Date: Sat, 14 Nov 2009 00:17:14 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Russell King <rmk+lkml@arm.linux.org.uk>
Cc: Soeren Sandmann Pedersen <sandmann@redhat.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linux Kernel List <linux-kernel@vger.kernel.org>
Subject: Re: d451564 breakage
Message-ID: <20091113231714.GA21666@elte.hu>
References: <20091113151119.GA27752@flint.arm.linux.org.uk>
 <20091113224820.GB29657@elte.hu>
 <20091113230223.GF27752@flint.arm.linux.org.uk>
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* Russell King <rmk+lkml@arm.linux.org.uk> wrote:

> On Fri, Nov 13, 2009 at 11:48:20PM +0100, Ingo Molnar wrote:
> > 
> > * Russell King <rmk@arm.linux.org.uk> wrote:
> > 
> > > Change:
> > > 
> > > highmem: Fix debug_kmap_atomic() to also handle KM_IRQ_PTE, KM_NMI, and KM_NMI_PTE
> > > 
> > > Appears to break ARM:
> > > 
> > > mm/highmem.c: In function ???debug_kmap_atomic???:
> > > mm/highmem.c:436: error: ???KM_NMI??? undeclared (first use in this function)
> > 
> > indeed - sorry.
> > 
> > Note that debug_kmap_atomic() will be removed in v2.6.33 so i'd suggest 
> > to just do the easy solution and add #ifndef dummy definitions to 
> > mm/highmem.c to cover ARM - we'll remove the whole cruft for good.
> 
> Actually, the following patch is probably the simplest solution.
> 
> > Btw., testing sidenote: i test the ARM defconfig and it didnt break 
> > there. Perhaps highmem is off in the ARM defconfig? It would be helpful 
> > if the ARM defconfig enabled highmem.
> 
> Given that highmem on ARM is experimental, I'd rather not have it enabled
> in too many machine defconfigs as standard just yet.
> 
> However, enabling highmem on itself is not enough to show this breakage,
> you also need highmem debugging enabled.
> 
>  arch/arm/include/asm/kmap_types.h |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kmap_types.h b/arch/arm/include/asm/kmap_types.h
> index d16ec97..c019949 100644
> --- a/arch/arm/include/asm/kmap_types.h
> +++ b/arch/arm/include/asm/kmap_types.h
> @@ -22,4 +22,10 @@ enum km_type {
>  	KM_TYPE_NR
>  };
>  
> +#ifdef CONFIG_DEBUG_HIGHMEM
> +#define KM_NMI		(-1)
> +#define KM_NMI_PTE	(-1)
> +#define KM_IRQ_PTE	(-1)
> +#endif

Please solve this in mm/highmem.c as Andrew suggested it - other 
architectures could be affected as well beyond ARM.

	Ingo
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