On Thu, 21 Jun 2007, Christoph Lameter wrote:
> Maybe this will address the issue on ARM?
Looks like it would indeed address the immediate issue on ARM -
IF they've no particular reason to be using kmalloc there.
However... what gives you confidence that flush_dcache_page is
never applied to other slab pages?
This looks to me like a clean way forward to try in -mm; but that
2.6.22 should go with the safety PageSlab test in page_mapping.
Hugh
>
>
> ARM: Allocate dma pages via the page allocator and not via the slab allocator
>
> Slab allocations are not guaranteed to be page aligned and slab allocators
> may use the page structs for their own purposes. Using the page allocator
> yields a properly aligned page and also makes the page flushing logic work
> right.
>
> Passing a kmalloced "page" to a flushing function will not work reliably.
>
> This will hopefully address the issue with SLUB on ARM. SLUB uses the
> page->mapping field which is also checked by the flushing logic. The
> flushing logic expects a normal page and not a slab page.
>
> Signed-off-by: Christoph Lameter <[EMAIL PROTECTED]>
>
> ---
> arch/arm/mm/consistent.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> Index: linux-2.6/arch/arm/mm/consistent.c
> ===================================================================
> --- linux-2.6.orig/arch/arm/mm/consistent.c 2007-06-21 18:18:15.000000000
> -0700
> +++ linux-2.6/arch/arm/mm/consistent.c 2007-06-21 18:29:16.000000000
> -0700
> @@ -277,7 +277,7 @@ dma_alloc_coherent(struct device *dev, s
> if (arch_is_coherent()) {
> void *virt;
>
> - virt = kmalloc(size, gfp);
> + virt = get_free_pages(gfp, get_order(size));
> if (!virt)
> return NULL;
> *handle = virt_to_dma(dev, virt);
> @@ -364,7 +364,7 @@ void dma_free_coherent(struct device *de
> WARN_ON(irqs_disabled());
>
> if (arch_is_coherent()) {
> - kfree(cpu_addr);
> + free_pages((unsigned long)cpu_addr, get_order(size));
> return;
> }
>
>
-
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