 by Tony Prisk and should be addressed by
> the following patch.
> 
> Signed-off-by: Mel Gorman <[email-masked]>
> --- 
>  compaction.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 2c4ce17..9eef558 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -346,7 +346,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
>  	 * pages requested were isolated. If there were any failures, 0 is
>  	 * returned and CMA will fail.
>  	 */
> -	if (strict && nr_strict_required != total_isolated)
> +	if (strict && nr_strict_required > total_isolated)
>  		total_isolated = 0;
>  
>  	if (locked)

I don't need to test that again.. thats exactly what I did to fix it
myself :)

Tested-by: Tony Prisk <[email-masked]>

.. if needed.

Nice to know I'm not completely bonkers.

Thanks for your help
Tony P