lkml.org 
[lkml]   [2007]   [Jun]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Oops in a driver while using SLUB as a SLAB allocator
    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 <clameter@sgi.com>
    >
    > ---
    > 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;
    > }
    >
    >
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-06-22 07:09    [W:3.904 / U:0.056 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site