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    SubjectRe: [PATCH] mm/vmalloc: don't use vmalloc_end
    On 12/08/2009 08:35 AM, Andrew Morton wrote:
    > (cc linux-ia64)
    >
    > On Mon, 07 Dec 2009 16:24:03 +0000
    > "Jan Beulich" <JBeulich@novell.com> wrote:
    >
    >> At least on ia64 vmalloc_end is a global variable that VMALLOC_END
    >> expands to. Hence having a local variable named vmalloc_end and
    >> initialized from VMALLOC_END won't work on such platforms. Rename
    >> these variables, and for consistency also rename vmalloc_start.
    >>
    >
    > erk. So does 2.6.32's vmalloc() actually work correctly on ia64?
    >
    > Perhaps vmalloc_end wasn't a well chosen name for an arch-specific
    > global variable.
    >
    > arch/m68k/include/asm/pgtable_mm.h does the same thing. Did it break too?

    Hmmm... ISTR writing a patch updating ia64 so that it doesn't use that
    macro. Looking it up.... Yeap, 126b3fcdecd350cad9700908d0ad845084e26a31
    in percpu#for-next.

    ia64: don't alias VMALLOC_END to vmalloc_end

    If CONFIG_VIRTUAL_MEM_MAP is enabled, ia64 defines macro VMALLOC_END
    as unsigned long variable vmalloc_end which is adjusted to prepare
    room for vmemmap. This becomes probnlematic if a local variables
    vmalloc_end is defined in some function (not very unlikely) and
    VMALLOC_END is used in the function - the function thinks its
    referencing the global VMALLOC_END value but would be referencing its
    own local vmalloc_end variable.

    There's no reason VMALLOC_END should be a macro. Just define it as an
    unsigned long variable if CONFIG_VIRTUAL_MEM_MAP is set to avoid nasty
    surprises.

    Signed-off-by: Tejun Heo <tj@kernel.org>
    Acked-by: Tony Luck <tony.luck@intel.com>
    Cc: Fenghua Yu <fenghua.yu@intel.com>
    Cc: linux-ia64 <linux-ia64@vger.kernel.org>
    Cc: Christoph Lameter <cl@linux-foundation.org>

    2.6.32 doesn't use new allocator on ia64 yet and the above commit will
    be sent to Linus soon which will also enable new allocator.

    Thanks.

    --
    tejun


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